H IS TO RY A OF A T H E M A T IC S FL OR IA N P RO F E SS OR O F H I ST U NI VE I by a an y m s u re a tt e G L A IS H E tha t mp t no C AJO R I , ORY R SITY j PH D . . O F M ATHE MATIC S I N O F C AL I s u b ec t F OR NIA ” —J l ose s more t ha n ma t hema t i c s t o d i sso c ia t e i t f ro m i t s hi s t o ry . . W R S E C O N D E D ITIC N , R E V I S E D AN D E N LAR G E D Na n finrk THE M AC M I L L AN C O M P ANY L O ND O N M AC M I LL A N C0 L m : A ll . r i g hts res erved . L . C O P Y RIG HT 1 8 93 M AC M IL LAN AN D , , BY S et 1 8 95 ; u p a nd el ec t ro typ ed Jan uary Oc t o be r mber Febru ary , , 1 91 1 1 89 7 ; N ov e 1 8 94 , 1 90 1 ; , . CO . Rep r i nt ed M arc h Jan uary , 1 90 6 ; J ul y . S econd Edi t ion , Rev i sed and Enl arg ed C OP Y RI GHT 1 9 1 9 M AC M I LLAN C O M PANY , BY Set THE u p a n d el ec t ro type d . P ubl ished 9 7 5 03 J u ly , 1 9 19 , , 1 909 P REFA C E TO TH E S E C ON D ED I TI ON preparing this second edition the earlier portions of the book have been partly r e written while the chapters on recent mathematics are greatly enlarged and al most Wholly new The desirability of having a reliable one volume history for the use of readers who cannot devote the mselves to an intensive study of the history of mathe matics is generally recogniz ed On the other hand it is a diffi cult task to give an adequate bird s eye View of the develop m ent of mathem atics from its earliest beginnings to the present time In compiling this history the endeavor has been to use only the most reliable sources Nevertheless in covering such a wide territory mi stakes are su re to have crept in References to the sources used in the revision are given as fully as the limitations of space woul d permit These ref er en c es will assist the reader in following into greater detail the his tory of any special subject Frequent use without acknowledgment has been m ade of the following publications : A n nu ar i o B i ografi co del Ci r col o M atemati co di P al ermo 1 91 4 ; J ahrbu ck nber di e Fortschr i tte def M a themati k B erlin ; J C P oggen dorfi s B i ogr aphi scli L i ter ari sches H an dworter buch Leip zig ; Geden k tagebn cli f u r M a themati k er v on Felix M ii ll e r 3 A u fl Leip z ig und B erlin 1 9 1 2 ; Revu e S emes tri ell e des P u b l i cati on s M a thémati qu es A ms terda m The author is indebted to M iss Falk a M G ibson of Oakland Cal for assistan c e in the reading of th e proofs FL ORIA N CA J ORI University of California M arch 1 9 1 9 IN - , . - . ’ , - - . . , , . . . , ’ , - . . ' ' , , . . , , , . , . , . . , , . IN TRO DUCTI O N THE B A B Y L O N IANS TH E E GY P TIANS THE GRE E K S . . . Gr eek Geometry The The The The The The Ionic School ” School of P yth agor a s Sop hi st School P latonic School First Alexandrian School Second Alexandrian School . . . . Gr eek A r i thmeti c THE R O MA NS THE M AY A and . A l gebr a . . C HI NESE THE JAP A NESE TH E H IND U S THE . . . EUR OP E D UR I N G TH E M I DD L E A G ES I n tr odu cti on of Roman Ma thema ti cs Tr an sl ati on of A r a bi c M an u scr i pts The Fi rs t A wa k en i n g a n d i ts S equ el . . EURO P E DUR IN G TH E SIX TEEN TH EE N TH CEN TU RI ES . S EV EN T EEN T H A ND EI GH T “ , The Ren a i ssan ce Vi eta and Desca r tes Descartes to N ew ton N ewton to E ul er Eul er , L agr ange an dE apl ac e ” . . TH E NIN E T EEN T H I n tr odu cti on Definition O f . AN D T WEN TI E TH CEN TURI ES a tics Ma them C ONT EN T S S yn theti c Geometry Elementary G eometry of the Triangle and Circle Link motion P arallel L ines Non Euclidean G e ometry and G eometry of n D i mension s - , . A n al yti c Geometry . Analysis Situs Intrinsic Co ordinates . - . D efi n i t ion of a C u rv e Funda mental P ostul ates . Geom etric M odels . . . Al gebr a TheoryOf Equations and Theory O f Groups Solution of Nu merical M agic Squares and Co mbinatory A n aly sis A n al ysi s Calcul u s f . O V a riations . Convergence of Series P robabil ity and S tatistics Diff erential Equations D ifference Equations ” Integral Equations Integro differential Equatio n s Ge n eral Analysis Functional Theories of Irrationals and Theory Of Aggre ga tes M athe matical Logic . . - , , Theory f o Fu n cti on s . Elliptic Functions General Theory O f Functio n s Unifor m ization . . . Theory f N u“ mber s o . Fer mat s Last Theorem Waring s Theore m O ther Recent Researches Nu mber Fields Transcendental Nu mbers The Infinite ’ ’ , . . . A ppli ed M a thema ti cs . . Celestial M echanics P roble m O f Three B odies General M echanics Fluid M otion Sound Elasticity Light Electricity Heat P otential Relativity Nomog raphy ables M athe matical T imet ers I n teg raph s Calculating M achines Pl a n . . . , , , “ . . . , Al phabeti cal I n dex i , . A H I S TO R Y O F M A T H E M A TI C S I NT ROD U CTI ON contemplation of the various steps by which mankind has come into possession of the vast stock of m athe matical knowledge can hardly fail to interest the mathe matician He takes pride in the fact that his S cience more than any other is an exact science and that hardl y anything ev er done in m athematics has proved to be use less The che mi st smiles a t the chi ldish e fforts of alche m ists but the mathe matician finds the geo metry O f the Greeks and the arithmetic of the Hindus as useful and adm irable as any research of to day He is pleased to notice that though in course of its develop ment mathe ma ti cs has had periods of S low growth yet in the main i t has been pre e minently a pr ogr ess i ve science The history of m athematics may be instructiv e as well as agreeable ; it may not only remind u S of what we have but m ay also teach us “ how to increase our store Says A D e M organ The early history O f t h e m ind of m en with regard to mathe m atics leads us to point out our own errors ; and in this respect it is well to pay attention to the hi stor y of mathe m atics It warns us against hasty conclusions ; it points out the importance of a good notation upon the progress O f the science ; it discourages excessive S pecialisation on the part of investi gators by S howing how apparently distinct branches have been foun d to possess unexpected connecting links ; it saves the student f rom wasting time and energy upon proble m s which were perhaps solve d long S ince ; it discourages him fro m attacking an unsolved problem by the sam e method which has led other m athem aticians to fail ure ; it teaches that fortifications can be taken in other ways than by di rect a ttack that when repulsed fro m a direct assault it is well to recon n oi t re and occupy the surrounding ground and to discover th e secret 1 paths by which the apparently unconquerable position can be taken The importance of this strategic rule m ay be e mphasised by citing a case in which it has been violated An untold a moun t of intellectual energy has been expended on the quadrature of the circle yet no con quest has been made by di rect assault The circle squarers have existed in crowds ever S ince the period of Archi m edes After in numerable failures to solve the problem at a time ev en when in TH E . , , , , . - . , , , - . , . . , . , , , , . . , - . . , S G un th er , Erl an g en , 1 8 7 6 l . . Zi el e und Resu l tate der n eu er en , M athemati sch hi stori schen For schu n g - . A H I S T ORY O F M AT HE M ATIC S possessed that m ost powerful tool the differential calculus persons versed in mathe matics dropped the subj ect whi le those who stil l persisted were completely ignorant of its history and generally “ m isunderstood the conditions of the problem Our problem says A D e M organ is to square the circle with the ol d al l owan ce of means : Euclid s postul ates and nothi ng m ore We cannot remember an instance in which a question to be solved by a defini te method was tried by the best heads and answered a t last by that method after thousa nds O f co mplete failures B ut progress w as made on this proble m by approaching it fro m a different direc tion and by newly di scovered paths J H Lambert proved in 1 7 6 1 that the ratio of the circum ference O f a circle to its diameter is irrational Som e years ago F Linde mann de monstrated that thi s ra t io is also transcendental and that the quadrature O f the circle by means O f the ruler and c o m passes only is i mposs i bl e He t h us showed by actual proof that which keen m inded mathem aticians had long suspected ; namely that the gre a t a rmy of circle squ a rers have for two thousand years been assaulting a fort i fication whi ch is as indestructible as the fir mamen t O f heav en Another reason for the desi rability of historical study is the valu e of historical knowledge to th e teacher of mathematics The interest which pupils take in their studies may be greatly increased if the solution O f problem s and the cold logic of geom etrical demonstrations are interspersed with historical remarks and anecdotes A class in arithm etic will be pleased to hear about the B abylonians and Hind us “ and their invention of the Arabic notation ; they will m arvel at the thousands of years which elapsed before people had even though t —the O f introducing into the num eral notation that Columbus egg z ero ; they will find it astounding that it S hould hav e taken so long to i nven t a notation which they th emselves can now l earn in a month After the pupils h ave learned how to bisect a given angle surprise them by telling of the many futile attempts whi ch have been made to solve by elementar y geometry the apparently very S imple proble m of the trisection O f an angle When they know how to construct a square whose area is double the area O f a given square tell them about the duplication O f the cube of its m ythical origin—how the wrath of Apollo could be appeased only by the construction O f a cubical altar double the given altar and how m athematicians long wrestled w ith this problem After the class have exhausted their energies on the theore m of the right triangle tell them the legend about its di sc ov erer—how P ythagoras j ubilant over his great accomplishm ent sacrifi ced a hecato mb to the M uses who inspired him When the value of m athe matical training is called in question quote the i n scription over the entrance into the acad em y of P lato the philosopher : Let no one who is unacquainted with geometry enter here S tudents in analytical geometry should know so methi ng of Descartes and v es tig a tors , , ” , . , “ . , ’ . ” , , , . . . . . . , , . , - , - , , . . ” . - . , , " , . , , , . , , , . , , “ . , , I N TROD U CTI ON after taking up the differential and in tegral calculus they should become familiar with the parts that Newton Leibniz and Lagrange played in creating that science In hi s historical talk it is possible for the teacher to make i t plain to the student that m athematics is 1 not a dead science but a living one in which steady progr ess is made 2 A S imilar point of V ie w is taken by Henry S Wh ite : The ac c ept ed truths of to day even the co mmonplace truths of any science were the doubtful or the novel theories of yesterday Some i n deed of prime importance were long esteem ed of sligh t importance and al most forgotten The first eff ect of readi ng in the hi story of science is a nai ve astonishment at the darkness of past centuries b ut the ul ti m ate e ffect is a fervent ad miration for the progress achieved b y for mer generations for the triumphs of persistence and of genius The easy credulity with whi ch a young student supposes that of course every algebraic equation m ust have a root gives place final ly to a delight in the slow conquest O f the realm of imaginary numbers and in the youthful genius of a Gauss who could demonstrate t hi s once obscure fundamental proposition The history of mathematics is i mportant also as a valuable con Human progress is closely t ri bu tio n to the history of civilisation identified with scientific thought M athematical and physical re search es are a reliable record of intellectual progress The history of mathematics is one of the large windows through which the p hilo sophic eye looks into past ages and traces the line of intellectual de , , , . , . “ . - , , . . , , . ” , . . . . v el opmen t 1 . C aj o r i , F . , The Tea c hi n g i ng ton , 1 8 90 , p 23 6 2 B ull A m M ath S oc . . . and Hi story of M athemati cs i n the Uni ted S tates . . . , Vo l . 1 5, 1 90 9 , p 3 25 . . . Wash THE B A B YL ON IA NS fertile valley of the Euphrates and Tigris was one of the prim eval seats of hu m an society Authentic history of the peoples inhabiting this region begins only with the foundation in Chal daea and Babylonia of a united kingdo m out of the pre v iously disunited tribes M uch light has been thrown on their history by the discov e ry of the art of reading the cu n eif orm or wedge shaped syste m of writing In the study of Babylonian m athe matics we begin with the notation of n umbers A vertical w edg e vstood for 1 while the characters and Y ) signified 1 0 and 1 00 respectively G ro t efen d believes the C haracter for 1 0 originally to have been the picture of two hands as held in prayer the pal m s being pressed together the fingers close to each other but the thu mbs thrust out In the Babylonian notation — two principles were e m ployed the ad ditiv e and m ultiplicative N u m bers below 1 0 0 were expressed by symbols whose respective values had to be added Thus VVs tood for 2 Y for 3 w for for 2 3 for 30 Here the symbols of higher order appear always to the left O f those of lower order In writing the hun dreds on the other hand a s mal l er sy mbol was placed to the left of Thus 1 0 0 and was in that case to be mu l ti pl i ed by 1 00 I signified 1 0 times 1 0 0 or 1 0 00 B ut this symbol for 1 000 was itself taken for a new unit which could take s maller coe fficients to its left Thus denoted not 2 0 tim es 1 00 but 1 0 ti m es 1 000 So e m y of the cuneiform nu mbers found on tablets in the ancient te mple library at Nippur exceed a m illion ; m oreov er so m e of these Nippur tablets exhi bit the s u btr acti ve principle ( 2 0 similar to that shown “ in the Ro man notation XIX If as is believ ed by m ost S pecialists the early S u m er1ans were the in v entors O f the Cuneiform writing then they were in all probability also the inv entors O f the notation of nu mbers M ost surprising in this connection is the fact that Sumerian inscriptions disclose the u se not only of the above deci mal syste m but also O f a s exages i mal one The latter was used chiefly in constructing tables for weights a n d measures It is full of historical interest Its consequential develop m ent both for integers and fractions reveals a high d egree O f m athe We possess two Babylonian tablets which exhibit mati cal insight i ts use O n e of t he m probably w ritten between 2 300 and 1 6 0 0 B C 2 contains a table O f square nu mbers up to 6 0 The nu mbers I 4 9 2 5 3 6 4 9 are given as the squares O f the first seven integ e r s r e 16 TH E . , , . - . , . . ” , , , . , . , , , . , . , . , , , , . , , . , , . , , , . , ” , . , , , , , . , , , , . . . , , . . , . . , , , , , . , , , B A B YL ON IA NS THE 5 2 2 2 10 11 8 etc We have ne xt 9 This remains unintelligible unless we assu me the sexagesimal scale 2 6O + I which makes The second 60 + 2 1 tablet rec ord s the magnitude of the illum inated portion of the moon s disc for e v ery day fro m new to full moon the whole disc being assumed to consist of 2 40 par ts The illum inated parts during the first fi v e which is a geo m etrical days are the series 5 1 0 2 0 40 progression From here on the series beco m es an arithm etical prog r es sion the numbers fro m the fifth to the fifteenth day being respectiv ely This table 4 not only exhi bi fs the use of the sexagesi mal syste m but also indicates the acquaintance O f the B abylonians with progressions Not to be overlooked is the fact that in the sexagesi mal notation of integers “ the principle O f position was e mployed Thus in the the unit of the second or der by virtue of I is m ade to stan d for 6 0 its position with respect to the 4 The intro d uction O f this principle at S O early a date is the m ore re markable because in the decimal n O t a ti on it was not regularly introduced till about the ninth century after Christ The principle of position in its general and systematic application requires a symbol for z ero We ask D id the Babylonians possess one ? Had they already taken the gigantic step of representing by a symbol the a bs en ce of units ? Neither O f the abo v e tables answers this question for they happen to contain no nu mber in which there was occasion to use a z ero Babylonian recor d s of many centuries later—O i about 2 00 B C —give a symbol for z ero which denoted the absence of a figure but apparently was not used in calculation It consisted O f two angular m arks 5 one abov e the other roughly re sembling two dots hastily written About I 30 A D Ptolemy in Alexan dria use d in his A l magest the B abylonian sexagesi m al fractions and also the o micron to represent blanks in the sexagesim al numbers This was not used as a regular z ero It app ears therefore that the Babyloni ans had the pr i nciple of local v alue and also a symbol for z ero to indicate the absence of a figure but did not use this z ero in comp utation Their sexagesimal fractions were intro duced into India and with th es e fractions probably passed the principle O f local value and the restric t ed use of the z ero The sexagesimal syste m w as used also in fractions Thus in the Babylonian inscriptions 3, an d are d esignated by 30 and 2 0 the “ r eader being expected in his mind to supply the word sixtieths The astrono mer Hipparchus the geo m eter H yp si c l es and the as t r on ome r P tole my borrowed the sexagesim al notation of fractions from the Babylonians and introd uced it into Gree c e From that tim e sexagesimal fractions hel d al m ost full sway in astronomical and mathe mati cal calculations until the S i xteenth century when they finally yielded their place to the dec imal fractions It may be asked What l e d to the invention O f the se xagesi mal syste m ? Why was it that 6 0 2 sp e c t i v e l y , , . . , , , , . . , ’ , . , , , , . , . , . ” . , , , . , . , . , , , . . . . , . . , . , , o . 0 . , , , . . . , , ” , , . , , . , . , A 6 OF M ATHE M ATIC S H I S TORY parts were selected ? To this we have no positive answer Ten was chosen in the decimal system because it r epresents the number O f fingers B ut nothi ng of the hu man body coul d have suggested 6 0 Did the system have an astronomical origin ? It was supposed that the early Babyloni ans reckoned the year at 3 6 0 days t hat this led to the di v ision of the circle into 3 6 0 degrees each degree representing the daily amount O f the supposed yearly revolution O f the sun around the ear th Now they were very probably familiar with the fact that the radius can be applied to its circu mference as a C hord 6 times and that ea ch of these chords subtends an ar e measuring exactly 6 0 degrees Fix ing their attention upon these degrees the division into 6 0 par t s m ay have suggested itself to them Thus when greater pre c i si on necessitated a subdivision of the degree i t was partitioned into 6 0 minutes In t h is way the sexagesim al notation was at one tim e supposed to have originated B ut it now appears that the Babylonians very early knew that the year exceeded 3 6 0 days M oreover i t is highly im probable that a higher unit of 3 6 0 was chosen first and a lower unit of 60 afterward The norm al develop ment of a number system is from lower to higher units Another guess is that the sexagesim al system arose as a m ixture of two earlier system s of the bases 6 and Certain it is that the sexagesimal system becam e closely inte rwoven with astronomical and geometrical science The di vision of the day into 2 4 hours and O f the hour into mi nutes and seconds on the scale of 6 0 is attributed to the Babylonians There is strong evidence for the belief that they had also a division of the day into 6 0 hours The e mployment O f a sexagesi mal division in nu meral notation in fractions in angular as well as in tim e m easurement i n di c a t e d a beautiful har m ony which was not disturbed for thousands O f years until Hindu and Arabic astrono m ers began to use S ines and cosines in place O f parts of chords thereby forcing the right angle to the front as a new angular unit which for consistency should have been sub divided sexagesimally but was not actually so divided It appears that the people in the Tigro Euphrates basin had m ade very cre di table a dvance in arithm etic Their knowledge of arith m etical and geo m etrical progressions has already been alluded to I amb l i chu s attributes to the m also a knowledge O f proportion and even the invention of the so called mu si cal proportion Though we . , , . . , , . , , , . , . , , . . . , , . . . , . , . , , , , , , , . , - . . , - . M C an tor Vorl esung en uber Geschi chte der M athematik , z B d , 3 A u fl , L e ip i g , Thi s w o rk h a s app ear ed i n fou r l arg e v o l um es an d c arri e s t he hi s t ory 1 90 7 , p 3 7 d ow n t o 1 7 99 Th e fou r t h v o l u me ( 1 90 8 w as w r i tt en w i t h t h e co op e ra i o n o f n i n e M ori t Cantor ( 1 8 2 9 sc hol a r s f r om G e rma n y , I t a l y , R u ssi a an d t he U n i t ed S a t es ran k s as t h e fore mos t g e n eral w r i t e r o f t h e n i n e t een t h ce n t u ry o n t he hi s tory o f ma t h e ma t i cs B or n i n M a nn h e im , a s tu de n t a t H e idelb e rg , a t G ott i ng e n u n der G au ss a n d Web e r , a t B e rl i n u n der D i r i c hl e t , h e l e c t u r ed a t H e id elb erg w he re i n H i s fi r s t hi s tori cal ar t i c l e w a s 1 8 7 7 h e b e came or di n a ry h o n o r a ry p r o fesso r b roug h t o u t i n 1 8 5 6 , b u t n o t u n il 1 88 0 d id t h e fi rs t v ol u me o f hi s w ell k n ow n hi s tory 1 . , . ) . . t 1. . . . z . t app ear . . - . t B A B YL ON IA NS THE possess no conclusive proof we have nevertheless reason to believe th at in practical calculation they used the abacu s A mong the races of middle Asia even as far as China the abacus is as old as fable Now Babylon was once a great commercial centre —the m etropolis of m any nations —an d it is therefore not unreasonable to suppose that her m erchant s e mployed this most improved aid to calculation In 1 8 89 H V Hil precht began to make excavations at N uffar ( the ancient Nippur) and found brick tablets containing m ultiplicatio n and division tables tables of squares and square roots a geo metric prog res sion and a few computations He p ublished an account of hi s fin dings l in 1 90 6 “ 4 The divisions in one tablet contain results like these : 6 0 divided “ 4 = by 2 each 6 0 divided by 3 = 4 3 2 0 OOO each and so on using the divisors 2 3 4 5 6 8 9 1 0 1 2 1 5 1 6 1 8 The very “ 4 first division on the tablet is interpreted to be 6 0 divided by I This strange appearance O f % as a divisor l s diffi cult to 3 explain P erhaps there 1S here a use of 2 corresponding to the Egyp tian use of 3 as found in the Ahmes papyrus a t a perhaps conte mporaneous 4 period It is noteworthy that 6 0 which H i l pr ech t found “ in the Nippu r brick text books is nothing less than the mystic P latonic “ number the lord of better and worse births m entioned in P lato s Repu bli c M ost probably P lato received the number fro m the 2 P ythagoreans and the P ythagoreans fro m the Babylonians In geo m etry the B abylonians accompli shed little B esides the divi sion O f the circu mference into 6 parts by i ts radius and into 3 60 de grees they had som e knowledge of geometrical figures such as the triangle and quadrangle which they used in their auguries Like the Hebrews ( 1 Kin they took 7r = 3 Of geo metrical de monstra “ tions there is of co u rse no trace A S a rule in the Oriental mind the intuitive powers eclipse the severely rational and logical H il pre ch t con cluded from his studies that the Babylonians pos sessed the rules for fin di ng the areas of squares rectangles right tri angles and t r ape zoids The astronomy of the B abylonians has attracted much attention They worshipped the heavenly bodies from the earliest hi storic times When Alexander the Great after the battle O f Arbela (33 1 B C took possession of Babylon C al li sthen es found there on burned brick as P orphyr ius says t r on omi c al records reaching back as far as 2 2 34 B C that these were sent to Aristotle P tole my the Alexandrian a s tr on o mer possessed a Babylonian record of eclipses going back to 74 7 B C , . , , . , , , , , . . . , , . ” . ” , , , , , , , , , , , , , , , . , . 7: , ” . , ” - , , ’ , . , . , . , , , , . ” . . , . , , . , , . , . . . , . , ‘ . . . , . . , M athemati cal , M etrol ogi cal of N i ppu r , b y H V H i l p r ec h t Chron ol og i cal Ta bl ets f r om the Templ e L i brary a r t I , S eri e s A , C u n e ifo rm Te xt s , p u b V ol , p l i shed by t h e B ab yl o n i a n Exp edi t io n o f t h e U n i v e r si ty o f P e n n syl va n i a , 1 90 6 C o n s u l t al so D E S mi t h i n B u l l A m M a th S oc , V O l 1 3 , 1 90 7 , p 3 9 2 “ 2 O n t h e P l a t o n i c n u mb er c on su l t P T a n n e ry i n R evu e phi l osophi q u e, V ol I , V , 1 88 3 , p 5 7 3 A l so G L ori a i n L e 1 8 7 6 , p 1 7 0 ; V ol X I I I , 1 88 1 , p 2 1 0 ; V o l s c i en e es atte n el l a n ti ca grec i a , 2 E d , M il a n o , 1 9 1 4 A pp en di ce a nd 1 . . . . XX . . . . . . . . z . . . . ’ . . . . . X . , . . . . A 8 H I S T ORY . OF M AT H E M ATIC S Epping and Strassmaier have thrown considerable light on Babylon ian chronolog y and astrono my by explaining two calendars of the years 1 2 3 B C and 1 1 1 B C taken from cuneifor m tablets coming presumably from an old observatory These scholars hav e succeeded in givi ng an account of the B abyloni an calc ul ation O f the new and full moon and have identi fied by calculations the B abyloni an names of the planets and of the twelve z odiacal signs and tw enty eight normal stars whi ch correspond to som e ex tent with the twenty eight n akshatr as of the Hindus We append part of an Assyrian astronomical report as translat ed by Opper t : 1 . . . . , , , . , - , - . , To the Ki ng my lord thy fai thful servant M ar Istar On the first day as the new moon 5 day of the month Thammu z d ecli ned the moon was a g ai n vi s i b le ov er the planet M ercury as I had already predi cted t o my master the King I erred not - , . , , , , . 1 A stronomi sches F rei burg , 1 889 Epp i ng , mai er . . aus B abyl on . . Unter M i twi rk u ng von P . J R S t rass . . H I S T ORY A 10 M AT HE M ATIC S OF papyrus—the most ancient m athematical handbook known to u s puts us at once in contact with the m athe matical thought in Egyp t of “ three or five thousand years ago It is entitled D irections for ob taining the K nowledge O f all Dark Things We see from it that the Egyptians cared but little for theoretical results Theorems are not found in it at all It contains hardly any general rules of procedure but chi efly mere state ments of results intended possibly to be ex 1 plained by a teacher to his pupils In geo metry the forte of the Egyptians lay in m aking constructions and deter mining areas The area of an isosceles triangle of which the sides me asu re 1 0 k hets (a unit of length equal to m by one guess and about thrice that 2 amount by another guess ) and the base 4 khets was erroneously given as 2 0 square k hets or half the product O f the base by one side The area O f an isosceles trape zoid is found similarly by multiplying half the sum of the parallel sides by one of the non p arallel S ides The 1 area of a circle is found by deducting fro m the dia m eter ,5 of its length 1 6 = and squaring the re mainder Here 71 is taken ( g a The papyrus explains also such problems v ery fair approxi m ation as these — TO mark out i n the field a right triangle whose sides are 1 0 a n d 4 units ; or a trape z oid whose parallel sid es are 6 and 4 and the non — parallel sides each 2 0 units So m e proble m s in this papyrus see m to imply a rudimentary knowl edge of proportion The base — lines O f t h e pyramids run north and south and east and west but probably only the lines running north an d south were deter This coupled with the fact mined by astrono mical observations that the word har pedon aptce applied to Egyptian geom eters means “ rope stretchers would point to the conclusion that the Egyptian like the Indian and C hinese geom eters constructed a right triangle upon a given line by stretching around three pegs a rope consisting 3 of three parts in the ratios 3 :4 5 and thus forming a right triangle If thi s e xplanation is correct then the Egyptians were fa miliar 2 years B C with the well known property of the right triangle for the special case at least when the sides are in the ratio 3 :4 :5 On the walls of the celebrated te mple of Horus at Edfu have been found hi eroglyp hics written about 1 00 B C which enumerate the pieces of land owned by the priesthood and giv e their areas The area of any quadrilateral however irregular is there found by the form ula fl g Thus for a quadrangle whose O pposite sides 4 are 5 and 8 2 0 and 1 5 is given the area $ The incorrect for ” . . . . , ” . . , . , . , , , - . -- . . , , . . , , “ ” - , , , , , , , . , , , - . . , , . “ . . , , . , , , , , , 1 James Go w A S hort Hi story of Gr eek M athemati cs C amb ri dg e , p 16 2 A Ei se n l o h r , E i n ma themati sches H a n dbu ch der a l ten A egypter , 2 A u sg ab e , L ei p z ig , 1 8 9 7 , p 1 0 3 ; F L G r i ffi t h i n P r oceedi n gs of the S oci ety of B i bli cal A rchaeol ogy, , . . M C an to r , op . . 4 H H a nk e l , Z u r . 1 8 74 , 1 88 4 , . . . . 3 . p 86 . . . V ol I , 3 A u fl , 1 90 7 , p 1 0 5 Geschi chte der M athema ti k i n A l ter thu m u nd M i ttel al ter , L e ip ig , ci t . . . . . . z THE E G Y P TIA NS mu l ae 1 of Ahme s of 300 0 years B C yield generally closer approxima tions than those of the Edfu inscriptions written 2 0 0 years after Euclid ! The fact that the geom etry of the Egyptians consists chiefly of constructions goes far to explain certain of its great defects The Egyptians failed in two essential points w i thout which a s ci en ce of geometry in the true sense of the word cannot exist In the first place they failed to construct a rigorously logical system of geometry resting upon a few axio m s and postulates A great many of their rules especially those i n solid geom etry had probably not been proved at all but were known to be true merely from ob serya tion or a s mat ters of fact The second great defect was their inability to bring the num erous S pecial cases under a more general view and thereby to ar rive at broader and more fun damental theorems Som e of the simplest geom etrical truths were divided into numberless special cases of which each was supposed to require separate treat ment So me particulars about Egyptian geometry can be mentioned more advantageously in connection with the early Greek mathe maticians who ca me to the Egyptian priests for instruction An insight into Egyptian methods of nu meration was obtained through the ingenious deciphering of the hierogl yphics by Champol lion Young and their successors The symbols used were the fol lowing : h for 1 for 1 0 G for 1 00 ii for 1 00 0 E for k for for The sy bol for for m Q if a pointing finger ; that 1 represents a vertical staff ; that for for a burbot ; that for a man in astonishm ent The significance of the re maining symbols is very doubtful The writing of numbers with these hieroglyphics was very cumbrous The unit symbol of each order was repeated as m any tim es as there were units in that order The principle employed was the addi ti ve Thus 2 3 was written [j uH B esides the hierogl yphics Egypt possesses the hi erati c and demoti c writings but for want of space we pass the m by Herodotus makes an i mportant state ment concerning the mode of “ computing among the Egyp tians He says that they cal cu l a te wi th pebbl es by m oving the hand fro m right to left while the Hellenes Herein we recognise again that i nstr u m ove it fro m left to right men tal method o i figuring so ex tensively used by peoples of antiquity The Egyptians used the decimal scale Since in figuring they moved their hands hori zontally it see ms probable that they used ciphering boards with vertical columns In each colum n there must have been not more than nine pebbles for ten pebbles would be equal to one pebble in the col umn next to the left . . , , . , . , , , . , , , . , . . . , , , m . , , , . . . mm . . , , . , ” . , . . . , , , . , . 1 M C a n to r . , p o . cit . V ol I , 3 A u fl . . . , 1 90 7, p 8 2 . . OF M ATHE M ATI C S HI S T ORY A 12 The A hmes papyr u s con tain s interesting information on the way in whi ch the Egyp tians e mployed fractions Their methods of opera tion were of course radi cally diff erent from ours Fractions were a subj ect of very great diffi culty with the ancients Simultaneous changes in both num erator and denominator were usually avoided In m anipul ating fractions the B abylonians kept the denominators ( 6 0 ) constant The Rom ans l i kewise kept them constant but equal to 1 2 The Egyp tians and Greeks on the other hand kept the numerators constant and dealt with variable denom inators A hmes used the “ term fraction in a restricted sense for he applied it only to u n i t f r acti on s or fractions having unity for the num erator It was desig n a t ed by writing the deno minator and then placing over it a dot Fractional values which could not be expressed by any one unit fracti on were exp ressed as the su m of two or more of them Thus he 1 2 _ wrote 4 4 5 in place of Whi le Ahmes knows to be equal to 4 4 he 2 cur iously allows 43 to appear often among the unit fractions and adop ts a special symbol for it The first important problem naturally arisi ng was how to represent any fractional value as the sum of unit fractions Thi s was solved by aid of a table given in the papyrus in which all f . , . , . . . . , , , , . , , . . . , . , . . , , fractions of the form 2 2n +1 , (where designates successively all the n are reduced to the sum of unit fractions Thus 4 9) 2 1 1 — h W en by who and how t h i s table was cal m 4 4 4 44 4 4 44 P robably i t was co mpiled e mpirically at c ul at ed we do not know di ff erent tim es by di fferent persons It will be seen that by repeated application of this table a fraction whose nu merator ex ceeds two can be expressed in the desired for m provided that there is a fraction in the table havi ng the same deno mi nator that i t has Take for ex a mple th e proble m to di vide 5 by 2 1 In the fir st place 5 1 + 2 + 2 2 = 1—1 5 _ Fro m the table we get 4 4 4 4 Then 2 1 2 4 4 1 1 1 2 J i = = The papyrus contains prob 3 4 4 f 4 4 , 4 4 T 2 1 I lem s i n which it is required that fractions be raised by addition or multi plication to given whole numbers or to other fractions For example 1 1 1 1 1 — en omi n a t or to The co mm on d 1 i t 18 requi red to mcr ea se 4 4 4 0 4 0 l taken appears to be 4 5 for the numbers are stated as 1 14 5 2 4 44 1 Add to this s um of these IS 2 3 1 1 i forty fifths and The 1 1 4 44 4 Hence the q uan tity to be added th e sum i s g Add ?4 and we have 1 1 1 to the gi ven fracti on i s 4 4 4 4 Ah mes gives the following e xample involving an ari thmeti cal “ of what the first persons r o r es si on : D m ivide loaves a ong 1 00 ; 5 p g 4 three get is what the last two get Wh at is the difference ? Ahm es “ gi v es the solution : M ake the diff erence 54; 2 3 1 74 1 2 6 4 1 How did m es co me upon M ultiply by 1 4 ; 3 84 2 94 12 A h 2 numbers up to - , . 1 , . , , . , . , , , . . , , 4 2 : , 4 , , . 1 4 4 . . 4 4 , , , , , . . . 0 , . , 0 0 , 1 . ” . 1 , , , , . , , - , . TH E E G Y P TIA NS I3 Let a and — d be the fir st ter m and th e di ffer ence in the required arithm etical progression then 4[a + (a—d H — — — 2 a d d whence the dif a d a e 4 ) 4d)i ( ) ] ( 5% ( fer ence d is 5% times the last term A ssu mi ng the last term 1 he gets his first progression The sum is 6 0 but should be 1 00 ; hence 2 2 _ 1 00 m multiply b y 1 s for We have here a ethod of solution a which appear s ag ain l at er among the Hindus Arabs and modern Europeans— the famous m ethod of f al se posi ti on Ahmes speaks of a ladder consisting of the nu mbers 7 49 343 2 40 1 1 680 7 Adjacent to t hese powers of 7 are the words pi ctu r e cat mou s e bar l ey measu re What is the meaning of these mysterious data ? Upon the consideration of the problem given by Leonardo of “ P isa in hi s Li ber abaci 3000 years later : 7 old wo men go to Ro m e ; M oritz each woman has 7 m ules each m ule carries 7 sacks etc Cantor o ffers the follo w ing solution to the Ahm es riddle : 7 persons have each 7 cats each cat eats 7 mice each mouse eats 7 ears of barley from each ear 7 measures of co rn may grow How many persons cats m ice ears of barley and measures of corn altogether ? Thus Ahm es gives 1 96 0 7 as the su m of the geometric progression the Ahmes papyrus discloses a knowledge of both arithmetical and geom etrical progression Ahm e s proceeds to the solution of equations of one unknown quan tity The unknown quantity is called hau or heap Thus the P erhap s t hus : 54? 1 , , . . , . , , - , . , . , , , . , , , , . , , . , , , , . , , , , , , . , . ’ ‘ . . problem heap its 4 its whole it , , , , makes % f = 1 9; i 1 9, x . e . = x 19 + 5 . In B ut 44 f in other problems the solutions are e ffected by various other m ethods It thus appears that the beginnings of algebra are as ancient as those of geometry That the period of Ahmes was a flowering time for Egyptian m athe matie s appears from the fact that there exist other papyri (more re c en tl y di scovered ) of the same period They were found at Kahun south of the pyr amid of Il l ahun These docu m ents bear close t e semblance to Ahm es They contain moreover e xamples of quadratic 2 equations the earliest of whi ch we have a record One of them is : A given surface of say 1 00 units of area shall be represented as the sum of two squares whose S ides are to each other as 1 :4 In 2 2 modern symbols the problem is to find as and y such that x + y 1 00 and x :y = 1 m The solution rests upon the ethod of false 4 2 2 = = = position Try x 1 and y 4 then x + y 44 and B ut §g 4 = The rest of the solution canno t be made 8 V 1 9 9 1 0 and 1 0 M C antor p ci t Vol I 3 Au fl 9 7 p 7 8 C an tor op ci t V l I 90 7 pp 95 96 t hi s case the solution , as follows 15 ; 3 x= 16 . . , . , . . . , , , . . , , , . , , , , . . , 4 1 , . o . 2 , . . . . , o . , 1 , . , . . , 1 , 0 , . . . M ATHE M ATI CS A HISTORY OF 14 out but probably was x = 8 X 1 y = 8 X 4 6 This solution leads to the relation The symbol r was used to designate square root In so m e ways similar to the A hmes papyrus is also the Akh mim 1 papyrus writ t en ov er 2 00 0 years later at Akhm i m a city on the Nile in Upper Egypt It is in Greek and is supposed to hav e been written at som e time between 50 0 and 8 0 0 A D I t contains besides “ arith metical exa mples a table for finding unit fractions like that of Ahm e s Unlike Ahmes i t tells how the table was constructe d The : , , . . , , . . , ” . , - , , . , . rule expressed in , modern symbols is as follows , 9 A hm e s For z = 2 this for mula reproduces part of the table in The principal defect of Egyptian arithmetic was the lack of a simple co mprehensive symbolism—a defect which not even the Greeks were able to remove The Ahmes papyrus and the other pap yri of the same period r epr e sent the m ost advanced attain m ents of the Egyp tians in arith m etic and geo m etry It is re m arkable that they should have reached so great proficiency in m athe m atics at so re mote a period of a ntiquity B ut strange indeed is the fact that during the ne xt two thousand years they should hav e made no progress whatsoe v er in it The con that they rese mble the Chinese in the c l u si on forces itself upon us not only of their govern ment but also of their s ta ti on ar y char acter learning All the knowledge of geometry whi ch they possessed when Greek scholars v i sited the m s ix centuries B C was doubtless known to the m two thousand years earlier when they built those stupendous — and gigantic structures the pyra mids , . , . . . , , , . , , , , . . , . , , . L e p a py ru s m a t h éma t iq u e d Ak hmi m, M émo i r es pu bl i es par l es B a ill e t , membr es de l a mi ss i on ar chéol og i q u e f r a nga i s e a u Cai r e , T I X , 1 r fasc i c u l e , P a r i s , — 1 S ee al so C an to r , op c i t V ol I , 1 90 7 , pp 6 7 , 50 4 2 88 1 8 9 , pp ’ . . . . . . . . THE GREEKS Gr eek Geometry About the seventh century B C an active co mmercial intercourse sprang up between Greece and Egyp t Naturally there arose an interchange of ideas as well as of merchandise Greeks thirsting for knowledge sought the Egyp tian priests for instruction Thales P ythagoras ( En op ide s P lato De mocritus Eu d oxus all visite d the land of the pyram ids Egyptian ideas were thus transplanted across the sea and there stimulated Greek thought directed it into new lines and gave to it a basis to work upon Greek culture therefore is not primitive Not only in mathematics but also in mythology and art Hellas owes a deb t to older countries To Egypt G reece i s i n debted among other things for its elementary geometry B ut this does not lessen our ad miration for the Greek m ind From the mo ment that Hellenic philosophers applied the mselves to the study of Egyptian geo metry this science assu med a radically different aspect “ Whatever we Greeks receive we improve and perfect says P lato The Egyptians carried geometry no further than was absolutely n e ces sary for their practical wants The Greeks on the other hand had within them a strong speculative tendency They felt a craving to discover the reasons for things They found pleasure in the con t empl a ti on of i deal relations and loved science a s science Our sources of inform ation on the history of Greek geo m etry before Euclid consist merely of scattered notices in ancient writer s The early m athe m aticians Thales and P ythagoras left behind no written records of their discoveries A full history of Greek geom etry and astrono my during this period written by Eu demu s a pupil of Aris t o tl e has been lost It was well known to P roclus who in his com men tar i es on Euclid gives a brief account of it This abstract con s t i tu t es our m ost reliable infor m ation We shall quote it frequently under the name of Eu demi an S ummary . . . . , . , , , , , , , . , , . , , , . . , ' . , , . ” , , . , . . , , . . . , . , , . , , , . , , . , . . The I on i c S chool To Th al e s ( 6 40—546 B of M iletus one of the seven wise men an d the founder of the Ionic school falls the honor of having intro D uring middle life he du c ed the study of geo metry into Greece engaged in commercial pursuits which took him to Egypt He is said to have resided there and to have studied the physical sciences and mathe matics with the Egyptian priests P lutarch declares that Thales soon excelled his m asters and a ma z ed King Ama si s by meas u r . , , , . . , , . , I S A HISTORY OF M ATHE M ATICS 16 ing the heights of the pyramids fro m their shadows Accordi ng to P lutarc h this was done by considering that the shadow cast by a vertical stafi of known length bears the same ratio to the shadow of the pyramid as the height of the staff bears to the heigh t of the pyra mi d This sol ut ion presupposes a knowledge of proportion and the Ahmes papyrus actually sho ws that the rudiments of proportion were kn own to the Egyp tians According to D iogenes L aer ti u s the pyra mids were m easured by Thales in a di ff erent way ; viz by finding the length of the shadow of the pyramid at the moment when the shadow of a staff was equal to its ow n length P robably bo th methods were used The E udemi a n S u mmary ascribes to Thales the inventi on of the theore ms on the equality of vertical angles the equality of the angles at the base of an isosceles triangle the bisection of a circle by any diam eter and the congruence of two triangles having a side and the two adjacent angles equal respectively The last theorem combin ed (w e have reason to suspect ) with the theorem on similar triangles he applied to the measurement of the distances of ships fro m the shore Thus Thales w as t he first to apply theoretical geometry to practical uses The theore m that all angles inscribed in a semicircle are right angles is attributed by so me ancient writers to Thales by others to P ythag oras Thales was doubtl e ss famili ar with other theorem s n ot r e corded by the ancients I t has been inferred that he knew the su m of the thr e e angles of a triangle to be e q u l to two right angles and 1 the sides of equiangular triangles to be pr o or ti on al The E gyptians m ust have m ade use of the above theorem s on the straight line in some of their constructions found in the Ahmes papyrus but it was left for the Greek phi losopher to giv e these tr uths whi ch others saw but did not formulate into words an explicit abstract expression and to put i nto scientifi c language and subj ect to proof that which o thers merely felt to be true Thales m ay be said to have created the geom etr i of lines essentially abstract in its character wh le the E gyp tians y studi ed only the geo metry of surfaces and the rudi ments of solid 2 geometry e mpirical in their character With Thales begins also the study of scientifi c astronomy He acquired great celebrity by the prediction of a solar eclipse in 58 5 B C Wh ether he predicted the day of the occurrence or simply the year is not known It is told of hi m that while conte mplating the stars dur ing an evening walk he fell into a ditch The good old wo man “ attendi ng him exclaimed How canst thou know what is doing in the heavens when thou seest not what is at thy feet ? The two most pro minent pupils of Thales were An axi man der (b 6 1 1 . , . , . , . . . , , , . , , . . , , . . g , . , , , , , , , . , , . , . . . , , . ” . , , , . 1 G J Allman , Gr eek Geometry . . John s to n G eorg e C o ll eg e , 2 G J . . A l lm a n ( 1 8 2 4- 1 90 4 G al w a y , I r el an d Al lm an , op ci t , p 1 5 . . . . . D ubl i n, 1 889 , p 1 0 Thal es to Eu clid ’ w as p rofessor of mathemat i c s a t Q u ee n s fr om ) . . . A HISTORY OF M ATH EM ATICS 18 the teaching of philosophy m athe matics and natural science but it was a brotherhood the me mbers of whi ch were united for life This brotherhood had O bservances approaching m asonic peculiarity They were forbi dden to div ulge the discov eries and doctrines of their school Hence we are obliged to speak of the P ythagoreans as a body and fi n d it di ffi cult to deter m ine to who m each particular discovery is to be ascribed The P ythagoreans the mselves were in the habit of r e ferring every discovery back to the great founder of the sect This school grew rapidly and gained considerable political ascend ency B ut the mystic an d secret O bservances introduced in i mitation of E g yptian usages and the aristocratic tendencies of the school caused it to beco m e an object of suspicio n The dem ocratic party in Lower Italy re v olted and destroyed the buildings of the P ythagorean school P ythagoras fled to Tarentum and thence to M e t apon t u m where he was m urdered P ythagoras has left behind no m athematical treatises and our sources of infor mation are rather scanty Certain it is that in the P yt hag P ythagorean school m athe m atics was the principal study oras raised mathe matics to the rank of a science Arithmetic was courted by h im as fervently as geo metry In fact arithm etic is the foundation of his philosophic system The E u demi a n S u mmar y says that P ythagoras changed the study of geom etry into the form of a liberal education for he examined its principles to the bottom and investigated its theore m s in an i mma t er i a l and intellectual m anner His geo metry was connected closely with hi s arithm etic He was especially fond of those geom etrical relations which ad mitted of arithmetical e xpression Like Egyptian geom etry the geo metry of the P ythagoreans is much concerne d with areas To P ythagoras is ascribed the i mportant theore m that the square on the hypotenuse of a right triangle is equal to the s u m of the squares on the other two sides He had probably learned from the Egyptians the truth of the theorem in the special case when the sides are 3 4 5 respectively The story goes that P ythagoras was so j ubilant over this discovery that he sacrificed a hecato mb Its authenticity is doub ted because the P ythagoreans believed in the transmigration of the soul and opposed the shedding of blood In the later traditions of the Neo P ythagoreans this ob “ j ec ti on is re m oved by replacing this bloody sacrifice by that of an ox m ade of flour ! The proof of the law of three squares given in Eucli d s El emen ts I 4 7 is due to Euclid hi mself and not to the P ythagoreans What the P ythagorean m ethod of proof was has been a favorite topic for conj ecture The theore m on the su m of the three angles of a triangle presu m ably known to Thales was pro v ed by the P ythagoreans after the manner of Euclid They de monstrated also that the plane about a point i s co mpletely filled by six equilateral triangles four squares or , , , . , . . , . . , . , , . , . . , . , . , . . , . , ” , . . . , . . , , . . , , , - ” . , ’ , . , , . . , , . , , GREEK GEO M ETRY 19 three regular hexagons so that it is possible to di vide up a plane into figures of either kind From the equilateral triangle and the square arise the solids nam ely the tetraedron o c t a edro n i c osa edron and the cube These solids were in all probability known to the Egyp tians e xcepting perhaps the i cosaedron In P ythagorean p hi losophy they represent r esp ec ti v el y the four elements of the physical world ; nam ely fire air water and earth Later another regular solid was discovered namely the dodecaedro n which in absence of a fifth ele ment was m ade to r epr e sent the universe itself I ambli chu s states that H ippa su s a P ytha g or ean perished in the sea because he boasted that he first div ulged the sphere with the twelve pentagons The sam e story of death at sea is told of a P ythagorean who disclosed the theory of irrationals The star shaped pentagram was used as a symbol of recognition by the P ythagoreans and was called by them Health P ythagoras called the sphere the most beautiful of all solids and the circle the most beautiful of all plane figures The treatm ent of the subjects of proportion and of irrational quantities by hi m and his school will be t aken up under the head of arithmetic According to Eu demu s the P ythagoreans invented the problem s concerning the application of areas including the cases of defect and excess as in Euclid VI 2 8 2 9 They were also familiar with the construction of a polygon equal in area to a given polygon and sim ilar to another given polygon This proble m depends upon several i mportant and som ewhat advance d theore m s and testifies to the fact that the P ythagoreans made no mean progress in geo metry Of the theorems generally ascribed to the Italian school so m e cannot be attributed to P ythagoras himself nor to his earliest suc The pro gress from e mpirical to reasoned solutions m ust of c e ssors nec essity have been slow It is worth noticing that on the circle no theorem of any i mportance was discovered by this school Though pol i tics broke up the P ythagorean fraternity yet the school continued to exist at least two centuries longer Among the later P ythagoreans P hilolaus and Archytas are the most pro minent P h il ol au s wrote a book on the P ythagorean doctrines By him were first given to the world the teachings of the Italian school which had been kept secret for a whole century The brilliant Ar ch ytas (4 2 8 of Tarentum known as a great statesman and general and 34 7 B C ) universally admired for his virtues was the only great geometer among the Greeks when P lato opened his school Archytas was the first to apply geometry to mechanics and t o t reat the latter subject methodically He also found a very ingenious m echanical solution to the problem of the d uplication of the cube His solution in v olves clear notions on the generation of cones and cylinders This proble m reduces itself to finding two m ean proportionals between two giv en , . , , . , , , , , , . , , , , , . , , , , , , , . , , , . . - . , , . . , , , , . , . . , . , , . , . , . , . . , . , . . . , , , . ' . . ‘ . A HISTORY OF M ATHE M ATICS 20 lines These mean proportionals were ob tained by Archytas from the secti on of a half cylinder The doctrine of proportion was a d v an ced through him There is every reason to believe that the later P ythagoreans exer c i se d a strong influence on the study and develop m ent of mathe m atics at Athens The Sophists acquired geo metry fro m P ythagorean sources P lato bought the works of P hilolaus and had a warm friend in Archytas . - . . . , . . The S ophi s t S chool After the defeat of the P ersians under Xerxes at the battle of Salamis 480 B C a league was formed among the Greeks to preserv e the freedo m of the now liberated Greek cities on the islands and coast of the E g aean Sea Of this league Athens soon becam e leader and dictator She caused the separate treasury of the league to be merged into that of Athens and then spent the m oney of her allies for her own aggran dise ment Athens was also a great comm ercial centre Thus she became the richest and most beautiful city of antiquity All menial work was perfor med by sla v es The citiz en of Athens was well to do and enjoyed a large a mount of leisure The govern ment being purely de mocratic e v ery citizen was a politician To make hi s influence felt a mong his fellow men he mu st first of all be educated Thus there arose a dem and for teachers The supply ca me principally from Sicily where P ythagorean doctrines had S pread These teachers were calle d S ophi s ts or wise m en Unlike the P ythagoreans they accepted pay for their teaching Although rhetoric was the principal feature of their instruction they also taught geometry astronom y and philosophy Athens soon becam e the headquarters of Grecian The ho me of m en of letters and of m athe maticians in particular mathe m atics a m ong the Greeks was first in the Ionian Islan ds then in Lower Italy and during the tim e now under consideration at Athens The geo metry of the circle which had been entirely neglected by the P ythagoreans was taken up by the Sophists Nearly all their disco v eries were m ade in connection with their innum erable atte mpts to sol v e the following three fa mous problems To trisect an are or an angle (1) To double the cube i e to find a cube whose vol u me is (2) double that of a given cube To square the circle i e to find a square or some other ( 3) rect i linear figure exactly equal in area to a given circle These proble m s have p robably been the subject of more discuss i on and research than any other proble m s in m athe matics The bisec tion of an angle was one of the easiest proble ms in geom etr y The t ris eé tion of an angle on the other hand presented unexpected diffi cult ies A r i ght angle had been divided into three equal parts by the P ytha . , . , . . , . . . . - - . . , - , . , . ” , “ . . , , . , , , . . , , , , . , . , ” “ , . . . , . “ , . . . . . , , . GREEK GEO M ETRY B ut the g o r e an s cannot be eff ected 21 general construction though easy in appearance by the aid only of rul er and co mpasses Among the first to wrestle with it was H ippi as of El i s a conte mporary of Socrates and born about 46 0 B C Unable to reach a solution by ruler and compasses only he and other Greek geo meters resorted to the use of other means P roclus mentions a man Hippias pr esum ably Hippias of Elis as the inventor of a transcendental curve which served to div ide an angle not only into three but into any nu mber of equal parts Th is same curve was used later by D i nos tra t u s and others for the quadrature of the circle On this account it i s p all ed the qu adr atri x The curve may be described thus :The side AB of the square shown in the figure turns uniformly about A the point B moving along the circular arc BED In the sa me ti me the side B C moves p arallel to i t X self and uniformly from the position of B C B to that of AD The locus of intersection of AB and B C when thus m oving is the quadratrix BFG Its equation we now write . , , . , . , . , . , , , , . . . ' , . , . ‘ , , . The ancients considered only the part of the curve that lies inside the quadrant of the circle ; they did not know that x = i 2 r are asymptotes nor that there is an infinite number of branches Accor ding to P appus D in o str a t u s e ffected the quadrature by establishing the theore m that B ED :AD = AD :AG The P ythagore ans had shown that the di agonal of a square is the side of another square having double the area of the original one Thi s probably suggested the proble m of the d uplication of the cube i e to find the edge of a cube having d ouble the volum e of a gi v en cube Eratosthenes ascribes to this problem a diff erent origin The D elians were once suffering fro m a pestilence and were ordered by the oracle to double a certain cubical altar Thoughtless workm en simply constructed a cube with edges twice as long but brainless work like that did not pacify the gods The error being discovere d He and his disciples searched P lato was consulted on the m atter “ eagerly for a solution to this D elian P roble m An i mportant con t r ib u t i o n to this proble m was m ade by Hi ppo c r ate s of C h i os ( about m m He was a talented athe atician but having been de B 0 43 It is frau ded of his property he was pronounced slow and stupid also said of him that he was the first to acc ept pay for the teaching of mathe matics He showed that the Delian P roblem could be reduced to fi n di ng two mean proportionals between a given line and another 2 = twice as long For in the proportion a :x x :y y 2 a since x 4 3 3 3 2 2 4 2 we have x 2 a x and x 2 a But a y ay and y = 2 ax and x , . , . . , . . , . . . , . , . . , . . , . : . , , , . , A HISTORY OF M ATHE M ATICS 22 of course he failed to find the two m ean proportionals by geo metric construction with ruler and compasses He m ade h imself celebrated by squaring certain lunes According to Simplicius Hippocrates believed he actually succeeded in applying o n e of his lune quadratures to the quadrature of the circle That Hippocrates really committed this fallacy is not generally accepted In the first lune which he squared he took an isosceles triangle AB C right angled at C and drew a sem i circle on AB as a diam eter and passing through C He drew also a se mi circle on AC as a dia m eter and lying outside the triangle AB C The lunar area thus form ed is half the area of the triangle AB C This is the first example of a cur v ilinear area which ad mits of exact quadrature Hippocrates squared other lunes hoping no doubt that he might be led to the 1 qua drature of the circle In 1 840 Th Clausen found other quadrable lunes but in 1 90 2 E Landau of G ottingen pointed out that two of the four lunes which Clausen supposed to be new were known to 2 Hippocrates In his study of the quadrature and duplication problem s Hip He showed p o cr a t e s contributed much to the geo metry of the circle that circles are to each other as the squares of their diam eters that si milar segments in a circle are as the squares of their chords and contain equal angles that in a segment less than a se mi circle the angle is ob tuse Hippocrates contr ibuted vastly to the logic of geo m e t ry His inv estigations are the oldest reasoned geo metrical proofs in existence ( Gow)For the purpose of describing geometrical figures he used letters a practice probably introduced by the P yth agoreans The subj ect of si milar figures as developed by Hippocrates i n volved the theory of proportion P roportion had thus far been used by the Greeks only in numbers They never succeeded in uniting “ the notions of numbers and m agnitudes The term number was used by the m in a restricted sense What we call irrational nu mbers was not inclu ded under this notion Not even rational fractions w ere called nu mbers They use d the word in the same sense as we use positive integers Hence nu mbers were conceived as di scon ti n u ou s while m agnitudes were c on ti n u ou s The two notions ap The chasm between them is ex pea r ed therefore entirely distinct posed to full view in the state ment of Euclid that incomm ensurable m agnitu des do not hav e the sam e ratio as nu mbers In Eucl id s El emen ts we find the theory of proportion of m agnitudes de v eloped and treated independent of that of numbers The transfer of the theory of proportion from nu mbers to m agnitudes (and to lengths in particular) was a diffi cult and i mportant step , . . , - . . , - - , , , - . . . . , , , . . . , , . . - , . , - , . ” . . , . , , ’ . , , . ” . . . . “ - . . , , . , ” “ ’ . . . . z ’ i s g i ve n b y G L or i a i n hi s L e s ci en e esa tte n ell an ti ca Gr eci a , M il an o , 2 edi ti on , 1 9 1 4 , pp 7 4 94 L o r i a g i ves a l so f u ll bibliog r ap hi cal r e fe r en ce s t o t he e x t e n s i ve l i t e r a t u r e o n H ip p oc ra t es 2 E W H ob son , S q u a r i ng the C i rcl e, C a mb ri dg e , 1 9 1 3 , p 1 6 1 A fu ll ac cou n t — . . . . . . . . f GREEK GEO M ETRY 23 Hippocrates added to his fam e by writing a geo metrical te xt boo k called the El emen ts This publ i cat i on shows that the P ythagorean habit of secrecy was being abando ned ; secrecy was contrary to the spirit of Athenian life The sophist An tiph o n a conte mporary of Hippocrates introduce d the pr ocess of exhaustion for the purpose of solving the proble m of the quadrature He did hi m self credit by re marking that by i n scr ib ing in a circle a square or an equilateral triangle and on its sides erecting isosceles triangles with their vertices in the circum ference and on the sides of these triangles erecting new triangles etc one could obtain a succession of regular polygons of which each approaches nearer to the area of the circle than the previous one until the circle is finally exhau sted Thus is obtained an inscribed polygon whose sides coincide with the circu mference Since there can be foun d squares equal i n area to any polygon there also can be found a square equal to the last polygon inscribed and therefore equal to the circle itself B rys o n of H erac l ea a contemporary of Antiphon advance d the proble m of the quadrature consi derably by circu mscribing poly gons at the sa me tim e that he inscribed polygons He erred howev er in assum ing that the area of a circle was the arithm etical m ean b e tween circu mscribed and inscribed polygons Unlike Bryson a n d the rest of Greek geo meters Antiphon seem s to have beli eved it possible by continually doubling the sides of an inscribed polygon to obtain a polygon coinciding with the circle This question gave rise to liv ely disputes in Athens If a polygon can coincide with the circle then says Simpliciu s we m ust put aside the notion that m agni tudes are di v isible ad i nfi n i tu m This diflficu l t philosop hi cal q p e st ion led to paradoxies that are difli c u l t to e xplain and that deterre d Greek m athe maticians fro m introducing ideas of infin i ty into their geo m etry ; rigor in geometric proofs de manded the exclusion of obscure c on c ep tions Famous are the argu ments against the possibility of m otion that were adv anced by Z e no of Elea the great d i alectician ( early in the 5 th century B None of Zeno s writings have co me down to We know of his tenets only through his critics P lato Aristotle uS Si mplicius Aristotle in his P hys i cs VI 9 ascribes to Zeno four “ “ argu ments called Zeno s paradoxies ( 1 ) The Dichotom y : You cannot trav erse an infinite number of points in a finite time ; you m ust traverse the half of a given distance before you traverse the whole and the half of that again before you can traverse the whole Th is goes on ad i nfin i tum so that (if space is m ade up of points) there is an in finite number in any given S pace and it cannot be traversed “ in a finite time ( 2 ) The Achi lles : Achilles cannot overtake a tor toise For Achilles must first reach the place from which the tortoise started By that tim e the tortoise will have m oved on a little way Achilles m ust then trav erse that and still the tortoise will be ahead “ The Arrow He is always nearer yet never m akes up to it (3) - , . . , , . , , , . , , , . . , , , . , . , , . , , , . . ' , , . . , ’ . , . . , , , ’ , ” , , . , , ” , . , . . . , , . HISTORY A 24 O F M ATHE M ATICS ” An arrow in any given m om ent of its flight m ust be at rest in so m e “ particular point (4 ) The S tade : Suppose three paral l el rows of poi nts in j ux taposi tion as in Fig 1 One of these ( B ) is imm ov able A A B B C C Fig 1 Fig 2 while A and C m ove in opposite directions with equal velocity so as to co m e into the position in Fig 2 The m ove m ent of C relatively to A will be double its movem ent relatively to B or in other words any given point in C has passed twice as m any points in A as i t has in B It cannot therefore be the case that an instant of tim e corre spon d s to the passage fro m one point to another “ P lato says that Zeno s purpose was to protect the arguments of P armenides against those who m ake fun of him ; Zeno argues that there is no many he denies plurality That Zeno s reasoning was wrong has been the view universally held since the tim e of Aristotle down to the m iddle of the nineteenth century M ore recently the opinion has been advanced that Zeno was incompletely and incor rec t l y reported that his argu ments are serious e ff orts conducted with logical rigor This view has been advanced by Cousin Grote and P 1 Tannery Tanne ry clai ms that Zeno did not deny motion but wanted to S how that motion was im possible under the P ythagorean conception of S pace as the su m of points that the four arguments must be taken together as constituting a dialogue between Zeno and an adversary and that the arguments are in the form of a double dilemm a into whi ch Zeno forces his adversary Zeno s arguments involve con cept s of continuity of the in fi nite and infinitesi m al ; they are as m uch the subjects of debate now as they were in the time of Aristotle Aristotle di d not successfully explain Zeno s paradoxes He gave no reply to the query arising in the m ind of the student how is it pos sible for a variable to reach its limit ? Aristotle s continuum was a sensuous physical one ; he held that since a line cannot be b ui lt up “ of points a line cannot actually be subdiv ided into points The continued bisection of a quantity is unlim ited so that the unlimited exists potentially but is actually never reached No satisfactory e xplanation of Zeno s argu m ents was given before the creation of Georg Cantor s continuu m and theory of aggregates The process of e xhaustion due to Antiphon and B ryson gave rise “ to the cum brous but perfectly rigorous method of e xhaustion In deter mining the ratio of the areas between two curvilinear plane figures say two circles geometers first inscribed or circu mscribed S i milar polygons and then by increasing indefinitely the number of . , . , — . , . . , . . . , , , , , . ’ ” ” ” ’ . , . , , . . , , . , ’ . , . ’ . , ’ , , . , , . , ’ ’ ” . . , , S ee F C aj or i , Th e H i s to ry o f Z e no M ath M onthly , Vol 2 2 , 1 9 1 5 , p 3 1 . . . . . ’ s A rg u men t s on M o ti o n i n t h e A mer i c . A HISTORY OF M ATHE M ATICS 26 groves of the A cademi a and devoted the remainder of his life to teach ing and writing P lato s physical p hi losophy is partly based on that of the P yth a Like them he sought in arithm etic and geometry the key g or e an s to the universe When questioned about the occupation of the D eity “ He geom etrises continually Accordingly a P lato answered that knowledge o f geo metry is a necessary preparation for the study of philosophy To show how great a value he put on m athem atics an d how necessary it is for higher S peculation P lato placed the i n s crip tion over his porch Let no one who is unacquainted with geo metry enter here Xenocrates a successor of P lato as teacher in the Academ y followed in his master s footsteps by declining to admit a “ pupil who had no m athe matical training with the remark D epart for thou hast not the grip of philosophy P lato observed that geo m e t ry trained the m ind for correct and vigorous thinking Hence it was that the E udemi an S u mmary says He filled hi s writings with mathem atical d iscoveries and exhibited on every occasion the r e markable connection between m athe m atics and p hilosophy With P lato as the head m aster we need not wonder that the P l a tonic school produced so large a nu mber of mathe maticians P lato did little real original work but he made valuable improve ments in the logic and m ethods employed in geo metry It is true that the Sophist geo m eters of the prev ious century were fairly rigorous in their proofs but as a rule they did not reflect on the inward nature of their They used the axio ms without giv ing the m e xplicit ex methods pression and the geo metrical concepts such as the point line surface 1 m fi i i etc without assigning to them for al de n t on s The P ythagoreans called a point unity in position but thi s is a statem ent of a phi lo sophical theory rather than a definition P lato objected to calli n g a “ point a geometrical fiction He defined a point as the beginning “ “ of a line or as an indivisible line and a line as length wi thout breadth He called the point line surface the boundaries of the line surface solid respecti v ely M any of the d efinitions in Euclid are to be ascribed to the P latonic school The sam e is probably true of Euclid s axiom s Aristotle refers to P lato the axiom that equals subtracted fro m equals leav e equals One of the greatest achieve ments of P lato and his school is the i n To be sure this m ethod v en t ion of a n al ys i s as a m ethod of proof had been used unconsciously by Hippocrates and others ; but P lato like a true philosopher turned the instinctive logic into a conscious legitimate method , . ’ . , ” . , . , . , ” “ , . , ’ , , ” , , , . . “ , ” , . - , ‘ . , . , . , . ” , “ , , , , . , ” . ” . “ ” , . , , . , , , , . ’ . . . , , , , . If a n y o n e sc i en t ifi c i n v en t i on c an c l ai m p re e mi n en c e o v e r a l l o t h ers , I sho u l d b e i n cl i n ed m ys e l f t o e r ec t a mon u m e n t to t h e u n k n o w n i n ve n t or o f t he ma t he m a t i cal p o in t , a s t h e s u p r eme typ e o f ha p r oc ess o f a b s t ra c t i o n w hi ch h as b ee n Horace L amb s a n ecessary co n di t i on o f sc i e n t i fi c w o rk from t h e v ery b eg i nn i ng ’ A ddress , S ec t ion A , B r i t A ss n , 1 90 4 1 “ - ” t t . . . ’ GREEK G EO M ETRY 7 The term s syn thesi s and an al ylsi s are used in mathematics in a more special s ense than in logic In ancient mathe matics they had a dif fe r en t meaning fro m what they now ha v e The oldest definition of mathe matical analysis as O pposed to synthesis is that gi v en in Euclid “ XIII 5 which in all probability was fra m ed by Eudoxus : Analysis is the obtaining of the thing sought by assum ing it and so reasoning up to an admitted truth ; synthesis is the obtaining of the thing sought by reasoning up to the inference and proof of it The analytic m ethod is not conclusive unless all operations involved in it are know n to be reversible To remove all doub t the Greeks as a rule added to the analytic process a synthetic one consisting of a reversion of all O perations occ u rring in the analysis Thus the aim of analysis was to aid in the discovery of synthetic pro ofs or solutions P lato is said to have sol v ed the proble m of the duplication of the cube B ut the solution is open to the very sam e objection whi ch he m ade to the solutions by Archytas Eudoxus and M en ae c hm u s He called their solutions not geom etrical but mechanical for they r e quired the use of oth er instru ments than the ruler and co mpasses He said that thereby the good of geo m etry is set aside a n d d estroyed for we again reduce it to the worl d of sense instead of elev ating and i mbuing it with the eternal and inco rporeal i mages of thought even as it is employed by God for which reason He always is God These objections indicate either that the solution is wr ongly attributed to P lato or that he wished to S how how easily non geom etric solutions of that character can be found It is now rigorously established that the duplication problem as well as the trisection and quadrature proble ms cannot be solved by means of the ruler and compasses only P lato gave a healthful stim ulus to the study of stereo m etry which until his tim e had been entirely neglected by the Greeks The S phere and the regul ar solids have been stu die d to som e extent but the prism pyramid cylinder and cone were har dly known to exist All these solids becam e the subj ects of investigation by the P latonic school One result of these inquiries was epoch m aking M e n ae c h mu s an associate of P lato and pupil of Eu doxus invented the conic sections which in course of only a century raised geo metry to the loftiest height whi ch it was destined to reach during antiquity M en ze c hmu s cut “ — t hree kinds of cones the right angled acute angled and ob tuse angled by planes at right angles to a side of the cones and thus obtained the three sections which we now call the parabola ellipse and hyperbola Judging fro m the two very elegant solutions of the Delian P roblem by means of intersections of these curves M en aech mu s m ust have succeed ed well in investigating their properties In what manner he carried out the graphic construction of these curve s is not known Another great geo meter was D i n os tratu s the brother of M en wch . . , , , ” . , . , , , , . . . , . , , , . , , , . , - . , , . , . , . , , , . - , . , , , ” ” - , , ” . , , , , . , ” , , . . , A HISTOR Y OF M ATHE M ATICS 28 and pupil of P lato Celebrated is hi s mechanical solution of the quadrature of the circle by m eans of the qu adr a tr i x of Hippias P erhaps the most brilliant mathe matician of t hi s period was He was born at Cnidus about 40 8 B C studied under Eu doxu s Archytas and later for two m onths under P lato He was i mbued with a true spirit of scientific inquiry and has been called the father of scientific astronomical observation F mm the fragmentary notices of his astronom ical researches found in later writers Ideler and Schiaparelli succeeded in reconstructing the system of Eudoxus with “ its celebrated representation of planetary motions by concentric spheres Eudoxus had a school at Cyz icus went with his pupils to Athens visiting P lato and then returned to Cyz icus where he di ed The fa me of the academy of P lato i s to a large extent due 3 55 B C to Eudoxus 3 pupils of the school at Cyzicus among whom are M e n D iogenes L aer tiu s de wchmu s D i n os t r a t u s A t hen ze u s and Helicon scribes Eudoxus as astronomer physician legislator as well as geo m “ eter The E u demi an S u mmary says that Eudoxus first increased the nu mber of general theore ms added to the three proportions three m ore and raised to a considerable quantity the learning begun by P lato on the subj ect of the section to which he applied the analytical “ By this section is m eant no doub t the golden section m ethod (secti o au r ea )which cuts a line in e x tre me and m ean ratio The fi rs t fi v e propositions in Euclid XIII relate t o lines cut by thi s section and are generally attr i buted to Eudoxus Eudoxus added m uch to the knowledge of solid geometry He proved says Archi medes that a pyram id is exactly one third of a prism and a cone one third of a cylinder having equal base and altitude The proof that spheres are to each other as the cubes of their radii is probably due to hi m He made frequent and skilful use of the m ethod of exhaustion of which he was in all probability the inv entor A scholiast on Euclid thought to be P roclus says further that Eudoxus practically invented the whole of Euclid s fifth book Eudoxus also found two m ean propor t i on al s between two given lines but the m ethod of solution is not known P lato has been called a maker of m athe maticians B esides the pupils already named the E ud emi an S u mmary m entions the following : Th eaete tu s of Athens a m a n O f great natural gifts to who m no doubt 1 Euclid was greatly indeb ted in the composition of the r o th book treating of i n comrn en su rab l es and of the 1 3 th book ; L e odamas of Thasos ; N e ocl e i d e s and his pupil L e on who added m uch to the work of their predecessors for Leon wrote an El emen ts carefully designed both in nu mber and utility of its proofs ; Th e u di u s of M ag n e s i a who compose d a very good book of El emen ts and generalised propositions which had been confined to particular cases ; H e rmoti mu s of Col oph on who discovered m any propositions of the El emen ts and c om G J Al lma op ci t p 2 1 2 mu s . , . . . , , , . , , . , , . , , , , . . ’ , , , . , , , , . , ” , , ” , , . , , - . , , . . , , - - , . , . , . . , , ’ . , . . , , , , , , , , , , , , 1 . . n, . . , . . GREEK GEO M ETRY 29 posed so me on l oci ; and finally the nam es of Amycl as of H e r acl e a C yzi c e n u s of Ath en s and P hi l i ppu s of M e n d e A skilful mathe matician of whose life and works we have no details is An s taeu s the elder probably a senior conte mporary of Euclid The fact that he wrote a work on co ni c sections tends to S how that m uch progress had been made in their study during the tim e of M en mchmus Aristaeus w rote also on regular solids and cultivated the analytic m ethod His works contained probably a su mma ry of the researches 1 of the P latonic school Ari st o tl e (3 84—3 2 2 B the syste matiser of deductive logic though not a professed mathematician promoted the science of geom etry by improving so me of the most difli c u l t defin itions His P hysi cs contains passages with suggestive hints of the principle of virtual velocities He gave the best discussion of continuity and of Zeno s argu ments against motion found in antiquity About his tim e there appeared a work called M echani ca of which he is regarded by some as the author M echanics wa s totally neglected by the P latonic school , , , , , , . . . . . , , . . ’ . , . , . The Fi rst Al exandr i an S chool In the previous pages we have seen the birth of geometry in Egyp t its transference to the Ionian Islands thence to Lower Italy and to Athens We have witnessed its growth in Greece from feeble child hood to vigorous m anhood and now we shall see it return to the land of its birth and there der ive new vigor D uring her declining years imm e di ately following the P eIOpon n e si an War Athens produced the greatest scientists and philosophers of antiquity It was the time of P lato and Aristotle In 33 8 B C at the battle of Chae ronea Athens was beaten by P hilip of M acedon and her pow er was broken forever Soon after Alexander the Great the son of P hi lip started out to conquer the world In eleven years he built up a great e mpire which broke to pieces in a day Egypt fell to the lot of P tole my Soter Alexander had founded the seaport of Alexandria whi ch soon became the noblest of all cities P tolemy made Alexandria the capital The history of Egypt during the nex t three centuries is mainly the histo ry of Alexandria Literature p hi losophy and art were di ligently cultivated P tole my created the university of Alexandria He founded the great Library and built laboratories m useums a zoological garden and promenades Alex andria soon beca me the great centre of learnin g De metrius P h al er eu s was invited from Athens to take charge of the Library and it is probable says Gow that Eu cli d was invi ted with him to O pen the m athe matical school According to the studies of H Vogt 2 Euclid was born about 3 6 5 B C and wrote his El emen ts , , . " , . , , . . . . , , , . , , . , . . . , . . , . , . ’ , . , , . , , , . . . , G J Al l man , op ci t , p 20 5 2 B i bl i otheca mathemati ca , 3 S , V ol . 1 . . . . . — . . . 1 3 , 1 91 3, pp . 1 93 20 2 . O F M ATHE M ATICS HISTORY A 30 between 3 30 and 3 2 0 B C Of the life of Euclid little is known except what is added by P roclus to the E u demi an S u mmar y Euclid says P roclus was younger than P lato and olde r than Eratosthenes and Archi medes the latter of who m mentions him He was of the P latonic sect and well read in its doctrines He collected the El emen ts put in order m uch that Eudoxus had prepared co mpleted many things of Theze t e t u s and was the first who reduced to unobj ectionable de mon When P tole my s t r a t i o n the i mperfect atte mpts of his predecessors Once asked hi m if geo m etry could not be m astered by an easier process than by studying the E l emen ts Euclid returned the answer There is no royal road to geo m etry P appus states that Euclid was distin g u i sh ed by the fairness and kindness o t his disposition particularly toward those who could do anything to advance the m athematical sciences P appus is evidently m aking a contrast to Apollonius of 1 who m he m ore than insinuates the opposite character A pretty 2 “ little story is related by S tob mu s : A youth who had begun to read geo metry with Euclid when he had learnt the first proposition i n quired What do I get by learning these things ? So Euclid called his slav e and said Give hi m threepence since he m ust m ake gain out of what he These are about all the personal details preserved by Greek writers Syrian and Arabian writers clai m to know m uch more but they are unreliable At one time Euclid of Alexandria was universally confounded with Euclid of M egara who liv ed a century earlier The fa me of Euclid has at all times rested mainly upon his book on geom etry called the El emen ts This book was so far superior to the E l emen ts written by Hippocrates Leon and Th eu di u s that the latter works soon perished in the struggle for existence The Greeks gave Euclid the S pecial title of the author of the E l emen ts It is a r e m arkable fact in the history of geo metry t hat the El emen ts of Euclid wr itten over two thousand years ago are still regarded by som e as the best introduction to the m athem atical sciences In England they were used until the present century extensively as a text book in schools Som e editors of Euclid have however been inclined to credit They would have us believe that a him with m ore than is his due finished and unassailable syste m of geometry sprang at once from the brain of Euclid an arm ed M inerva fro m the head of Jupiter They fail to mention the earlier eminent m athe m aticians from whom Euclid got his material Comparatively few of the propositions and proofs in the El emen ts are his own discoveries In fact the proof of the “ Theore m of P ythagoras is the only one directly ascribed to him All man conj ectures that the substance of Books I II IV comes from the P ythagoreans that the substance of Book VI is due to the P ytha . . , , . , , . , . , , , , . ” , , . ' , . , . , , ‘ ’ , ‘ , , . . , , . . , , , , . “ . , , , . - . , , ” . . , ” . . , . , A D e M org an , Eucl e i des a n d M ythol ogy 2 J G ow , op ci t , p 1 95 1 . . . . . . . i n S mi th s Di cti onary of Gr eek ’ , a nd Roma n Bi ography GREEK GEO M ETRY and Eudoxus the latter contributing the doctrine of propor tion as applicable to inco mmensurables and also the M ethod of Ex h au s ti on s ( Book XII )that The mt e t u s contributed m uch towar d Books X and XIII that the principal part of the original work of 1 Eucli d hi mself is to be found in Book X Euclid was the greatest syste matiser of his time B y careful selection fro m the m aterial before hi m and by logical arrange m ent of the propositions selected he built up from a few definitions an d a xio m s a proud and lofty structure It woul d be erroneous to belie v e that he incorporated into his El ements all the elem entary theorem s known at his ti me Archimedes Apol l o n i u s and even he him self refer to theore m s not included in his El e men ts as being well — known truths The tex t of the El emen ts that was co mmonly used in schools was Theon s edition Theon of Alexan dria the father of Hypatia brought out an edi t ion ab ou t 700 years after Euclid with som e alterations in the tex t A S a consequence later comm entators especially Robert Simson who labored under the idea that Euclid m ust be absolutely perfect m ade Theon the S capegoat for all the defects which they thought they c ould discover in the text as they knew it B ut a mong the manuscripts sent by Napoleon I from the Vatican to P aris was found a copy of the El emen ts believed to be anterior to Th eon s recen sion M any variations fro m Th eon s version were noticed therein but they were not at all i mportant a n d S howed that Theon generally m ade only verbal changes The defects in the El emen ts for which Theon was bla med m ust therefore be due to Euclid hi mself The El emen ts used to be considered as o ff ering m o dels of scrupulously rigorous de monstrations It is certainly true that in point of rigor it compares fav orably with its modern ri v als ; but when examined in the light of strict m athe matical logic i t has been pronounced by C S P eirce to be rid dled with fallacies The results are correct only because the writer s experience k eeps him on his guard In m any proofs Euclid relies partly upon intuition At the begi nning of our editions of the E l emen ts under the hea d of definitions are given the assumptions of such notions as the point line etc and so me v erbal explanations Then follow three postul ates “ or de m ands and twel v e axio m s The term axio m was used by P roclus but not by Euclid He S peaks instead of co mmon no tions — co mmon either to all m en or to all sciences There has been m uch contro v ersy a mong ancient and m o dern critics on the postulates and axiom s An i mmense prepon derance of m anuscripts and the “ testimony of P roclus place the axiom s about r i ght angl es and 2 This is i ndeed their proper place parall el s a mong the postulates g or ea n s , , , . . , , , , . . , , . , ’ . , , , , , . , , , , . ’ ’ . , , . ‘ , . , . , . . . ’ . . , , . , ” . . , ” , , , , . . ” . , . G J Al l man , op ci t , p 2 1 1 2 A D e M org an , l oc c i t ; H H a n k e l , Theor i e der C o mpl exen Z a hl ensys teme, L e ip z i g 1 86 7 , p 5 2 I n t he v a rio u s e d i t io n s o f E u cl id s El emen ts di f e re n t n u mb e rs a re assig ne d t o th e axi oms Thus t he parall el a xi om i s cal l ed by R ob er S i mso n t he 1 . . . . . . . . . . ’ , . . . t A HISTORY OF M ATHE M ATICS 32 for they are really assu mpti on s and not common n oti ons or axioms The post u late about par al l el s plays an i mportant rOl e in the history of non Euclidean geo metry An important postulate which Euclid m issed was the one of superposition according to which figures can be moved about in S pace without any alteration in form or magnitude The El emen ts contains t hi rteen books by Euclid and two of which it is supposed that H yp si cl es and D amasc i us are the authors The first four books are on plane geometry The fifth book treats of the theory of proportion as applied to magn itudes in general It has been greatly admired because of its rigor of treatment B eginners find the book di fficult E xpressed in modern symbols Euclid s definition of proportion is thus :Four magnitudes a b c d are in proportion when . , - - . , . , , . . . . ’ . , ‘ , m for any integers and n, , , , , , and mo we have simul taneously < 1 “ Says T L Heath certain it is that there is an exact corre spo n d e n c e al most coincidence between Euclid s definition of equal ratios and the m odern theory of irrationals due to D edekind H G Zeuthen finds a close resemblance between Euclid s definition and Weierstrass definition of equal nu mbers The S ixth book develops the geo metry of si milar figures Its 2 7th P roposition is the earliest m axim u m theore m known to history The seventh eighth ninth books are on the theory of nu mbers or on arithm etic According to P Tannery the knowledge of the ex istence of irrationals m ust have greatly aff ected the m ode of writing the E l emen ts The old nai v e theory of proportion being recogniz ed as untenable proportions are not used at all in the first four books The rigorous theory of Eudoxus was postponed as long as possible because of its difli c u l ty The interpolation of the arithm etical books VII— IX is explained as a preparation for the fuller treatment of the irrational in book X Book VII explains the G C D of two numbers by the process “ of division ( the so called Euclidean The theory of proportion of ( rational ) nu mbers i s then developed on the basis of the definition Nu mbers are pr opor tion al w hen the first is the sam e mul tiple part or parts of the second that the third is of the fourth 2 Thi s is believed to be the older P ythagorean theory of proportion The tenth treats of the theory of inco mm ensurables D e M organ con We give a fuller account of i t s i der ed this the m ost wonderful of all The nex t three books are on u nder the head of Greek Arithm etic nd . . . , ’ , , . . . ’ ’ . . . , . , . , , . , . ‘ . , . . . . - “ ” ‘ , , . , . , . . . . b y C l av i us t he 1 3 t h , by F P eyrard t he 5 th I t i s call ed t he st h pos tu l ate i n ol d m a n u sc r ip t s , a l so by H e i be rg a n d M e n g e i n t he i r a nn ot a t e d ’ e di t i o n o f E u c lid s w o rk s , i n G r eek an d L a t i n , L ei p i g , 1 88 3 , a n d b y T L H ea t h ’ ’ — H eat h s i n hi s Thi rteen B ook s of Eu cl i d s El emen ts , Vo l s I I I I , C a mb r idg e , 1 90 8 i s t he mo s t r ece n t ran sl a t io n i n to Eng li sh a nd i s v ery f ull y an d a bl y a n n o tat e d 1 T L H ea th , op ci t V ol II , p 1 2 4 2 R a t io , P ropor io n an d M e as uremen i n t he E eme n t s o f R ead H B F i n e , Euclid, A nnal s of M athemati cs, Vo l X IX , 1 91 7, pp 70 7 6 1 2 th , by B ol yai t he r 1 th , . . z . t . ” . . . . . . . . . . t . . . t — . . l O F M ATHE M ATICS A HISTORY 4 ” the meaning of whi ch title is not understood Heiberg believes it to “ m ean loci which are surfaces The im mediate successors of Euclid in the mathe matical school at Alexandria were probably C o n o n D os i th e u s and Z e u xi ppu s but little is k now n of the m 212 B the greatest mathe matician of an Ar c h im e d e s ( 2 8 7? — P lutarch calls him a relation of King t i q u i ty was born in Syracuse H i eron ; but more reliable is the sta tement of Cicero who tells us he was of low birth Di odor u s says he visited Egypt and since he was a great friend of Conon and Eratosthenes it is hi ghl y probable that he studied in Alexandria This belief is strengthened by the fact that he had the m ost thorough acquaintance with all the work previously done in m athem atics He returned however to Syracuse where he made hi m self useful to his ad m iring friend and patron King Hieron by applying hi s ex traordinary inventive genius to the construction of various war engines by which he inflicted m uch loss on the Romans during the siege of M arcellus The story that by the use of mirrors reflecting the sun s rays he set on fire the Ro man ships when they came within bow shot of the walls is probably a fi c ti on The city was taken at l ength by the Ro mans a n d Archi medes perished in the in di scrim inate sl aughter which followed Accordi ng to tradition he was at the ti me studying the diagram to so m e proble m drawn in the sand As a Roman soldier approached hi m he called out Don t S poil The soldier feeling insulted rushed upon him and killed my circles No blam e attaches to t he Ro man general M arcel l us who ad hi m m ired his g enius and raised in his honor a tomb bearing the figure of a sphere inscribed in a cylinder When Cicero was in Syracuse he found the to mb buried under rubbish Archim edes was admired by his f ellow citiz ens c hi efly for hi s me c han i c al inventions ; he hi m self pri z ed far more ighly his discoveries h “ in pure science He declared that every kind of art whi ch was con n ec t ed with daily needs was ignoble and vulgar So m e of his works have been lost The following are the e xtant books arranged ap proximately in chronological order : 1 Two book s on E qu i pond er a n ce of P l an es or C en tr es of P l an e Gr a vi ti es between which is inserted his treatise on the Qu adr a tu r e of the P ar abol a; 2 The M ethod; 3 Two books on the S pher e and Cyl i n der ; 4 The M eas u r emen t of the C i rcl e; 5 On S pi r al s; 6 C on oi ds and S pher oi ds ; 7 The S a nd C ou n ter ; 8 Two books on Fl oati ng B odi es; 9 Fifteen L emmas In the book on the M easu r emen t of the Ci r cl e Archimedes prov es first that the area of a circle is equal to that of a right triangle having the length of the circumference for its base and the radius for its altitude In this he assumes that there exists a straight line equal in length to the circu mference—an assu mption obj ected to by som e ancient critics on the ground that it is not ev i dent that a straight line can equal a curved one The finding of such a line was the next . . , , , . . . , , ‘ . , , , . . , , ’ , , , - , . , ’ , , - . , , . ” , . , , ’ , , , . , , . , . , . - ” . . . , . , . . . . - . . . . . , , . , . ° GREEK GEO M ETRY 35 problem H e first finds an upper lim it to the ratio of the circum fer ence to the diam eter or To do this he starts with an equilate ral triangle of which the b ase 1s a tangent and the verte x is the centre of the circle By successiv ely bisecting the angle at the centre by c om paring ratios and by taking the irrational square roots always a little too small he finally arrived at the conclusion that 7r < 34 Nex t he finds a lower limit by inscribing in the circle regular polygons of 6 1 2 sides finding for each successive polygon its perimeter 24 which is of course always less than the circu mference Thus he “ finally concludes that the circu mference of a circle e xceeds three ti mes its diameter by a part which is less than 4 but more than 44 of the diameter Thi s approximation is e xact enough for most pur poses The Ou adr a tu r e of the P ar abol a contains two solutions to the prob l em—one m echanical the other geo m etrical The m ethod of ex hau s tion is used in both It is noteworthy that perhaps through the influenc e o f Zeno in fi n i t esi mal s (i n finitely s mall constants ) were not used in rigorous de monstration In fact the great geom eters of the period now under consideration resorted to the radical m easure of excluding them fro m demonstrative geo metry by a postulate This was done by Eudoxus Euclid and Archimedes In the preface to the Ou adr atu r e of the P ar ab ol a occurs the S O called Archimedean postulate which Archi me des “ himself attributes to Eu doxus : When two spaces are unequal it i s possible to add to itself the diff erence by which the lesser 1s su rpassed by the greater so often that every finite space will be exceeded Euclid (El emen ts V 4) gives the postulate in the for m of a definition : M agnit udes are said to hav e a ratio to one another when the less can be multiplied so as to exceed the other Nevertheless i n fi n i t esi m als m ay have bee n used in tentative researches That such was the case with Archimedes is evident fro m his book The M ethod formerly thought to be irretrievably lost but fortunately discovered by Heiberg in 1 90 6 in Constantinople The contents of this book S hows that he considered i n fi n i t esimal s sufficiently scientific to suggest the truths O f theorem s but not to furnish rigorous proofs In finding the areas of parabolic segments the volumes of S pherical segments and other solids of revolution he uses a mechanical process consisting of the weighing of infinitesimal ele ments which he calls straight lines or plane areas but which are really infinitely narrow strips or infinitely thin plane 1 a l min ae The breadth o r thickness is regarded as being the sa me in the elem ents weighed at any one tim e The Archim e dean postulate d i d not co m mand the interest O f m athe m aticians until t he m o de r n arithm etic continuu m was created I t was 0 S tol z that showed that it was a consequence of Dedek i n d s postulate relating to sections . , , . , , . , , , , , , ~ , . , ” ‘ . . . , . . , . , , . , . , , , , , . , ” , . , - . , , , , . , . , , , , , . . . ‘ . ” . ’ . 1 T L H ea t h , M ethod . . f o A rchi medes , C a mb r i dg e , 191 2, p 8 . . A HISTORY OF M ATHE M ATICS 36 It would seem that in his great researches Archimedes mode of procedure was to start with mechanics ( centre of mass of surfaces and solids) and by his i n fi ni t esimal m echanical m ethod to discover new resul ts for whi ch later he deduced and published the rigorous proofs 1 Archimedes knew the integral f x3dx Archi medes studied also the ellipse and accomplished its quadrature but to the hyperbola he seem s to have paid less attention It is b e l i ev ed that he wrote a book on conic sections Of all his discoveries Archim edes priz ed most hi ghl y those in his In it are proved the new theore m s that the S pher e a nd Cyl i nder surface of a sphere is equal to four times a great circle ; that the surface segment of a sphere is equal to a circle Whose radius is the straight line drawn from the vertex of the segment to the circ umference of its basal circle ; that the volume and the surface of a sphere are 4 of th e volum e and surface respectiv ely of the cylinder circum scribed about the sphere Archimedes desired that the figure to the last proposition be inscribed on hi s to mb Th is was ordered done by M arcellus “ The spiral now called the spiral of Archi medes and described in the book On S pi ral s was discovered by Archimedes and not as some 2 believ e by his friend Conon His treatise thereon is perhaps the Nowadays subj ects of this kind most wonderful of all his works are m ade easy by the use of the infinitesimal calculus In its stead the ancients used the m ethod of exh austion Nowhere is the fertility of hi s genius m ore grandly displayed than in hi s masterly use of thi s m ethod With Euclid and his predecessors the method of exhaustion was only the me ans of prov ing propositions whi ch m ust have been seen and belie v ed before they were proved B ut in the hands of Archi medes this m ethod perhaps combined with his i nfi ni te simal mechanical m ethod becam e an instru m ent of discovery By the word conoid in his book on C on oi ds and S pher oi ds is meant the solid produced by the revolution of a parabola or a hyper bola about its axis Spheroids are produced by the rev olution of an ellip se and are long or flat according as the ellipse revol v es around the major or minor axis The book leads up to the cubature of these solids A few constructions of geo metric figures were given by A rchi medes and Appolonius whi ch were “ eff ected by insertions In the followi ng trisection of an angle at tributed by the Arabs to Archi m edes the insertion is achieved by the aid of a gr adu a ted ruler 3 “ To trisect the angle CAB draw the arc B CD Then insert the — H G Z th i B i bl i th c m th m ti l 6 S V o 7 p 34 7 3 7 9 ’ , , , - . . , . . . , , , . . . , , , , . , , . , , . . . . , ” , “ . , , . , , . . ” . , ” , . . , 1 . 2 . M C an to r . en eu , F E n riq u es , L eip i g , 1 90 7 , p 3 z . . o e a a e a ca , . . , Vo l I , 3 A u fl , 1 90 7 , p 3 0 6 Fr a gen der El emen targ eometri e, deu p o n . ci t 2 34 . . , . . . , 1 0 , . . . tsche A u sg . v. H F l e i sc he r , II , . GREEK GEO M ETRY 7 distance F E equal to AB marked on an edge passing through C and moved until the points E and F are located as shown in the figure The required angle is E FD His arithmetical treatise and problem s wil l be considered later We shall now notice hi s works on mechani cs Archimedes is the author of the first sound knowledge on this subject Archytas Aris to tl e and others attempted to form the known m echanical truths into a science but failed Aristotle knew the property of the lever but coul d not establish its true m athematical theory The ra di cal and fatal defect in the speculations of the Greeks in the opinion of Whewell was that though they had in their possession facts and ideas the ideas wer e n ot di sti n ct and appr opri ate to the f acts For i nstance Aristotle asserted that when a body at the end of a lever is moving it may be considered as having two motions ; one in the direction of the tangent and one in the direction of the ra di us ; the former m otion is he says accor di ng to n atu r e the latter con tr ary to n atu r e These “ “ inappropriate notions of natural and unnatural m otions to gether with the habits of thought whi ch dictated these spec u lations made the perception of the true grounds of mechanical properties 1 impossible It see ms strange that even after Archi medes had en t er ed upon the right path thi s science should have re mained ab s ol u t el y stationary till the tim e of Galileo— a period of nearly two thousand years The proof of the property of the lever given in hi s Equ i ponder an ce 2 of P l an es holds its place in many text books to this day M ach “ criticiz es it From the m ere assumption of the equilibrium of equal weights at equal distances is derived the inverse proportionality of weight and lever arm ! How is that possible ? Archi medes estim ate of the efli ci en cy of the lever is expressed in the saying attribute d to him Give me a fulcrum on whi ch to rest and I will m ove the earth While the E qu i pond eran ce treats of solids or the equilibrium of solids the book o n Fl oati ng B odi es tr eats of hydrostatics His atten tion was first drawn to the subject of specific gravity when King Hieron asked hi m to test whether a crown professed by the m aker to be pure gold was not alloyed with silver The story goes that our phi losopher was in a bath when the true m ethod of solution flashed on his m ind “ He i mmediately ran hom e naked shouting I hav e found it ! TO solve the problem he took a piece of gold and a piece of silver each weighing the same as the crown According to one author he deter mined the volu m e of water displaced by the gold silver and crown respectively and calculated from that the amount of gold and silver , , . . . . . , , . , , . ” , , , . , , , , ” , ” . , , . , . , - . , ” . ’ ” , . , , ‘ . , , . , , ” , . , , , , . , , , Will i am Whew ell Hi s tory of the I nducti ve S ci ences 3 rd Ed N ew York w as M as t e r of Tr i n i ty C oll eg e 1 86 6) V ol I p 8 7 Will i am Wh ew el l ( 1 7 94— 1 , , . . , . . , , , 1 85 8, C am b ri dg e 2 E M ach , The S ci ence of M echa n i cs , t r b y T M c c orm ack , C h i ca g o , 1 90 7 , p 1 4 Ern st M ac h ( 1 8 3 8 1 9 1 6 w as p ro fesso r o f t h e hi story an d t heo ry o f t he i n d uc ti ve s ci en c es at t he u n i versi ty o f V i e nn a . . — ) . . . . . A HISTORY OF M ATHE M ATICS 38 in the crown According to another writer he weighed separately the gold sil v er an d crown while immersed in water thereby deter m ining their loss of weight in water Fro m these data he easily found the solution It is possible that Archim edes solved the problem by both m ethods After exa mining the writings of Archimedes one can well under stand how in ancient tim es an Archi medean problem cam e to m ean a proble m too deep for ordi na r y minds to solve and how an “ Archi medean proof came to be the synonym for unquestionable certainty Archim edes wrote on a ver y wide range of subj ects and displayed great profundity in each He is the Newton of antiquity Er ato s t h e n e s eleven years younger than Archi m edes was a native of Cyrene He was educated in Alexandria under Callimachus the poet who m he succeeded as custo dian of the Alexandrian Library His many— sided acti v ity m ay be inferred fro m his works He wrote on Good a nd E vi l M easu r emen t of the E ar th C omedy Geogr aphy He was C hr on ol ogy C on s tel l a ti on s and the Du pl i ca ti on of the Cu be also a philologian and a poet He m easured the obliquity of the ecliptic and invented a device for finding prime numbers to be de scribed later Of hi s geo metrical writings we possess only a letter to P tole m y Euergetes giving a history of the duplication proble m and also the description of a very ingenious mechanical contriv ance of his own to sol v e it In his old age he lost his eyesight and on that account is said to ha v e co mmitted suicide by voluntary starvation About forty years after Archimedes flourished Apo l lo ni u s of P e r g a whose genius nearly equalled that of his great predecessor He i n c on t es t ab l y occupies the second place in distinction a mong ancient m athe m a t i c i an s Apollonius was born in the reign of P tole m y Euergetes and died under P tole my P hi l op ator who reigned 2 2 2 —2 0 5 B C H e studied at Alexandria under the successors of Euclid and for so m e ti m e also at P ergamum where he m a de the acquaintance of that E u dem u s to who m he d edicated the first three books of his C on i c S ecti on s The brilliancy of his great work brought him the title of the Great Geo m eter This is all that is known of hi s life His C on i c S ecti on s were in eight books of whi ch the first four only have come down to us in the original Greek The nex t three b ooks were unknown in Europe till the m iddle of the seventeenth century when an Arabic t ranslation m ade about 1 2 50 was discov ered The eighth book has never been found In 1 7 1 0 E Halley of Oxford pub l i sh ed the Greek text of the first four books and a Latin translation of the re maining three together with his conj ectural restoration of the eighth book foun d e d on the intro ductory le mm as of P appus The first four books contain little more than the substance of what earlier geometers had done Eu t oc i u s tells us that H erac li des in his life of Archim edes accused Appolonius of hav ing appropriate d in his Con i c S ecti on s the unpublished d iscoveries of that great m athe mati cian . , , , , , . . ” . , , , , . , . . , , . . , . , , , , , , . . ' , . , . , . , . . . . , , , , , ” . . . , . , , . , . . , . , . , , , , . GREEK GEO M ETRY 39 It is diffi cult to believe that this charge rests upon good foundation Eu to ci u s quotes Ge m inus as replying that neither Archi medes nor Apollonius claimed to have invented the conic sections but that Apollonius had introduced a real i mprove ment While the first three or four books were founded on the works of M en aechmu s Aristaeus Euclid and Archim e des the remaining ones consisted alm ost entirely of new matter The first three books were sent to Eu dem u s at inter vals the other books (after E u demu s s death ) to one Attalus The preface of the second book is interesting as showing the m ode i n which Greek books were published at this time I t reads thus : “ I have sent m y son Apollonius to bring you (Eu d emu s) the secon d book of my Conics Read it carefully and comm unicate it to such others as are worthy of it If P hil on ide s the geom eter who m I intro du c e d to you at Ephesus co m es into the neighbourhood of P erga m um 1 giv e it to him also The first book says Apollonius in his preface to it contains the m o de of pro d ucing the three sections and the conj ugate h yperbolas and their principal characteristics more ful ly and generally worked out than in the writings of other authors We rem e mber that M e n aechm u s and all his successors down to Apollonius considered onl y sections of r i ght cones by a plane perpendicular to their si des and tha t Apol t he three sections were ob taine d each fro m a di fferent cone He produce d all the l o n i u s introduced an i mportant generalisation sections fro m one and the sam e cone whether right or scalene and by sections which m ay or may not be perpen dicular to its sides The Instea d O l d nam es for the three curves were now no longer applicable “ “ of calling the three curves sections of the acute angled right “ angled and obtuse angled cone he called them ell i pse par abol a “ To be sure we find the words parabola a n d hyper bol a respectively “ and ellipse in the works of Arch i medes but they are probably only “ 2 interpolati ons The word ellipse was applied because y < px p “ being the parameter ; the word parabola was introduced because 2 2= > the ter hyperbola because x a n d m y px p y The treatise of Apollonius rests on a unique property of conic sec tions whi ch is deriv ed directly fro m the nature of the cone in wh i ch these sections are found How this property form s the key to the 2 syste m of the ancients is told in a m asterly way by M Chasles “ “ Conceive says he an obl i que cone on a circ u lar base ; the stra ight l i ne draw n fro m its su mmit to the centre of the circle forming its base is called the axi s of the cone The plane pass i ng through the axis perpen dicular to its base cuts the cone along two lines and determi nes in the circle a diameter ; the triangle havi ng th i s diam eter for its base . , . , , , , . ’ , ‘ . ” “ . . ” , , . , , . , , , . , , , . . , , . ” , ” . ” , - , - ” ” , . , , , , . , ” , . , , . ” . , . , , . , 1 H . 1 8 86 , 2 G . Ze u t h e n Di e , L ehr e e on den K eg el schn i tten i m A l ter thu m, K op e n h ag en , p 50 2 M C h a sl e s , Geschi chte der Geometr i c L A S o h n ek e , H a l l e , 1 8 39 , p 1 5 . . . Dr . . . . . . A u s d em Fr a n z os i sc h e n u b e r t r ag e n d u rc h , A HISTORY OF M ATHE M ATICS 40 and the two lines for its sides is called the tr i an gl e thr ough the axi s In the formation of his conic sections Apollonius supposed the cutting plane to be perpendicul ar to the plane of the triangle through the axi s The points in whi ch thi s plane meets the two sides of this tri angle are the ver ti ces of the c u rve ; and the straight line whi ch j oins these two points is a diameter of it Apolloni us called this di ameter l atu s tr an sversu m At one of the two vertices of the curve erect a per to t he plane of the triangle thr ough the p e n di c ul ar (l atu s r ectu m) axis of a certain length to be determined as we shall specify later and from the ex trem ity of this perpendicular draw a straight line to the other vertex of the curve ; now thr ough any point whatever of the diameter of the curve draw at right angles an ordi n ate the square of this ordinat e co mprehended between the diameter and the curve will be equal to the rectangle constructed on the portion of the ordi nate co mprised between the diameter and the straight li ne and the part of the di am eter co mprised between the first vertex and the foot of the ordinate Such is the characteristic property which Apollonius recog mises in hi s conic sections and whi ch he uses for the purpose of i n ferring fro m it by adroit transformations and deductions nearly all the rest It plays as we shall see in his hands al most the same rOl e as the equation of the second degree with two variables ( abscissa and ordinate ) in the syste m of analytic geom etry of D escartes Apol 1 — l on i u s m ade use of c o ordinates as di d M enaechmu s before hi m Chasles continues : It will be observed fro m thi s that the di ameter of the curve and the perpendi cular erected at one of its extrem ities suffi ce to construct the curve These are the two element s whi ch the ancients used with whi ch to establish their theory of conics The perpendicul ar in ques tion was called by the m l atu s erectu m; the m ode m s changed this nam e first to that of l a tu s r ectu m and afterwar d s to that O f par ameter The first book of the C on i c S ecti on s O f Apollonius is al most wholly de v o ted to the generation of the three principal conic sections The second book treats mainly of asymptotes axes and diameters The third book treats of the equality or proportionality of triangles rectangles or squares of whi ch the co mponent parts are determi ned by portions of transversals chords asymptotes or tangents which are frequently subj ect to a great number of con di tions It also touches the subj ect of foci of the ellipse and hyperbola In the fourth book Apollonius discusses the harmonic di v ision of straight lines He also examines a syste m of two conics ; and shows t hat they cannot cut each other in m ore than four points He i nv es t ig a t es the various possible relative positions of two co ni cs as for instance when they have one or two points of contact with each other The fifth book reveals better than any other the giant intellect of its author D iffi cult questions of maxi ma and mi n i ma of whi ch few T L He t h A p l l ni u f P e g C amb i dg 8 96 p C X V , . , . . . ’ , , , , . , , , , . , , . , , ” , . . “ . , ” . . , . , , . , , , , , , , . . , . . , , , . . , 1 . . a , o o s o r a, r e, 1 , . . A HISTORY OF M ATHE M ATICS 2 adapted to the invention of general m ethods Instead of a cli mb to st ill loftier heights we observe therefore on the part of later Greek geometers a descent during which they paused here and there to look around for details which had been passed by in the hasty ascent 1 A mong the earliest successors of Apollonius was N i c ome d e s Noth ing definite is known of him e xcept that he invented the con choid a curv e of the fourth order He devised a little ( m ussel m achine by w hi ch the curve could be easily described With aid of the conchoid he duplicated the cube The curve can also be used for trisecting angles in a manner rese mbling that in the eighth le mma of Archi medes P roclus ascribes this mode of trisection to N i comedes but P appus on the other hand claims it as his own The conchoid was used by Newton in constructing curv es of the third degree About the tim e of N i c omedes ( say 1 8 0 B flourished also “ D iocl e s the in v entor of the ci ss oi d ( ivy Thi s curve he used for finding two mean proportionals between two given straight lines The Greeks did not consider the co mpanion curve to the cissoid ; in fact they considered only the part of the cissoid proper whi ch lies insi de the circle used in constructing the curve The part of the area of the circle left over when t he two circular areas on the concave sides of the branches of the curve are remove d looks somewhat like an ivy leaf Hence probably the nam e of the curve That the two branches ex ten d to infinity appears to have been noticed first by G P de Rob er al in 1 6 40 and then by R de Sluse 2 About the life of P e r s e u s we know as little as about that of Nico m edes and Diocles He lived so m e tim e between 2 00 and 1 00 B C From Heron and Ge m inus we learn that he wrote a work on the spi r e a sort of anchor ring surface described by Heron as being produced by the revolution O f a circle around one of its chords as an axis The sections of this surface yield peculiar curves called spi r al s ecti ons whi ch according to Gem inus were thought out by P erseus These cu rves appear to be the sam e as the H i ppopede of Eudoxus P robably som ewhat later than P erseus lived Z e n od oru s He wrote an interesting treatise on a new subj ect ; namely i s oper i metr i cal figu r es Fourteen propositions are preserved by P appus and Theon Here are a few of the m :Of isoperimetrical regular polygons the one having the largest num ber of angles has the greatest area ; the circle has a greater area than any regular polygon of equal periphery ; of all iso p eri me n t r i c al polygons of n S ides the regular is the greatest ; of all solids having surfaces equal in area the sphere has th e greatest volu me H yps i cl e s (between 2 00 and 1 0 0 B C ) was supposed to be the author of both the fourteenth a n d fifteenth books of Eucli d but recent criti cs are of opinion that the fifteenth book was written by an author . , , , , . . , “ . . . . , , . , . . , , . - , . , - . , . , . . . . . . . , - . , , . , . . . , . , , , , . . . , 1 M C an t or . 2 , p o . G L or i a , E ben e . V o l I , 3 A u fl , 1 90 7 , p 3 5 0 C ur ve/i , t ra n s l by F S c h ii tte , I , ci t . , . . . . . . 1910, p 37 . . G REEK G EO M ETRY 3 who lived several centuries after Christ The fourteenth book con tains seven elegant theore m s on r eg ul ar sol i ds A treatise of Hypsi cl e s on Ri s i ngs is of interest because it gi v es the div ision of the circum ference into 3 60 degrees after the fashion of the B abylonians H ippar c h u s of N i c aea i n B i thyn i a was the greatest astrono mer of antiquity He took astronom ical observations between 1 6 1 a n d 1 2 7 B C He established in d uctiv ely the famous theory of epicycles and eccentrics As might be expected he was interested in m athe matics not per s e but only as an aid to astronomical inquiry No mathe mat i c al writings O f his are extant but Theo n of Alexandria infor m s us that Hipparchus originate d the science of tr igon ometry and that he calculated a table of chor d s in twelve books Such calculations m ust have required a ready knowle dge of arithm etical and algebraical operations He possessed arithmetical and also graphical devices for solving geo metrical proble m s in a plane and on a S phere He gives indication of having sei zed the idea of c o ordinate representation found earlier in Apollonius About 1 0 0 B C flourished H e r o n th e El d e r of Alexandria He was the pupil of C t esib i u s who was celebrated for his ingenious mechanical inventions such as the hydraulic organ the water clock an d catapult It is belie v ed by some that Heron was a son of C t esi b i u s He ex hi bi t ed talent of the sam e order as did his m ast er by the invention of “ the eolipile and a curious mechanism known as Heron s fountain Great uncertainty exists concerning his writings M ost authorities believe him to be the author of an i mportant Tr eati s e on the D i optr a of which there exist three m anuscript copies quite dissimilar B ut 1 M M arie thinks that the D i optr a is the work of H eron the Y ou nger who lived in the seventh or eighth century after Christ an d that Geodesy another book supposed to be by Heron is only a corrupt and defective Copy of the former work Di optr a contains the im portant formula for finding the area O f a triangle expressed in te r m s O f its sides ; its derivation is quite laborious and yet excee dingly ingenious “ It see m s to me difficult to believe says Chasles that so beautiful a theore m sho uld be found in a work so ancient as that of Heron the Elder without that so me Greek geo meter should have thought to M arie lays great stress on thi s silence of the ancient writers cite it and argues fro m it that the true author m ust be Heron the Younger or some writer m uch more recent than Heron the Elder B ut no r e liable evidence has been found that there actually existed a second mathem atician by the nam e of Heron P Tannery has shown that i n applying this for mula Heron found the irrational square roots by . . . . . . . , , . , ' , ” , . . . - , . . . . , - , . , , . ” ’ . . , . , . , , , , . ” “ . , , ” , , . . . , . - , the approximation 1 , ~ / x Z 4 M axi mil i en M a r i e H i s toi r e des To me I , , 1 88 3 , p . 1 78 . A where s c i e nc es a 2 is the square nearest to mathemati q u es et phys i q u es . P ar i s , A . HISTORY A 44 more When a O F M ATH E M ATICS A accurate value was wanted Heron took , in the place of a in the above form ula Apparently Heron some “ times found square and cube roots also by the method of double false position “ Dioptra says Venturi were instrum ents which had g reat re semblance to our modern theodolites The book Di optr a is a treatise on geodesy contai ning solutions with aid of these instru ments of a large nu mber of questions in geometry such as to find the dista nce between two points of which one only is accessible or between two points which are visible but both inaccessible ; from a given point to draw a perpendi cular to a line which cannot be approached ; to find the difference of level between two points ; to measure the area of a field without entering it Heron was a practical surveyor This may account for the fact that his writings bear so little resemblance to those of the Greek authors who considered it degrading the science to apply geometry to surveying The character of his geometry is not Grecian but de This fact is the m ore surprising when we consider c idedl y Egyp tian that Heron de monstrated his familiarity with Euclid by writing a com m entary on the El emen ts So m e of Heron s for mulas point to an old Egyp tian origin Thus besides the above e xact formula for the area . ” , ” . , , . , , , , , . . , . , . ’ . . , of a triangle in ter ms of its sides Heron gives the formula al , whi ch bears a striking likeness to the formula x 2 + az 01 + az (3 1+ bz x fO 1 2 2 finding the area of a quadrangle found in the Edfu inscriptions There are m oreov er points of resemblance between Heron s writings and the ancient Ahmes papyrus Thus Ahm es used unit fractions exclusively (except the fraction Heron uses them oftener than o ther fractions Like Ahmes and the priests at Edfu Heron divides c om plicated figures into simpler ones by drawing auxiliary lines ; like the m he shows throughout a special fondness for the isosceles trapez oid The writings of Heron satisfied a practical want and for that reason were borrowed extensively by other peoples We find traces of them in Ro me in the Occident during the M iddle Ages and even in In dia The works attributed to Heron including the newly discovere d M el ri ca published in 1 90 3 have been edited by J H Heiberg H S chOn e and W Schmidt G e mi n u s of Rhodes (about 7 0 B c ) published an astronomical work still ex tant He wrote also a book now lost on the A rr angemen t of M a themati cs which contained m any valuable notices of the early history of Greek mathematics P roclus and Eu toc iu s quote it fre quently Theodosius is the author of a book of little m erit on the . , ’ , , - . . , , , . , , . . , , , . , . . . . , . , . . . , . , GREEK GEO M ETRY 45 geometry of the sphere Investigations due to P Tannery and A A l BjOrnb o see m to indicate that the m athe m atician Theodosius was not Theodosius of Tripolis as formerly supposed but was a resident of Bithyni a and conte mporary of Hipparchus Di onys odoru s of Ami sus in P ontus applied the intersection of a parabola and hyperbola to the solution of a problem whi ch Arc hi medes in his S phere and “ Cyl i nder had left inco mplete The proble m is to cut a sphere so that its segments shall be in a giv en rati o We have now sketched the progress of geometry dow n to the time of Christ Unfortunately very little is known of the histor y of geo m e t ry between the ti m e of Apollonius and the beginning of the Christian era The names of qui te a number of geo meters have been mentioned but very few of their works are now extant It is certain however that there were no mathe maticians of real genius from Apollonius to P tole my excep ting Hipparchus and perhaps Heron . . , . . , . ” . , , . . , . , , . , , . The S econd A l exandr i an S chool The close of the dynasty of the L ag i des which ruled Egyp t from the tim e of P tole my Soter the builder of Ale xandria for 3 00 years ; the absorption of E g ypt into the Ro man E mpire ; the closer co mm ercial relations between peoples of the East and of the West ; the gradual decline of paganism and spread of Christianity these events were of far reaching influence on the progress of the sciences which then had their ho me in Alexandria Alexandria became a comm ercial and intellectual e mporium Traders of all nations m e t in her busy streets and in her magnificent Library museu ms lecture halls scholars fro m the East mingled wi th those of the West ; Greeks began to stu dy older literatures and to compare them with their own In consequence of this interchange of ideas the Greek philosophy becam e fused with Oriental philosophy N eo P ythagoreanism and Neo P latonism were the names of the modified system s These stood for a ti me in Op position to Christianity The study of P latonism and P ythagorean mysticism led to the revival of the theory of nu mbers P erhaps the dispersion of the Jews and their introduction to Greek learning helped in bringing about this reviv al The theory of numbers became a favorite study This new line of mathematical inquiry ushered in what we may call a new school There is no doub t that even now geometry continued to be one of the most i mportant studies in the Alexandrian course This Second Alexandrian School may be said to begin with the Christian era It was m ade fam ous by the na mes of Claudius P tolemaeus D iophantus P appus Theon of S myrna Theon of Alexandria I ambli chu s P orphyrius and others By the side of these we may place S er e n u s of An t i noei a as ha v ing hi t ri n of m the Axel A t ho B j r b ( 8 7 4—9 )f C op e n hag en w — — l m t i c S V o 1 i e S ee B i bl i o t m a t h s a a t h c m 3 9 pp 3 3 7 344 , , - , - , . . , - , , , . - - . . , , . . . . . . . , , , , , . . , , , 1 n . n o n e o 1 1 e a 11 a, as a o . , . 1 2, 1 1 1 2, s o . a a . M ATHE M ATICS A HISTORY OF 46 been connected more or less with this new school He wrote on sec tions of the cone and cylinder in two books one of whi ch treated only of the triangular section of the cone through the apex He solved “ the problem given a cone ( cylinder )to find a cylinder ( cone)so that the section of both by the sam e plane gives similar ellipses Of partic ul ar interest is the following theore m which is the foundation of the m odern theory of harmonics : If from D we draw DF cutting the triangle A B C and choose H on it so that DE DF = EH :H E and if we draw the line A H then every transversal through D such as DG will be div ided by A H so that DK DG = K] J G M e n e l a u s of Alexandria ( about 98 A D ) was the author of S phce r i ca a work extant in Hebrew and Arabic but not in Greek In it he proves the theorem s on the congruence of spherical triangles and describes their properties in m uch the sam e way as Euclid treats plane tri In it are also found the D angles theore m s that the sum of the three sides O f a spherical triangle is less than a great circle and that the s u m of the three angles exceeds two right angles Celebrated are two theorem s of his on plane and spherical triangles The one on plane tri “ angles is that if the three sides be cut by a stra ight line the product of the three segm ents which ha v e no comm on ex trem ity is equal to the product of the other three L N M Carnot m akes this proposition “ known as the lemm a of M enelaus the base of his theory of trans versals The corresponding theorem for spherical triangles the so called regula s ex q u an ti ta t u m is obtained fro m the above by “ “ rea ding chords of three segments doubled in place of three seg ments C laudiu s P tol e my a celebrated astrono m er was a native of Egypt Nothing is known of his personal history except that he flourished in Alexan dria in 1 39 A D and that he m ade the earliest astronomical O bser v ations recor ded in his works in 1 2 5 A D the latest in 1 5 1 A D The chief of his works are the S yn taxi s M a themati ca (or the A l mages t as the Arabs call it) and the Geog r aphi ca both of which are extant The for mer work i s based partly on his own researches but m ainly on those of Hipparchus P tolemy see m s to have been not so m uch of an independent investigator as a corrector and i mprover O f the work of his great predecessors The A l mages t 1 form s the foundation of all astrono mical science down to N Copernicus The fundam ental “ i dea of his syste m the P tole maic System is that the earth is in the centre of the un i verse and that the sun and p l anets revolve around the earth P tolem y did considerable for m athematics He creat ed . , , . ” , , , . , , , , , , , . , . . , . , , . , . . , , . ” ” . . . , , . ” , , , . , . , . . . , . . , . , . , , . , . ” . . , , , . . 1 On t he i mpor tan c e Tann ery , Recher ches s ur of ’ t h e Al ma g e s t i n th e hi s tory l hi s toi r e de l ’ mi e, P a ri s, as tron o o f as t ron o 1 8 93 . , my, co n s u l t P . GREEK GEO M ETRY for astrono mical use a tri gon ometry remarkably perfect in form The foundation of this science was laid by the illustrious Hipparchus The A l mages t is in 1 3 books Chapter 9 of the first book shows how to calculate tables of chords The circle is div ided into 3 6 0 degrees each of which is halved The diameter is di vided into 1 2 0 divisions ; each of these into 6 0 parts which are again subdivided into 6 0 smaller parts In Latin these parts were called par tes mi n u tae pr i mae and r tes mi n u tx s ecu nd a a Hence our nam es m inutes and seconds p The se xagesimal m ethod of div iding the circle is of Bab ylonian origin and was known to Geminus and Hipparchus B ut P tolemy s m ethod of calculating chords seem s original with hi m He first proved the “ proposition now appended t o Euclid VI (D)that the rectangle contained by the diagonals of a quadrilateral figure inscribed in a circle is equal to both the rectangles contained by its opposite S ides He then shows how to find from the chords O f two arcs the chords of their su m and di fference and from the chord of any arc that of its half These theore m s he applied to the calculation of his tables of chords The proofs of these theorems are v ery pretty P tole my s construction of sides of a regular inscribed pentagon and decagon was giv en later by C Clavius and L M ascheroni and now is used m uch by engineers Let the radius B D be _ L to A C DE = EC M ake E F = EB then B F is the side of the pentagon and DF is the side of the decagon Another chapter of the first book in the A l ma g es t is de v oted to tr i gon ometry and to s pher i ca l A F D E C trigonom etry in particular P tole my proved the “ “ lemma of M enelaus and also the regula sex q u an t i tatum Upon these propositions he built up his trigono metry In trigono m etric co mputations the Greeks di d not use as did the Hindus half “ the chor d of twice the arc ( the sine the Greeks used ins tead the whole chord of double the arc Only in grap hic constructions referred to again later did P tolemy and hi s predecessors use half the chord of double the arc The fundamental theorem of plane trigo n ome t ry that two sides of a triangle are to each other as the chords of double the arcs m easuring the angles opposite the two sides was not stated e xplicitly by P tole m y but was contained i mplicitly in other theorem s M ore complete are the propositions in spherical trigo . , . . . , . , . ” , ’ . . , , ’ . . , , ” . , . ’ . . . . , . , , . , ” . . , . . , , , . , , . , , , . n om e try . fact that trigonometry was cultivated not for its own sake but to aid astrono mical inquiry explains the rather startling fact that spherical trigonometry cam e to e xist in a developed state earlier than plane trigono metry The re maining books of the A l mages t are on astronomy P tolemy has written other works which have little or no bearing on mathe m aties except one on geo m etry Extracts fro m this book m ad e by P roclus indicate that P tole my did not regard the parallel a xiom of The , , ‘ . . , . , , - A HISTORY OF M ATHE M ATICS 48 Euclid as self evident and that P tole my was the first of the long line of geom eters fro m ancient time down to our own who toiled in the vain attempt to pro v e it The untenable part of his de monstratio n is the assertion that in case of parallelism the su m of the interior angles on one side of a transversal must be the sam e as their su m on the other side of the transversal B efore P tolemy an attempt to improve the theory of parallels was made by P os i do ni u s (firs t cent B C ) who de fined parallel lines as lines that are coplanar and equidistant Fro m an Arabic writer A l N i r i zi ( ninth cent ) it appears that Si mplicius brought forward a proof of the 5th postulate based upon this def inition and due to his friend Ag ani s In the m aking of maps of the earth s surface and of the celestial sphere P tolemy ( following Hipparchus) used stereograp hic projection The eye is im agined to be at one of the poles the projection being thrown upon the equatorial plane He devised an instrum ent a form of astrolabe plani sphere whi ch is a stereographi c proj ection of the celestial sphere 2 P tole my wrote a m onograph on the an al emrn a which was a figure invol v ing orthographic proj ections of the celestial sphere upon three m utually perpendi cular planes ( the horiz ontal meridian and vertical circles)The anale mm a was used in deter mining positions of the sun the rising and setting of the stars The procedure was probably known to Hipparchus and the older astronom ers It fur nished a graphic m ethod for the solution of spherical triangles and was used subsequently by the Hindus the Arabs and Europeans as late 3 as the seventeenth century Two prominent mathematicians of this tim e were Ni comachu s and Their favorite study was theory of n umbers Theon _ of S m yrna The investigations in this science cul m inated later in the algebra of Diophantus B ut no important geometer appeared after P tole my for 1 50 years An occupant of this long gap was S e xtu s J u li u s Afric an u s who wrote an u nM por t an t work on geo metry appli ed to the art of war entitled C estes Another was the sceptic S extu s “ he endeavored to elucidate Zeno s Arrow Empi ri cu s ( 2 00 A by stating another argument equally p aradoxical and therefore far fro m illu minating : M en never die for if a man die it must either be at a t ime when he is alive or at a time when he is not aliv e ; hence he never dies Sextus Empiri cu s ad vanced also the paradox that when a line rotating in a plane about one of its ends describes a circle w ith each of its points these concentric circles are of u m equal area yet each circle must be equal to the neighbouring circle 1 which it touches l aw C hi g o R B o ol N n E cli dean G om t y t an s by H S C 9 2 — — R B l w i R om e b 8 t a 8 ( 75 9 ) p of pp 3 - , . , , . . . . . - . , , , ’ . , , . , , . , . . , . , , . . . . . , . , ” , ’ . , , , , . , , , . 1 n . . a, er o . o u - ono e r e 1 1 11 r ” Am M , as r . . essor n . a rs , ca 1 , 1 . T h e A s t r ol a b e , 24, 1 91 7, p 162 a th M on thl y, V ol S e e M L a t ham , 3 S ee A v B r au n mii hl , Geschi chte der Tr i gon ometr i e, L e ip ig , I , 1 90 0 , p 1 1 A l exan d er von B rau n m ii hl ( 1 8 5 3 1 90 8 w a s pro fe ssor a t t he t e c hn i ca l h ig h sc hoo i n M u n i ch “ 2 . . . . . — ) . , z . . . . . l HISTORY A 59 O F M AT H E M ATIC S cylinder and imagine a cone of revolution having for its axis the side of the cylinder passing through the initial point of the spiral then thi s cone cuts the cylinder in a curve of double curvature The per p en di cu l ar s to the a xis drawn through every point in this curve form the surface of a screw which P appus here calls the pl ectoi dal s u rf ace A plane passed t hrough one of the perpendiculars at any convenient angle cuts that surface in a curve whose orthogonal proj ection upon the plane of the spiral is the required qu adr atr i x P appus considers curves of double curvature still further He produces a spher i cal s pi r al by a point m oving unifor mly along the circu mference of a great circle of a sphere while the great circle itself revolves un i formly around its diameter He then finds the area of that portion of the “ surface of the S phere determ ined by the spherical spiral a co mplana tion which claim s the m ore lively admiration if we consider that although the entire surface of the S phere was known since Archi m edes tim e to m easure portions thereof such as spherical triangles was 1 then and for a long time after wards an unsol v ed proble m A q uestion whi ch was brought into pro m inence by D escartes and Newton “ is the proble m of P appus Given several straight lines in a plane to find the locus of a point such that when perpendiculars (or more generally straight line s at given angles) are drawn fro m it to the giv en lines the product of certain ones of them shall be in a given ratio to the product of the re maining ones I t is worth noticing that it was P appus who first found the focus of the parabola and pro pounded the theory of the involution of points He used the directrix and was the first to put in definite form the definition of the conic sections as loci of those points whose distances fro m a fixed point and from a fix ed line are in a constant ratio He solved the problem to draw through three points lying in the same straight line three straight lines which shall form a triangle inscribed in a given circle From the M athemati cal C oll ecti on s m any more equally d ifli c ul t the orem s m ight be quoted which are original with P appus as far as we know It ought to be re marked however that he has been charged in three instances with copying theore ms without giving due cre dit and that he m ay have done the same thi ng in other cases in whi ch 2 we have no data by which to ascertain the real discoverer About the tim e of P appus liv ed T h e o n of Alexandria He brought out an e dition of Eucli d s El emen ts with notes which he probably used as a text book in his classes His comm entary on the A l magest is valuable for the m any historical notices and especially for the speci mens of Greek arithm etic which it contains Theon s daughter Hypati a a wo man celebrated for her beauty and m odesty was the last Alexandrian teacher of reputation and is said to have been an , , . . . . , . , , , ” , , . ” . , , , , . . . , . . , , , . . ’ , - . , ’ . , , , 1 M C an tor . , p o . ci t . , V ol I , 3 Au fl . . 1 90 7 , , 2 Fo r a d e fe n ce o f P a pp u s a g a i n s t t h e s e M ath S oc , V ol 2 3 , 1 9 1 6 , pp 1 3 1 — 1 33 . . . . . p 45 1 c ha rg e s , . . se e J H . . Weav er i n B ul l A m . . GREEK GEO M ETRY 5: abler philosopher and m athematician than her father Her notes on the works of D iophantus and Apollonius hav e been lost Her tragic death in 4 1 5 A D is vividly described in Kingsley s H ypati a From n ow on m athematics ceased to be cultivated in Ale xandria The lea d ing subj ect of m en s thoughts was Christian theology P aganism disappeared and with it pagan learning The Neo P latonic school at Athens struggled on a century longer P roclus Isidorus and “ P rocl u s others kept up the gold en chain of P latonic succession the successor O f S yr ian u s at the Athenian school wrote a co mm entary on Euclid s El emen ts We possess only that on the first book which is valuable for the information it contains on the history of geom et ry D ama s ci u s of D a m ascus the pupil of Isidorus is now believ ed to be the author of the fifteenth book of Euclid Another pupil of Isidor us was Eu toci u s of Ascalon the co mm entator of Apollonius and Archi m edes S i mplici u s wrote a co mmentary on Aristotle s D e Cce l o “ Simplicius reports Zeno as saying : That which being added to another does not m ake it greater and being taken away fro m another does not m ake it less is nothing According to this the denial of the existence of the infinitesimal goes back to Zeno This m om entous question presented itself centuries later to Leibni z who gave d iff erent answers The report ma d e by Simplicius of the quadratures of Anti phon and Hippocrates of Chios is one of the best sources of historical 1 information on this point In the year 5 2 9 Justinian disapproving heathen learni ng finally closed by i mperial edict the schools at Athens As a rule the geometers of the last 50 0 years showed a lack of creative power They were commentators rather than discoverers The principal characteristics of ancient geom etry are A wonderful clearness and defi ni t en ess of its concepts and an (1) a l most perfect logical rigor of its conclusions A co mplete want of general principles and m ethods Ancient (2 ) geometry is decidedly speci al Thus the Greeks possessed no general The determination of t he tangents method of drawing tangents to the three conic sections did not furnish any rational assistance for drawing the tangent to any other new curve such as the conchoid the cissoid etc In the demonstration of a theorem there were for the ancient geom eters as many different cases requiring separate proof as there were diff erent positions for the lines The greatest geometers considered it necessary t o treat all possible cases inde pendently of each other and to prove each with equal fulness To devi se m ethods by whi ch the various cases could all be disposed of “ by one stroke was beyond the power of the ancients If we c om pare a mathem atical problem with a huge rock into the interior of wh ich we desire to penetrate then the work of the Greek mathe . . ’ . . . . , ’ . - . , . ” , , , . , , ’ . , . , , . , ’ . . ” , , , . , , . , . . , , , . , . . . . . . ” , , . , , , , . . , . , , , 1 S ee F R u dio i n B i bl i otheca ma themati ca , 3 S . . , V ol 3 , . 1 90 2 , pp 7 6 2 - . . 5 A HISTORY OF M ATHE M ATICS 2 ma ti ci an s appears to us like that of a vigorous stonecutter who wi th chisel and ha mmer begins with indefatigable perseverance from with out to cru mble the rock slowly into fragm ents ; the m odern m athe m ati ci an appears like an excellent m iner who first bores through the rock som e few passages from which he then bursts it into pieces 1 wi th one powerful blast and brings to light the treasures withi n , , , , ” , , . , Greek A r i thmeti c and Al gebra Greek mathematicians were in the habit of discrimina ti ng between the s ci en ce of nu mbers and the art of calcul ation The former they called ar i thmeti ca the latter l og i sti ca The drawing of this distinction between the two was very natural and proper The di ff erence b e tween the m is as m arked as that between theory an d practice Among the Sophists the art of calculation was a favorite study P lato on the other hand gave considerable attention to phil osop hi cal arith metic but pronounced calculation a vulgar and c hildish art In sketching the history of Greek calculation we shall first give a brief account of the Greek mode of counting and O f writing n um bers L ike the E g yptians and Eastern nations the earliest Greeks counted In case of large num bers the pebbles o n their fingers or with pebbles were probably arranged in parallel vertical lines P ebbles on the first line represented units those on the second tens those on the thi rd hundreds and so on Later frames cam e into use in which strings or wires took the place of lines According to tradition P ythagoras who travelled in Egyp t and perhaps in India first introduced this valuable instrument into Greece The abacu s as it is called e xisted a mong di ff erent p eoples and at di fferent times in various stages of perfection An abacus is still e mployed by the C hi nese under the nam e of S w an pan We possess no specific inform a tion as to how the Greek abacus looked or how it was used Boethius says that the P ythagoreans used with the abacus certain nine signs “ called api ces whi ch resembled in form the nine Arabic n umerals B ut the correctness of thi s assertion is subject to grave doubts The oldest Grecian num erical sym bols were the so called H er odi ani c s i gn s ( after H ero di an u s a Byz antine grammarian of about 2 00 A D who describes them) These signs occur frequently in Athenian i n For s c r ip t i o n s and are on that account now generally called A tti c som e unknown reason these sym bols were afterwards replaced by the a l pha beti c n u mer al s in which the letters of the Greek alphabet were used together with three strange and antique letters I 9 and TD This change was d ecide dly for the worse for the a n d the sy mbol M old Attic numerals were less burdensome on the memory inasm uch . , . . . . , , . , , . , . , . , , . , , , . , , , , , . , , , . - . ” . . , . - 1 . , . , . . , , , , , , . , , H H a n k el , Di e E n twi ck el u n g der M athemati k i n den l etzten J a hr hund er ten T ub i ng en , 1 8 84 , p 1 6 1 . . . . GREEK ARITH M ETI C AND ALGEB RA 53 as they contained fewer symbols and were better adapted to show forth analogies in nu m erical operations The following table shows the Greek alphabetic numerals and their respective values . fl a 2 I r 3 3 4 ' 0 p 1 00 s 5 6 3 00 ) 1 8 7 v 42 400 500 7 2 00 Z e 9 t K it pt v 9 10 20 30 40 50 x 6 00 T?) p 1» 700 8 00 1 900 , f 0 71 Q 60 70 80 90 c “8 o. 1 000 , y etc . 3 000 2 000 It will be noticed that at 1 00 0 the alphabet is begun over again but to prevent confusion a stroke is now placed before the lett er and generally so mewhat below it A horiz ontal line drawn over a number served to distinguish it m ore rea dil y from words The c o eff icient for M was sometim es placed before or behind instead of o v er the M Thus was written 8M yxon It is to be observed that the Greeks had no z ero Fractions were denoted by first writing the num era tor m arked with an accent then the deno minator marked with two accents an d written twice Thus y d K 9 = 44 In case of fractions having unity for ' the nu merator the a was omitted and the denomi nator was written 1 only once Thus " 21 , , , , . . , . . . ” , . , u ’ n . , . The Greeks had the nam e e pi m Archytas 1 2 proved the theorem that if term s Thi s theorem is found later in the then an for the ratio mori on ep i or i on [ is reduced to its lowest m usical writings of Euclid and of the Rom an B oethius The Euclidean for m of arithmetic without perhaps the representation of nu mbers by lines existed as early as the tim e of Archytas 1 Greek writers seldo m refer to calculation with alphabetic nu m erals Addition subtraction and even m ultiplic ation were probably per form ed on the abacus E xpert mathe m aticians m ay have used the symbols Thus Eu t oc i u s a co mm entator of the sixth century after Christ gives a grea t many multiplications of wh i ch the following i s 2 a specimen : . , , . . , , . . , - , P Ta n n e ry i n B i bl i otheca ma thema ti ca , 3 S 2 J G o w , op c i t , p 5 0 1 . . . . . . . , V ol V I , . 1 90 5 , p . 2 28 . A 54 HISTORY M ATHE M ATICS OF The operation is e xplained suf fi c i en t l y by the modern nu merals appended In case of mixed nu mbers , the process was still more clum sy D ivisions are found 1 0 00 1 2 000 MM 8 400 0 0 in Theon of Alexandria s com 1 2 000 M 53 9 m entary on the A l mag es t As 3 00 3 6 00 m xpected the process is ight be e 00 2 1 000 5 3 long and tedi ous We have seen in geo m etry that 70 2 25 the more advanced m athematicians frequently had occasion to extract the square root Thus Arc hi m edes in his M en su r ati on of the Ci r cl e gives a large nu mber of square roots 1— 3— 2 6 5 5— 1 He states for instance that but he gives no and 1 5 3 clue t o t lie m ethod by which he obtained these approxim ations I t is not improbable that the earlier Greek m athematicians found the square root by trial only E u toci u s says that the m ethod of extracting it was given by Heron P appus Theon and other co mm entators on the A l magest Th eon s is the only one of these m ethods known to us It is the sam e as the one used nowadays except that sexagesimal fractions are e mployed in place of our decimals What the m ode of procedure actually was when sexagesimal fractions were not used has been the subj ect of conj ecture on the part of nu merous m odern writers Of interest in connection with arithm etical symbolism is the S and C ou n ter (Arenarius )an essay addressed by Ar chi m e d e s to G elon ki ng of Syracuse In it Archi m edes sho w s that people are in error who think the sand cannot be counted or that if i t can be counted the n umber cannot be e xpressed by arithm etical symbols He shows that the number of grains in a heap of sand not only as large as the whole earth but as large as the entire universe can be arithm etically ex pressed Assum ing that grains of sand suffice to make a little solid of the magnitude of a pop y seed and that the diameter of a p 1 poppy seed be not smaller than 4 part of a finger s breadth assum ing further that the diameter of the un i verse (supposed to extend to the sun) be less than diam eters of the earth and that the latter be less than stadia Archi medes finds a num ber which would e xceed the number of grains of sand in the sphere O f the universe He goes on even further S upposing the universe to reach out to the fix e d stars he finds that the S phere having the distance fro m the earth s centre to the fixed stars for its radi us would contain a num ber of grains of san d less than 1 00 0 myriads of the eighth octad In our notation this number would be 1 0 6 3 or 1 with 6 3 ciphers after it It can hardly be doubte d that one object which Archi medes had in vie w in making this calculation was the i mprov em ent of the Greek sym b ol i sm It is not known whether he inve nted so m e short notation by which to represent the abo v e num ber or not . ” ,, a , 7 a K6 , . , ’ , , , , . , . a K 6 . . , - , . . . , , , ’ . . , . , . , , , , . , , . , , . - , ’ - - , , , , . . , , ’ , . . , . . GREEK ARITH M ETI C AND ALGEBRA 5 We j udge fro m fragments in the second book of P appus that Apol l on i u s proposed an i mprove m ent in the Greek m etho d of writing numbers but its nature we do not know Thus we see that the Greeks never posses sed the boon O f a clear co mprehensive symbolism The honor of giving such to the world was reserved by the irony of fate for a nam eless Indian of an unknown ti m e and we know not who m to thank for an invention of such i mportance to the general progress of intelligence 1 P assing fro m t he subj ect of l ogi s ti ca to that of ari thmeti ca our a t tention is first drawn to the science O f numbers of P yt h ag or as B efore foun ding his school P ythagoras stu die d for m any years under the Egyptian priests and fa miliarise d him self with Egyp tian mathe matics a n d m ysticis m If he ever was in Babylon as so me authorities claim he may have learned the sexagesimal notation in use there ; he may have picked up considerable knowledge on the theory of proportion a n d m ay have found a large nu mber of interesting astrono m ical observations Saturated with that speculativ e spirit then pervad ing the Greek m ind he endeavored to d iscover so me principle of ho m o B efore hi m the philosophers of the Ionic g e n ei t y in the univ erse school had sought it i n the m atter of thi ngs ; P ythagoras looke d for it in the structure of things He O bserve d var i ous nu m erical relations or analogies betwee n num bers and the pheno m ena of the universe B eing con v inced that i t was in nu m bers and their relations that he was to fi n d the foundation to true philosophy he procee d ed to trace the origin of all things to nu mber s Thus he observed that m usical strings of equal length stretched by weights having the proportion of pro uced intervals hi c h w e r e an octave a fifth and a fourth d w 444 Harm ony therefore depe n ds on m usical proportion ; it is nothing but a m yster i ous num eri cal relation Where harm ony is there are Hence the or der and beauty of the univ erse have their n u mbers origin i n n umbers There are sev en intervals in the m usical scale and also seven planets cross i ng the heavens The sam e num erical relations wh i ch underlie the former m ust underlie the latter B ut where nu mbers are there is harm ony Hence his spiritual ear dis cerne d in the planetary m otions a won derful harm ony of the spheres The P ythagoreans inv este d particular nu mbers with ex traor dinary attributes Thus on e is the essence of things ; it is an absolute nu mber ; hence the origin of all nu mbers and so of all things Fou r is the m ost erf ec t nu mber and was in so m e m ystic way conceived to correspond to the hum an soul P hi lolaus bel i e v ed that 5 is the cause of color 6 O f 2 i of m ind and health and l ght 8 of love and frien d ship In cold 7 P lato s works are evi d ences of a s i m i lar bel i ef i n rel i gious relations of numbers E v en Aristotle referre d the virtues to nu mbers Enough has been said about these m ystic speculations to show what l i vely interest in m athe m ati cs they m ust have created and . , . , , . , . , . , , , . , . , . . , . ' , , . , , , , , , . . . , . . . ” . , . . . . , . , , ’ . . 1 J . G ow , p o . ci t . , p 6 . 2 J . G ow , p o . ci t . , p 69 . . A H ISTORY O F M ATHE M ATICS 6 m aintained them which time . Avenues of m athe matical inquiry were opened up by otherwise would probably have remained closed at that . The P ythagoreans classified numbers into odd and even They observed that the sum of the series of odd nu mbers from 1 to 2 n + 1 was always a complete square and that by ad dition of the even n u m bers arises the series 2 6 1 2 2 0 in which every number can be de composed into two factors diff ering from each oth er by unity Thus These latter nu mbers were considered of 6 = 2 3 1 2 = 3 4 etc suffi cient importance to receive the separate name of heteromeci c ( not . , , , , , . . , , . ” ) Z . ( equilateral ) Nu mbers of the form . H , - were call ed tr i an gu l ar , because they could always be arranged thus Num bers which were equal to the su m of all their possible factors such as 6 2 8 4 96 were called perf ect; those exceeding that su m excessi ve; and those whi ch were less def ecti ve A mi cabl e numbers were those o f w hi ch each was the sum of the factors in the other M uch attention was paid by the P ythagoreans to the subj ect of proportion The quan tities a b c d were said to be in ar i thmeti cal proportion when a —b c— d; in g eometr i cal proportion when a :b = c :d; in har mon i c propor — — tion when a b :b c = a zc It is probable that the P ythagoreans , , , , , , ' . , . . , , , , . , were also familiar with the mu si cal proportion — a az +b 2a b m z :b . says that P ythagoras introduced it from Babylon In connection with arithmetic P ythagoras made ex tensive i n yesti m i n s into geo etry He believed that an arithmetical fact had a t o g its analogue in geo m etry and vi ce ver sa In connection with hi s theore m on the right triangle he dev ised a rule by which integral numbers could be found such that the sum of the square s of two of the m equalled the square of the third Thus take for one side an odd I ambl i chu s . , . . , , . 2 n+ ( then number + 2 n + 1 )hypotenuse 1 = , + 2n2 2 2n = t he other side and , If 2 n + 1 9 then the other two nu mbers are 40 and 4 1 B ut this rul e only applies to cases in which the hy fers fro one of the sides by In the study of the right e s f m 1 o t n u e di p triangle there doubtless arose q uestions of pu zzl ing subtlety Thus given a number equal to the side of an isosceles right triangle to find the number which the hypotenuse is equal to The side may have been taken equal to 1 2 4 4 or any other nu mber yet in every i n stance all e ff orts to find a number exactly equal to the hypotenuse m ust have re mained fruitless The problem may have been attacked again and again until finally so me rare genius to who m i t is granted during som e happy mom ents to soar with eagle s flight above the lev el of human thinking grasped the happy thought that this prob ( 2n2 . , . . . , , . , , , , , . ” , , , , ’ , - “ A HISTORY OF M ATHE M ATICS 58 Euclid devot es the seventh eighth and ninth books of his El emen ts to arithm etic E xactly how m uch contained in these books is Euclid s ow n invention and how m uch is borrowed fro m his predecessors we have no means of knowing Without doub t m uch is original with Euclid The s even th book begins with twenty one definitions All except that for prim e num bers are known to have been given by the P ythagoreans Nex t follows a process for fin di ng the G C D The ei ghth book deals with numbers in con O f two or m ore nu m bers t i n u e d proportion and with the m utual relations of squares cubes and plane numbers Thus XXII if three num bers are in cont i nued proportion and the first I S a square so is the thi rd In the n i n th book the sam e subject is continued I t contain s the proposition that the nu mber of primes is greater t han any give n number After the dea t h of Euclid the theory of num bers remained al most stationary for 40 0 years Geo metry monopolised the attention of all Greek mathematicians Only two are known to have done work in — invented arithm etic worthy of m ention Er ato s th e n e s ( 2 7 5 1 94 B C ) “ a sieve for finding prime nu mbers All co mposite nu mbers are “ sifted out in the following manner : Write down the odd numbers fro m 3 up in succession By striking out every third nu mber after the 3 we remove all m ultiples of 3 By striking out every fifth n u m ber after the 5 we rem ove all m ultiples of 5 In this way by rejecting m ultiples of 7 1 1 1 3 etc we have left prim e nu mbers only H yp worked at the subj ects of polygonal s icl e s ( between 2 0 0 and 1 00 B C ) nu mbers and arith m etical progressions which Euclid entirely neg “ l e c t ed In his work on risings of the stars he showed ( 1 ) that in an arithm etical series of 2 n term s the s u m of the last n term s exceeds the sum of the first n by a mul tiple of n 2 ; ( 2 ) that in such a series of 2 n + 1 ter ms the s u m of the series is the number of term s multiplied that m such a series of 2 n term s the sum is by the m i ddle term ; (3) 1 half the number of term s m ultiplied by the two m iddle term s For two centuries after the tim e of H ypsi cl es arithm etic disappears fro m hi story I t is brought to light again about 1 00 A D by Ni c omach u s a N e o P ythagorean who inaugurated the final era of Greek Fro m now on arithm etic was a favorite study while m athem atics geom etry was neglected N i com achu s wrote a work entitled I n The great tr odu cti o A r i thmeti ca which was very fa mous in its day nu mber of co mmentators it has received vouch for its popularity Boethius translated it into Latin Lucian could pay no higher c om “ i c om ac h u s of l i e t to a calculator than t s You reckon like N m h i n : p Gerasa The I n tr odu cti o A ri thmeti ca was the first exhaustive work in whi ch arith met ic was treated quite independently of geom etry Instead of drawing lines l i ke Eucl i d he illustrates things by real numbers To be sure in h i s book the O l d ge om etrical nomenclature is “ retained but the m etho d is in ductive instead of deductive Its sole , , ’ . , , ” . “ . , - . . . . . . , , , . , , , . , , . . , . . ” ” . . . . . , . , . , , . , , , . , . . ” , . , , , , . , . . . - , , . , , . . , . ” . . . , , . , . , 1 J G ow . , p o . ci t . , p 87 . . GREEK ARITH M ETIC AND ALGEB RA 59 business is classification and all its classes are derived from and exhibited by actual numbers The work contains few results that are really original We mention one important proposition whi ch is probably the author s own He states that cubical num bers are al ways equal to the su m of successive O dd numbers Thus 3 27 1 3 + 1 5 + 1 7 4 1 9 and so on Thi s 3 theorem was used later for finding the s um of the cubical num ber “ themselves Th e on of S myrna is the author of a treatise on t The work is mathe matical rules necessary for the study of P lato ill arranged and of little m erit Of interest is the theore m that every square number or that nu mber m inus 1 is divisible by 3 or 4 or both A remarkable discovery is a proposition given by Iamb li ch u s in his treatise on P ythagorean philosophy It is founded on the observation that the P ythagoreans called 1 1 0 1 00 1 0 00 units of the first second “ third fourth course respectively The theore m is this : If we add any three consecutive nu mbers of whic h the highest is di v isible by3 then add the digits of that su m then again the di gits of that su m and so on the final su m will be 6 Thus 63 1 86 15 This discove r y was the more re markable because the 1+ 5 = 6 ordinary Greek num erical symbolism was m uch less likely to suggest “ any such property of numbers than our Arabic notation would have been Hippolytus who appears to hav e been bishop at P ortus Rom ae in Italy i nthe early part of the third century m ust be m entione d for the “ giving of proofs by casting out the 9 s and the 7 s The works of N i comachu s Theon of S m yrna Thymaridas and others contain at tim es in v estigations of subjects which are really algebraic in their nature Thym ar i das in one place uses the Greek word m eaning unknown q uantity in a way which woul d lead one to believe that algebra was not far distant Of interest in trac i ng the inventio n of algebra are the arithm etical epigram s in the P al ati ne A n thol ogy which contain about fifty proble m s leading to linear equa tions Before the intro d uction of algebra these problem s were pro poun ded as pu zzles A riddle attributed to Eucl i d and containe d in the A n thol ogy is to this e ffect : A m ule an d a d onkey were walking along la den with corn The m ule says to the donkey If you gave m e one m easure I should carry twice as m uch as you If I gave you one we S hould both carry equal burdens Tell m e their burdens O m ost learned m aster of geo m etry 1 I t will be allowed says G ow that this problem if authentic was not beyond Euclid an d the appeal to geom etry s m acks of antiquity A far more diffi cult pu zzle was the famous cattle proble m which Archimedes propoun de d to the Alexandrian m athe mati c ia ns The proble m is in determ inate for fro m only sev en equations eight u m known quantities in integral numbers are to be found I t may be , , . , . ’ . . , - : , . ” . . . , , , ” . . , , , , , , . , , , , , . , , , , , . , ” , . , , ’ ’ . , , , ” . “ , . , . . “ , . , , . ” , , . . , , , , ” , - , ‘ ‘ . , , . 1 J Gow . , p o . ci t . , p 99 . . . A HISTORY O F M ATH E M ATICS 60 stated thus : The sun had a herd of bulls and cows of different colors Of B ulls the white ( W) were in number of the blue (B ) ( 1) : the P of the Y and piebald (P ) and yello w ( Y ) : the B were ( 4—) 4 4 were of the W and Y ( 2 ) Of Cows which had the sam e colors . , (w , , . ) b, y, P , , , , (B 6 4 2 1) 1 2 (P é 2 - Find the nu mber of bulls and cows This leads to high numbers but to add to its complexity the con ditions are superadded that W+ B = a square and P + Y = a triangular n umber leading to an i n deter minate equation o i the second degree Another problem in the “ A n thol ogy is quite fa miliar to school boys : Of four pipes one fills the cistern in one day the next in two days the third in three days the fou r th in four days : if all run together how soon will they fill the cistern ? A great m any O f these problem s pu zzling to an ari th m eti ci an would hav e been solved easily by an algebraist They b e cam e very popular about the tim e of D iophantus and doubtless acted as a powerful stim ulus on his m ind D io ph an tu s was one of the last and m ost fertile mathematicians of the second Alexandrian school He flourished about 2 50 A D His age was eighty four as is known from an epitaph to this e ff ect : D io 1 1 4 m in youth and of his life 1n childhood ore as h a n t u s passed p 6 , 7 a bachelor five years after his m arriage was born a son who died four years before his father at half his father s age The place of nativity and parentage of D iophantus are unknow n If his works were not written in Greek no one would think for a m om ent that they were the product of Greek m ind There is nothing in his works that remin ds us of the classic period of Greek m athem atics His were al In the circle of Greek m ost entirely new ideas ou a new subject Except for him m athem aticians he stands alone in his specialty we should be constrained to say that among the Greeks al gebra was almost an unknown science Of his works we have lost the P ori sms but possess a fragment of P ol ygon al N u mber s and seven books of his great work on A ri thmeti ca said to have been written in I 3 books Recent e ditions of the A ri th meti ca were brought out by the in defatigable historians P Tannery and T L Heath an d by G Wertheim If we except the Ahm e s papyrus which contains the first sug g es tions of algebraic notation and of the solution of equations then his A r i thmeti c a i s the earliest treatise on algebra now ex tant In this work is introduced the idea of an algebraic equation expressed in algebraic symbols His treat m ent is purely analytical and Completely divorced “ from geom etrical methods He states that a num ber to be sub 1 , . , , , , . - , , ” , , , , , . , , . . . _ . , , . , 1 2 , ’ . , “ . , . . . . , . 1 , , , . , . . . . , . , , , . . - . 1 J G ow . , p o . ci t . , p 99 . . GREEK ARITH M ETIC AND AL GEB RA ” 61 tracted m ultiplied by a nu mber to be subtracted gives a nu mber to be added This is applied to the multipli cation of differences such as (x I )(x I t must be remarked th at Diophantus had no notion whatever of negative numbers standing by themselves All he knew were diff erences such as ( 2 x in which 2 x could not be s mal ler than 1 0 wi thout leading to an absurdity He appears to be 2) the first who could perform such operations as (x 1 ) without X (x 2 = 2 reference to geom etry Such identities as ( a + b) a + 2 ab + b2 which with Euclid appear in the elevated ran k of geometric theorems are wi th Diophantus the simplest consequences of the algebraic laws of operation His S ign for subtraction was fl‘ for equality L For u n known quantities he had only one symbol 9 He had no sign for addition except j uxtaposition D iophantus used but few symbols and sometimes ignored even these by d es cribing an operation in words when the symbol would have answered just as well In the solution of simultaneous equations D iophantus adroitly managed with only one symb ol for the unknown quantities and ar rived at answers m ost commonly by the method of ten tati ve assu mp ti on whi ch consists in assigning to som e of the unknown quantities prelimi nary values that satisfy only one or two of the conditions These values lead to expressions palpably wrong but which generally suggest som e stratagem by which values can be secured satisfying all the conditions of the problem Diophantus also solved determinate equations of the second degree Such eq uations were solved geo metrically by Euclid and Hippocrates Algebrai c solutions appear to have been found by Heron of Alexandria who gives 8 4 as an approxim ate answer to the equation 1 44x ( 1 4 x) 6 7 2 0 In the Geometry doubtfully attributed to Heron the solution of 2 2 the equation 44x + 4x = 2 1 2 is practically stated in the form x , , , . - , . ‘ , . . , , . . , . , . , . , , , . , , . . . , . , . , ~ “( 1 54 x 2 1 2 + 84 1 )2 9 D iophantus . nowhere goes through with the whole process of solving quadratic equations ; he merely states the “ result Thus 84x2 + 7x = 7 whence x is found Fro m partial explanations found here and there it appears that the quadratic equa tion was so written that all terms were positive Hence from the point of view of D iophantus there were three cases of equations with a positive root : d x2 + bx = c ax2 = bx + c ax2 + c = bx each case requiring a rule slightly diff erent from the other two Notice he gives only one root His failure to observe that a quadratic equation has two roots eve n when both roots are positive rather surprises us I t m ust be remembered however that this sam e inability to perceive more than one out of the several solutions to which a proble m may po i nt is c om mon to all Greek m athe maticians Another point to be observ ed is that he never accepts as an answer a q uantity which is negative or i rration al . , , . , , , , , . . , , , , ‘ . . . A HISTORY OF M ATHE M ATICS 2 D i ophantus d e v otes only the first book of his A r i thmeti ca to the solution of d eterminate equations The re maining books extant \ t reat m ainly of i ndeter mi n ate qu adrati c equ ati on s of the for m A x2 + B x + C = y2 or of two s im ultaneous equations of the sa m e for m He considers several but not all the possible cases which may arise in these equations The opinion of N essel man n o n the m ethod of Dio Indeterm inate equations phan tu s as stated by Gow is as follows : ( 1 ) of the secon d degree are treated completely only when the quadratic or the absolute term is wanting : his solution of the equations A x2 2 — 2 is in m any respects cra mped 2 = = n A x B x For C y a d +C y 1 ( 2) the double equation of the second degree he has a definite rule only when the qua dratic ter m is wanting i n both expressions : ev en the n his solution is not general M ore co mplicated expressions occur only under specially favourable circu mstances Thus he solves B x + C 2 . . \ , . . , , - . ’ ‘ ” . . = y +C 1 l 2 2 , = The extraordinaryability of Diophantus l ies rather i n another di rection namely in his won derful ingenu i ty to reduce all sorts of equations to particular form s which h e knows how to solve Very great is the variety of proble m s considered The I 30 prob l em s found in the great work of D iophantus contain over 50 different classes of proble m s which are strung together without any attempt at classi B ut still more m ult i farious than the problem s are the solu fi ca ti o n tions General m ethods are al most unknown to D ip ohan tu s Each problem has its own distinct m ethod which is O ften useless for the I t is therefore d iffi cult for a m odern most close l y related proble m s after stu dy i ng 1 0 0 Diophantine solutions to sol v e the I o r s t This state m ent d u e to Hankel is som ewhat overdrawn as is shown by Heath 1 That which robs his work of m uch of its scientific value is the fact that he always feels satisfied with one solution though his equa tion may ad m it of an indefinite nu mber of values Another great M o dern m athe maticians defect is the absence of gene ral m ethods such as L Euler J Lagrange K F Gauss had to begin the study of in determinate analysis anew and receiv ed no direct aid from D io In spite of these defects u s in the for m u l ation of m ethods h a n t p we cannot fail to a dm ire the work for the won derful ingenuity ex h ib i t e d therein in the solut i on O f particular equations , , , . . , . . . ” , “ . , , . , , , , , . , . . . . , . , . . , , . . 1 T L H eat h, Di ophan tu s . . f o Al exa ndr i a , 2 Ed . , C a mb r i dg e , 1 910 - , pp 54 9 7 . . THE RO M ANS Nowhere is the contrast between the Greek and Ro man m inds shown forth more distinctly than in their attitude toward the mathe m a ti cal science The sway of the Greek was a flowering ti me for m athe m atics but that of the Roman a period of sterility In philos B ut in mathe ophy poetry and art the Ro man was a n i m itator m aties he did not e v en rise to the desire for i m itation The m athe In him a ma ti cal fruits of Greek genius lay before h im untasted science which had no direct bearing on practical life could awake no interest As a consequence not on l y the higher geo metry of Archi m edes and Apollonius but e v en the El emen ts of Eucl i d were neglected What little m athe matics the Romans possesse d did not co me altogether fro m the Greeks but cam e in part from m ore ancient sources E xactly where and how so m e of it originated is a m atter of doubt I t seem s “ Ro m an notation as well as the early m ost probable that the practical geom etry of the Rom ans ca m e fro m the old Etruscans who at the earliest period to which our knowledge of them ex tends inhabited the district between the Arno and Tiber Livy tells us that the Etruscans were in the habit of representing the number of years elapsed by dri v ing yearly a nail into the sanc t u a ry O f M iner v a and that the Ro m ans continued this practice A less pri mitive m ode of designating nu mbers presum ably of Etruscan “ origin was a notation rese mbling the prese nt Ro man notation This system is noteworthy from the fact that a principle is involved in it which is rarely m e t with i n others namely the principle of sub traction I f a letter be placed before another of greater value its value is not to be added to but subtracted from that of the greater In the designation of large nu mbers a horiz ontal bar place d ov er a letter was m ade to increase its value one thousand fold In fractions the Ro mans used the duo deci mal syste m Of arithm etical calculations the Romans e mployed three di fferent kin d s : W W pare d or t e purpose i n er s mb wm a e aM i he p l fimm k time of King Nu ma for he ad erecte d says P liny a statue O f the double faced Janus of which the fingers in dicated 3 6 5 (3 5 the number of days in a year M any other passages fro m Roman authors point out the use of the fingers as aids to calculation In fact a fi n g er symbolism of practically the sam e form was i n use not only in Rome but also in Greece and throughout the East certainly as early as the beginning of the Christian era and continued to be used in Europe . . , . , , . . . , , , . . , . , , , , , . , . , ” , , . , , . , , , . . . W , - . , , , - , . . , , , , 1 M C an tor , op . . ci t . , V ol I , 3 A u fl . 63 . , 1 90 7 , p 5 26 . . A HISTORY OF M ATHE M ATICS during the M iddle Ages We possess no knowledge as to where or when it was invented The second mode of calculation by the abacus was a su bject of elem entary instruction in Rom e P assages m oman writers indicate that the kind of abacus m ost commonly used was covered with dust an d then di v ided into colu mns by drawing straight “ lin es Each colum n was supplie d with pebbles ( calculi whence cal c u l ar e and calculate ) which served for calculation The Rom ans used also another kind of abacus consisting of a m etallic plate hav ing grooves w ith m ovable buttons By its use all integers between 1 and as well as so m e fractions could be 1 represented In the two adjoining figures the lines represent grooves . . , , . . ” ” , . , . , . i c w c ii c x i c x w i T the circles buttons The Ro man numerals indicat e the value of each button in the correspon ding groove below the button in the shorter groov e above ha v ing a fi v efold value Thus If hence each button in th e long left— hand groove when in use ; stands for and the button in the short upper groo v e stands for The sam e holds for the other groov es labelled by Roman num erals The eighth long groove from the left (havin g 5 buttons) 1 represents d uodecimal fractions each button indicating 44 while the 6 button above the dot m eans 4 4 In the ninth column the upper 1 1 Our button represents 4 4 the m id dle 4 4 and two lower each first figure represents the positions of the buttons before the operation 1 begi ns ; our second figure stands for the nu m ber 8 5 2 4 4 The eye has here to dist i nguish the buttons in use and those left idle Those counte d are one button abov e c and three buttons below c one butto n abov e x two buttons below I = 2 )four 1 buttons indicating duodecimals and the button for ; 3 1 1 Suppose now that The is to be added to 8 2 5 4 3 operator could begin with the hig est un its or the lowest units as he pleased Naturally the hard est part is the addition of the fract i ons an d . , " . , . , , . - , - , 7 4 . . 2 4 h 2 4 , , . . z G Fri e dl ei n , Di e Z a hl ei chen u nd das el ementare Rechn en der Gr i echen a nd Romer , “ G o t t fr i ed Fr i edl ci n ( 1 8 2 8 1 8 7 5 w as R ek tor d er K g l Erl an g en , 1 8 6 9 , Fi g 2 1 S t u di e n an stal t zu H ot i n B av ar i a 1 . . — ) ” . . . A HISTOR Y OF M ATHE M ATICS 66 Ro me a science of geometry with definitions axio ms theore ms and proofs arranged in logical ord er will be disappointed The only geometry know n was a pr acti c al geom etry whi ch like the old Eg yp tian consisted only of e mpirical rules This practical geo metry was e mployed in surveying Treatises thereon have co me d own to us co mpile d by the Ro man surveyors called agr i i n ensores or gr omati ci One would naturally expect rules to be clearly form ulated B ut no ; they are left to be abstracted by the reader fro m a m ass of nu merical examples The total impression is as though the Ro m an gromatic were thousands of years older tha n Greek geom etry and as though a deluge were lying between the two So me of their rules were prob ably inherited fro m the Etruscans but others are identical w ith those of Heron Among the latter is that for finding the area of a triangle fro m its sides and the approxi mate formula 44a2 for the area of equilateral triangles (a being one of the sides ) B ut the latter area was also calculated by the form ul as and 4a2 the first of which was unknown to Heron P robably the expression 4a? was de , , , , . , , , . , . , , . . . , . , . , , . , . a rived from the Egyptian form ula +b 2 for the determ ination of 2 the surface of a quadrilateral This Egyptian formula was used by the Ro mans for finding the area not only of rectangles but of any quadrilaterals whate v er Indeed the gromatici considered it e v en suffi ciently accurate to determ ine the areas of cities laid out i rreg u 1 s ply by m easuring their circu m ferences Whatever Egyptian l arl y im geom etry the Ro mans possessed was transplanted across the M edi ter r a n ea n at the ti m e of Ju l i u s C ws ar who ordered a survey of the whole e mpire to secure an equitable m o d e of taxation C a sar also reform ed the calendar and for that purpose dre w from Egyptian learnin g He secured the services of the Alexan drian astronomer S osi gen es Two Roman ph ilosophical writers deserve o u r attention The in his D e r er u m philosophical poet Ti tu s L u cr ei i u s (96 ? — 55 B n atu r a entertains conceptions of a n infinite m ultitu d e and of an i n finite m agnitude which accord with the m odern definitions of those terms as being not variables but constants However the Lucretian i nfi n i t e s are not com posed of abstract things but of m aterial particles His infinite m ultitude is of the denu merable variety ; he m ade use of the whole part property of infinite m ultitudes 2 Cognate topics are discussed several centuries later by the c ele — in t A u u s t i n e b ra t ed father of the Latin church S ( 3 54 4 3 0 A g hi s references to Zeno of Elea In a d i alogue on the question whether or not the m ind of man m oves when the body moves a n d trav els with the bo dy he is led to a definition of m otion in wh i ch he di splays so m e le v ity I t has been said of scholast i c i sm that it has no sense of hum or . , , . , , . , , . , , . , . , . . , , , . . , - . . , . . , , , , . . H H an k el , op ci t , p 2 9 7 2 C J K eyse r i n B u l l A m Al 1 . . . . . . . . . al / z . S oc . , V ol . 24, 1918, p . 2 68, 3 21 . RO M ANS TH E 67 Hardly does this apply to S t Augustine He says : When this dis course was concluded a boy ca m e running from the house to call us to dinner I the n remarked that this boy co mpels us not only to define motion but to see it before our very eyes So let us go and pass fro m this place to another ; for that is if I am not mistaken nothing else than m otion S t Augustine deserves the credit of having accepted the e xistence of the actually infinite and to have recogniz ed it as being not a variable but a constant He recognize d all finite positive integers as an infinity of that type On this point he occupied a radically diff erent position than his forerunner the Greek father of the church Origen of Alexandria Origen s argu ments against the actually infinite have been pronounced by Georg Cantor the profoundest ever advanced against the actually infinite In the fifth century the Western Ro man E mpire was fast falling to pieces Three great branches— Spain Gaul and the province of Africa—broke off fro m the decaying trunk In 4 7 6 the Western E mpire passed away and the Visigothic chief Odoacer beca m e king Soon after I taly was conquered by the Ostrogoths under Theodor ic It is re markable that this very period of political hu m iliation should be the one during which Greek science was studied in Italy m ost z ealously School— books began to be co mpiled fro m the elem ents of Greek authors These compilations are very deficient but are of absorbing inte rest fro m the fact that down to the twelfth century they were the only sources of mathe matical knowledge in the Occident Fore most among these writers is B o e thiu s (died At first he was a great favorite of King Theodoric but later being charged by envious courtiers with treason he was imprisoned and at last decapi t a t ed While in prison he wrote On the C on sol ati on s of P hi l osophy As a m athematician B oethius was a B robdingnagian a mong Roman Scholars but a Liliputian by the si de of Greek m asters He wrote an I n sti tu ti s A r i thmeti ca which is essentially a translation of the arith m etic of N i c omac h u s and a Geometry in several books So m e of the m ost beauti ful results of N i comachu s are o m itted in B oethius arith m etic The first book on geo m etry is an extract fro m Euclid s El e men ts which contains in addition to definitions postulates and axioms the theore ms in the first three books without proofs How can this omission of proofs be accounted for ? I t has been argued by some that Boethius possessed an incomplete Greek copy of the E l e men ts ; by others that he had Th e on s edition before hi m and b e li ev ed that only the theore ms ca m e fro m Euclid while the proofs were supplied by Theon The second book as also other books on geometry attributed to Boethius teaches from numerical examples the men su rati on of plane figures after the fashion of the agri m ensores A celebrated portion in the geom etry of Boethius is that pertaining to an abacus wh ich he attributes to the P ythagoreans A consi der P ebbles able improve m ent on the ol d abacus is there introduced . . , . , . ” , , . , . , . , . , ’ , . . , . , , . , , . , , , . . . , , , , . , , , , . . , , . , . , ’ ’ . , , , , , . , ’ , , , . , , , , . , . . A HISTORY OF M ATHE M ATICS 68 are discarded and api ces (probably s mall cones) are used Upon each of these apices is drawn a numeral giving it some value below 1 0 The nam es of these numerals are pure Arabic or nearly so but are added apparently by a later hand The 0 is not m entioned by Boethius in the text These numerals bear striking resemblance to the Gubar numerals of the West Arabs which are ad mittedly of Indian origin These facts have giv en rise to an endless controversy Som e contended that P ythagoras was i n India and from there brought the nine nu merals to Greece where the P ythagoreans used the m secretly This hypothesis has been generally abandoned for it is not certain that P ythagoras or any disciple of his e v er was in India nor is there any e v idence in any Greek author that the apices were known to the Greeks or that nu meral signs of any sort were used by them with the abacus I t is improbable m oreover that the Indian signs fro m which the apices are derived are so old as the tim e of A second theory is that the Geometry attributed to P ythagoras Boethius is a forgery ; that it is not older than the tenth or possibly the ninth century and that the apices are derived from the Arabs B ut there is an Encyclop aedia written by C assi odori us (died about in which both the arithm etic and geom etry of B oethius are m en 58 5) t i on e d Som e doubt exists as to the proper interpretation of this passage in the Encyclop aedia At present the weight of evidence is that the geom etry of B oethius or at least the part mentioning the nu merals is spurious 1 A third theory (Woepck e s)is that the Alexandrians either directly or indirectly obtained the nine nu merals from the Hindus about the seco n d century A D and gave them to the Ro mans on the one hand and to the Western Arabs on the other Thi s explanation is the most plausible It is worthy of note that C assi odori u s was the first writer to use “ the term s rational and irrational in the sense n ow current in arith metic and algebra 2 . , . , . , , , . - - , . . , , , . , , , , . , , , . , . , , . . , ’ . , , . . , . , ” . ” . t A g ood di sc u ssi o n of t hi s so c all ed B oe hi us q uest io n , w hi ch ha s b een de b at ed for t w o c en t u ri e s , i s g i v e n b y D E S mi t h a n d L C K a rp i n sk i i n t hei r H i nd u A ra bi c N u mer al s , 1 9 1 1 , C hap V 2 E n cycl opédi e des s ci en ces ma themati q u es , To me I , V o l A n il p 2 ’ l um in a t i n g a r i cl e o n an c i en fi n g e r symb o l i s m i s L J R i c ha rd so n s Di g i ta l R e c k o n i n g A mon g t he A n ci en s i n the A m M ath M onthl y, Vol 2 3 , 1 8 1 6 , 1 - . . . . . . ’ pp — 7 3 1 t . t ” . - t . . . . . . T H E M AYA The M aya of Central America and Southern M exico developed hieroglyphic writing as found in inscriptions and codices dating ap pa t ently fro m about the beginning of the Christian era that ranks probably as the foremost intellectual achieve m ent of pre Colu mbian M aya nu mber syste m s and chronology times in the New World are rem arkable for the extent of their early develop m ent P erhaps five or s ix centuries before the Hindus gave a system atic e xposition of the n deci mal nu mber system with its z ero and principle of local value the M aya in the fl a tl an ds of Central A m erica had evolved system atically a vi gesi mal number system e mploying a z ero and the principle of local value In the M aya number syste m found in the co dices the ratio of increase of successive units was not 1 0 as in the Hindu system ; it was 2 0 in all positions e xcept the third That is 2 0 units of the lowest order ( ki n s or days ) m ake one un i t of the next higher order (u i n al s or 2 0 days)1 8 u i n al s m ake one unit of the third order (tu n or 3 6 0 days)2 0 tuns m ake one unit of the fourth order (k atu n or 7 2 00 days )2 0 k at u n s m ake one unit of the fifth order days ) and finally 2 0 cycles m ake 1 gr eat cycl e of (cycl e or days I n M aya codices we find symbols for 1 to 1 9 ex pressed by bars and dots Each bar stands for 5 units each dot for For insta nce 1 unit , ” , - . . . , . , . , , , , , , , , , , . , . . , , 2 4 7 5 symbol 11 19 The z ero is represented by a that looks roughly like a half closed eye In writing 2 0 the principle of local value enters It is expressed by a dot placed over the sym bol for z ero The nu mbers are written vertically the lowest ord er being assigne d the lowest position Accordingly 3 7 was expressed by the symbols for 1 7 ( three bars and two dots ) in the kin place and one dot representing 2 0 placed above 1 7 in the uinal place T 0 write 3 6 0 the M aya dre w two z eros one above the other with one dot higher up i n third place The highest number found in the codices ( 1 x 1 8 x 2 0 +0 +0 is in our deci mal notation A second numeral system is found on M aya inscriptions I t em ploys the z ero but not the principle of local value Special sym bols are e mployed to designate the diff erent units I t is as if we were to 1 write 2 0 3 as 2 hun dreds 0 tens 3 ones F n a l g y see S G M l y o n t o f t he M aya n m b e sy st m d h . . . , . , , , . , , , . , ” . , 1 or a cc u A n I n tr oduc ti on to the S tudy Washi ng on , 1 9 1 5 t . f o the r- . . , u . e s an c ro n o o , . . or e M aya Hi erogl i phs , G ove rn men t P ri n t i n g O ffi c e , M ATHE M ATICS A HISTORY OF 70 The M aya had a sacred year of 2 6 0 days an offi cial year of 3 6 0 days a n d a solar year of 3 6 5 + days The fact that see ms to account for the break in the vigesimal system m aking 1 8 u i n al s equal to 1 tun The lowest common multiple (instead of 2 0 ) “ of 2 6 0 and 3 6 5 or 1 8 980 was taken by the M aya as the calendar “ round a period of 5 2 years which is the m ost important period in M aya chronology We m ay add here that the nu mber systems of Indian tribes in North Am erica while disclosing no use of the z ero nor of the principle of local value are of interest as exhibiting not only quinary d ecimal and viges imal syste ms but also ternary quarternary and octonary sys 1 tem s ” S W C E ll N mb S y tem f t h e N t h A me i I di i Am , . , . ” ” , , , , . , , , , , , , . 1 ee . . e s, u er s s o i ca n M a th M on thl y, V o l 2 0 , 1 9 1 3 , pp — l 1 1 2 ca S o 1 1 8 222 mati , 3 , V 3 , 9 3 , pp . . . . 263 . . . —2 7 2 or , 2 93 r can —2 99 ; a l so n an s n er B ibl i othec a ma the THE CHINESE 1 The oldest extant Chinese work of mathe matical interest is an anonymous publication called Chou pei and written before the second century A D perhaps long before In one of the dialogues the Chou pei is believed to reveal the state of mathematics and astronomy in China as early as 1 1 00 B C The P ythagorean theorem of the right triangle appears to have been known at that early date Next to the Chou — pei in age is the Chi u chang S u a n— Arith shu metic in Nine commonly called the Chi u chang the most celebrated Chinese Text on arith m etic Neither it s authorship nor the time of its co mposition is known definitely By an edict of the “ d espotic emperor Shih Hoang ti of the Ch in D ynasty all books were burned and all scholars were buried i n the year 2 1 3 B C After the death of this e mperor learning revived again We are told that a scholar nam ed CHA N G T S A N G found so me old writings u pon which he based this famous treatise the Chiu chang About a century later a revision of it was m ade by Ching Ch ou ch ang ; comm entaries on this classic text were m ade by Liu Hui in 2 6 3 A D and by Li Ch un “ fén g in the seventh century H ow much of the Arithm etic in Nine Sections as it exists to day is due to the old records ante dating 21 3 B C how much to Chang T sang and h ow m uch to Ching Ch ou ch ang it has not yet been found possible to determine “ The Arith metic in Nine Sections begins with m ensuration ; it gives the area of a triangle as 4 b h of a trapez oid as 4 (b of a 1 ? circle variously as %c éd 4cd 4d and 4 4 c2 where c is the circumference and d is the diam eter Here 7r is taken equal to 3 The area of a 2 segment of a circle is give n as where c is the chord and a +a ) the altitude Then follow fractions commercial arithmetic including percentage and proportion partnership and square and cube root of numbers Certain parts exhibit a partiality for unit fractions Divi sion by a fraction is effected by inverting the fraction and m ultiplying The rules of operation are usually stated in obscure language There are given rules for finding the volu mes of the prism cylinder pyramid truncated pyra mid and cone tetrahedron and we dge Then follow m roble s in alligation There are indications of the use of positive p and negative nu mbers Of interest is the following problem because centuries later it is found i n a work of the Hindu Brahmagupta : Al l our i n fo mati on o C hi e e ma t hemati cs i s draw n from Y hi o M ik mi Th D l pme t f M th m ti i Chi d J apa L e ip z ig 9 a d f om D v i d - , , . . , . - . . . - - , . . ’ - . , . . ’ , - . , ’ - ’ ’ . . . - - , , ’ ’ . . ” , ’ , . , , , , . . , . , , , - . . . . , , , . , . . ‘ 1 eve o e n E u g e n e S mi t h 1 91 4 n r . o an d a e n s a cs os n Yo shi o M ik ami na an ’ s n, , 1 1 2, n a r ’ s a Hi story of J apa n ese M athemati cs , C hi cag o , A 2 7 HISTORY or M ATHE M ATICS There is a bamboo 1 0 ft high the upper end of which is broken and reaches to the ground 3 ft from the stem What is the height of the . , . break ? In the solution . the 3 height of the break is taken 2 2 x 10 Here is another : A square town has a gate at th e mid point of each side Twenty paces north of the north gate there is a tree which is vi sible from a point reached by walking fro m the south gate 1 4 paces south and then 1 7 7 5 paces west Find the side of the square x The problem leads to the quadratic equation x2 10 x + 1 4) The derivation and solution of thi s equation are not made 1 7 75 = 0 clear in the text There is an obscure statem ent to the eff ect tha t the answer is obtained by evol ving the root of an expression which is not monomial but has an additional term [ the term of the first It has been surmised that the process here r e ferred to was evolved more fully later and led to the method closely resembling Horner s process of approxim ating to the roots and that the process was carried out by the use of calculating boards Another proble m leads to a quadratic equation the rule for the solution of which fits the solution of li teral quadratic equations “ — We co me next to the S u n Tsu S u an chi ng ( Arithmetical Classic of Sun which belongs to the first century A D The author “ S U N TS U says : In m aking calculations we m ust first know positions of numbers Unity is vertical and ten hori zontal ; the hundred stands whi le the thousand lies ; and the thousand and the ten look equally and so also the ten thousand and the hundred This is evidently a reference to ab acal computation practiced from time i mmemorial in Chi na and carried on by the use of computing rods These rods made of s m al l bamboo or of wood were in Sun Tsu s tim e m uch longer The later rods were about 1 4 inches long red and black in color representing respectively positive and negative nu mbers According to Sun Tsu units are represented by vertical rods tens by horiz ontal rods hundreds by vertical and so on ; for 5 a single rod suffices The n umbers 1 9 are represented by rods thus : I u inn un n 1, n the n umbers i n the tens column 1 0 2 0 90 are wri tten thus l l | The n umber 6 2 8 is designated - . ‘ . . . . ’ , . , . - . , . , - , . , . , . , , ’ - , . , , . - , , , , - , , z 2 , m . , E , E , , , , , , , , 7 . The rods were placed on a board ruled in colu ns m by W W and were rearranged as the computation advanced The successive steps in the mul tiplication of 3 2 1 by 46 must have been about as fol lows , . . 1 38 46 321 1 4 7 66 46 32 1 147 2 46 32 1 . The product was placed between the The 46 is multiplied first by 3 then by , m ultiplicand 2, and m ultiplier and last by 1 the 46 being . , A 74 or M ATHE M ATICS HISTORY In the first half of the seventh century WAN G H s IAo T U N G brought for th a work the Ch i — k u S u an — chi n g in which nu merical cubic equa tions appear for the first time in Chinese m athe matics This took place seven or eight centuries after the first Chinese treatment of quadratics Wang Hs iao t ung gives several problem s leading to “ There is a right triangle the product of whose two S ides is cu bi cs z 9 l 1 — and whose hypotenuse is greater than the first side by 0 0 6 3 44 7 5 0 It 18 requi red to k n ow the lengths of the three sides He gives the “ 7— l being answer 1 4 4 0 4 9 4 5 1 4 and the rule : The P roduct (P ) m ake the result squared and being divided by twice the S urplus (S ) Halve the surplus and make it the li en f a s hi h or th e constant class or the second degree class And carry out the operation of evolution according to the extraction of cube root The result gives the first side Adding the surplus to it one gets the hyp otenuse Divide the product with the first side and the quot i ent is the second side Thi s 3 =0 The mode of solu rule leads to the cubic equation x + S /2 x tion is similar to the process of extracting cube roots but detail s of the process are not revealed In 1 2 4 7 C H I N C HI U — S H A O wrote the S u s hu Chi u cha ng Nine Sections of M athe matics ) which makes a decided advance on the solution of nu merical equations At first Ch i n Chiu— shao led a m ili tary lif e ; he lived at the tim e of the M ongo l ian invasion For ten years stricken with disease he recovered and then devoted himself to study The following problem led him to an equation of the tenth degree : There is a circular castle of unknow n diameter having 4 gates Three miles north of the north gate is a tree which is visible from a point 9 m iles east of the south gate The unknow n diameter is found to be 9 He passes beyond Sun Tsu in his ability to solve indeterminate equations arising for a number which will give the r residues r 1 r 2 when divided by m l m2 mm respectively 4 2— — Ch in C hi u shao solves the equation x + 7 6 3 2 00 x 40 6 4 2 56 0 00 0 However 0 by a process al m ost identical with Horner s method the co mputations were very probably carried out on a computing board divided into colu mns and by the use of computing rods Hence the arrange ment of the work m ust have been different from that of Ho m er B ut the operations perform ed were the sam e The fir st digit in the root being 8 (8 hundreds )a transformation 15 ef 4 — 3— 2— 8 2 6 8 800 0 0 x + 3 8 2 0 544 fec t ed which yields x 3 2 00 3c 30 7 6 8 00 9c the same equati on that i s obtained by Horner s process 0000 = 0 Then taking 4 as the second figure i n the root the abs olute term Thus the C hinese had v anishes in the operation giving the root 8 40 ’ - ’ ’ , , . ’ ’ - . , . , . , , , , - . . . ” . , . . ° . , . ” ’ - - ’ . . , . , . ‘ . - . , n , ’ , . , , - ’ . , . , , . . , , . ’ . , , , , t ion Vol of t h e fr a c t 1 9 14, p . 1 10 , c i rc l e w i t h a 3 +4 2 1s g i ven an on ymou sl y I n Gru n er t s A r chi v P H ug h es g i v e s i n N a tu r e, V ol 93 , ’ U si n g 34 , T M me t hod o f con s t ru c t i ng a t ri ang l e t h at g i v es the p . — 5 5 3 — io n - . g r ea t 5 . acc u rac y . . . . . ar ea o f a g i ve n CHINESE TH E 75 invented Horner s method of solving num erical equations more than five centuries before R uffi n i and Ho m er Thi s solution of higher numerical equations is given later in the writings of Li Y ek and others Ch in Chiu— shao marks an advance over Sun Tsu in the use of 0 as a symbol for z ero M ost likely this symbol is an i mportation from India P ositive and negative nu mbers were distinguished by the use of red and black computing rods This author gives for the first time a proble m which later became a favorite one a mong the Chinese ; i t involved the trisection of a trapezoidal field under certain restrictions in the mode of selection of boundaries We have already m entioned a contemporary of Ch in Chiu — shao namely L I Y EH ; he lived far apart in a rival m onarchy and worked “ — independently He was the author of T sé yu an H ai chi ng ( Sea M easurem ents M irror of the Circle— 1 2 4 8 and of the I 4 m Y en m an He used the symbol 0 for z ero On account of the i n c onv en I 2 59 i en ce of writing and printing positive and negative nu mbers in dif fe ren t colors he designated negative nu mbers by drawing a cancella tion m ark across the symbol Thus stood for 6 0 stood for — The unknown quantity was represented by unity which was 60 probably represented on the counting board by a rod easily disti n The term s of an equation were written g u i she d fro m the other rods not i n a horiz ontal but in a vertical line In Li Yeh s work of 1 2 59 as also in the work of Ch in Chiu shao the absolute term is put in the top line ; in Li Yeh s work of 1 2 4 8 the order of the term s is reversed so that the absolute term is in the botto m line and the highest power of the unknown in the top line In the thirteenth century C hi nese algebra reached a m uch hi gher develop m ent than form erly This science with its rem arkable m ethod ( our Horner s ) of solving nu mer “ ical equations was designated by the Chi nese the celestial elem ent m ethod A third prom inent thirteenth century m athe m atician was Y A N G They deal with the H U I of who m several books are still extant summation of arithmetical progressions of the series I +3 + 6 ’ . . ’ - . . . . ’ , , ’ - . - , . , . , . , . . , ’ . , , ’ - , ’ , . . ’ ” , , . . , ( 1 +2 + 11 — 6 ) , , 2 = 1 1 + I2 § n (n also with proportion s imultaneous linear equations quadratic and quartic equations Half a century later Chinese algebra reached its height in the “ — treatise S u c m Izsi ao Chi mén g ( Introduction to M athe matical S tudies 1 2 99 and the S zu yu en Vii chi en ( The P recious M irror of the Four Ele ments which ca me from the pen of CH U 1 30 3 S HIH CHI EH The first work contains no new results but exerted a great stimulus on Japanese m athematics in the seventeenth century At one time the book was lost in China but i n 1 839 it was restored by the discov ery of a copy of a Korean reprint m ade in 1 66 0 The is a m ore original work It treats fully of the P recious M irror celestial element method He gives as an ancient method a , , . , - - “ - , , - , . . , ” ” . , . . A HISTORY OF M ATHE M ATICS 76 triangle (known in th e West as P ascal s arithmetical tria ng le )dis playi ng the binomial c oeffi c i en ts which were known to the Arabs in the eleventh century and were probably imported into China Chu shi h Chi eh s algebraic notation was altogether diff erent from our modern notation Thus a + 6 + 0 + d was written ’ , , . ’ - . , as shown on the left excep t that in the central position we e mploy an asterisk in place of the Chi nese character t ai ( great extrem e ab solute term) and that we use the modern nu m erals in place of the The square of a + 6 + 6 +d namely a 2 + 62 + c 2 + d2 + 2 ab s angi for m s is represented as shown on the right In further illustration of the Chinese notation at the t im e of Chu Shih Chieh we give 1 , , , ’ , , . , . , - , - 2 I = In the fourteenth century astrono my and the calendar were studied They involved the rudi ments of geo m etry and spheric al trigonometry In thi s field i mportations from the Arabs are disclosed After the noteworthy achieve ments of the thirteenth century Chinese mathematics for several centuries was in a period of decline “ The famous celestial elem ent m ethod in the solution of higher equations was abandoned and forgotten M ention must be m ade however of C H IEN G TA I WE I who in I 593 issued his S u an f a T u ng “ which is the ol dest tsu ng ( A Syste matised Treatise on work now extant that contains a diagram of the form of the abacus called m an pan and the explanation of its use The instrument was known in China in the twelfth century Rese mbl i ng the old Roman abacus it contained balls m ovable along rods held by a wooden “ frame The suan pan replaced the old computing rods The Sys is famous also for containing som e t ema ti sed Treatise on Arith m etic m agic squares and m agic circles Little is know n of the early history . . . . ” , . . ’ , - ’ - , , , - . , . , , - . . . “ ”i ) 111 t he symb ol for xz n o t i c e t h a t t he I s on e sp a c e dow n ( x an d o n e I n t h e symb ol a n d i s m ad e t o s t a n d for t he p rod u c t xz spa ce t o t h e r i g h (2 o f ’ “ “ for zyz t he t h ree o s i n di ca t e t h e a b se n c e o f t he t erm s y, x, xy; t he s mall 2 mean s t w i ce t he p ro d u c t o f t h e t w o l e t t e r s i n t he same ro w , resp ec t i vel y o n e spac e to t he ri g h an d to t he l e f o f i e , 2 yz Th e li mi t a ti on s o f hi s n o t a t i on a re o b 1 ” t v 10 u s . t ) . t . . . t ” CHINESE TH E 7 squares M yth tells us that in early ti mes the sage Y u the enlightened emperor saw on the cala mitous Yellow River a divine tortoise whose back was decorated with the figure made up of the numbers from I to 9 arranged in form of a magic square or l o shu of magic . , , , , , - . , The l o-s hu . The nu merals are indicated by knots in strings : black knots repre sent even numbers (symbolizing i mperfection )white knots r epre sent odd nu mbers (perfection ) Christian missionaries entered China in the six teenth century The Italian Jesuit M a tteo Ri cci ( 1 5 5 2 — 1 6 1 0) introduced European astronomy and mathematics With the aid of a Chinese scholar named H sit he brought out in 1 6 0 7 a translation of the first six books of Euclid Soon after followed a sequel to Euclid and a treatise on surveying The missionary M u N i k o sometim e before 1 6 60 intro In 1 7 1 3 Adrian Vl ack s logarithmic tables to 1 1 duced logarithm s 1 places were reprinted Ferdi n and Verbi es t of West Flanders a noted J esuit missionary and astronomer was in 1 66 9 made vice president of the Chinese astrono mical board and in 1 6 73 its president European algebra found its way into China M ei K u — ch én g noticed that the European algebra was essentially of the same principles as “ the Chinese celestial elem ent method of form er days which had been forgotten Through him there cam e a revival of their own algebraic method W ithout however displacing European science Later Chinese studies touched m ainly three subjects : The determina tion of 71 by geom etry and by infinite series the solution of n um erical equations and the theory of logarithm s We shall see later that Chinese m athematics stimulated the growth of mathematics in Japan and India We have seen that in a small way there was a taking as well as a giving B efore the influx of recent European science China was influenced som ewhat by H i ndu and Arabic m athematics The Chinese achievements which stand out most conspicuously are the solution of nu merical equations and the origination of magic squares and magic circles Extrac t from Revu e C n sult H B osman s Fe di nd V bi st L ouv ai n 1 9 1 2 , . . . , . - . ’ . . , , . ’ ” . . , , , . , . , . , . , , . . 1 o . uesti ons sci enti des Q r , fi q ues , J na — Ap an u ary er e , n l , 191 2 . , . JAP ANESE TH E 1 According to tradition there existed in Japan in rem ote ti mes a system of num eration which extended to high powers of ten and re sembled som ewhat the sand counter of Archim edes About 5 5 2 A D B uddhis m was introduced into Japan This n ew m ove ment was fostered by P rince Shotoku Taishi who was deeply interested in all learning M athematics engaged his attention to such a degree that he came to be called the father of Japanese m athem atics A little later the Chinese syste m of weights and measures was adopted In 7 0 1 a university syste m was established in which m athe matics figured prom inently Chinese science was i mported special m ention being m ade in the offi cial Japanese records of nine Chinese texts on m athe mati cs which include the Chou pei the S u an chi ng written by Sun Tsu and the great arithm etical work the C hi u chang B ut this eighth century interest in mathem atics was of sho rt duration ; the Chiu— chang was forgotten and the dark ages returned Calendar reckoning and the rudiments of co mputation are the only signs of m athematical activity until about the seventeenth century of our era On account of the crude n umeral syste ms devoid of the principal of local value and of a sym bol for z ero m echanical aids of co mputation became a necessity These consisted in Japan as in China of som e form s of the abacus In China there ca m e to be developed an instrument called the su an— pan in Japan it was called the s or oban The i mporta tion of the suan pan into Japan is usually supposed to have occurred before the close of the S ix teenth century B amboo computing rods were used in Japan in the seventh century These round pieces were replaced later by the square prism s (s angi pieces) Numbers were represented by these rods in the m anner practiced by the Chinese The nu merals were placed inside the squares of a surface ruled like a chess board The s or oban was simply a more highly de v eloped form of ab acal instru ment The years 1 60 0 to 1 6 7 5 mark a period of great mathematical ac t i vi ty It was inaugurated by M oRI K A M B E I S H I G EY O S H I who pop u l ari z ed the use of the s or oba n His pupil Y O S H I DA SH I CH I B E I K OY IJ is the author of Ji n k o ki 1 6 2 7 which attained wide popularity and is the oldest Japanese mathematical work n ow ex tant I t explains operations on the soroban including square and cube root In one of , . . . . . . . . , - - , , - . , . . , , . , , . , . , - . . . . . . , . - . , , - , , . . , mpil ed from D av i d Eu g en e S mi t h and Yoshio M ik a mi s Hi story of J apa n es e M a themati cs C h i c ag o , 1 9 1 4 fro m Yo sh io M i k am i s D evel op men t of M athemati es i n Chi n a a nd J apa n L ei p z i g , 1 9 1 2 an d from T Hayashi s A B r i ef Hi stor y of the J apa n es e M a thein a ti es , O verg edruk t u i t h et N i eu w A rchi ef 1 Thi s is accou n t ’ co ’ , , ’ , , voor Wi sk u nde VI , pp . 2 96 — 36 1; V I I , pp . 1 05 —6 1 1. . ' JAP ANESE TH E 9 his later editions Yoshida appended a number of ad v anced proble ms to be solved by co mpetitors This procedure started a mong the Japanese the practice of issui ng problem s which was kep t up until 1 8 1 3 and helped to sti mulate mathe m atical activity Another pupil of M ori was I MA M U RA CH I S H 6 who in 1 639 pub l ished a treatise entitled Ju gai roku written in classical Chinese He took up the m ensuration of the circle sphere and cone Another author I S O MU RA KI TTO K U in his K etsu gi s hb 1 66 0 ( second edition whe n considering problem s on m ensuration m akes a crude approach to integration He gives magic squares both odd and even celled and also magic circles Such squares and circles became fav or ite topics among the Japanese In the 1 6 84 edition Isom ura gives also magic wheels TA N A KA KI S S H I N arranges the integers 1 96 in 2 si x 4 celled m agic squares such that the su m in each row and colu m n “ are 1 94 ; placing the s ix squares upon a cube he obtains his magic “ 1 M U RA M A TS U in cube Tanaka formed also m agic rectangles 2 1 6 6 3 gi v es a m ag ic square containing as m any as 1 9 cells and a m agic circle i n volving 1 2 9 numbers M uram atsu gives also the fam ous “ Josephus P roblem in the following form : Once upon a time there li ved a wealthy farmer who had thirty children half being of his first The latter wished a fa v orite son to w ife and half of his second one inherit all the property and accordingly she asked h im one day say ing :Would it not be well to arrange our 30 children on a circle calli ng one of them the first and counting out every tenth one until there should re main on l y one who should be called the heir The hus band assenting the wife arranged the children the counting resulted in the elimination of 1 4 step children at once leaving only one Thereupon the wife feeling confident of her success said let us reverse the order The husband agreed again and the counting proceeded in the reverse order with the unexpected result that all of the second wife s children were stricken out and there r e m ained only the step — c hild and accordingly he inherited the property The origi n of this problem Is not known It 15 found m uch earlier I n of the tenth century th e Co d ex Ei n si de l en si s ( Ei n si d el n Switz erland ) while a Latin work of Roman ti m es attributes it to Flavius Josephus I t co mmonly appears as a problem relating to Turks and Christians half of whom m ust be sacrificed to save a sinking S hip I t was very co mmo n in early printed European books on arithmetic and in books on mathe matical recreations In 1 666 S A N )S E I K O wrote hiS Kongen ki which i n co mmon with other works of his day considers the computation of 7r ( “ He is the first Japanese to take up the Chinese celestial elem ent m ethod i n algebra He applies it to equations of as high a degree as the six th His successor S A WA GU CH I and a contemporary N OZA WA give a crude calculus resembling that of Cavalieri Sawaguchi rise s . , . , , , . . , , , , , . , . , . , - . - , ” , . . ” . ‘ , . , , , . , , - , , . , , . , , ” ’ . , . , , . , . . " , , . . , , , . 1 Y . M ik ami i n A rchi v der M athernati k u . P hys i k , Vol . 2 0, pp . —86 1 83 1 . A HISTORY OF M ATHE M ATICS 80 above the Chinese masters in recogni sing the plurality of roots bu t he declares problem s which yield them to be erroneous in their nature Another evidence of a continued Chinese influence is seen in the ii — m Chinese value of 71 i 4 which was ade known in J a an by I KE DA p 4 — m A 2 We co e now to S E KI K 6 W ( 1 6 4 1 70 8) whom the Japanese con sider the greatest m athematician that their country has produced The year of hi s birth was the year in which Galileo died and Newton was born Seki was a great teacher who attracted m any gifted pupils L ik e P ythagoras he discouraged divulgence of m athematical dis c ov er i es m ade by hi m self and his school For that reason it is difficult to determ ine with certainty the exact origin and nature of some of the discov eries attributed to him He is said to have left hundreds of manuscripts ; the transcripts of a few of them still re main He pub li sh ed only one book the H a tsu bi S ampo 1 6 74 in which he solved 1 5 problem s issued by a conte mporary writer S ek i s explanations are quite incomplete and obscure Tak eb e one of his pupils lays stress upon S ek i s clearness The inference is that Seki gave his ex planations orally probably using the computing rods or s angi as he proceeded Noteworthy a mong his m athe matical achieve ments are th e ten zon m ethod and the yendo n m ethod B o th of these refer to i mpro v e m ents in algebra The ten zan m ethod is an improvem ent of “ the Chinese celestial elem ent m ethod and has reference to nota tion while the yendan refers to explanations or method of analysis The exact nature and value of these two m ethods are not altogether “ clear By the Chinese celestial ele ment m ethod the roots of equa tions were computed one digit at a tim e Seki re moved this lim ita tion B uilding on results of his predecessors Seki gives also rules for writing dow n magic squares of ( 2 n cel ls In the case of the more troublesom e even celled squares Seki first gives a rule for the con 2 2 struction of a m agic square of 4 cells then of 4 (n and 1 6 n cell s He sim plified also the treatment of magic circles P erhaps th e most original a n d i mportant work of Seki is the invention of determinants som etim e before 1 683 Leibniz to whom the first idea of determinants is usually assigned m ade hi S discove ry in 1 6 93 when he stated that three l i near equations in x and y can have the sam e ratio only when the determ inant arising fro m the coeffi cients vanishes Seki took n equations and gave a m ore general treatm ent Seki knew that a th determinant of the n order when expanded has u 1 term s and that 1 rows and colu mns are interchangeable Usuall y attributed to Seki “ is the invention of the yenri or circle principle which i t is claimed accomplishes som ewhat the same things as the differential and i n Neither the e xact nature nor the origin of the yenri t eg ral calculus is well u nderstood D oubt e xists whether Seki was its discoverer TA KE B E a pupil of Seki used the yenr i and may be the chief originator ” On t he J apan ese theory of det e mi nan ts in F r de tail s con s l t Y M ik ami I i s V ol II 9 4 pp 9— 36 , . , . , . . . , . . . , , , ’ . . , , ’ . , , . . ” . , ” , . . . , . . , . , . , . , , . /' . , , . - , , . . . , , 1 s u o , “ . , 1 1 , , . . . r A HISTORY OF M ATHE M ATICS 82 can be drawn upon a folding fan Here mathematics finds application to artistic design After the m iddle of th e nineteenth century the native mathematics of Japan yiel d ed to a strong infl ux of Western mathematics The m ovem ent in Japan beca m e a part of the great international advance In 1 9 1 1 there was started the Tohoku M athemati cal J ou r n al under the editorship of T Hayashi I t is devoted to advanced m athematics contains articles in many of our lea ding modern languages and is quite 1 international in character Looking back we see that Japan produced some able mathemati c i an s but on account of her isolation geographically and socially her scientific output did not aff ect or contribute to the progress of m a them atics in the West The Babylonians Hindus Arabs and to som e extent even the Chinese through their influence on the Hindus contributed to the onward m arch of m athematics in the West B ut the Japanese stand out in complete isolation . . . . , . . , . , , , . , , , , . . 1 G A M ill e r , H i s tor i cal I ntroduc ti on to M athemati cal Li teratu re, . . 1 91 6 , p . 24 . THE HIND U S After the time of the ancient Greeks the first people whose re searches wielded a wide influence in the world m arch of m athe matics belonged like the Greeks to the Aryan race It was however not a European but an Asiatic nation and had its seat in far o ff India Unlike the Greek Indian society was fix ed into castes The only castes enjoying the privilege and leisure for advanced study an d thinkn were the B rahmi ns whose prim e busin ess was religion and philosophy and the K shatri yas who attended to war and govern m ent Of the dev elop ment of Hin d u mathem atics we know but little A few man u Sc rip ts bear testimony that the Indians had c l imbed to a lofty height but their path of ascent is no longer traceable It woul d seem that Greek m athematics grew up under m ore favorable con di tions than the Hindu for in Greece it attained an independent exist ence and was studied for its own sake while Hindu m athe m atics always remained merely a servant to astronomy Furthermore in Greece m athem atics was a science of the people free to be cultivated by all who had a liking for it ; in India as in E g ypt it was in the hands chiefly of the priests Again the Indians were in the habit of putting into verse all m athe matical results they obtained and of clothing them in obscure and m ystic language which though well adapted to aid the me mory of him who already understo od the subject Although the great Hindu w as often unintelligible to the uninitiated mathem aticians doubtless reasoned out m ost or all of their discoveries yet they were not in the habit of preserving the proofs so that the naked theorems and processes of operation are all that have com e down to our time Very di fferent in these respects were the Greeks Obscurity of language was generally avoided and proofs belonged to the stock of knowledge quite as m uch as the theorem s themselves Very striking was the difference in the bent of m ind of the Hindu and Greek ; for while the Greek mind was pre e minently geometri cal the Indian was first of all ari thmeti cal The Hindu dealt wi th nu mber the Greek with form Nu merical symbolism the science of numbers and algebra attained i n India far greater perfection than they had previously reached in Greece On the other hand Hindu geo metry was merely m ensuration unaccompanied by dem onstration Hindu trigonometry is m eritorious but rests on a rith metic more than on geomet ry An interesting but difficult task is the tracing of the relation be tween Hindu a n d Greek m athem at i cs It is well known that more or less trade was carried on between Greece and In di a fro m early , , . , , , , - . , , . , , . , , . . , , , , . , , , . , , , , , , . , , . . , . - , , . , . , . , , , . , . . ‘ 83 A HISTORY OF M ATHE M ATICS 84 times Af ter Egypt had become a Roman province a more li vely comm ercial intercourse sprang up betw een Rome and India by way of Al exandria A pri ori it does not seem improbable that wi th the traffi c of merchandise there should also be an interchange of ideas That comm unications of thought from the Hindus to the Alexandrians actually did take place _ is e v ident from the fact that certain phi lo sophic and theologic teachings of the M anicheans N eo P latonists Gnostics S how un mistakable li k eness to Indian tenets Scientific facts passed also from Alexandria to India Thi s is shown plainly by the Greek origin of so me of the technical terms used by the Hindus Hindu astronomy was influenced by Greek astronomy A part of the geometrical knowledge whi ch they possessed is traceable to Alex andria and to the writings of Heron in particular In algebra there was probably a m utual giving and receiv ing There is e v idence also of an intimate connection between Indian and Chinese m athe matics In the four th and succeedin g centuries of our era Indian embassies to China and Chinese visits to India are 1 recorded by Chinese authorities We shall see that undoubtedly there was an influx of Chinese m athematics into India The history of Hindu m athem atics may be resolved into two periods : First the S u l vasutr a peri od which terminates not later than 2 00 A D second the as tr on omi cal and mathemati cal peri od extendin g from about 400 to 1 2 00 A D The term S ulvasutra m eans the rules of the cord it is the name giv en to the supplem ents of the K al pasfi tras which explain the con 2 struction of sacrificial altars The S u l vasut ras were composed som e ti me between 80 0 B C and 2 00 A D They are known to m odern scholars through three quite modern m anuscripts Their aim is prim arily not m athe m atical but religious The m athem atical parts relate to the construction of squares and rectangles S trange to say none of these geom etrical constructions occur in later Hindu works ; later Indian mathematics ignores the S u l vasfi t ras ! The second period of Hindu m athe matics probably originated with an influ x fro m Alexandria of western astronomy Z To the fif th j century of our era belongs an anonymous Hindu astronom ical work “ calle d the S urya S i ddhan ta ( Kn w l edg e from the sun ) whi ch cam e to be regarded a standard work 11 the six th century A D Varah a M ihi ra wrote his P ancha S i ddhan ti k a whi ch giv es a s umm ary of the S urya S i ddhan ta and four other astronom ical works then in use ; it contains matters of mathem atical interest J I n 1 8 8 1 there was found at B ak hshd l i in northwest India buried in the earth an anonymous ari thmetic supposed from the peculiar . , , . , , . , - , , . , . . . ' . , , . , . . . ’ . . , , , . . ’ ’ . . . . . . . , . , ’ . . ” . . , . . . , , , Siml a , G R K aye , I ndi a n M a themati cs , C al c u t t a i ng heav i l y u po n t h i s b ook w h i ch e mb odi es th e res ul t s m a t hem a ti c s 2 G R K aye , op ci t , p 3 1 . . . . . . . . . , , 1 9 1 5, p 38 . o f r ec en t . We a re draw s t u di es of H i ndu TH E HIND US 85 ities of its verses to date from the third or fourth century after Christ The document that was found is of birch bark and Is an inco mplete copy prepared probably abo ut the eighth century of an older manu 1 s cr i pt I t conta ins ari thmetical co mputati on SgTh e noted Hindu astrono mer Aryab h ata was born 4 7 6 A D at P atahpu t ra on the upp er Ganges His celebrity rests on a work entitled Aryabhati ya of which the third chapter is devoted to mathe matics sfi fil b ou t one hundred years later m athem atics in India reached the highest mark At that time flourished B rah mag u pta (born “ — In 6 2 8 he wrote his B r ahma sphu ta si ddhan ta ( The Revised System of of which the twelfth and eighteenth chap ters belong to m athematics 5 P robably to the nin th century belongs M ah avi ra a Hindu author on elem entary m athem atics whose wr i tin s have only recently been g brought to the attention of historians He 18 the author of the Gani ta S ar a S an gr aha which throws light upon Hindu geom etry and arith meti c j The follow ing centuries produced only two names of impor “ — tance ; namely S ri dh ar a who wrote a Gani ta s ara ( Q uintessence o f C al c u l a t i on 9 f an d P adman abh a the author of an algebra The science seems to have m ade but little progress at this t im e ; _for a “ work enti tled S i ddhan ta S i r omani ( D iadem of an Astronom ical 7 written by B h as k axa in 1 1 50 stands little higher than that System ) of Brahm agupta written over 50 0 years earlier The two m ost im portant m athem atical chap ters I n thi s work are the Li l avati the “ beautiful i e the noble science ) and Vij a gani ta root extrac devoted to arithm etic and algebra From n ow on the Hindus in the Brahmin schools seemed to content them selves with studying the masterpieces of their predecessors Scientific intelligence de creases continually and in m ore m odern tim es a very deficient Arabic w ork of the sixteenth century has been held in great authority The mathematic al chapters of the B r ahma s i ddhanta and S i ddhanta S i r oman i were translated into English by H T Colebrooke London The S ur ya s iddhan ta was translated by E B urgess and anno 18 1 7 M ah avi ra s ta ted by W D Whitney N ew Haven Conn 1 860 Goni ta S ar a S angr aha was published in 1 91 2 in M adras by M Rangi carya We begin with geometry the field in which the Hindus were least proficient The S ul vasutras indicate that the Hindus perhaps as early as 80 0 B C applied geom etry in the construction of altars 2 Kaye states that the m athematical rules found in the S u l vasutras “ relate to ( 1 ) the construction of squares and rectangles ( 2 ) the rela equivalent rectangles and squares tion of the diagonal to the S ides (3) equivalent circles and squares A k nowledge of the P y tha gorean (4) , . , , , . . . , . . , , . - . ‘ , , . - ” ’ , , , . ” . ’ ” , , . , , . ' - - . . , . , . - ’ . . , - . . , , ’ . . , , . , . - - . . , ’ . , . . . , ’ , ” , , . The B ak hs hal i M a n u scr i pt, e di t ed b y R u dolf Hoernl y xv11, 3 3 48 an d 2 75 2 7 9 , B omb ay, 1 888 2 G R Kaye, op ci t , p 4 1 — — . . . . . . . in the I ndi an A n ti qu ar y, A HISTORY OF M ATHE M ATICS 86 theorem is disclosed in such relations as 5 2 = There is no evidence that these expressions were 39 obtained fro m any general rule I t will be remembered that sp ecial cases of the P y thagorean theorem were known as early as 1 000 B C in China and as early as 2 00 0 B C in Egyp t A curious expression for the relation of the diagonal to a square namely 2 = = 202 , , . . . . . . , , 1 . . 1 l . ” is explained by Kaye as being an expression of a direct m easure m ent which m ay be obtained by the use of a scale of the kind named in one of the S ul v asu tra m anuscripts and based upon the change ratios 3 4 34 I t is noteworthy that the fractions used are all unit fractions and that the expression yields a result correct to fi v e decimal places The S ulvasutra rules yield by the aid of the P ythagorean theorem constructions for finding a square equal to the su m or dif ference of two squares they yield a rectangle equal to a giv en square with a s/ 2 and 2 a \/ 2 as the sides of the rectangle they yield by geometrical construction a square equal to a given rectangle and 2 — — = satisfying the relation ab (b + [a i ( a b) corresponding to Euclid II 5 In the S u l vasfi t ras the altar building ritual explains the construction of a square equal to a circle Let a be the S ide of a square and d the d iam eter of an equivalent circle then the given 1 —2 d/1 5 a rules m ay be expressed thus d = a =d 1 — This third expression m ay be ob d(1 8 2 6 + 6 t ai n e d fro m the first by the aid of the appro xi mation for V 2 given above Strange to say none of these geo metrical constructions occur in later Hindu works the latter completely 1g nore the ma th em atical contents of the S u l v asu t ras D uring the six centuries from the tim e of A ryabhata to that of Bh askara Hindu geom etry deals m ainly with m ensuration The Hindu gave no d efinitions no postulates no axioms no logical chain of reasoning His knowledge of m ensuration was largely borrowed from the M editerranean and from China through i mperfect channels of comm unication A ryabha ta gives a rule for the area of triangle which holds only for the isosceles triangle Brahm agupta distinguishes between approxim ate and exact areas and gives Heron of Alexan — — w / dria s fa m ous form ula for the triangular area s (s a) (s b) (s 2 Heron s for mula is given also by M ah avi ra who advanced b e yond his predecessors in giving the area of an equilateral triangle as Brah magupta and M ah avi ra m ake a remarkable ex tension — — — s of Heron s formula by giving w’ (s —a ) as the area b s c ) ( d) ) (s ( of a quadri lateral whose sides are a b c d and whose semi perim eter is s That this form ula is true only for quadrilaterals that can be i n ’ , . , , ’ . , , , , , , , ’ , . . , . 5 9 , 2 9 , . , , ’ . . , , , , . , . . , ’ , ’ ’ , , , , . G R K a y e , op c i t , p 7 2 D E S mi t h , i n I s i s , Vol 1 . . . . . . . . . 1, 19 1 3, pp . 1 99 , 2 00 . HINDUS TH E 87 a circle was recogniz e d by Brahmagupta according to Can l 1 2 tor s and Kaye s interpretation of B rah magupta S obscure ex position but Hindu co mmentators did not unders tand the li mi tation and Bhaskara finally pronounced the formula unsound Remarkable 2 — m m a is Brah agupta s theore on cyclic quadrilaterals x ( d b) c 2= — — a where x and and y ( b l cd) y are the diagonals and a b c d the lengths of the sides ; also the the 2= 2 2 2 2 orem that if a + b c and A + B then the quadrilateral “ is cyclic and has its ( Brahmagupta s (aC cB bC cA ) diagonals at right angles Kaye says : From the triangles (3 4 5) and ( 5 1 2 1 3 ) a commentator ob tains the quadrilateral (3 9 60 5 2 with diagonals 6 3 and 56 etc B rahm agup ta (says Kaye ) also i n t rodu ces a proof of P tole my s theore m and in doing this follows D io in constructing from right triangles (a b c) and phan t us ( III 1 9) new right triangles (a y 6 7 c y) and ( a c 6 c 7 c ) and ( a B y) uses the actual examples given by Diophantus nam ely (3 9 5 2 , 6 5) and ( 2 5 6 0 6 P arallelisms of this sort S how un m istakably that the Hindus drew from Greek sources In the mensuration of solids remarkable inaccuracies occur in A ryabhat a He gives the volume of a pyrami d as half th e product of 3 2 the base and the height ; the volu me of a sphere as 71 r A ryab hata gives in one pl ace an extremely accurate value for an v iz but he him self never utiliz ed it nor did any other Hindu m athematician before the twelfth century A frequent Indian p rac Bh askara gives two values —the tice was to take 7r = 3 or 3 9 2 7 and the inaccurate Archi m e ean above m entioned accurate d 5 0 value A comm entator on L i l avati says that these values were calculated by beginning with a regular inscribed hexagon and apply 2 — = ing repeatedly the form ula A D AB wherein A B is the side of the given polygon and A D that of one with d ouble the number of S ides I n this way were obtained the perim eters of the inscribe d = 1 0 0 the polygons of 1 2 sides Taking the radius 8 3 4 perim eter of the last one gives the value which A ryab h a ta use d for 7r The empirical nature of Hin du geom etry is illustrated by Bhaskara s proof of the P ythagorean theorem He draws the right triangle four tim es in the s q u ar e of the hypo te nuse so that in the m iddle there r e m ains a square whose side equals the difference between the two sides of the right triangle Arranging this square and the four triangles in a difl eren t way they are seen together to m ake up the su m of the “ s quare of the two sides B ehol d ! says Bh askara wi thout a dding — i t l I E C t V o d d 6 p 3 49 6 5 3 9 7 pp ' scr ib ed I n , ’ ’ ’ , ” ’ . : . , , , , , , ’ , , , . , , , , , , , . , ’ , , , ‘ , , , , , , , , , , . . - . . , . , ‘ ’ ‘ , ’ 1 2 , , , , . , , . . ’ . ' , . , ” , , . 1 2 an or , o . c G R K aye, . . . , op . ci t., r , pp , . 20 — . , 2 2. 1 0 , . . A HISTORY O F M ATHE M ATICS 88 another word of e xplanation B re tsc hnei de r conjectures that the P ythagorean proof was substantially the sa m e as this Rec ently it has been shown that this interesting proof is not of Hindu origin but was giv en m uch earlier ( early in the Christian era ) by the Chinese writer Chang Chu n — Ch i n g in his comm entary upon the ancient treat 1 ise the Chou pei In another place Bhaskara gives a second dem on s t r a t i on of this theore m by drawing fro m the verte x of the right angl e a perpendicular to the hypotenuse and comparing th e two tri angles thus obtained with the given triangle to which they are similar This proof was unknown in Europe till Wallis rediscovered it The only Indian work that touches the subj ect of the conic sections is M a h avi ra s book which gives an inaccurate treatment of the ellipse It is readily seen that the Hindus cared little for geome try B rah ma gupta s cyclic quadrilaterals constitute the only g em in their geo m . . , ’ , - . , , , . . ’ , . . ’ e t ry . The grandest achieve ment of the Hindus and the one which of all mathe matical inventions has contributed m ost to the progress of intelligence is the perfecting of the so called Arabic Notation That thi s notation d id not originate with the Arabs is n ow admitted by every one Until recently the preponderance of authority favored the hypothesis that our nu meral syste m with its concept of local value and our symbol for z ero was wholly of Hindu origin Now i t appears that the principal of local value was used i n the sexagesim al syste m found on B abylonian tablets dati n g from 1 6 0 0 to 2 30 0 B C and that Babylonian records from the centuries i mm ediately preced ing the Christian era contain a symbol for z ero which ho w ever was not used in computation These sexagesimal fractions appear in P tole my s A l mages t in 1 30 A D where the o micron o is m a d e to des i g na t e blanks in the se xagesim al nu mbers but was not used as a reg ular zero The Babylonian origin of the sexagesim al fract i ons used by Hindu astronomers is denied by no one The earliest form of the I n 2 dian symbol for z ero was that of a dot which according to B ii hl er “ was commonly used in inscriptions and manuscripts i n order to This restricted early use of the symbol for z ero r e mark a blank sembles som ewhat the still earlier use m ade of it by the Babylon i ans and by P tole my I t I S therefore probable that an imperfect notation invol ving the principl e of local value and the use of the z ero was i m ported into India that it was there transferred from the sexagesimal to the deci mal scale and then in the course of centuries brought to final perfection If these views are found by further research to be “ correct then the name Babylonic Hindu notation will be m ore “ appropriate than eithe r Arabic or Hindu Arabic It appears , ” , - , . . , . , . . , , . ’ . . , , . . ” , , . . , , ” . - , , ” ” - . Yo shio M i k ami , The P ythag orean Theo rem i n A r chi e d M ath u P hysi k , 3 S , V ol 2 2 , 1 9 1 2 , pp 1 4 2 e m i t a n L C K r i n s k i n t h e i r H i A r a bi c N u mer al s , n d uo t d b D E S h d a i u y p Q B o sto n an d L on don , 1 9 1 1 , p 5 3 1 . — . . . . . . . . . . . . . A HISTORY OF M ATHE M ATICS 90 follows :Vasu (a class of 8 gods) + two + eight+ m ountains ( the 7 m oun — — — d i i tain the t s se v en l mountains H unar ( H 9 g days (half of which equal The use of such notations made it pos sible to represent a nu mber in se v eral different w ays This greatly faci li tated the fram ing of verses containing arithmetical rules or sci en t i fi c constants which could thus be m ore easily re me mbered At an early period the Hindus exhibited great skill in calculating e v en with large numbers Thus they tell us of an exa mination to which B uddha the reform er of the Indian religion had to sub m it when a youth in order to w i n the maiden he lov ed In arith metic after ha ving astonished his exa miners by naming all the periods of numbers up to the 53d he was asked whether he could determine the num ber of primary atoms which when placed one against the other would form a line one m ile in length B uddha found the required a n swer in this way : 7 primary atoms make a very minute grain of dust 7 of these m ake a m inute grain of dust 7 of these a grain of dust whirled up by the wind and so on Thus he proceeded step by step until he finally reached the length of a mile The m ultiplication of all the fac tors gave for the m ultitude of primary atom s in a m ile a number con sisting of I 5 digits This problem rem inds one of the Sand— Counter of Archim edes After the nu merical symboli s m had been perfected figuring was m ade m uch easier M any of the Indian m odes of operation diff er from ours The Hindus were generally i n clin ed to follow the motion fro m left to right as in writing Thus they added the left hand col u mn s first and m ade the necessary co rrections as they proceeded For instance they would have added 2 54 and 6 6 3 thus : 8 which changes 8 into 9 4+ 3 7 Hence the su m 9 1 7 In I I Thus In 8 2 1 348 they would say su btr ac ti on they had t w o m ethods Or they would say 8 from 8 fro m 1 1 = 3 4 fro m 1 1 7 3 fro m In mu l ti pl i cati on of a number by 1 1 = 3 5 fro m 1 2 = 7 4 fro m 25 another of only one digit say 56 9 by 5 they generally said 5 which changes 2 5 into 2 8 hen ce the 0 m ust be i n creased by 4 The product is 2 84 5 In the m ultiplication with each other o f m any fi g u red nu mbers they first multiplied in the manner just indicated with the left hand digit of the multiplier which was written above the m ultiplicand and placed the product abo v e the multiplier On m ultiplying with the next digit of the m ultiplier the product was not placed in a new row as with us but the first prod uct obtained was corrected as the process continued by erasing when e v er necessary the old digits a n d replacing the m by n ew ones until finally the whole product was obtained We who possess the m odern luxuries of pencil and paper would not be l i kely to fall in love with “ this Hindu m ethod B ut the In dians wrote with a cane pen upon a small blackboard with a white th i nly liquid paint which m ad e marks that could be easily erased or upon a white tablet less than a foot - . , . , . , , , , , . , , , , . “ , , . , , , . . . , . . - . , , ' , . , , , . , . . , , , , , , , , , . , ’ , . . - , , - , , , ' , . , , , , , , , , . , - . , , , HIND US TH E 91 ” square strewn w ith red flour on which they wrote the figures with a 1 small stick so that the figures appeared white on a red ground Since the digits had to be quite large to be distinctly legible an d S ince the boards were s m all it was desirable to have a m ethod which would not require much space Such a one was the above m ethod of m ultiplication Figures could be easily erased and replaced by others without sacrificing neatness B ut the Hindus had al so other ways of m ultiplying of which we m entio n the following : The tablet was divided into squares like a chess board Diagonals were also drawn as seen in the figure The m ultiplication of I 2 X 7 3 5 8 8 2 0 is 3 2 exhibited in the adjoining diagram According to Kaye this mode of m ultiplying was not of Hindu origin and was know n earlier to the Arabs The m anuscripts extant give no i n formation of how di vi s i ons were executed Hindu m athematicians of the twel fth century 8 test the correctness of arithmetical computations 8 2 0 by casting out nines but this process is not of Hindu origin i t was kno w n to the Rom an bishop Hippolytos in the third cen tury In the B ak hshal i ari th metic a knowledge of the processes of c om putation is presupposed In fractions the nu merator is written above the denom inator Without a dividing line Integers are written as fractions wi th the denominator 1 In mix ed expressions the integral 1 part is written above the fraction Thus 1 1 3 In place of our they used the word phal am abbreviated into pha Addition was i n d ic at ed by yu abbreviated from yu ta Numbers to be combined 7 5 were often enclosed in a rectangle Thus pha 1 2 yu jmean s T f An unknown quantity is su nya and is des i gnated thus by a 12 “ 3 heavy dot The word su nya m ea ns empty and is the word for This double use of z ero which is here likewise represe nted by a dot the word and dot rested upon the idea that a position is e mpty if not filled out It IS also to be considered e mpty so long as the n um 4 ber to be placed there has not been ascertained The Bakhshah arithm etic contains proble ms of which so me are solved by reduction to unity or by a sort of f al s e posi ti on E xample : B gives twice as much as A C three t imes as much as B D four tim es as much as C ; together they give 1 3 2 ; how much did A give ? Take 1 for the unk nown (su nya)then A = 1 B = 2 C = 6 D = 2 4 their su m 33 D ivide 1 3 2 by 3 3 and the quotient 4 is what A gave The method of f al se posi ti on we have encountered before among , , . , , , . . . , - . : , . , . . . ” ‘‘ , , . . , . . . . , . , , . . , ” , . . , ” . , “ . . . ° , , , , , , , ' . , . H H an k el , op ci t , 1 8 74 , p 1 8 6 2 M C an tor , op ci t , V ol I , 3 A u fl , 1 90 7 , p 6 1 1 3 G R K aye , op ci t , p 34 4 C an to r I Ed , 1 90 7 , p p 6 1 3 6 1 8 , , 3 1 . . . . . . . . . . . . . . . . . . . — . . ” H ISTOR Y A 92 OF MATH EMATIC S the early Egyptians With them it was an instinc t ive procedure ; w i th the Hindus it had risen to a conscious m ethod Bh askara uses it but while the Bakhsh ali docu ment preferably assum es 1 as the u nk nown Bhaskara is partial to 3 Thus if a certain nu mber is taken fi v e fol d 3 of the product be subtracted the rem ainder di v ided l 1 1 by 1 0 and 3 3 and z of the original nu mber added then 6 8 is ob t ai n ed What IS the number ? Choose 3 then you get 1 5 and 3— 3 1 7 3 — — — 1 1 Then ( 6 8 1 1 4 8 t he answer 3 We shall now proceed to the consideration of som e arith m etical problems and the Indian m odes of solution A favorite m ethod was that of i nver si on With laconic brevity A ryabha ta describes it thus : “ M ultiplication becomes division division becom es m ultiplicatio n; what was gain becom es loss what loss gain ; inversion Q u i_ te d i ff erent fro m th is quotation in style is the following proble m fro m A ryabha ta “ which illustrates the m ethod : B eautiful maiden with bea ming eyes tell me as thou u n d er stan ds t the right method of inversion which 3 is the number which m ultiplied by 3 then increased by 4 of the prod u c t divided by 7 dim inished b y % of the quotient multiplied by i t self dimi nished by 5 2 the square root extracted addition of 8 and division by 1 0 gives the nu mber The process consists in begin ning with 2 and working backwards Thus — = 3 3 1 2 8 the answer 6 1 and v 9 4 Here is another example taken from L i l dvati a chapter in Eb as “ the kara 5 great work : The square root of half number of bees in a S — swarm has flown out upon a jessamine b u sh g of the whole swarm has remained behind one fem ale bee fli es about a m ale that 1s buzz in g withi n a lotus fl ow e r into which he was allured in the night by its sweet odor but is now imprisoned in it Tell m e the number of bees Answer 7 2 The pleasing poetic garb in which all arithm etical p rob lem s are clothed is due to the Indian practice of writing all s chool books in verse and especially to the fact that th ese problem s propoun ded as puz zles were a fav orite social am use m ent Says B rah magupta : “ These proble m s are proposed simp l y for pleasure ; the wise man can invent a thousand o thers or he can sol v e the problem s of others by th e rules given here As the sun eclipses the stars by hi s brilliancy so the man of knowledge will eclipse the fam e of others in assemblies of the people if he proposes algebraic problem s and still m ore if he solves t hem The Hindus solv e d proble m s in interest discount partnership alligation summation of arith m etical and geom etric series and de vised rul es for determining the num ber s of combinations and permu t at i o n s I t may here be added that chess the profoundest of all games had its origin in India The invention of magic squares is som etimes erroneously attributed to the Hindus Am ong the Chi nese and Arabs m agic squares appear m uch earlier The first occur rence of a m ag ic square among the Hindus is at D udh ai I han si in . . , , . , , , , , — , . , , - - 4 . . . , . . , ” , , , . , , , , , l , , , , , , , , , . , . , , ’ ' - , , ” - , , . . . - , , , . , , . ” , . , , , , , , . , . . . , , A H ISTORY OF M ATHE M ATICS 94 exists between the continuous an d discontinuous Yet by doing so the Indians greatly aided the general progress of m athematics In deed if one understands by algebra the application of arit hm etical operations to complex magnitudes of all sorts whether rational or irra t i on al num bers or space m agnitudes then the learned Brahm ins of 1 Hindostan are the real inventors of algebra Let us now examine more closely the Indian algebra In extract 2 ing the square and cube roots they used t he form ulas a + 2 2 3= 3 2 3 2 a b+ b and ( a + b In this connection A ryab a + 3 a b+ 3 ab + b ha ta speaks of dividing a nu mber into periods of two and three digits From this we infer that the principle of position and the zero in the nu m erical notation were already known to him In figuring wi th z eros a state m ent of Bh askara is interesting A fraction whose de nominator is z ero says he admits of no alteration though m uch be added or subtracted Indeed in the same way no change takes place in the infinite and i mm utable D eity when worlds are destroyed or created even though nu merous orders of beings be taken up or brought forth Though in this he apparently evinces clear mathematical no tions yet i n other p l aces he m akes a co mplete failure in figuring with fractions of z ero denominator In the Hindu solutions of deter minate equations Cantor thinks he can see traces of D iophantine m ethods Some technical term s be tray their Greek origin Even ii it be true that the Indians borrowed fro m the Greeks they deserve credit for improving the solutions of linear and quadratic equations Recogniz ing the existence of neg ati v e nu mbers B rah magupta was able to unify the treatm ent of the three form s of quadratic equations considered by Diophantus 2 2 = = vi z ax + bx c b x+ c ax a x + c = bx a and b c being pos ( 2 i t i v e nu m bers )by bringing the three under the one g en era l ca s e ' “ To S ri dhara is attributed the Hin d u m ethod of co mpleting the square which begins by m ultiplying both sides of the equation by 4p Bh askara adv ances beyond the Greeks “ and e v en beyond B rahm agupta when he says that the square of a positive as also of a negative number is positive ; that the square root of a positive nu mber is twofold positive and negative There is no square root of a negative nu mber for it is not a square Kaye points out howev er that the Hindus were not the first to giv e double 2 solutions of quadratic equations The Arab Al K how ari zmi of the 2 ninth century gave both solutions of x + 2 1 = 1 0 90 Of equations of higher degrees the Indi ans succeeded in solving only some special cases in which both sides of the equation could be made perfect powers by the addition of certai n term s to each Incom parably greater progress t h an i n the solution of determinate equations was m a de by the Hindus in the treat m ent of i nd eter mi n ate equ ati on s In determ inate analysis was a subject to which the Hindu . “ . , , ” - , . . . . . . , , , , . , , , . , . , . . , . , , . , , , , , ” , , . , , . , . , , , - . . , . . 1 H H an k e l , . p o . ci t . , p . 1 95 . 2 G R Kaye , . . p o . ci t . , p 34 . . TH E mind HIND US 95 showed a happy adaptation We hav e seen that this very sub j ec t was a favorite with Diophantus and that his ingenuity was al most ine xhaustible i n devising solutions for particular cases B ut the glory of having invented gen er al methods in this m ost subtle branch of mathematics belongs to the Indians The Hindu indeterm inate analysis difl ers fro m the Greek not only in m ethod but also in aim The obj ect of the former was to find all possible integral solutions Greek analysis on the other hand de man ded not necessarily integral but simply rational ans w ers D iophantus was content with a_s i ng l e solution ; the Hindus endeavored to find all solutions possible A ryab h ata gives solutio n s in integers to linear equations of the form axi by = c where a b c are integers The rule e mployed is called the pu t ver i zer For this as for most other rules the Indians gi v e no proof Their solution is essentially the same as the one of Euler Euler s . , . . , . . , , , . . , , . , . , , . ’ . process of reducing a b to a cont i nued fracti on a mounts to the same as the H indu process of findi ng the greatest co mmon di v isor of a and b by division Thi s is frequently called the Diophantine m ethod Han kel protests against this na me on the ground that D iophantus not only ne ver kne w the method but did not e v en ai m at solutions purely 1 integral These equations probably grew out of proble ms in astron They were applied for instance to determ ine the time when omy a certain constellation of the planets would occur in the heavens P assing by the subject of linear equations with more than two u m known quantities we come to indeterminate quadratic equations In the solutio n of they applied the m ethod r e invented l ater by Euler of deco mposing (a b+ c) into the product of two integers = m n and of placing x = m— and b l y n+ a 2 Re markable is the Hindu solution of the quadratic equation cy 2— With great keenness of intellect they recogniz ed in the special dx i b 2= 2 case y ax + 1 a funda mental problem in indeterm inate qua d ratics They solved it by the cycl i c method I t consists says D e M organ “ 2= 2 in a rule for finding an indefinite nu mber of solutions of y ax + I (a being an integer which is not a square )by m eans of one solution giv en or found and of feeling for one so l ution by making a solution 2 2= 2 2= 2 of y ax + b give a solution of y ax + b It amounts to the fol 2 2 lowing theore m :If p and g be one set of v alues of x and y i n y ax + b and p and q the sam e or another set then qp+ pq and app + qq 2 2 2 From this it is ob v ious that one ax + b ar e values of x and y in y 2 2 solution of y ax + I may be m ade to give an y number and that if 2= 2 2 taking b at pleasure y ax + b can be solved so that x and y 2 2 are divisible by b then one preliminary sol II t i o n of y ax + I can be be found Another m o de of trying for solutions is a combination of the preceding with the cu ttaca These calculations were used in astronomy . . , , . . , , . , . - — , . . . ” “ . . , , , , . ’ ’ ’ ’ ’ , . , , ‘ , . . 1 H Han k e l , op . . ci t . , p . 1 96 . , A HISTORY OF M ATHE M ATICS 96 this cyclic method constitutes the greatest invention in the theory of nu mbers before the time of Lagrange The perver 2= 2 s i ty of fate has willed it that the equation y ax + 1 should now be called P el l s equ ati on; the first incisive work on it is due to Brahmin scholarship reinforced perhaps by Greek research I t is a problem that has exercised th e highes t fac ul ties of some of our greatest modern analysts By them the work of the Greeks and H i ndus was done over again ; for u nfortunately only a small portion of the Hindu algebra and the Hindu manuscripts which we now possess were known in the “ Occident Hankel attributed the invention of the cyclic me thod entirely to the Hindus but later hi storians P Tan nery M Cantor T Heath G R Kaye favor the hypothesis of ultim ate Greek origin If the m issing parts of Diophantus are ever found light will probably be thrown upon this question Greater taste than for geom etry was shown by the Hindus for trig o n o me t r y Interesting passages are found in V araha M ihira s P ancha 1 S i ddhan ti k a of the six th century A D which in our notation for 2 unit radius gives S in 30 si n y 3 sin — — sin 2 i 0 210 This is followed by a table of l [ I S n (9 7 ] ] { 2 4 sines the angles increasing by i n terv al s of ( the eighth part of obviously taken from P tolemy s table of chords However instead of dividing the radius into 6 0 parts in the m anner of P tolemy the Hindu astronomer divides it into 1 2 0 parts which dev ice enabled hi m to convert P tole m y s table of chords into a table of sines without changing the numerical values A ryabha ta took a sti ll different value for the radius nam ely 3 43 8 obtained apparently from the relation 2 X 3 1 4 I 6r = The Hindus followed the Greeks and B abyl o n ia n s in the practice of dividi ng the circle into quadrants each quad — rant into 90 degrees and 5400 m inutes thus dividing the whole circle into equal parts Each quadrant was divided also into 2 4 equal parts so that each part e mbraced 2 2 5 un i ts of the whole circu mference and corresponded to 3 3 degrees Notable is the fact that the Indians ne v er reckoned l ike the Greeks with the whole chord of double the arc but always with the si n e ( j oa) and vers ed s i n e Their m ode of calcula ting tables was theoretically very S imple The sine of 90 was equal to the radius or 3 43 8 ; the sine of 30 was evidently half that or 1 7 1 9 D oub tl ess . , ’ , , . , ‘ . , , ” , , . , , . . , . , . , . . , . ’ . . . , , ° ‘ , , ° “ , ’ . , , , ’ . , , , . , . , , . , , , . ° . ° . , , = m r the for ula sin cos they obtained sin + 45 fi fl 2 43 1 Substituting for cos a its equal sin ( 90 —a) and making a = Apt 2 a 2 a ng ° 2 , , . they obtained sin 6 0 ° 2 97 8 . With the sines of 90 , 6 0 , 4 5, and 30 as starting points they reckoned the S ines of hal f the angles by the 2 = formula v er sin 2 a 2 sin a thus obtaining the sin es of 2 2 - , ° , 1 G R K aye , . . p ci t , p o . . . 10 . 98 A . HISTORY O F M ATHE M ATICS they would have exerted had they com e two or three centu ries earli er At the beginni ng of the twentieth century mathematical activ ity along mode rn lin es sprang up in In dia In the year 1 90 7 there was founded the I ndi an M athemati cal S oci ety; in 1 90 9 there was started 1 at M adras the Jou rn al of the I n di an M athemati cal S oci ety fl u en ce , . , ’ . . 1 (Th ree r ec en t o rig i n o f o u r n u w r i t er s me ral s We a dv an c e d a rg u r efe r to G (I) t e n di n g t o di sp ro v e t h e H i n du ’ K aye s ar t i c l e s i n S ci en ti a , V ol 2 4 , men t s R — n I I 0 B l i J o u rn a l A s i a t i c oc e n a I 1 S 9 7 , pp 4 7 5 5 0 8 , a l so V I I , pp , g , ’ — — 1 9 1 1 , p p 8 0 1 8 1 6 : i n I n di a n A n ti u ar y, 1 9 1 1 , p p 5 0 5 6 ; ( 2 t o C a r ra de V au x s q — a r t i c l e i n S ci en ti a , V o l 2 1 , 1 9 1 7 , p p 2 7 3 2 8 2 ; (3 t o a R u ssi an bo o k b r o ug h t o u t b y N ik ol B u b n ow i n 1 90 8 a n d t ran sl a t e d i n t o G e rman i n 1 9 1 4 b y J os L ez i u s K ay e c l a i ms t o S h ow t h a t t h e p ro o f s o f t h e H i n d u or i g i n o f o u r n u me ral s a re l arg el y l eg en dar y, t h at t he q u e st i on ha s b e en c l o u ded b y a co n fu sio n b e t w een t he w o rd s hi ndi ( I n di an an d hi n das i ( m ea s ur e g e o m e t ri c a l , t ha t t h e sym b ol s ar e n o t m odi fi e d l e t t e r s o f t he al p ha b e t We m u st ho ld o u r mi n ds i n su spen se on t hi s d i fli c u l t q u es i on an d aw ai t fu r t h e e vi den ce 19 1 8, — 5 3 55 ; h av e . . . . . ) . . ) . . . . . . ) ) t . r . ) . THE ARAB S After the flight of M oha mm ed fro m M ecca to M edina in 6 2 2 A D an obscure people of Se mitic race began to play an important part in the dra ma of history B efore the lapse of ten years the scattered tribes of the Arabian peninsu l a were fused by the furnace blast of religious enthusias m into a po w erful nation With sword in hand the united Arabs subdued Syria and M esopota m ia Distant P ersia and the lands beyond even unto India were added to the dom inions of the Saracens They conquered Northern Africa and nea rl y the whol e Spanish peninsula but were finally checke d fro m fu rther prog ress in Western Europe by the fi rm han d of Charles M artel ( 73 2 A The M osle m dominion extended now from In dia to Spain ; but a war of succession to the caliphate ensued and in 7 5 5 th e M ohamm e dan — e mpire w as di vi ded one caliph reigning at Bagdad the other at Cor dova in Spain Astoun ding as was the grand m arch of conquest by the Arabs still m ore so was the ease with which they put aside their former nomadic life adopted a higher civiliz ation an d assum ed the sovereignty ov er cultiv ated peoples Arabic was made th e written language throughout the conquered lands With t he rule of the Abba sides in the East began a new period in the history of learning The capital Bagdad situated on the Euphrates lay half way between two old centres of scientific thought — India in the East and Greece in the West The Arabs were destined to be the custodians of the torch of Greek science to keep it ablaz e during the period of c on fu sion and chaos in the Occident and afterwards to pass it over to the Europeans This remark applies in part also to Hindu science Thus science passed from Aryan to Sem itic races and the n back again to the Aryan Formerl y i t was held that the Arabs a dded but little to the knowledge of mathematics ; recent studies in di cate that they must be credited w ith novelties once thought to be of later origin The Abba sides at Bagdad encouraged the introduction of the sciences by inviting able special ists to their court irrespective of na t i on ali ty or religious belief M e dicine and ast ronom y were their fa v ori t e sciences Thus Harun al Rashid the m ost d istin g uished Sara cen ruler drew Indian physicians to Bagdad In the year 77 2 there cam e to the court of Caliph A lm an su r a Hindu astronom er wi th as t ron omi c al tables which were ordered to be translate d into Arabic These tables known by the Arabs as the S i ndhi n d an d probably taken from the B r ahma sphu ta si ddhan ta of B rah magupta stoo d in great authority They contained the i mportant Hin du table of s i nes Doubtless at this time and along w ith these astronomical tables . . . , , . . , , , . , . , ' , , . , , , . . . - , , , , , . , , . . , . . , . - . - , . , . , , - - , . . , , A HISTORY OF M ATHE M ATICS 1 00 the Hi n du numerals with the z ero and the principle of position were introduced am ong the Saracens B efore the time of M ohammed the Ar abs had no num erals Numbers were written out in words Later the num erous co mputations connected with the financial administra tion over the conquered lands m ade a short symboli s m indispensable In some localities the nu merals of the more civiliz ed conquered na tions were used for a tim e Thus in Syria the Greek notation was retained ; in Egypt the Coptic In some cases th e num eral adj ec t i v e s may have been abbreviated in writing The Di w ani — n u mer al s found in an Arabic P ersian dictionary are supposed to be such ab b r evi ati on s Gradually it becam e the practice to e mploy the 2 8 Ara bic letters of the alphabet for num erals in analogy to the Greek sys te n i This notation was in turn superseded by the Hindu nota tion which quite early was adop ted by m erchants and also by writers on arith metic Its superiority was generally recogniz ed excep t in as Here t r on omy where the a l phabetic notation continued to be used the alphabetic notation o ffered no great disadvantage since in the sexagesimal arith m etic t ak en f rom the A l mages t numbers of gen 1 e ral l y only one or two places had to be written As regards the form of the so called Arabic numerals the state m ent of the Arabic writer A i B i r u n i ( died who spent m any years in India is O f interest He says that the shape of the nu mer als as also of the letters in India d iff ered in di fferent localities and that the Arabs selected fro m the various form s the m ost suitable An Arabian astronom er says there was a mong people m uch di fference in the use of sym bols especially of those for 5 6 7 and 8 The symbols used by the Arabs can be traced back to the tenth century We find m aterial diff erences between those used by the Saracens in the East and those used i n the West B ut m ost surprising is the fact that the symbols of both the East and of the West Arabs deviate so ex tra ordi of n ar il y fro m the Hindu D eva n ag ar i nu m erals ( = divine nu m erals ) to day and that they resemble much m ore closely the apices of the Rom an writer Boethius This strange similarity on the one hand and dissimilarity on the other is difficult to explain The m ost plau sible theory is the one of Woepc k e : ( 1 ) that about the second cen tury after Christ before the z ero had been invented the Indian nu meral s were brought to Alexandria whence they spread to Rom e and also to West Africa ; ( 2 ) that in the eighth century after the no t a t i o n in In dia had been already m uch m o d ified and perfected by the invention of the z ero the Arabs at B agdad got it from the Hindus ; that the Arabs of the West borrowed the Columbus egg the z ero 3) from those in the East but retained the O l d form s of the nine num er als if for no other reason simply to be contrary to their political ene that the ol d form s were rem embered by the West m ies O f the East ; ( 4) Arabs to be of Indian origin and were hence called Gu bar n u mer ats , , . . . , . , . , , . , , . , - , . , . , , . , . , . , ' , , . - , - . , , , , . , , , . , . , . - , , . . , , , , , , - , , , , - , 1 H Hank el , op . . ci t., p . 2 55. , A HISTORY OF M ATHE MATICS 2 In astronomy great activity in original research existed as early as the ninth century The religious O bservances demanded by M oham me dan i sm presented to astrono mers several practical proble m s The M oslem do minions being of such enormous ex tent it rem ained in “ some localities for the astronomer to determine which way the B e liever must turn during prayer that he m ay be facing M ecca The prayers and ablutions had to take place at definite hours during the day and night This led to m ore accurate determinations O f tirn e To fi x the e xact date for the M oha mm edan feasts it beca m e n eces sary to observe m ore closely the motions of the m oon In addition to all this the O l d Oriental superstition that e xtraordinary occurrences in the heavens in som e mysterious way a ff ect the progress of hu man 1 a ffairs adde d increased interest to the prediction of eclipses For these reasons considerable progress was m ade Astronomical tables and instrum ents were perfected observatories erected and a connected series of observations instituted This intense love for as t ron om y and astrology continued during the whole Arabic scientific period As in India so here we hardly ever find a man exclusively de v oted to pure m athe matics M ost of the S O called mathematicians were first of all astronomers The first notable author of m athematical books was M oh amme d ib n M u s a Al Kh ow ar i z mi who lived during the reign of Caliph A l Our chief source of information about Al Khow M amun ( 8 1 3 —8 3 entitled K i tab A i — Fi hr i s t written by r iz m i is the book of chronicles and containing biographies of learned A i N adi m about 98 7 A D m en A l K h ow ari z mi was engage d by the caliph in m aking ex tracts from the S i ndhi nd in revising the tablets of P tole m y in taking O b and in measuring a degree of serv a t i ons at Bag da d and Da m ascus the earth s m eridian I mportant to us is his work on algebra and arith metic The portion on arithm etic is not extant in the original and it was not till 1 8 5 7 that a Latin translation of it was found I t “ begins thus : Spoken has Algorit mi Let us give deserved praise to God our leader and defender Here the name of the author A l K how a r i zmi has passed into A l g ori tmi fro m w hich com e our m o dern word al gori thm signif ying the art of computing in any particular 2 way and the obsolete form au gri m used by Chaucer The arith m etic of Kh ow ar izmi being based on the principle of position and “ the Hindu m ethod of calcula t ion excels says an Arabic writer all others in brevity and easiness and exhibits the Hindu intellect and sagacity in the grandest i n ven t ions This book was foll owed by a large nu mber of arithm etics by later authors which diff ered from the earl i er ones chiefly in the g reater variety of m ethods Ara bian arithmetics generally contained the four operations with inte . . , ” . . . . , . . , , . , , . - . . - , - , , - . , . , - . , , , ’ . . , ” . . . , , , , . , , , , , , ” “ , . , . 1 2 H . H ank el , o p See L 1 9 1 2, pp . . C 206 pp K arp i n sk i , —2 0 9 . ci t . . . , . 2 26 “ —2 2 8 . A u g r i ms t o n e s i n M oder n L a n guag e N otes , V ol . 27, ' THE ARAB S 1 03 gers and fractions modelled after the Indian processes They ex pla ined the operation O f casti ng ou t the o s also the regu l a f al sa an d the regu l a du oru m f al s oru m som etimes called the rules of false po sition and of double position or double false position by which algebraical examples could be solved w ithout algebra The r egu l a o was the assigning of an assu m ed value to th e a l s a or a s s i t i l a o f f p unknown quantity which value if wrong was corrected by some “ process like the rule of three I t was known to the Hindus and to the Egyptian Ahmes D iophantus used a m ethod alm ost identical 1 with this The regu l a du oru m f al soru m was as foll ows : To solve an equation f (x)V assume for the m om ent two values for x; namely = A and (b) = 3 and deter m ine the x = a and x = b Then form f (a) f , . ’ ” , ” , “ , . ” , , , . . . , , , , , . V —A = Ea errors and V —B = Eb then th e , b required — 12° i 2 it d b a generally a close approxim ation but is absolutely accurate whenever x) is a linear function of x ( f We now return to Kh o warizmi and consider the other part O f his — work the algebr a This is the first book known to contain this word itself as title Really the title consists of two words al j ebr w ai mu the nearest English translation O f which is restor a tion and a b a l a q “ reducti on By restoration was m eant the transposing of negative term s t o the other side o the equation by reduction the uniting of f 2 2= — = sim ilar terms Thus x 2 x 5x+ 6 p asses by al j eb r into x 5x+ = x+ 6 The work on alge 2 x+ 6 ; and this by a hn u q ab al a into 7 bra like the arith metic by the sam e aut hor contains little that 18 original I t explains the elem entary operations and the solutions of linear and quadratic equations From whom did the author borro w his knowledge of algebra ? That it cam e entirely fro m Indian sources “ is impossible for the Hindus had no rules like the restoration and “ reduction They were for instance never i n the habit of m aking all term s in an equation positive as is done by the process of r es to ra tion Diophantus gi v es two rules which rese m ble somewhat those of our Arabic author but the probability that the Arab got all his al gebra fro m D iophantus is lessened by the considerations that he rec og n i z e d both roots of a quadratic while D iophantus noticed only one ; and that the Greek algebraist unlike the Arab habitually rejected irratio n al solutions It would see m therefore that the algebra of Al Al Kh ow a ri z mi was neither purely In dian nor purely Greek He gave the K ho w ar izi m i s fa m e a mong the Arabs was great 2 2 2 = = a mples x + 1 0 x 3 9 x + 2 1 1 o n 3x+ 4 x which are use d by later authors for instance by the poet and m athematician O mar Khayya m “ 2 The equatio n x + 1 0 x = 3 9 runs like a thread of gol d through the algebras of several centuries ( L C Karpinski ) I t appears in the algebra of A bu K ami l who d rew extensiv ely upon the work of A l , . , . , ’ - . ” , , ” “ . ‘‘ , , - . , , . , , , , . . ” ” , . ” , , , . , , , , . , , - . ’ . , , , ” , . . . . ‘ 1 H H an k e l , . p o . ci t . , p . 2 59 . A HISTORY OF M ATHE M ATICS 04 Khow ariz mi Abu Ka m il , in turn , was the source largely drawn u pon b v the I tahan , Leonardo of P isa , in his book of 1 2 0 2 The algebra of Al -Kh ow ariz mi conta i ns also a few meagre frag ments on geometry He gives the theorem of the right triangle , but proves it after H i ndu fashi on and on l y for the simplest case , when the right triangle is isosceles He then calc ulates the areas of the tri angle , parallelogram , and circle For 71 he uses the value 34, and also the two Indi an , ar = w/E)and 7r = S trange to say , the last value . . . . . was afterwards forgotte n by the Arabs and replaced by o thers less accurate Al Kh owarizmi prepared astronomical tables whi ch about 1 00 0 A D were revised by M asl ama ai M aj ri ti and are of importa nce 1 as containing not only the si n e function but also the tangent function The former is evidently of Hindu origin the latter may be an addi tion m ade by M asl ama and was formerly attributed to Abu l Wefa Next to be noticed are the three sons of M u s a S akir , who lived in B agdad at the court of the Caliph A l M a mun They wrote several works of which we m ention a geometry containing the well known formula for the area of a triangle expressed in terms of its sides We are told that one of the sons travelled to G reece probably to collect astronom ical and mathematical manuscripts and that on his way back he made acquaintance with Tabit ibn Korra Recogniz ing in him a talented and learned astronomer M ohamm ed procured for him a place a mong the astronom ers at the court in Bagdad Tab i t i b n K orra — 8 was born at Harran in M esopotamia He was proficient 6 ( 3 90 1 ) not onl y in astronomy and m athematics but also in the Greek Arabic and Syrian languages His translations of Apollonius Archimedes Euclid P tolemy Theodosius rank among the best His disserta tion on ami cabl e n u mbers (of which each is the su m of the factors of the other ) is the first know n specimen of original work in m athematics on Arabic soil I t shows that he was fa miliar w ith the P ythagorea n the ory of numbers Tabit invented the foll owing rule for finding ami cable nu mbers which is related to Euclid s rule for perfect num bers : If — 2 — 1— 1— = 2 "— = = r 1 1 (n being a whole n um ber ) 1 p 3 q 3 2 92 are three pri mes then a = 2 pq b 2 "r are a pair of a micable numbers Thus if n = 2 then p 1 1 q = 5 r = 7 1 and a = 2 2 0 b = 2 84 Tabit also trisected an angle Tabit ibn Korra is the earliest writer outside of China to discuss magic squares Other Arabic tracts on this subj ect are due to Ibn 2 A l Haitam and later writers Foremost among the astronomers of the ninth century ranked Al , - . , , - . . , . , , ’ . - . - , . , , . , . . , , . , , , , . , , . . ” , . ” , . , . . , , , ” ’ , , , . , , . . - . S ee H S u t e r , D i e ast ron o mi sc he n Tafel n des M u hammed ib n M ii sa Al K hwari mi i n der B e a rb ei t u n g des M asl a ma ib n A hme d Al M adj r i ti u n d de r L a t e i n ’ U eb er se t zu n g d es A t hel h ard v on B a t h , i n M emoi res de l A cad émi e R des S ci ences et des L ettr es de Dan emar k , C op en hag u e , 7 1116 S , S ec t io n des L e t res, t I I I , no 1 , 1 z ” . - . ‘ t . 1 9 14 2 . . S ee H S u t e r , Di e M a themati k er PD 3 6 . 93 . 1 3 6 . 1 39. 1 40 . 1 46 , 2 1 8 . . u . A stron omen der A raber u . . . i hre Werk e , 1 900 , A HISTORY OF M ATHE M ATICS 06 last Arabic translators and co mmentators of Greek authors The fact that he estee m ed the algebra of M ohamm ed ibn M usa Al K how ariz imi worthy of his comm entary indicates that thus far algebra had m ade little or no progress on Arabic soil Abu l Wefa invented a method for computing tables of sines which gives the sine of half a degree correct to nine deci mal places He used th e tangent and calculated a table of tangents In considering the sha dow triangle of sun dials he intro d u c e d also the secan t and cos ecan t Unfortunately these new trigo n ome t r i c fu n ctions and the discovery O f the m oon s variation ex cited appare n tly no notice a m ong his conte mporaries and follo w ers “ A treatise by Abu l Wei a on geometric constructions indicates that e ff orts were being m ade at that ti me to i mprove draughting I t con tains a neat construction of the corners of the regular poly edron s on the circum scribed sphere Here for the first tim e appears the con dition which afterwards becam e very famous in the Occident that the construction be e ffected with a single O pening of the compasses K u hi the second astrono mer at the observatory of the em ir at Al — Bagdad was a close stu dent of Archim edes and Apollonius He solved the proble m to construct a segm ent of a sphere equal in volu me to a given segment and having a curved surface equal in area to that of a nother giv en segment He Al S ag an i and Al B iru ni m ade a stu dy of the trisection of angles Ab u l Ju d an able geometer solved the problem b v the intersection of a parabola with an equilateral hyper bola The Arabs had already discovered the theore m that the su m of two cubes can ne v er be a cube This is a special case of the last theore m of F erma t Ab u M oh am m e d Al Kh oj an di of C ho ra ssan thought he had prov ed this His proof now lost is said to have been defective Several centuries later B eha Eddin declared the impossibility of 3 3= 3 x +y z Creditable work in theory of nu mbers and algebra was done by Al Kar k hi of Bagdad who liv ed at the beginning of the ele v His treatise on algebra is the greatest algebraic work e n th century of the Arabs In it he appears as a discip l e of D iophantus He was the first to operate with higher roots and to sol v e equations of the 2 " form x + ax = b For the solution of quadratic equations he gives both arithmetical and geo m etrical proofs He was the first Arabic author to give and prove the theorem s on the summation of the se . - ’ - . . - - . . , ’ ’ ” - . . . , , , . , . , , - . - , , ’ , . , . ” . - . . , . , - . - , . . . ” . . r Ies : 1 2 ( + l + 1 1 3 g a ( 1+ + Karkhi also busied hi mself with in determ inate analysis He showe d S kill in han dling the m ethods of D iophantus but ad ded no thing whatever to the stock of knowledge already on hand Rather surprising is the fact that A l K a rk h i s algebra S hows no traces what Al - . , . ’ - THE ARAB S 19 7 ever of Hindu indeterminate analysis B ut most astonishing it is that an arithm etic by the sam e author completely excludes the Hindu numerals I t is constructed wholly after Greek pattern Abu l Wefa also in the second half of the tenth century wrote a n arith metic in which Hindu nu merals find no place This practice is the very oppo site to that of other Arabian authors The question why the Hindu nu merals were ignored by so e minent authors is certainly a puzz le Cantor suggests that at one tim e there may have been rival schools O f which one followed al most exclusively Greek m athe m atics the other Indian The Arabs were fam iliar with geometric solutions of quadratic equa tions Attempts were n ow m a de to solve cubic equations geo metri cally They were led to such solutions by the stu dy of questions like the Archi medean problem de man ding the section of a sphere by a plane so that the two segments shall be in a prescribe d ratio The first to state this proble m in form of a cubic equation was Al M ah ani of Bagdad while Ab u J a f ar Al ch azin was the first Arab to sol v e the equatio n by co nic sections Solutions were given also by A l Kuhi Al Hasan ibn A l Haita m and others Another diffi cult proble m to determine the S ide of a regular heptagon required the construction of 3— 2 — the S ide from the equation x x 2 x+ 1 = 0 I t was attempted by m any and at last sol v ed by Abu l Jud The one who did m ost to elevate to a method the solution of alge b rai c e quations by intersecting conics was the poet O mar Kh ayyam of Chorassan (a bout 1 0 4 5 He divides cubics into two classes the tri nomial and quadrinomial and each class into fa milies and spe cies Each species is treated separately but according to a general plan He believed that cubics could not be solved by calculation nor quadratics by geom etry He rejected negative roots an d often b i— failed to discover all the positive ones Attempts at b i qua drat i c 4 1 equations were made by Abu l Wefa who solved geom etrically x a 4 3 and x + ax b The solution of c u bi c e q ua t i on s by intersecting conics was the great est achievement O f the A rabs in algebra The foundation to this work had been laid by the Greeks for it was M en ae chm u s who first con 3 3— = 3 structed the roots of x a o or x 2 a 0 It was not his aim to find the number corresponding to x but simply to determine the side The Arabs on the other a t of a cube double another cube of S ide a hand had another object in vie w : to find the roots of given num erical equations In the Occident the Arabic solutions of cubics remained u nknown until quite recently D escartes and Thom as B aker invented these constructions ane w The works of Al Khayyam A l Karkhi Abu l Jud show how the Arabs departed further and further fro m . , ’ . - . , , , . . , , . , , . . . , . - ’ , - . - , - . , , , . ’ . , , , . . , . - . ’ - : , . . , . , , . ' , . , . - . - , , ’ , L M att hi essen , Gr u ndzu ge der A n ti ken a nd M oder n en A l gebra der L i tteral en hi n 1 c L i i u w i M a tt esse 8 0 l e i h u n e n e 1 8 8 2 L d G ( 3 1 90 6 w as p rofesso r p g, 7 , p 9 3 g g , o f physi c s a t Ros o c k 1 . z t . . . ) A H ISTORY 108 OF M ATHE M ATICS - the Indian methods and placed themselves more immediately under Greek infl uences With Al Karkh i and O mar Khayya m mathematics among the Arabs of the East reached fl ood mark and now it begins to ebb B e tween 1 1 0 0 and 1 30 0 A D com e the crusades with war and bloodshed during which European Christians profited m uch by their contact with Arabian culture then far superior to their o wn The crusaders were not the only adversaries of the Arabs D uring the first half of the thirteenth century they had to encounter the wild M ongol ian hordes and in 1 2 56 were conquered by them under the leadership of H u l aga The caliphate at Bagdad now ceased to exist At the clos e of the four t ee n th century still another e mpire was form ed by Ti m ur or Tamer D uring such s w eeping turm oil it is not surprising l a n e the Tartar that science declined Indeed it is a marv el that it existed at all D uring the supre macy of H ul ag u lived N a sir-Edd in ( 1 2 0 1 a man of broad cul ture and an able astronom er He persuaded H u lagu to build hi m and his associates a large O bservatory at M araga Treatises on algebra geometry arith m etic and a translation O f Eu c l i d s El emen ts were prepared by hi m He for the first tim e elabo rated trigonom etry independently of astronomy and to such great perfection that had his work been known Europeans of the fif teenth 1 century m ight have spared their labors He tried hi s skill at a proof of the paral lel postulate His proof ass umes that if AB is perpen di c ular to CD at C and if another straight line ED P makes an angle ED C acute then the perpendiculars to AB co mprehended betwee n AB an d EF and drawn on the side of CD toward E are shorter and shorter the further they are fro mCD His proof in Latin translation was published by Wallis in Even at the court of Ta m erlane in Samarkand the sciences were by no means neglected A group of astronomers was draw n to this a Ul e g B e g ( 1 393 B court grandson of Tamerlane was hi m self an astronomer M ost prominent at this tim e was Al Kas h i the author O f an arithm etic Thus during intervals of peace science continued to be cultivated in the East for several centuries The last Oriental writer was B eha Eddi n ( 1 54 7 His E ssence of A r i thmeti c stands on about the sa m e level as the work of M ohamm ed ibn M usa Kh ow a r iz mi written nearly 8 0 0 years before “ Wonderful is the expansive power of Oriental peoples w ith which upon the wings of the w ind they conquer half the world but more wonderful the energy with which in less than two generations they raise the mselves from the lowest stages O f cultivation to scientifi c , "I f . - - , - . , . . , . , . , , , . , . , . , . . , , . . , , , ’ , . , , . - . , , , , , , . , , , . . , - , . . , , . - . , , , , , B i bli otheca ma thema ti ca 7 , 1 8 93 , p 6 2 R B o n o l a , N on-E u cli dean Geometry, t ran s l by H S C a rsl aw , C h i cag o , pp 1 0 1 2 1 . . . - . . . . . 1 9 1 7, A HISTORY OF M ATHE M ATICS 1 10 Fro m this he derives the formulas for spherical right triangles This sine form ula was probably known before this to Tabit ibn Korra and 1 others To the four fundamental formulas already given by P tolemy he added a fifth discov ered by hi mself If a b c be the sides and A B C the angles of a spherical triangle right angled at A then cos E = cos b sin C This is frequently called Geber s Theorem Radical and bold as were his innovations in spherical trigonometry in plane trigono metry he foll owed slavishly the old beaten path of “ “ the Greeks Not even did he adopt the Indian sine and cosine “ but still used the Greek chord of double the angle So painful was the departure fro m old ideas even to an independent Arab ! It is a re markable fact that a mong the early Arabs no trace what e v er of the use of the abacus can be discov ered At the close of the thirteenth century for the first tim e do we find an Arabic writer Ib n Al b anna who uses processes which are a mix ture of ab acal and Hindu computation Ibn Al ban n a lived in B ugia an African seaport and it is plain that he ca me under European influences and thence got a knowledge of the abacus Ibn A lbann a and Abraham ibn Esra be fore h im solv ed equations of the first degree by the rule of double false position After Ibn A lban na we find it used by A i — K al s adi a n d B eha Eddi n ( 1 54 7 If ox+ b = o let m and n be any two nu mbers ( double false position let also am+ b = M a n + b = N — — = + then x (u M mN ) (M N ) 3 Of interest is the approxi mate solution of the cubic x + Q = P x which gre w out of the computation of x = si n The m ethod is shown only in this one nu merical example I t is giv en in M i r am C hel ebi in 1 4 98 in his annotations of certain Arabic astrono mical 3 tables The solution is attributed to A tabeddi n Ja mshi d Write x= If then a is the first app r oxi ma tion x being sna l l We have Q = aP + R and consequently x = a + 3 say Then a + b is the second app roxima ( R+ a ) 3 3 — = = P S a Hence tion We have R bP + S a and Q (a + b) 3 3 — = x P say Here a + b a + b+ (S a + (a l b) P = + c Is the third approximation a n d so on In general the a mount of computation is considerable though for find i ng x = sin I the m ethod answered v ery well This example is the onl y known approximate arithm etical solution O f an a ffected equation due to Arabic writers Nearly three centuries before this the Italian Leonardo of P isa carried the solution of a cubic to a high degree of approximation but without disclosing his method The latest prominent Spanish Arabic scholar was Al K al s adi of Grana da who died in 1 486 He wrote the Rai si ng of the Vei l of the “ “ The word gubar m eant originally dust and S ci en ce of Gu bar . - . , . , , , , , ” - , , , , , ’ . . , ” ” . , . , . , , , , . , . ” , , . - , “ , , . , . , . . , . , . . . - , . , . , ° , . . , , , , . - - ” ” . , . S ee B i bli otheca ma thema ti ca , 2 S , Vol 7 , 1 893 , p 7 2 zen u moder n en A l g ebra , L eip i g , L M a tthi essen , Gr u ndzug e d A n ti / 3 S e e C an to r , op ci t V o l I , 3 rd Ed , 1 90 7 , p 7 8 2 1 . . . . . . . . . . . . . z 1 8 78, p . 2 75 . THE ARAB S 111 stands here for written arithmetic with nu m erals in contrast to men tal arithmetic In addition subtraction and mu l tiplication the result is written a bove the other figures The square root was indi c a t ed by the initial Arabic letter of the word idre m eaning root j “ particularly square root He had symbols for the unkn own and His h ad in fact a considerable a mount of algebraic symbolis m 2 2 3 approximation for the square root wl a + b nam ely (4a + 3ab) / ( 4a + is believed by S G unther to disclose a m ethod of continued frac b) tions without our m odern notation since Al K al sadi s work e xcels other Arabic works in the am ount of algebraic s ymbolism used Arabic algebra before h im contained m uch less symboli sm then Hindu al gebra With Nessel 1 mann we di v ide algebras with respect to notation into three classes : Rhetori cal al gebr as in which no s ymbols are used everything (I ) being written out in words ( 2 ) S yn copa ted a l gebr as in which as in S S e v erything is written out in words excep t that abbrev ia sed for certain frequently recurring O perations and ideas al gebr as in which all forms and operations are repre fully developed al gebraic sym bo l is m as for exa mple 2 x + 1 0 x+ 7 According to this classification Arabic works ( e xcepting those of the later western Arabs)the Greek works of I amb l i chu s an d Thymari das and the works of the early Italian writers and of Regio montanus are r hetor i cal in form ; the works of the later western Ara b s of Diophantus and of the later European writers down to about the m iddle of the seventeenth century ( excepting Vieta s and O u g h t r e d s ) are syn copated in form ; the Hin d u works and those of Vieta and O u gh t r ed and of the Europeans since the m i ddle of the se v enteenth century mboti c in form It is thus seen that the western Arabs took an n in m atters of algebraic notation and were inferior predecessors or contemporaries excep t the Hindus I n the year Columbus discovered Am erica the M oors lost their last on Spanish soil ; the productive period of Arabic science was passed We have witnessed a laudable intellectual activity among the Arabs They had the good fortune to possess rulers who by their m u n ifi cen ce furthered scientific research At the courts of the c a l iph s scientists were supplied with libraries and observatories : A large number of astronomical and m athem atical works were written by Arabic authors I t has been said that the Arab s were learned but not original With our present knowledge of their work this dictu m needs revision they have to their credit several substantial accomplishments They solved cubic equations by geometric con struction perfected trigonom etry to a m arked degree and made nu , , . ” , ” . ” , , . , . , , . , , , ’ - . . , , , , , , , , , , , , , . , , , , , ’ ’ , . , , , . , . . , . , , ' . , , , ° . , 1 G H F N esselmann , Di e A l gebra der Gr i echen , B erl in , . . . 1 84 2 , pp . 30 1 — 3 6 0 . A HISTORY OF M ATHE M ATICS merou s s maller and astronomy advances all along the line of m athematics physics Not least of their services to science consists in this that they adopted the learning of Greece and India and kept what they received with care When the love for science began to grow in the Occident they transmitted to the Europeans the valuable treas ures of antiquity Thus a Se mitic race was during the D ark Ages the custodian of the Aryan i ntellectual po ssessions , . , , . , . , , . A H ISTOR Y O F M AT H E MATI CS 1 14 ance of B e de th e Ven er abl e ( 6 7 2 —73 the most learned man of hi s tim e He was a native of Wea rmou th in England His works con tain treatises on the C ompu tu s or the computation of Easter time and on fi ng er reckoning It appears that a fi ng er symbolism was then w idely used for calculation The corre c t determ ination of the time of Easter was a proble m which in those days greatly agitated the Church I t became desirable to have at least one m onk at each mon as t ery who could determ ine the day of religious festivals and could compute the calendar Such determ inations required some knowledge of arith metic Hence we find that the art of calculating always found som e little corner in the curriculum for the education of m onks The year in which B ede died is also the year in which Al c u i n ( 73 5 was born Alcui n was educated in Ireland and was called to the 80 4) court of Charle m agne to direct the progress of education in the great Frankish E mpire Charle magne was a great patron of learning and of learned m en In the great sees and m onasteries he founded schools in which were taught the psal ms writing singing computation (com s and gra mm ar By was here m eant probably not m u t u c t u s u o ) p p m erely the deter m ination of Easter ti m e but the art of computation in general E xactly what m odes of reckoning were then e mployed we have no m eans of knowing I t is not likely that Alcuin was fa miliar with the apices of Boethius or with the Roman m ethod of reckoning on the abacus He belongs to that long list of scholars who dragged the theory of nu mbers into theology Thus the nu mber of beings created by God who created all things well is 6 because 6 is a perfect nu mber ( the s u m of its divisors being 1 + 2 + 8 on the other hand is an i mperfect nu mber ( 1 + hence the second origin of m ankind e m anated fro m the nu mber 8 which is the number of souls said to have been in Noah s ark There is a collection of P roble m s for Quickenin g the M ind (pr op which are certainly as old as 1 0 0 0 A D os i ti on es ad acu endos i u ven es ) and possibly older Cantor is of the opinion that they were written much earlier and by Alcuin The following is a speci m en of these P roble m s : A d og chasing a rabbit which has a start of 1 50 feet ju mps 9 feet every ti me the rabbit ju mps 7 In order to determine in how many leaps the dog overtakes the rabbit 1 50 is to be di v id ed by 2 In this collection of proble ms the areas of triangular and quadrangular pieces of land are found by the same formulas of approxim ation as those used by the Egyp tians and give n by B oethius in his geo metry “ An old problem is the cistern proble m (given the ti me in which several pipes can fill a cistern singly to fi n d the time in which they fi ll it jointly ) which has been foun d previously in Heron in the Greek A n thol ogy and in Hin d u works M any of the proble ms sho w that the col lection was compile d ch i efly fro m Ro man sources The prob l em which on account of its un i queness gi v es the m ost pos i tiv e testi mony regarding the Roman origin is that on the interpretation of a . . , - , , - - . . . . . . . , . . , , , , . , , - , . . . . , , , , , , ’ . “ . , ” “ . . . , , . . , , ” - . , , , . , . , , INTROD UCTION OF RO M AN M ATHE M ATICS 1 15 wil l in a case where twins are born The problem is identical with the Roman except that diff erent ratios are chosen Of the exercises for recreation we mention the one of the wolf goat an d cabbage to be rowed across a river in a boat hol ding only one besides the ferry man so that the goat shall not eat Q uery : H ow m ust he carry the m across 1 the cabbage nor the wolf the goat ? The solutions of the proble ms for quickening the m ind require no further knowledge than the rec ol lection of so me few form ulas used in surveying the ability to solve linear equations and to perform the four funda mental operations with integers E xtraction of roots was nowhere de manded ; fractions hardly 2 ever occur The great e mpire of Charlemagne tottered and fell a l most i mm e War and confusion ensued Scientific pur dia t el y after his death suits were abandoned not to be resu m ed until the close of the tenth century when under Saxon rule in Germ any and Capetian in France more peacef u l tim es began The thick gloo m O f ignorance co mmenced to disappear The zeal with which the study o f mathe matics was now taken up by the m onks is due principally to the energy and influence — of one mam G e rb e rt He was born in Aurillac in Auvergne After receiving a m onastic education he engaged in study chiefly of m athe m a ti c s in Spain On his return he taught school at Rhei m s for ten years and beca me distinguished for his profound scho l arship By King Otto I and his successors G e rb e r t was held in highest esteem He w as elected bishop of Rheim s then O f Ravenna and finally was made P ope under the nam e of Sylvester II by his form er E mperor Otho III He died in 1 00 3 after a life intricately involved in many political and ecclesiastical quarrels Such was the career of the great est m athe matician oi the tenth century in Europe By his conte m po ra ri es his mathe matical knowledge was considered wonderful M any even accused him O f cri minal intercourse with evil spirits G erb er t enlarged the stock O f his knowledge by procuring copies O f rare books Thus in M antua he found the geometry of B oethius Though this i s of s mall scienti fic value yet it is of great importance in history It was at that ti m e the principal book fro m which Euro pean scholars could learn the elements of geom etry G e rb er t studied it w ith z eal and is ge n erally believed hi mself to be the author O f a g e H Weissenborn denied his authorship and clai med that the ometry book in question consists of three parts which cannot co me from one and the sam e author M ore recent study favors the conclusion that 3 G erb e r t is the author and that he co mpiled it fro m diff erent sources This geo metry contains little more tha n the one of B oethius but the fact that occasional errors in the latter are herein corrected s hows that . . , , , , , - . “ , , . . . . , , , . . . . , , . , . . , , , - , . , . . . . . . , . . , . , . . . , 1 S G u n the r , Ges chi chte des mathem Un ter r i chts i m deu ts chen M i ttel al ter . . 1 88 7 , 2 p 32 . . M C a n t or , . 3 S G un t her , . V o l I , 3 A u fl , 1 90 7 , p 8 3 9 Ges chi chte der M athemati k , 1 Tei l , L e i p i g , p o . ci t . , . . . . . . z 1 90 8 , p . 2 49 . . B e rl i n , A HISTORY OF M ATHE M ATICS 1 16 ” the author had mastered the subj ect The first mathe matical paper “ of the M iddle Ages which deserves thi s nam e says Hankel is a letter of G e rb e r t to A dal bol d bishop of Utrecht in which is explained “ the reason why the area of a triangle ob tai n ed geometrically by taking the product of the base by half its altitude diff ers fro m the area calculated arithm etically according to the formula used by surveyors where a stands for a side of an equilateral triangle He gives the correct explanation that in the latter form ula all the s mall squares in which the triangle is supposed to be divided are counted in wholly e v e n though parts of the m proj ect beyond it 1 D E S mith calls attention to a great m edi eval num ber game called I t was played r i thm om ac h i a clai med by so me to be of Greek origin as late as the six teenth century I t called for considerab l e ari thme ti cal ability and was kno w n to G erb er t O ron c e Fi n é Thomas B rad A board rese mbling a chess board was used R e w a rdi n e and others 1 = 2 4 3 of 7 2 4 2 l a t ion s like 8 1 3 6 + 7g of 3 6 were involved 7 G e rb e r t m ade a careful study of the arith metical works of B oethius He himself published the first perhaps both of the foll owing two works —A S mal l B ook on the D ivi si on of N u mbers and Rul e of Compu They giv e an insight into the methods of cal c u tal i on on the A bacu s lation practised in Europe before the introduction of the Hindu nu meral s G e rb er t used the abacus which was probably unknown to Al cuin B e rn el i nu s a pupil of G erb e r t describes it as consisting O f a s mooth board upo n which geom etricians were accustomed to stre w blue sand and then to draw their diagra ms For arithmetical pur poses the board was divided into 3 0 colu mns O f which 3 were reserved for fractions while the re maining 2 7 were divi d ed into groups wi th colu ns in each In every group the colu m ns were m arked r s e c m e p 3 and S (si n gu l ari s ) or t i v el y by the letters C (cen tu m)D (decem) M (mon as ) B e rn eli n u s gives the nine nu m erals used which are the apices of Boethius and then re marks that the Greek letters may be used in their place By the use of these columns any nu mber can be written without introducing a z ero and all operations in arithmetic can be perform ed in the sa me way as we execute ours without the col u mu s but wi th the symbol for z ero Indeed the m ethods of adding subtracting and m ultiplying in vogue among the abac i s ts agree sub B ut in a di vision there is very great s tant i all y with those O f to day difference The early rules for division appear to have been fram ed to satisfy the follo w ing three conditions : ( I ) The use of the multipli cation table shall be restricted as far as possible ; at least it shall never be required to m ultiply m entally a figure of two di gits by another of one digit ( 2 ) Subtractions shall be avoided as m uch as possible and The operation shall proceed in a purely replaced by additions (3) 2 m echanical way without requiring trials That it should be meces sary to m ake such conditions see ms strange to us ; but it m ust be re — A m M ath M thl y Vol 8 9 H Hank el op ci t p 3 1 8 pp 7 3 8 . , ” , , , , “ , . , , , . , . , . . , . , , , . . - . , . , , , , . . , , . , . , , , . , , . , , . , , , . , , - . . , . . . , 1 . . on , . 2 , 1 1 1, . 0. 2 . , . . , . . . A HISTORY OF 1 18 f Tr ansl ati on o M ATHE M ATICS A r a bi c M a nu s cr i pts By his great erudition and pheno menal acti v ity G erb e r t infused new lif e into the study not only of m athe matics but also Of philosophy P upils fro m France Germ any and I taly gathered at Rhei ms to enj oy his instruction When they themselves becam e teachers they taught of course not only the use of the abacus and geometry but also what they had learned of the philosophy of Aristotle His philosophy was known at first only through the writings of B oethius B ut the grow ing enthusias m for it created a demand for his complete works Greek texts were wanting B ut the Latins heard that the Arabs too were great ad mirers of P e ripa t e ti sm and that they possessed translations of Aristotle s works and comm entaries thereon This led them finally to search for and translate Arabic m anuscripts D uring this search m athe m atical works also came to their notice and were translated into Latin Though som e f ew uni mportant works m ay have been translated earlier yet the period of greatest activity began about 1 1 0 0 The z eal displayed in acquiring the M oha mmedan treasures of knowl edge excelled even that of the Arabs the mselves when i n the eighth century they plun dered the rich co ffers of Greek and Hindu science A m ong the earliest scholars engaged i n translating manuscripts into Latin was Ath el ar d of B ath The period of his activity is the first quarter of the t w elfth century He travelled e xtensiv ely in Asia M inor Egypt perhaps also in Spai n and braved a thousa n d perils that he m ight acquire the language and science of the M oha mmedans He made one of the earli est translations from the Arabic of Eucli d s He translated the astronom ical tables of A l K ho w a rizmi El emen ts In 1 8 57 a m anuscript was found i n the l ibrary at Ca mbr i dge which prov ed to be the arithm etic by A l K how a riz mi in Latin This trans lation also is very probably due to A thel a rd At about the sa m e tim e flourished P l ato of Ti voti or P l ato Ti bu r ti n u s He e ff ected a translation of the astronomy of A l Battani and of the S phceri ca of Theodosius About the m iddle of the twelfth century there was a group of Chris tian scholars busily at work at Tole do un der the lea d ersh ip of Ray m ond then archbishop of Toledo A mong those who worke d un der his d irection Joh n of S evi ll e was m ost prom inent He translated works chiefly on Aristotelian ph i losoph y Of i mportance to u s is a The rule for l iber al ghoa ri s mi co mpiled by him from Arabic authors , , , . , . , , . , , . . . , , , ’ . . , , . , . , , . , . . , , , , . ’ , , - . . , , - . . . - . , . , . , . . , the ad bd di v I S I on bc bd ad bc of one Th I S f rac t I on ' me sa by another expl a n a t IO n I s Is proved as follows : gi v en by the a c d d t h Ir t ee n t h cen tury Germ an writer Jor dan u s N emorariu s On comparing works like this with those of the a b a c i s t s we notice at once th e most striking diff erence which shows that the two parties d rew from i n dependent . , , , T RANSLATION OF ARABI C M ANUSCRI P TS 1 19 sources It is argued by some that G erb er t got his apices and his arith metical knowledge not fro m Boethius but fro m the A rab s in Spain and that part or the whole of the geo metry of B oethius is a forgery dating from the time of G erbe rt If this were the case then the writ ings of G erber t would betray Arabic sources as do those of John of Seville B ut no points of rese mblance are found G erb e r t could not have learned from the Arabs the use of the abacus because all evidence we have goes to S how that they did not employ it Nor is it probable that he borrowed fro m the Arabs the apices because they were never used in Europe except on the abacus In illustrating an example in division m athe maticians of the tenth and eleventh centuries state an example in Ro man nu merals the n draw an abacus and insert in it the necessary nu mbers with the apices Hence it see ms probable that the abacus and apices were borro w e d fro m the sam e source The contrast between authors like John of Se v ille drawing fro m Arabic works and the abac is ts consists in this that unl i ke the latter the former mentio n the Hindus use the term al gori sm calculate with the z ero and do not e mploy the abacus The form er teach the extraction of roots the ab aci s ts do not ; they teach the sexages im al fractions used by th Arabs while the abaci s t s employ the duodecim als of the R o q mans A little late r than John of Seville flourishe d G e r ard of C r e mo n a i n Lo mbardy B eing desirous to gain possession of the A l mages t he went to Toledo and there in 1 1 7 5 translated this great work of P t ol emy Inspired by the richness of M oha mm e d an literature he gave hi mself up to its stu d y He translate d into Latin over 70 Arabic works Of mathe matical treatises there were a mong these besides the A i magest the 1 5 books O f Euclid the S phcer i ca of Theo dosius a work of M enelaus the algebra of A l — K ho w a ri z mi the astrono my of Jabir ibn Afl ah and others less i mportant Through Gerard of Cre m ona the term si n u s was introduced into trigono metry Al Kh aw ar izmi s a l gebra was translated also by Robert of Chester ; his translation prob ably antedated Cre mona s In the thirteenth century the z eal for the acquisition of Arabic learning continued Fore most a m ong the patrons of science at this ti m e ranked E mperor Frederick II of Hohenstaufen (died Through frequent contact with M ohamm edan scholars he becam e familiar with Arabic science He e mploye d a nu mber of scholars i n tra n slating Arabic manuscripts and it was through him that we came i n possess i on of a n ew translation of the A l mages t Another royal head d eserv ing m ention as a z ealous pro moter of Arabic science was Alfonso X of Castile (di ed He gathe re d aroun d hi m a nu m ber of Jewish and Christian scholars who transl ated an d co mpiled astro Astrono m ical tables prepare d n omi c al works fro m Arabic sources by two Jews spread rapi dly in the Occi dent and constitute d the bas i s . , , , ‘ , . , , . . , . , . , , . . , , , , , , , , . , , , . . , , , , . , . . , , , , , , , . , ’ - . ’ . , . , . , . , . , 1 M C an tor . , p o . ci t . , V ol I , 3 A u fl . . . , 1 90 7 , p 8 79 , . c h ap t e r 40 . A HISTORY OF M ATHE M ATICS 1 20 of all astronomical calculation till the sixteenth century The n u m ber of scholars who aided in transplanting Arabic scie nce upon Chris tian soil was large B ut we m ention only one G i ovanni C ampano of Novara (about who brought out a new translation of Euclid which drove the earlier ones from the field and which formed the 1 basis of the printed editions At the m iddle of the twelfth century the Occident was in possession of the so called Arabic notation At the close of the century the Hindu m ethods of calculation began to supersede the cu mbrous me th ods inherited from Ro me Algebra with its rules for solving linear and quadratic equations had been m ade accessible to the Latins The geometry of Euclid the S phceri ca of Theodosius the astronomy of P tole m y and other works were n ow accessible in the Latin tongue Thus a great a mount of n ew scientific m aterial had com e into the hands of the Christians The talent necessary to digest this hetero g e n eo u s m ass of knowle d ge was not wanting The figure of Leonardo of P isa adorns the vestibule of the thirteenth century It is i mportant to notice that no work either on m athematics or astronom y was translated direc tly from the Greek previous to the fif teenth century . . , , , . , - . , . , . , , , , . . . . . The Fi r s t A w ak en i n g a nd i ts S equ el Thus far France and the B ritish Isles hav e been the headquarters of m athe m atics in Christian Europe B ut at the beginning of the thirteenth century the talent and activity of one man was suffi cient to assign the m athe matical science a new ho me in I taly This man was not a monk like B ede Alcuin or G e rb e r t but a laym an who found time for scientific study L e o n ardo of P i s a is the man to whom we owe the first renaissance of m athem atics on Christian soil He is also called Fi bon acc i i e son of B on ac c i o His father was secretary at one of the nu merous factories erected on the south and east coast of the M ed i t err an ea n by the enterprising m erchants of P isa He m ade Leonar do when a boy learn the use of the abacus The boy acquire d a strong taste for m athematics and in later years during extensive travels in Egypt Syria Greece and Sicily collected from the various peoples all the knowle dge he could get on this subj ect Of all the m ethods of calculation he found the Hindu to be unquestionably the best R e turning to P isa he published in 1 2 0 2 his great work the Li ber A baci A revised edition of this appeared in 1 2 2 8 This work contains the knowledge the Arabs possessed in arith m etic and algebra and treats the subject in a free and indepen dent way This together with the other books of Leonardo shows that he was not merely a compiler nor like other writers of the M iddle Ages a slavi sh im itator of the form in which the subject had been previously presented The extent , . . , , , , . . , . . . . , . , , , , , , , , . . , , , , , . . , , . , , , , . 1 H H an k el , . p o . ci t . , pp 33 8 , 339 . . A HISTORY OF M ATHE M ATICS 122 — B ritish M useum one English is of about 1 2 30 50 another is of 1 2 4 6 The earliest undoubted Arabic numerals on a grave s tone are at P forzheirn in Baden of 1 3 7 1 and one at U l m of 1 3 88 The earli est coins dated in the Arabic n umerals are as follows : Swiss 1 4 2 4 Austrian 1 4 84 French 1 48 5 German 1 4 8 9 Scotch 1 53 9 Engli sh I 5 5 1 The earl iest calendar with Arabic figures is that of KObel 1 5 1 8 The form s of the nu m erals varied considerably The 5 w as the most freakish An upright 7 was rare in the earlier centuries In the fifteenth century the abacus with its counters ceased to be used in Spain and I taly In France it was used later and it did not disappear in England and Germany before the middle O f the seven 1 The m ethod of abac al computation is found in the t een t h century English exchequer for the last tim e i n 1 6 76 In the reign of Henry I the exchequer was distinctly organized as a court of l aw but the fi nan The term ex c i al business O f the crown was also carried on there chequer is derived fro m the chequered cloth which covered the table at which the accounts were m ade up Suppose the sheriff was s u m mon ed to answer for the full annual dues in m oney or in tallies The liabilities and the actual payments of the sheri ff were balanced by m eans of counters placed upon the squares of the chequered table those on the one S ide of the table representing the value of the tallies warrants and specie presented by the sheriff and those on the other the a mount for which he was liable so that it was easy to see whether “ the sheriff had m e t his O bligatio n s or not In Tudor times pen and ink dots took the place O f counters These dots were used as late as The tally upon which accounts were kept was a peeled wooden rod split in such a way as to divide certain notches previously cut in it One piece O f the tally was given to the payer ; the other piece was kept by the exchequer The transaction could be verified easily by fitting the two halves together and noticing whether the notches ” tallied or nor Such tallies rem ained in use as late as 1 7 83 In the Wi n ter s Tal e (I V Shakespeare lets the clown be embar r assed by a proble m which he could not do without counters Iago (i n expresses his contempt for M ichael Cassio forsooth a Othel l o i 1 ) “ 3 great mathematician by calling h i m a counter caster S O gen eral indeed says P eacock appears to have been the practice of this species of arith metic that its rules and principles form an essential part of the arithm etical treatises of that day The real fact seem s to be that the old methods were used long after the Hindu nu merals were m anuscript , . . , , , , . , . , . . . . , . . , ” “ . ” . . “ , , ” , , . ” . . . . . ’ . , . ” , , - . , , , ” “ , , . i n t he En cycl ope di a of P u re M a themati cs , A ri thm e t i c G eo rg e P eacoc k , L on don , 1 8 4 7 , p 40 8 ’ “ 2 A r t i cl e Exc heq u er i n P al g rav e s D ic ti on ary of P ol i ti cal E con omy, L o n do n , 1 . 1 8 94 . . i n for ma t io n , c o n s u l t F P B a r n a r d , The Cas ti n g Cou n ter and H e g i ve s a l i st o f 1 5 9 e xt ra c t s f ro m E ng l is h the Cou n ti n g B oar d, O xfo r d , 1 9 1 6 i n v en to ri es re ferr i n g t o co u n t i n g bo ard s a n d a l so pho t og rap h s o f r ec k o n i ng t a bl e s a t B ase l a n d N ifrn be rg , o f rec k o n i n g c l o h s a t M u n i ch, e tc 3 For a ddi ti o n a l - . . - . t . FIRST AWAKENIN G THE SE Q UEL A ND I TS 1 23 in co mmon and general use With such dogged persistency does man c li ng to the old ! The L i ber A baci was for centuries one of the storehouses from which authors got material for works on arith metic and algebra In it are set forth the most perfect methods of calculation w ith integers and fractions known at that tim e ; the square and cube root are ex plained cube root nor having been considered in the Christian o eci dent before ; equations of the first and second degree leading to prob le ms either determinate or indeterm inate are solved by the methods “ “ of s ingle or double position and also by real algebra He recog 2 n i zed that the quadratic x + c = bx may be satisfied by two values of x He took no cognizance O f negative and im aginary roots The book contains a large nu mber of problem s The following was proposed to Leonardo of P isa by a m agister in Constantinople as a d iffi cult prob l em : If A gets from B 7 denare then A s su m is fi v e f ol d B s ; if B gets from A 5 denare then B s su m is seven fold A s H ow m uch has each ? The Li ber A baci contains another problem which is of historical ih t er es t because it was given with so m e variations by Ahme s 3 0 0 0 years earlier : 7 old women go to Ro me ; each woman has 7 m ules each m ule carries 7 sacks each sack contains 7 loaves with each loaf are 7 knives each knif e is p ut up in 7 sheaths What is the s um total of all named ? l A ns Following the practice of Arabic and of Greek and Egyp tian writers Leonardo frequently uses unit fractions This was d one also by other European wr i ters of the M iddle Ages He ex plained how to resolve a fraction into the su m O f unit fractions He was one of the first to separate the nu merator from the denom inator by a fractional line B efore his time when fractions were written in Hindu Arabic nu merals the deno minator was written beneath the numera tor wi thout any S ign of separation In 1 2 2 0 Leonardo of P isa published his P r acti ca Geometri co which contains all the knowledge of geo metry and trigonometry transm itted to him The writings of Euclid and of so m e other Gr eek m asters were known to him either from Arabic manuscripts directly or from the translations made by his countrym en Gerard of Cremona and P lato of Tivoli A S previously stat ed a principal source of his geom etrical knowledge was P lato of Tivolis translation in 1 1 1 6 fro m the Hebre w 2 into Latin , of the L i ber embadoru m of Abraham S avasor da Leo nardo s Geometry contains an elegant geom etrical demonstration of Heron s formula for the area of a triangle as a function of its three sides ; the proof rese mbles Heron s Leonardo treats the rich material before hi m with S kill some originality an d Eu c l idean rigor Of still greater interest than the preceding works are those contain . , , . , , ” , ” , . , . . . , ’ ’ - , ’ ’ - . , , , , , , , , . . . , . . . , - , . , , , ’ . , , . , ’ , . ’ ’ , ’ . . , M C an tor S ee a p ro b l em i n t h e A hme s V ol II , 2 A u fl , 1 90 0 p 2 6 p apy r u s b e l i e ve d t o b e o f t h e sa m e t yp e as t h i s 2 S ee M C u r t e , Ur k u nden zu r G eschi chte der M a thema ti k I Th e i l , L e i p i g , 1 90 2 , 1 . . , p o z . ci t . , . . . , . . . z . A H ISTOR Y O F M ATH E M ATICS 1 24 ing Fibonacci s more original investigations We must here preface that after the publication of the L i ber A baci Leonardo was presented by th e astronom er D ominicus to E mperor Frederick II of Hohen staufen On that occasion John of P alermo an imperial notary proposed several proble ms which Leonardo solved promptly The first (probably an old fa m iliar problem to him) was to find a nu mber x 2 2 such that x + 5 and x 5 are each square nu mbers The answer is 5 7 = = His m asterly S O x 3 2 ; for (3 1 5 (21 l u t i on of this I s g i ven i n his l i ber qu ad r a toru m a manuscript which was not printed but to which reference is m ade in the second edition of his L i ber A baci The problem was not original with J ohn of P alerm o since the Arabs had already solved similar o nes Som e parts of Leo~ nar do s solution may have been borrowed fro m the Arabs but the m ethod which he e m ployed of building squares by the su mm ation of o dd nu m bers I S original with hi m The second proble m proposed to Leonardo at the fa mous scientific tournam ent which acco mpanied the presentation of this celebrated al r a i s t to that great patron of learning E mperor Fre d erick II was e b g 3 2 the sol v in g of the equation x + 2 x + 1 0 x = 2 0 As yet cubic equations Instead of brooding stubbornly h ad not been sol v ed a l gebraically ov er this knotty proble m and after many failures still entertaining new hopes of success he changed his m ethod of inquiry and showed by clear and rigorous dem onstration that the roots of this equatio n could not be represented by the Euclidean irrational quantities or in other words that they could not be constructed with the ruler and co mpass only He contented him self with finding a very close ap proxi mation to the required root His work on this cubic is found in the Fl os together with the solution of the fol lowing third probl em given him by John O f P alerm o : Three m en possess in common an u n know n sum of m oney t; the share of the first is E; that of the second 1; ’ . , . , . , , , . , . - 1 , , . , . ’ , . , , . . , , , , , . . f , that of the third , é . 2 D esirous of depositing the each takes at haz ard a certain a m ount ; th e 2 , deposi t s z 6 ' su 3 at a safer place m first takes only x the second carries y but deposits only , , , but deposits x, the third takes z and , 3 Of the am ount deposited each one m ust receive exactly 3 , in order to possess his share of the whole sum Find x y z Leonardo shows the problem to be indeterminate Assuming 7 for the su m drawn by each fro m the deposit he finds t = 4 7 x = 33 y = I 3 z = 1 One woul d have thought that after so brilliant a beginning the sciences transplanted from M ohamm edan to Christian soil would have enjoyed a stea dy a n d vigorous develop m ent B ut this was not the case D uring the fourteenth a n d fifteenth centuries th e mathe , . . , . , , , . , , . . , A HISTORY OF M ATHE M ATICS 1 26 in abbreviations of Italian words such as p for pi n (m ore ) m for men o 2 co for cos a ( the unknown x) c c for cen s o (x ) cece for cen s oce n s o (less ) “ 3 (x ) Our present notation has arisen by al most insensible degrees as convenience suggested d ifferent m arks of abbreviation to different authors ; and that perfect symbolic language which addresses itself solely to the eye and enables us to take in at a glance the m ost c om plicated relations of quantity is the resul t of a large series of sm all im , , , , , , prov em en t s ” , , . We shall now m ention a few authors who lived during th e thirteenth and fourteenth and the first half of the fifteenth centuries We begi n with the philosophic wri tings of Tho mas Aq u in as ( 1 2 2 5 the great I talian philosopher of the M iddle Ages who gave in the completest form the ideas of Origen on infinity A q ui n a s notion of a continuu m particularly a linear continuu m m a de it potenl i al l y di v isible to infinity since practically the d ivisions coul d not be carried out to infinity There was therefore no minimu m line On the other hand the poi nt is not a constituent part of the line since it does not possess the property of infinite divisibility that parts of a line possess nor can the continuum be constructed out of points However a 2 point by its m otion has the capacity of generating a line This con ti n u um held a fi rm ascendancy over the ancient ato m istic d octrine whi ch assu m ed m atter to be composed of very s mall in divisible par t i c l es No continuu m superior to this was created bef ore the nine t een th century Aquinas explains Zeno s argu ments against m otion as they are given by Aristotle but hardly presents an y new point of — m view The English an Ro g e r B a co n 1 2 94] l i kewise argued against a continuum of in divisible parts different from points R e newing argum ents presented by the Greeks and early Arabs he held that the doctrine of indivisible parts of uniform siz e would m ake the diagonal of a square commensurable with a side Likewise if through the ends of an indivisible arc of a circle ra dii are drawn these ra dii intercept an arc on a concentric circle of smaller radius ; from this it would follow that the i nner circle is of the sam e length as the outer circle which is i mpossible Bacon argued against infinity If tim e were infinite the absurdity would follow that the part is equal to the whole B acon s views were m ade known more wid ely through D u n s S co tu s ( 1 2 6 5 the theological and philosophical opponent of Thomas Aquinas However both argued against the existence of in divisible parts (points ) D uns Scotus wrote on Zeno s paradoxi es but without reaching new points of view Hi s commentaries were annotated later by the Italian theol ogian Fr an c i s c u s d e P i ti g i am s who expressed hi mself in favor of the a dmi ssion of the actual infinity “ “ to explain the D ichotom y and the Ach i lles but fa i ls to ade l u a t e Sc holastic ideas on in fi n i tv and th e q y elaborate the subj ect . , t> ’ . , , , . , , . , , , . , . , . ’ . , , . , . , . , , , . . , ’ . . , ’ . , . ' , , ” , ‘ 1 . 2 C W H ersch el M a t hema t i c s i n Edi n bur gh En cycl ope di a R Wa ll n e r i n B i bl i otheca mathemati ca 3 F B d I V 1 90 3 pp F J . “ . . . , , . , . . , , . 2 9, 30 . THE FIRST AWAKENING AND ITS SE Q UEL 12 7 continuum find expression in the writings of B radw ardi n e the Eng 1 lish doctor pr of u ndi s About the tim e of Leonardo of P isa ( 1 2 0 0 A lived the German monk J or dan u s N e m or an u s —1 who wrote a once fam ous work on th e properties of nu mbers printed in 1 496 an d m odelled after the arithm etic of B oethius The m ost trifling num eral properties are treated with nauseating pedantry and prolixity A practical arith metic based on the Hin d u notation was also written by hi m J ohn H alif ax ( Sacro B osco died 1 2 5 6 ) taught in P aris and m ade an extract from the A l mages t containing onl y the m ost elem entary parts of that work This extract was for nearly 400 years a work of great popular ity and standard authority as was also his arithm etical work the Tr acl a l n s de axl e nn mer an dl Other prom inent writers are A lb e r tu s M agn u s ( 1 1 93 ? —1 2 80 ) a n d G e or g P e ur b ach ( 1 4 2 3 1 4 6 1 ) in Ger m any I t appears that here and there som e of our m odern ideas were anticipated by writers of the M id dle Ages Thus N i c ol e O r e sme a bishop in Normandy first conceived the notion of (about 1 3 2 3 fractional powers afterwar ds re discovered by S tevin and suggested a 3= 1% % 8 O r esm e concluded that 4 notation Since 4 6 4 and 6 4 8 , . . , . . . , . , , . - . . , , , , . , In his notation , 4 154 . , expressed Is or , ma them atician s of the M iddle Ages possessed som e O r esme even atte mpted a graphic representation idea of a function B ut of a nu meric d ependance of one quantity upon another as found in D escartes 2 there is no trace a m ong the m In an unpublished m anuscript O r esme found the su m of the infinite 5 series an i nf Such recurrent infinite series were 35 + formerly suppose d to have m a de their first appearance in the eight The use of infinite series is explained also in the L i ber een th century 3 de tri pl i ci motn by the P ortuguese m athe m atician A l vor a s Thomas i n 1 50 9 He gi v es the d ivision of a line segm ent into parts represent ing the term s of a convergent geometric series ; that is a segm ent A B P iB :P i + 1 is d iv ided into parts such that A B :P IB = P 1B :P 2B B Such a d ivision of a line segm ent occurs later in Napier s kinematical d iscussion of logarithm s Th o mas B r adw ar din e ( about 1 2 90 archbishop of Canter bury studied star polygons The first appearance of such polygons was with P ythagoras and his school We next m eet with such polygons in the geometry of B oethius an d also in the translation of Euclid from th e Arabic by A th el ard of Bath To England falls the honor of hav ing produced the earliest European writers on trigonom etry The — F C j i A m i M t/ M thl y V l 9 5 pp 4 5 4 7 — H W l t B i bl i th S l V m ll m l 3 9 3 pp 3 5 45 . . , , . . . , , - . , ’ - . - . , . . . 1 a or . 2 . , er c 1e e I n e r 1n Etu des . a on z . o eca , a ze o . 2 2, a zca , 1 . 1 o , . . , . 1 , 1 1 , . 11 1 . L eon ar d da Vi nc i , V o l I I I , P ari s , 1 9 1 3 , pp 393 , 5 40 , 5 4 1 , by P i e rr e D u h em ( 1 8 6 1 1 9 1 6 o f t h e U n i v e r si ty o f B or d eau x ; se e a l so Wi el e i t n er i n 168 B i bl i otheca ma thema ti ca , V o l 1 4 , 1 9 1 4 , pp 1 50 — 3 S ee s ur ) . . . . . A HISTORY OF M ATHE M ATICS 1 28 writings of B radw ardi n e of Richard of Wallin gford and John M aud i th both professors at Oxford and of Si m on B redon of Win che comb e contain trigonom etry drawn fro m Arabic sources The works of the Greek monk M axi mu s P l an u de s (about 1 2 6 0 are of interest only as showing that the Hindu nu m erals were then known in Greece A writer belonging like P l an u des to the B y z an t i n e school was M an u e l M os c h opu l u s who lived in Constantino ple in the early part of the fourteenth century To him appears to be due the introduction into Europe of magic squares He wrote a treatise on this subj ect M agic squares were kno w n before this to the Arabs and Japanese ; they originated w ith the Chinese M edimv al astrol og er s and physicians believed the m to possess m ystical properties and to be a charm against plague when engraved on silver plate Recently there has been printed a Hebrew arith m etical work by the French J ew L evi ben Ger s on writte n in and handed do w n in several m anuscripts I t contains for mulas for the number of per m utations and co mbinations of n things taken 13 at a ti m e It is worthy of note that the earliest practical arith metic known to have been brought out in print appeared anonymously in Treviso I taly in 1 4 7 8 “ and is referred to as the Tre v iso arithm etic Four years later in cam e out at B a mberg the first printed German arithm etic I t 1 48 2 is by Ul ri ch Wagn er a teacher of arith metic at N urnberg I t was 2 printed on parchm ent but only f ragments of one copy are now extant According to E n e s trom P h C al an dri s De ari thmetri ca opn s cnl u rn “ Florence 1 49 1 is the first printed treatise contain i ng the word z ero it is found in so m e fourteenth century m anuscripts In 1 494 was pr i n ted the S n mma de A ri thmeti ca Geometr i a P r opor ti on e et P r opor ti on al i ta written by the Tuscan m onk Lu c a P a ci oli who as we rem arked introduced several symbols in ( 1 44 5 algebra This contains all the knowledge of his day on arithm etic algebra and trigono metry a n d is the first com prehensive work which appeare d affi fi fi é f fl baci of Fibonacci I t contains li ttle of im portance which can n o t b e found in F i b o n acci s great work published three centuries earlier P ac i oli ca m e in personal touch with two ar 3 — i t s t s who were also m athe m aticians L eon a rdo da Vi n ci 1 2 ( 4 5 1 5 1 9) and P i er del l a Fr an ces ca ( 1 4 1 6 D a Vinci inscribed regular polygons in circles but did not distinguish between accurate and ap I t is interesting to note that da Vinci was proxi mate constructions familiar with the Greek tex t of Archim edes on the measurement of the circle P ier della Francesca advanced the theory of perspectiv e and left a manuscript on regular solids which was published by , , , , , . . , , , . . . . . , , , . . , , , . , . , . , . , ’ ’ , , . , , . , , , , , . , , , ’ . ’ ' , . , , . . , B i bl i otheca ma themati ca , 3 S , V ol 1 4 , 1 9 1 6 , p 2 6 1 2 S ee D E S mi t h , Rar a ar i thmeti ca , B os ton a n d L on don , 1 908 , pp 3 , 1 2 , 1 5 ; F U n g e r , M ethodi k der P r ak ti s chen A r i thmeti k i n H i s tor i s cher E n twi c k el u n g , L e ip z ig , 1 8 88 , p 39 ’ 3 C o n su l t P D u hem s Etudes s ur L eonard dc Vi nci , P a ri s, 1 90 9 1 . . . . . . . . . . . . . EURO P E D URING TH E SIXTEENTH SE VE NTEENTH A N D EIGHTEENTH CENTUR IES , We find it conv enient t o choose the time of the capture of Constan t i n opl e by the Turks as the date at which the M id dl e Ages ended and M o dern Ti m es began In 1 4 53 the Turks battere d the walls of this celebrated m etropolis with cannon and finally capt u red the city ; the Byzantine E mpire fel l to ri se no m ore Calam itous as was this event to the East it acted fa v orably u pon the progress of learning in the West A great nu mber of learned Greeks fled into Italy bringing with the m precious m anuscripts of Greek literature This contri buted vastly to the revi v ing of classic learning Up to this ti m e Greek mas ters were known only through the often very corrupt Arabic m a nu scripts but n ow they began to be studied from original sources and in their own language The first English transl ation of Euclid was m ade in 1 5 7 0 fro m the Greek by S i r H en ry B i l l i ngsl ey assisted by 1 John D ee About the m id dle of the fifteenth century printing was invented ; books beca m e cheap an d plentiful ; the printing press trans form ed Europe into an au dience — roo m Near the close of t he fifteenth century A m erica was discov ered and soon after the earth was cir The pulse and pace of the world began to quicken c u m n av i g a t ed M en s m inds beca m e less serv i le ; they becam e clearer and stronger The in di st inctness of thought which was the characteristic feature of m edi aeval learni n g began to be re m e died chiefly by the steady cultiva tion of P ure M athe m atics and Astronomy D ogmatism was attacked ; there arose a long struggle with the authority of the Church and the establish ed schoo l s of ph il osophy The Copernican Syste m was set up in opposition to the tim e honored P tolemaic Syste m The long and eager contest between the two cul minated in a crisis at the ti m e of Ga l i leo and resulte d in the victory of the new syste m Thus by slow degrees the m in ds of m en were cut adrift from their old scholastic moorings and sent forth on the wide sea of scientific inquiry to dis cover new islands and continents of truth . , , . , , , . . . , , . , , . - . , , , , . . ’ . , , . . - . . , , , , . The Ren ai ss an ce With the sixteenth century began a period of increased intellectual activity The hu man m ind m ade a vast e ffort to achieve its freedom Atte mpts at its em ancipation from Church authority had been m ade before but they were st ifle d an d re n dere d abort ive The first great and successful re v olt against ecc l es i astical authority was made in . . , . 1 G B H al s t e d i n A m f . . . ou r 1 30 . f M ath o , V ol I I , . 1 8 79. THE RENAISSANCE 31 Germany The n ew desire for j udging freely and in depen dently I n matters of religion was prece ded and acco mpa n ied by a grow i ng spirit of scientific inquiry Thus it was that for a ti m e Germany led the van in science She produced Regi omon tan u s C oper ni cu s Rhwti cu s and K epl er at a period when France and England had as yet brought forth hardly any great scientific thinkers This re markable scientific producti v eness was no doubt d u e to a great extent to the co mmercial prosperity of Germany M aterial prosperity is an essential condition for the progress of knowle dge As long as every individual is obliged to collect the necessaries for his subsistence there can be no leisure for higher pursuits At this ti m e Germany had accu mulated con s i der abl e wealth The Hanseatic League commanded the trade of the North Close co mmercial relations existed between Germany and Italy Italy too excelled in comm ercial activ ity and enterprise We need only m ention Venice whose glory began with the crusades and Florence with her ban k ers and her manufacturers of silk and wool These two cities becam e great intellectual centres Thus Italy too prod uced m en in art literature and science who shone forth in fullest splen dor In fact Italy was the fatherland of what is term ed the R e naissance For the first great contributions to the m athe matical sciences we m ust therefore look to Italy and Ger many In Italy brill i ant acces sions were m a de to al gebra in Germany progress was m a de in astron o my a n d trigono metry On the threshold of this new era we m eet in Germany with the figure of John M ueller more general l y called R e g io mon tan u s ( 1 43 6 He studied as C hiefly to him we owe the re v i v al of trigono m etry t ro n omy and trigono m etry at Vienna u nder the ce l ebrated George P eu rb ach The l atter percei v ed that the existing Latin translations of the Al magest were full of errors and that Arabic authors had not rem ained true to the Greek original P eu rb ach therefore began to m ake a tra nslation directly fro m the Greek B ut he di d not live to finish it His work was continued by Regiomontanus who went be yond his m aster Regiomontanus learned the Greek language from Cardinal B essarion whom he followed to Italy where he remained eight years collecting manuscripts from Greeks who had fled thither from the Turks In addition to the transl ation of and the c omm en tary on the A l mag es t he prepared transl ations of the C on i cs of Apol l on i u s of Archi m e d es and of the m echanical works of Heron Regio m ontanus and P e u rb ach adopte d the Hindu s i n e in p l ace of the Greek c hord of dou bl e the a rc The Greeks and afterwards the Arabs divided the radius into 6 0 equal parts and each of these again into 6 0 sm aller ones The Hin du expressed the length of the rad ius by parts of the circu mference saying that of the 2 1 6 0 0 equal d iv isions of the latter i t took 343 8 to m easure the radius Regiomontanus to secure greater precision constructed one table of sines on a radius divided into . . , , . , , , , , . , , . . , . , . . . , , . , , . , . , , , ' , . , , , . . , , , . , . . , . . , . . , , . , , . , . , . , , . , , , HISTORY A 13 2 or M ATHE M ATICS parts and another on a ra di us divi ded decirn al l y into divisions He emphasiz ed the use of the tangen t in trigo Following out some ideas of his master he calcu l ated a n om e t ry table of tangents Germ an m athematicians were not the first Euro peans to use this function In England it was known a century earlier to B radw ar din e who speaks of tangent (u mbr a vers a) and cotangen t (u mbr a r ecta)and to John M au di th Even earlier in the twelf th century the u mbra versa and u mbr a r ecta are used in a translation from Arabic into Latin e ff ected by Gerard of Cremona of the Tol edian Tables of Al Z ark ali who lived in Toledo about 1 0 80 Regiomontanus was the author of an arithm etic and also of a co mplete treatise on trigonom etry containing solutions of both plane and spherical tri angles So m e innovations in trigonom etry formerly attributed to Regiomontanus are now known to have been introduced by th e Arabs before him Nevertheless m uch credit is due to hi m His complete m astery of astronom y and m athematics and his enthusiasm for them were of far reaching influence throughout Germ any So great was his reputation that P ope Six tus I V call ed him to I taly to improve the calendar Regiomontanus left his beloved city of N ii rn b erg for Rom e where he died in the following year montanus trig onom etry and A fter the tim e of P e u rbach and Regio— — t h e calculation of tables c ofit in u edl t o occupy Germ an schol l e sp e i ” g al y ars M ore refined as tron omi c ar ifl s t rm en t s were made which gave observations of greater precision ; but these would have been useless without trigonometrical tables of correspon ding accuracy Of the sev eral tables calculated that by Georg J oachi m of Feldkirch in Tyrol gen — e ti c u s ( 1 5 1 4 1 5 6 7 ) deserves special m ention He cal e ral l y called Rh a and from 1 0 c u l a t e d a table of S ines with the radius = to 1 0 and later on another with the radius = " and proceeding fro m 1 0 to He began also the construction of tables of tangents and secants to be carried to the sam e degree of accuracy ; but he died before finishing them For twelve years he had had in continual e mploym ent several calculators The work was c om This was pl e t ed in 1 5 96 by his pupil Val e n ti n e O th o ( 1 5 50 ? — indeed a gigantic work a monument of Germ an d iligence and in de fatigable perseverance The tables were rep ubl i shed in 1 6 1 3 by B ar — m i s u of Heidelberg who spared no pains th ol o alu s P ti c s £1 56 1 1 6 1 3 ) to free theri ifi eiiY ors P itiscus was perhaps the first to use the word trigonometry Astronomical tables of so great a degree of accu racy had never been dream ed of by the Greeks Hindus or Arabs That Rhaet ic u s was not a ready calculator only is indicated by h i s views on trigonometrical lines Up to his ti me the trigonometric functions had been considered always with relation to the arc ; he was the first to construct the right triangle and to make the m depend d i It was fro m the right triangle that Rhee ti c u s re c tl y upon its angles got his idea of calculating the hyp otenuse ; i e he was the first to plan , . . , . . , . , , , , , - . , , . , , - . . , , , - . , . , . 0 g. ‘ “ n o - 0 , 0 -" o . , . , , ” . ” , , , . . , , . ' ' ' “ ” , . . , , , . , . . . . ' HISTORY A 1 34 O F M ATHE M ATICS Each contestant proposed thirty problems The one who could solve th e greatest num ber within fifty days should be the victor Tar taglia solved the thirty proble ms proposed by Floridas in two hours ; Floridas could not solve any of Tartaglia s From now on Tartaglia studied cubic equations with a will In 1 54 1 he discovered a general 3i 2= t solution for the cubic x px o by transfor ming it into the for m 3i x The news of Tartaglia s victory spread all over Italy Tartaglia was entreated to m ake known his m ethod but he declined to do so saying that after his completion of the translation from the Greek of Euclid and Archimedes he would publish a large al gebra containing his m ethod B ut a scholar from M ilan nam ed H i e r oni mo after many solicitations and after giving the C ar d an o ( 1 50 1 most solemn and sacred pro mises of secrecy succeeded in obtaining from Tartaglia a knowle dge of his rules Cardan was a singular mix ture of genius folly self conceit and mysticism He was successively professor of m a them atics and m edicine at M ilan P avia and Bologna In 1 5 70 he was imprisoned for debt Later he went to Rom e was admitted to the college of physicians and was pensioned by the pope At this tim e Cardan was writing his A r s M agn a and he knew no better way to crown his work than by inserting the m uch sought for rules for solving cubics Thus Card an broke his m ost solem n vows and publi shed i n 1 54 5 in his A r s M agn a Tartaglia s solution of cubics However Cardan did cred i t his friend Tartaglia with the discov ery of the rule Nevertheless Tartagl i a beca m e d esperate His most cherishe d hope of giving to the world an imm ortal work which should be the m onum ent of his deep learning and power for original research was suddenly d estroyed ; for the crow n intended for hi s work had been snatched away His first step was to write a history of his i n to completely annih ilate his enem ies he challenged v e n t i on ; but Cardan and his pupil Lodovico Ferrari to a contest : each party S hould propose thirty one questions to be solved by the other within fifteen days Tartaglia solved most questions in seven days but the other party did not send in their solutions before the expiration of th e fifth m onth ; m oreover all their so l utions except one were wrong A replication and a rejoinder followed Endless were the problem s pro pose d and sol v ed on both sides The dispute produce d m uch chagrin and heart burnings to the parties and to Tartaglia especially who m e t with m any other d isappoint m ents After having reco v ere d hi m self again Tartaglia began in 1 556 the publ i cation of the work which he had h ad in hi s m in d for so long ; but he die d before he reached the consideration of cubic equations Thus the fon dest wish of his life r e m ained unfulfilled H O W mu c h c r e di t for the algebraic solution of the general cubic I S due to Tartaglia an d how m uch to D el Ferro it is now impossible to ascertain d efinitely D el Ferro s researches were ne v er publ i she d and were lost We k now of the m only through the rem arks of Car dan and his pupil L Ferrari who say that Del Ferro s an d Tar 22 d . . . ’ . , . , ’ . , , , . , , , . - , . , , , . , . , . , ” ’ . , , . . , , . , , - . , . , . . - , , . , , , ’ . ’ . . ’ . THE RENAISSAN CE ” were alike Certain it is that the customary des ig “ nation Cardan s soluti on of the cubic ascribes to Cardan what belongs to one or the other of his predecessors Remarkable is the great interest that the solution of cubics excited throughout I taly I t is but natural that after this great conquest mathe maticians S hould attack b i quadratic equations A S in the case of cubics so here the first impulse was given by Colla who in 1 540 4 2 proposed for solution the equation x + 6 x + 3 6 = 6 0 x To be sure Cardan had studied particular cases as early as 1 539 Thus he solved 2 4 3 the equation 1 3x x + 2 x + 2 x+ 1 by a process similar to that em ployed by D iophantus and the Hindus ; nam ely by adding to both 2 S ides 3 x and thereby rendering both nu m bers co mplete squares B ut Cardan failed to find a general solution ; it re mained for his pupil Lo dovi c o Ferrari ( 1 5 2 2 —1 56 5 ) of B ologna to make the brilliant di s c o ve ry of the general solution of bi quadratic equations Ferrari re 2— 2 = 2 d u c ed Colla s equation to the form (x l 6 ) 6 0 x+ 6 x In order to give also the right m ember the form of a co mplete square he added to both members the expression containing a new u n 2 known quantity y This gave him 2 y) x + 6 0 x+ 2 — — ( 1 2y l y )The condition that the right m e mber be a complete square 2 = is expressed by the cubic equation ( 2 y+ 6 ) ( 1 2y+ y )90 0 Ex tract 2 — ing the square root of the bi quadratic he got x + 6 + y= x xf 2y+ 6 t ag l i a ’ methods 135 s . ’ , . . - . , , , , , . , . , . - . ’ . . . . , Solving the cubic for y and substituting it remained , only to determine x from the resulting quadratic L Ferrari pursued 1 a similar m ethod with other nu merical b i quadratic equations Car dan ha d the pleasure of publishing this discovery in his A rs M agn a in 1 54 5 Ferrari s solution is som etim es ascribed to R B ombel l i but he is no m ore the discoverer of it than Cardan is of the solution called by his name To Cardan algebra I s m uch indebted Inhis A rs M agn a he takes notice of negative roots of an equation calling them fi cti ti ou s while the positive roots ar e called real He paid some attention to compu t a t i o n s involving the square root of negative nu mbers but failed to recogni z e i maginary roots Cardan also observed the diffi culty in the irre d ucible case i n the cubics which l ike th e quadrature of the “ circle has S ince so m uch torm ented the perverse ingenuity of m athe m aticians B ut he di d not un derstan d i ts nature It rem aine d for Raph a e l B omb ell i of B ologna who published in 1 5 7 2 an algebra of great m erit to point out the reality of the apparently imaginary ex pression which a root assu mes also to assig n i ts value when rational and thus to lay the foundation of a more intim ate knowledge of imagi nary quantities Cardan was an inveterate gambler In 1 6 6 3 there was published posthu mously his gambler s m anual De l u do al ece . . - . ' ’ . . , . . , , . , . ” , , , . . , , ‘ , , . , . ’ , 1 H H an k el , . op ci t . . , p 36 8 . . , A HISTORY OF M ATHE M ATICS 1 36 which conta ins discussions relating to the chances favorable for throw ing a particular nu mber with two dice and also with three dice Car dan considered another problem in probabilities S tated in general terms the problem is :What is the proper div ision of a stake between two players if the gam e is interrup ted and one player has taken s 1 1 points the o ther s z points s points being required to win Cardan 2+ gives the ratio ( 1 + 2 + Tar taglia + [s + [s — gives (s + s l —s 2) s s B oth of these answers are wrong Car /( + 2 s dan considered also what later became know n as the f P eter sbu rg p roblem After the brilliant success in solving equations of th e third and fourth degrees there was probably no one who doubted that wi th aid of irrationals of hi gher degrees the solution of equations of any degree whatever could be found B ut all atte mpts at the algebraic solution of the quintic were fruitless and finally Abel demonstrated that all hopes of finding algebraic solutions to equations of higher than the fourth degree were purely Utopian Since no solution by radicals of equations of higher degrees co uld be found there rem ained nothing else to be done than the d evising of processes by which the real roots of nu merical equations could be found by approximation The Chinese m ethod used by them as early as the thirteenth century w as unknown in the Occid ent We have seen that in the early part of the thirteenth century Leonardo of P isa solved a cubic to a high degree of approxi mation but we are ignorant of his m ethod The earliest known process in the Occident of ap m to a root of an a fected nu erical equation was invented by ro ac h i n f g p Nicolas Chu q u e t who in 1 4 84 at Lyons w rote a work of high rank entitled L e tri party en l a sci en ce des n ombr es It was not printed until . . , , , . , ” . ‘ . , , , . , , , . , . . , . , , , , . If then C hu q u e t takes the interm ediate value it; as a closer approxim ation to the root x He finds a series of successive interme di ate values We stated earlier that in 1 4 98 the Arabic writer 3 M iram Chelebi gave a method of solv ing x + Q = P x which he attrib utes to A tab eddi n J amshid This cubic arose in the computation of . . . x = S In The earl iest printed m ethod of approxim ation to the roots of af f ec t ed equations is that of Cardan who gave it in the A rs M agn a 1 54 5 under the title of r egu l a au r ea It is a skilful application of “ the rule of false position and is applicable to equations of any de gree This m ode of approxim ation was exceedingly rough yet this fact hardly explains why Clavius S te v in and Vieta did not refer to it ” , , , . , , . . , 1 M C an tor , I I Au fl , 1 900 , pp 50 1 , 5 2 0 , 5 3 7 2 P ri n t ed i n t h e B u l l eti n o B on compagn i , T xii i , 1 880 ; see pp 6 5 3 6 5 4 S ee a l so “ F C aj o ri , A H i s t o ry of t he A ri t hme t i cal M e t ho d s o f A pp ro xima t io n to the Roo t s of N u meri c al Eq u a t i o n s o f o n e U n k n ow n Q uan ti ty i n C ol or ado Col l eg e P u bl i cati on , G en eral S eri es N os 5 1 an d 5 2 , 1 9 1 0 . , 2 . . . ” . . . . — . A HISTORY OF M ATHE M ATICS 1 38 also to goniom etry de v eloping such relations as sin a = sin a a —w 1th — —sm ( 6 0 a )csc ctn a + cs c a = t a n ‘ a , . ° , ) th e 2 aid of whi ch he could compute from the functions of angles below essentially th e functions of the re maining angles below 3 0 or 4 by addition and subtraction alone Vieta is the first to apply alge braie transformation to trigonometry particularly to the m ultisection of angles Letting 2 cos a = x he expresses cos n a as a function of x for all integers n < 1 1 ; letting 2 sin a = x and 2 S in 2 a = y he expresses “ 2 Vieta exclaims : Thus the analysis 2x s i n n a in ter m s of x and y of angular sections involves geom etric and arithm etic secrets which hitherto have been penetrated by no one An ambassador fro m Netherlands once told Henry IV that France did not possess a S ingle geom eter capable of sol v ing a problem pro pounded to geo meters by a B el gian mathe m atician A dri an u s R o m anus I t was the solution of the equation of the forty fif th degree 5 3 11 43 45 = — C + o4 sy 4 sr 3 7 95y + 95 6 34y 4 5y + r ° . , , . ” , ‘ . ” . , - . ‘ - Henry IV called Vieta who having al ready pursued S i m ilar inv esti g a t i o n s saw at once that this awe inspiring proble m was simply the equation by which C 2 S i n cl)was expressed in terms of y = 2 si nf g d); it was necessary only to di v ide an angle once that S ince 4 5 = 3 — into 5 equal parts and then twice into 3 a division which could be efl ec t ed by corresponding equations of the fifth and third degrees Bril liant was the discovery by Vieta of 2 3 roots to this equation i n stead of only one The reason why he did not find 4 5 solutions is that the remaining ones involve negative S ines which were u n in tel ligible to him D etailed investigations on the famous old problem Of the section of an angle into an odd nu mber of equal parts led Vieta to the discovery of a trigonom etrical solution of Cardan s irreducible , , - , . , , , . , , . , . , ’ — cos q5) 3 case in cubics He appl ied the equation ( 2 2 = 2 3 > x a a 6 when a 2 c os qS to the solution of x 3b by placing x 3 and determining q rom b= 2 a c os qb 2a The m ain principle e mployed by him in the solution of equations is that of r edu cti on He solves the quadratic by making a suitable substitution which will rem ove the term containing x to the first de gree Like Cardan he reduces the general expression of the cubic to z — the form then assu m ing z )z and su b s ti G— 3 3= tut ing he gets z bz P utting z y he has a quadratic In the solut i on of b i— qua d ratics Vieta still re m ai ns true to his principle of reduction This giv es hi m the well known cubic resolvent He thus a dheres throughout to his fav orite principle and thereby i n t ro du c e s into algebra a un i fo rm ity of m etho d which clai m s our lively a dmiration In V i eta s a l gebra we d iscov er a partial knowl e dge of the relations existing between the c oefli c i en ts and the roots of an equa 3 . , , . . , . , , , . , - . . , ’ . RENAISSANCE TH E 1 39 tion He S hows that if the coeffi cient of the second term in an equa tion of the second degree is minus the su m of two nu mbers whose product is the third term then the two nu mbers are roots of the equa tion Vieta rej ected all except positi v e roots ; hence it was impossible for him to fully perceive the relations in question The most epoch m aking innovation in algebra due to Vieta is the denoting of general or indefinite quantities by letters of the alphabet To be sure Regiom ontanus and S tifel in Germany and Cardan in Italy used letters before him but Vieta extended the idea and first m ade it an essential part of algebra The new algebra was called by hi m l ogi s ti ca s peci os a in distinction to the old l ogi s ti ca n u merosa Vieta s form alism diff ered consid erably from that of to day The “ equation was written by him a c u bus cubo aeq u al ia a + b cubo In + 6 i n a quadr 3 + a in b quadr num erical equations the unknown quantity was denoted by N its 2 3 square by Q and its cube by C Thus the equation x 8 x + 1 6 x = 40 — was written 1 C 8 O+ I 6 N ( equ al 40 Vieta use d the term c o effi c i en t but it was little used before the close of the seventeenth “ 1 century So metimes he uses also the term polynom ial Observe that exponents and our symbol for equality were not yet in use ; but that Vieta employed the M altese cross as the short hand symbol for a ddition and the for subtraction These two Char a c t e r s had not bee n in very general use before the ti m e of Vieta It “ is very s ingular says Hallam that discoveries of the greatest con v e n i e n ce and apparently not above the ingenuity of a village school m aster S hould hav e been overlooked by men of extraor dinary acute nes s lik e Tartaglia Cardan and L Ferrari ; and har dly less so that by d int of that acuteness they dispensed with the aid of these c on t ri v ane c s in which we suppose that so much of the utility of algebraic ex pressio n consists Ev en after improvements in notat i on were once proposed it was with extre m e slowness that they were admitted into general use They were m ade oftener by accident than design and their authors had little notion of the effect of the Change which they were m aking The intro duction of the and symbols seem s to be du e to the Germ ans who although t h ey d i d not enrich algebra d u r ing the Renaissance with great inventions as did the Italians still cul The arith m etic of Joh n Wi dmann brought ti v at ed it with great z eal out in 1 48 9 in Leip z ig is the earliest printed book in wh i ch the and symbols have been found The sign is not restricted by hi m to “ ordinary addition ; it has the more general m eaning e t or and “ as in the heading regula au g m en t i decrem enti The S ign is “ used to indicate subtraction but not regular ly so The word plus “ d oes not occur in Wi dm an n s text ; the word m inus is use d only two or three t imes The symbols are use d regularly for ad d i an d . , . . - . , , , , . . ’ - . ” . . . , , . “ . . ” , . . - . , ” “ . , , , , , , ’ , . , , , , ” . , . , . , , , , , . , ” ” - . . , , . ’ . 1 Encycl oped i c des s c i en ces mathémal i q u es , Tome I , V ol . 2 , 1 90 7 , p . 2. A HISTORY OF M ATHE M ATI CS 1 40 tion and subtraction in in the arithm etic of Gr ammateu s a teacher at the University of Vienna (Heinrich Schreiber died I 5 2 5 ) His pupil Ch ri s tofi Ru dol fl the writer of the first text book on algebra in the German language (printed in e mploys these symbols also So did S tifel who brought out a second edition of R u dol fl s C oss in Thus by slow degrees their adoption became universal Sev 1 553 eral independent p aleographic studies of Latin m anuscripts of the fourteenth and fifteenth centuries m ake it alm ost certain that the comes from the Latin et as it was cursively written in m anu S ign 2 scripts j ust before the time of the i nvention of printing The ori gin of the S ig n is still uncertain There is another short hand symbol of which we ow e the origin to the Germans In a manu script published sometim e i n the fifteenth century a dot placed before a num ber is m ade to signify the extractio n of a root of that n umber This dot is the e mbryo of our present symbol for the “ square root Christoff R u dolff in his algebra re marks that the radix quadrata is for brevity designated in his algorithm wi th the Here the dot has grown into a symbol m uch character w/ as V4 like our own This sam e symbol was used by M i chael S tif el Our — the author of S i g n of equality is due to Rob e rt R e c or d e ( 1 5 1 0 1 5 which is the first E nglish treatise on The Whets ton e of Wi tte ( I 5 algebra He selected this symbol because no two things could be m ore equal than two parallel lines The S ign for division was first used by Johan n H ei nri ch Rahn a Swiss in his Teu tsche A l gebr a Zurich 1 6 59 and was introduced in England through Thom as B ran ck e r s translation of Rahn s book London 1 668 M i ch ae l S ti f e l ( 1 4 86 P the greatest German algebraist of the sixteenth century was born in Esslinge n and died i n Jena He was educated in the monastery of his native place and afterwards be came P rotestant m inister The study of the S ignificance of m ystic numbers in Revelation and in Daniel drew him to m athe matics He studied Germ an and I talian works and publishe d in 1 544 in Latin a book entitled A ri thmeti ca i ntegr a M elanchthon wrote a preface to it Its three parts treat respectively of rational nu mbers irrational numbers and algebra S tifel gives a table containing the nu merical values of the binomial coeffi cients for powers below the 1 8 th He ob serves an advantage in letting a geom etric progression correspond to an arithmetical progression and arriv es at the designation of integral powers by numbers Here are the germ s of the theory of expone n ts and of logarith ms In 1 54 5 S t ifel published an arithm etic in German His edition of R u dol ff s C oss contains rules for solving cubic equations d erived from the writings of Cardan — — G En est m i n B i bl i th ca m th m ti S l V 8 9 pp 9 9 55 5 7 ; 3 , , . , - , , . ’ , , . , . , . - . . , . . ” , , , , . . . . , , , , , ’ ’ . , , , . , , . . , , , . . , , . . , . . . ’ , . 1 ro . V ol . 1 4, 1914 , p o . 2 78 For re fe re n ces see M op ci t , Vol I , 1 90 2 , pp . . a e a ca , . . o , . , 1 0 0 . , 1 1 . 2 . e . . C a n tor , 1 3 3 , 1 34 p o . . ci t . , V o l I I, . 2 . Ed . , 1 9 00 , p . 23 1 ; J . Tr op fk e, A HISTORY OF M ATHE M ATICS 42 century From the notes of P appus he attempted to restore the miss ing fifth book of Apollonius on maxi ma and mi ni ma His Chief work is his m asterly and original treat ment of the conic sections wherein he discusses tangents and asymptotes m ore fully than Apollonius had done and applies them to various physical and astronom ical problems To M au rol yc u s has been ascribed also the discov ery of the inference 1 by mathematical induction I t occurs in his introduction to his Opu s 1 575 Later m athematical induction was cu l a ma thema ti ca Venice used by P ascal in his Tr ai l e du tr i angl e ari thméti qu e P rocesses akin to m athematical induction som e of which would yield the mod ern m athematical induction by introducing som e S light change in the mode of presentation or in the point of view were given before M au of Novara r ol yc us Gi ovan ni C a mpa n o (latini z ed for m Cam panus ) in Italy in his edition of Euclid proves the irrationality of the golden section by a recurrent m ode of inferen ce resulting in a reductio ad absurdum B ut he does not descend by a regular progression from n to n 1 n 2 etc but leaps irregularly over perhaps sev eral integers Campano s process was used later by F erma t A recurrent mo de of “ inference is found in B hask ara s cyclic m ethod of solving inde term inate equations i n Theon of S myrna (about 1 30 A D ) and in P ro c l u s s process for finding nu m bers representing the sides and di that a g on al s of squares ; i t is found in Euclid s proof (E l emen ts IX 2 0 ) the nu mber of prim es is infinite 2 The foremost geom etrician of P ortugal was P e d r o N u n e s ( 1 50 2 or N on i u s He showed that a ship sailing so as to m ake equal 1 5 7 8) angles with the m eri dians does not travel in a straight line nor usually along the arc of a great circle but describes a path called the l oxo “ Nunes invented the nonius and described it i n d rom ic cur v e his De cr epu scu l i s Lisbon 1 54 2 I t consists in the juxtapositio n of equal arcs one a re di v i ded into m equal parts and the other into m+ 1 equal parts Nonius took m = 8 9 The instrum ent is also called “ a vernier after the French m an P i erre Ver n i er who r e invente d it in 1 6 3 1 The forem ost French m athem atician before Vieta was P e te r who perished in the m assacre of S t B artholom ew Ramu s ( 1 5 1 5 The n ew Vi eta possessed great fam iliarity with ancient geom etry form which he gave to algebra by representing general quantities by letters enabled him to point out m ore easily how the construction of the roots of cubics depended upon the celebrated ancient problem s of the duplication of the cube and the trisection of an angle He reached the interesting conclusion that the former problem includes the solu tions of all cubics in which the radical in Tartaglia s form ula is real but that the latter problem includes o nly those leading to the i rredu cible case . , . , . , . . , , , , , . , , . . , , , . , , ” ’ . ’ . , . ’ ’ , . . ” , , . , , . , ” . . - , , . . . . , . , . ’ , . G V acca i n B ull eti n A m M ath S oci ety, 2 S , V ol F C aj o ri i n V ol 1 5 , pp 40 7 — 40 9 2 S e e R G ui mar ae s, P ed ro N u n es , C oi mp r e, 1 9 1 5 1 1 . . . . . . . . . . . . 16, 1 909 , p . 70 . S ee al so ' THE RENAISSANCE 1 43 The problem of the quadrature of the circle was revived in this age and was z ealously studied eve n by men of e minence and m athematical ability The ar my of circ l e squarers becam e most formidable q ing the seventeenth century A mong the first to revive this problem was the Germ an Cardinal N i c ol au s Cu san u s ( 1 40 1 who had the reputation of being a great logician His fallacies were expose d to full view by Regio montanus A S in this case so in others e v ery quad rator of note raised up an opposing mathematician : O ron c e Fine was — m et by Jean B uteo ( c 1 49 2 1 57 2 ) and P Nunes ; Joseph Scaliger by Vieta A drian u s Romanus and Cla v ius ; a Qu erc u by Adriaen A n Two mathem aticians of Netherlands Adri anu s thon i sz ( 1 5 2 7 Roman u s ( 1 56 1 —1 6 1 5) and Lu d ol ph van Geu l e u ( 1 540 oce n pie d themsel v es with appro xi mating to the ratio between the circumfer ence and the diam eter The form er carried the value 71 to 1 5 the lat ter to 3 5 p l aces The value of 7r is t herefore often nam ed L u dolph s nu mber His performance was considered so e xtraordinary that the nu mbers were cut on his to mb stone ( now lost ) in S t P eter s church yard at Leyden These m en had used the A rch imedian m ethod of i n and C ircu m S cribed polygons a m ethod refined in 1 6 2 1 by Wi l l e brord S n el l i u s ( 1 5 80 —1 6 2 6 ) who showed how narrower limits m ay be obtained for 71 without increasing the nu mber of S ides of the poly gon s Snellius used two theore ms equivalent to 1 ( 2 sin 6 tan 0) A 94 csc 0+ cot The greatest refinem ents in the use of the geo metrical m ethod of Archi m edes were reached by C Huyghens in his De ci r cu l i magn i tudi n e i n ven ta 1 6 54 and by J am e s G r e g or y ( 1 6 3 8 professor at S t Andre w s and Edinburgh in his E xer ci tati on es 167 geometri cae 1 668 and Ver a ci r cu l i et hyper bol a e q u adr a tu r a 1 6 6 7 Gregory gave s everal form ulas for approximating to 71 and in the second of these publications bol dly attem pted to prov e by the Ar c hi m e dean algorith m that the quadrature of the circle is i mpossible Huyghens S howed that Gregory s proof is not conclusive although he himself believed that the quadrature is impossible Other attempts to prove this impossib i lity were m ade by Thom as Fau ta t D e Lagny — — of P aris in 1 7 2 7 Joseph Saurin ( 1 6 59 1 7 3 7) in 1 7 2 0 ( 1 6 6 0 1 734) Isaac Newton in his P ri n ci pi a I 6 lemm a 2 8 E Waring L Euler , - . . . . , , ‘ . . , , , . ” , “ ’ . , . , ’ - . . , - , . . , , . , , , . , . ’ , . , , , , , , . , . , 1 77 1 That these proofs w ould lack rigor was al most to be expected as long as no distinction was made between algebraical and t ran sc en dental nu mbers The earliest explicit expression for i r by an infinite nu mber of op Considering regular polygons of 4 8 e ra ti on s was found by Vieta sides inscribed in a circle of unit r adi us he found that the 16 area of the circle i s , . . , , , , , A HISTORY OF M ATHE M ATICS 1 44 from which we obtain W I 1 x/i 2 « S in which may be derived from Euler s formul a ’ 1 5 0 cos 9/4 C05 0/8 As m entioned earlier it was Adri anu s Roman u s ( 1 56 1— 1 6 1 5) of L ou vain who propounded for solution that equation of the forty— fif t h d egree solved by Vieta On receiving Vieta s solution he at once departed for P aris to m ake his acquaintance with so great a master Vieta proposed to him the Apollonian problem to draw a circle touching three given “ circles Adri an u s Rom anus solved the proble m by the intersection of two hyperbolas but this solution did not possess the rigor of the ancient geom etry Vieta caused him to see this and then in his turn pre 2 sented a solution which had all the rigor desirable Rom anus did m uch toward S implifying spherical trigonom etry by reducing by means of certain proj ections the 2 8 cases in triangles then considered to only six M ention m ust here be m ade of the i mprovem ents of the J ulian cal endar The yearly determination of the movable feasts had for a long tim e been connected with an untold am ount of confusion The rapid progress of astronomy led to the consideration of this subject and many new calenda rs were proposed P ope Gregory XIII con v ok ed a large nu mber of m athe m aticians astrono m ers and prelates who decided upon th e adoption of the calendar proposed by the Jesuit — of Rom e To rectify the errors of h r i t o ho ru s C l a v iu s 1 s C ( 53 7 1 6 1 2 ) p the Julian calendar it was agreed to write in the new calendar the 1 5 th of October imm e diately after the 4 th of October of the year 1 58 2 The Gregorian calen dar m e t with a great deal of opposition both among scientists and a mong P rotestants Clavius who ranked high as a geom eter m e t the obj ections of the form er m ost ably and eff ec ti v el y ; the prejudices of the latter passed away with ti m e The passion for the study of mystical properties of nu mbers de scended fro m the ancients to the moderns M uch was written on numerical m ysticism even by such e minent men as P ac i ol i and Stifel The N u mer oru m M ysteri a of P eter B ungus covered 70 0 q uarto pages He worked wi th great industry and satisfaction on 6 66 which is the number of the beast in Revelation (xiii the sym bol of Antichrist He reduced the nam e of the i mpious M artin Luther to a form whi ch may express this form idable number P lacing a = 1 b = 2 etc k = 1 0 l 2 0 etc he finds after m isspelling the name that M constitutes the number required These attacks on the great reform er were not unprovoked for his c 0 5 9/2 , ’ . , . , , . . , ” , , . , , . . . , . , , , . . , . , . . . . , . , _ . . , , , , . , , , , . , E 2 A 1 . . W H ob son , S q u ari ng the Ci rcl e, C amb r idg e , 1 9 1 3 , pp 2 6 , 2 7 , 3 1 Q ue t el e t , Hi stoi r e des S ci ences mathémati qu es cl phys i q u es chez l es B el ges . . B ru xel l es , 1 86 4 , p . 1 37. . . A HISTORY OF M ATHE M ATI CS 1 46 now began to blossom Cardinal Richelieu during the reign of Louis XIII pursued the broad policy of n o t favoring th e opinions of any sect but of pro moting the interests of the nation His age was re m arkable for the progress of knowle dge It produced that great secu lar literature the counterpart of which was found in England in the S ixteenth century The seventeenth century was m ade illustrious also by the great French mathe maticians Roberval D escartes D es argues F erma t and P ascal M ore gloomy is the picture in Ger many The great changes which revolutioni z ed the world in the S ixteenth century and which led Eng land to national greatness led Germ any to degradation The first e ffects of the Reform ation there were salutary At the close of the fifteenth an d during the sixteenth century Germany had been con spi cu ous for her scientific pursuits She had been a leader in as t ro n omy and trigono metry Algebra also excep t ing for the disco v eries in cubic equations was before the ti me of Vieta in a m ore a dvanced state there than elsewhere B ut at the beginning of the seventeenth century when the sun of science began to rise in France it set in Ger m any Theologic disputes and religious strife ensued The Thirty Years War ( 1 6 1 8—1 64 8 ) proved ruinous The German e mpire was S hattered and beca m e a m ere lax confederation of petty despotis m s Co mmerce was d estroye d ; national feeling died out Art disappeared and in literature there was only a sl avish i mitation of French arti fi c i ali ty Nor di d Ger m any recover fro m this low state for 2 0 0 years ; for in 1 7 56 began another stru ggle the Seven Years War which turned P russia into a wasted l and Thus i t followed that at the b e ginn i ng of the seventeenth century the great Kepler was the only German mathe matician of e m inence and that in the interval of 2 00 years between Kepler and Ga uss there arose no great mathematician in Germany excepting Leibniz Up to the sev enteenth century mathe matics was cul tivated but l ittle in Great Britain D uring the sixteenth century she brought forth no mathe m atician comparable with Vieta S tifel or Tartaglia B ut with the tim e of Recorde the English becam e conspicuous for nu meri cal S kil l The first i mportant arith metical work of English authorship was published in Latin in 1 5 2 2 by Cu thb e rt Ton s tal l ( 1 4 74 He h ad stu d ied at Oxfor d Ca mbri dge and P a dua and dre w freely fro m the works of P a c i ol i and Regiomontanus Reprints of his arith metic appeared in England and France After Recorde the higher branches of mathematics began to be stu died Later Scotland brought forth John Napier the inventor of logarith m s The instantaneous app re c i a t i on of their value is d oubtless the result of superiority in calcula tion In Italy and especially in France geo metry which for a l ong ti me had been an al most stationary science began to be studied with success Galileo To rri c el l i Roberval F e rma t Desargues P ascal Descartes a nd the English Wallis are the great revoluti oners of thi s . , , , . . , . , , , , , . . , . , . , . . , , , , . , , . . ’ . , . . , . ’ , , . , , , . , . , , . , , . , , , . . , . . , , , , . , , . , , , , , , VIETA TO D ES CARTES 1 47 science Theoretical mechanics began to be studied The foundations were laid by F erma t and P ascal for the theory of numbers and the theory of probability We S hall first consider the i mprovements made in the a r t of c al c u lating The nations of antiquity experimented thousands of years upon numeral notations before they happened to stri ke upon the so “ called Arabic notation In the si mple expedient of the cipher which was perm anently introduced by the Hindus mathe matics re I t would see m that after c ei v ed one of the m ost powerful im pulses “ the Arabic notation was once thoroughly understood decim al fractions would occur a t once as an obvious extension of it B ut it is curious to think how m uch science had attempted in _ physical re search and how deeply nu mbers had been pondered before it was per powerful simplicity of the Arabic notation was as c ei v e d that the all — valuable and as m anageable in an infi nitely descending as in an i n 1 finitely ascending progression Simple as decim al fractions ap pear to us the inv ention of them is not the result of one mind or even of one age They came into use by al m ost imperceptib l e degrees The first m athematicians identified with their history did not perceive their true nature and i mportance and failed to invent a suitable no The idea of decim al fractio ns m akes its first appearance in t a ti on Thus methods for appro xi mating to the square roots of nu mbers John of Seville presu mably in imitation of Hindu rules adds 2 n ci m h r to the nu ber t en finds the square root and takes this as the h e s p nu merator of a fraction whose deno minator is 1 followed by n ciphers The same method was followed by C ardan but it failed to be generally adopted even by his Italian contemporaries ; for otherwise it would certainly have been at least mentioned by P i etr o C a taldi ( died 1 6 2 6 ) in a work devoted exclusively to the extraction of roots Cataldi and before him Bombelli in 1 5 7 2 find the square root by m eans of continued fractions— a m ethod ingenious and novel but for p ractical purposes inferior to Cardan s Or once Fi ne ( 1 4 94—1 55 5) in France ( called al so O ron ti u s F i n aeu s)and Wil l i am B u c k l e y ( died about in England extracted the square root in the sa m e way as 1 550 ) Cardan and John of Seville The invention of decim als has been frequently attributed to Regiom ontanus on the ground that i n stead O f placing the sinus to t u S in trigonometry equal to a m ultiple of 6 0 like the Greeks he put i t = 1 0 0 o oo B ut here the t rig o n ome t and not in fractions Though r i cal lines were e xpressed in i n teg er s he adopted a decim al division of the rad ius he and his successors d id not app l y the idea outside of tr i gono m etry an d indeed had no notion whatever of d eci mal f r acti on s To S i mo n S tevi n ( 1 548 1 6 20) of Bruges in Belgiu m a m an who did a great d eal of work in most d iverse fields of science we owe the first system atic treat m ent of he describes in very express d ecim al fractions In his L a Di s me ( r 5 8 5) . . . . ” . , ” , . , “ . , ‘ ’ ” . , . . , . . , , , , . , . , , , ’ . , , . , , , , , , . . , , , , . , , . 1 M ark N api er , M emoi rs of J ohn N api er of M erchi ston . Edi n b u rg h, 1 8 34 . A HISTORY OF M ATHE M ATICS 1 48 terms the advantages not only of decimal fractions but also of the S tevin applied decimal division in systems of weights and measures “ 1 the new fractions to all the operations of ordinary arithmetic What he lacked was a suitable notation In place of our decimal point he used a cipher ; to each place in the fraction was attached the cor responding index Thus i n his notation the nu mber wo uld be , , ” . . ‘ . . 0 1 2 , , , 3 or These indices though cum brous in practice are of interest because they e mbody the notion of powers of nu mbers “ Stevin considered also fractional powers He says that g placed within a circle would mea n x / but he does not actually use his nota tion This notion had been advanced m uch earlier b y O resme but it had re mained unnoticed Stevin found the greatest common di 2 2 3 visor of x +x and x + 7x + 6 by the process of continual division thereby applying to polyno mials Euclid s mode of finding the greatest comm on divisor of nu mbers as explained in B ook VII of his El emen ts Stevin was enthusiastic not only over decimal f ractions but also over the decimal div ision of weights and m easures He considered it the duty of gov ern ments to establish the latter He advocated the deci m al subdivisio n of the degree N 0 i mprove ment was made in the notation of deci mals till the beginning of the seventeenth century After Stevin decimals were used by J oos t B urg i ( 1 55 2 a Swiss by birth who prepared a manuscript on arithmetic soon after 1 592 and by Joh ann H art mann B ey er who assu mes the invention as his own In 1 6 0 3 he published at Frankfurt on the M ain a L ogi sti ca Deci mali s Historians of m athe matics do not yet agree to whom the first intro duction of the decim al point or c omma should be ascribed Among the candidates for the honor are P ell os B ii rg i P itiscus Kepler Napier ( 1 6 1 6 This divergence ( 1 60 8 of opinion is due m ainly to different standards of j udgm ent If the require ment m ade of candidates is not only that the decimal point or co mma was actually used by them but that they must give evidence that the numbers used were actually deci mal fractions that the point or comma was with them not m erely a general symbol to indicate a sepa ration that they must actually use the dec imal po int i n opera tions including m ultiplication or div ision of deci mal fractions then it would seem that the honor falls to John Napier who e xhibits such use in his Rabdol ogi a 1 6 1 7 P erhaps Napier received the suggestion 2 for this notation from P itiscus who according to G En estrOm uses the point in his Tr i gon ometri a of 1 60 8 and 1 6 1 2 not as a regular deci mal point but as a more general S ign of separation N api er s decimal point did not meet with i mm ediate adoption W Ou ghtred in 1 63 1 designates the fraction 56 thus 0 | 56 Al ber t Gi r ard a pupil of S tevin in 1 6 2 9 uses the point on one occasion J ohn Wal lis in 1 6 57 writes A Q ue tel e t p ci t p 58 59 1 2 , ” , , . . 2 3 , , . . , ’ . , , . . . . , , , , . , . . , , . , , , , , , . . , , , ’ . , . , , . . 1 . 2 , o . . , . 1 . B i bl i otheca ma themati ca , 3 S . . , Vo l 6 , . 1 90 5 , . p . 1 09 . , A HISTORY OF M ATH E M ATICS 1 50 its logarithm We notice that as the m otion proceeds B C decreases in geo metrical progression while DE increases In arith 7 = = m etical progression Let A B a 1 0 let x = DF y= B C then d ( a —y) The velocity of the point C is AC = a— y; this gives y DE , . , . —nat log . dx dt =a , , , . dt y = t+ c When . then t= o , y be the velocity of the point =a and F, then and c their values and reme mbering that tion x = N ap log y we get t . Nap log . c . nat log a Again . , Substituting for x = at . 7 = 10 a , = 1 07 y —nat log and that by defini — . y I t is e v ident from this formula that Napier s logarithms are not the sam e as the natural logarith m s N api e r s logarithm s increase as the nu mber itself decreases He took the logarith mof sin i e the logarith m of The logarith m of S i n or increased from z ero as a decreased from Napier s genesis of logarith ms from the con c ep ti on of two flowing points re m inds us of Newton s doctrine of The relation between geo metric an d arith metical pr og res fl u xion S sions so skilfully utiliz ed by Napier had been observed by Archi m edes Stifel and others What was the base of Napier s system of logarith m s ? To this we reply that not only did the notion of a “ base nev er suggest itself to him but it is inapplicable to his system This n ot io n deman ds that z ero be the logarithm of 1 ; in 7 Napier s syste m z ero is the logarith m of 1 0 Napier s great i n v en t i on was given to the world in 1 6 1 4 in a work entitled M i r ifi ci In it he exp l ained the nature of l oga ri thmor u m ca non i s descri pti o his logarithm s and gave a logarith mic table of the natural S ines of a quadrant fro m m inute to m inute In 1 6 1 9 appeared Napier s M i r ifi ci l ogar i thmor u m ca n on i s con s tr u cti o as a posthu m ous work i n which his m ethod of calculating logarith ms is explained An English translation of the Con s tru cti o by W R M acdonald appeared in Edinburgh in 1 88 9 H e n ry B rigg s ( 1 556 in Napier s ti me professor of geometry at Gresham College London , and afterwards professor at Oxford was so struck with ad m iration of N apier s book that he left his studies in Lon don to do ho mage to the Scottish ph ilosopher Briggs was de “ layed in his journey and Napier complained to a comm on friend Ah John M r Briggs will not com e At that very mom ent knocks were heard at the gate and B riggs was brought into the lord s chamber Alm ost one quarter of an hour was spent each beholding the other “ w ithout speaking a word At last Briggs began : M y lord I have undertaken this long j ourney purposely to see your person and to know by what engine of wit or ingenuity you cam e first to think of ’ ’ . . . . ’ ’ . , , ’ , , ” . , ' . ’ ’ . , . , ’ . , , . . , . , . , ’ , , ’ , ” , , . . , , . ’ , . - , . , , VIETA TO DES CARTES 1 51 this m ost excellent h elp in astrono my v iz the l ogarithm s ; but my lord being by you foun d out I wonder nobody found it out before when now kno w n it is so easy B riggs suggested to Napier the ad vanta ge that would result fro m retaining z ero for the logarithm of the whole sine but choosing 1 0 0 00 00 0 0 00 for the logarith m of the r o th Napier said that he had al part of that same S ine i e of 5 44 ready thought o i the change and he pointed out a slight i mprovem ent on Briggs idea ; vi z that z ero that of the whole i s ti c of nu mbers greater than uni gested by Briggs Briggs ad mitted “ invention of B r igg ian logarith ms occurred therefore to Briggs and Napier indepen dently The great practical advantage of the n ew system was that its fun da mental progression was acco mm odated to the base 1 0 of our nu merical scale B riggs d e v oted all his energies to the construction of tables upon the new plan Nap ier died in 1 6 1 7 with the satisfaction of having found in Briggs an able fri en d to bring to completion his unfinished plans In 1 6 2 4 B r i ggs published his A r i thmeti ca l ogari thmi ca c ontaining the logarit hm s to 1 4 places of numbers from 1 to and from to The gap fro m to was filled up by that illustrious successor of Napier and Briggs A dri an Vl aca ( 1 60 0 ? He was born at Gouda in Holland and lived ten years i n Lon don as a bookseller and publishe r B eing dri v en out by London bookdealers he settled I n P aris where he m e t opposition aga i n for selling foreign books He died at The Hague John M ilton in his Def en s i o s ecu nda publishe d an abuse of hi m of V l ac q published in 1 6 2 8 a table of logarith m s fro m 1 to which were calcul ated by him self The first publ i cation of B r ig gi a n logarith m s of t rigono m etric functions was ma d e in 1 6 2 0 by Ed mu n d G u nt e r ( 1 58 1 — 1 6 26) of London a colleague of Br i ggs who found the logarith m ic S ines and tangents for every m inute to seven places Gunter was the inventor of the words cosi n e and cotangen t . , , , , , . , , 0 ° , . , , ’ . , ’ . . - , , . , . , . , . ‘ , , _ , . , , . , . . , . , , . The word cosi n e was an abbreviation of compl emen tal si n e The invention of the words tan gen t and s ecan t is d u e to the physician and m athematician Thomas Fi n ch a native of Flensburg who use d them in his Geometr i a r otu ndi Basel 1 583 Gunter is known to engineers “ for his Gunter s chain I t is tol d of hi m that When he was a stu d ent at Christ College it fell to his lot to preach the P assion ser m on which so me ol d divines that I knew di d hear but they said that i t was said of hi m then in the Univ ersity that our Savior never su ffered so m uch since his passion as in that sermon it was such a lamented 1 one Briggs devoted the last years of h i s l i fe to calculating more extensive B r igg ia n logarith m s of tri gonom etric functions but he d ie d in 1 63 1 leaving his work unfinished It was carried on by H e nr y G el . , , , . , ’ . , , , ” , . , . 1 Au br ey ’ s B r i ef Li ves , Edi t i on A C l ark , . 1 8 98 , V ol I , p . . 2 76 . A HISTORY OF M ATHE M ATICS 1 52 — i r l b an d ( 1 5 9 7 1 6 3 7 li shed by V l ac q at )of Gresham College in London and then pub his own e xpense Briggs divided a degree into 1 0 0 parts as was done also by N Roe in 1 6 33 W O u g h t r ed in 1 6 5 7 John Newton in 1 6 58 but owing to the publication by V l ac q of tr igo n ome t r i cal tables constructed on the old sexagesim al division Briggs innovation did not prevail B riggs and V l ac q published four funda m ental works the results of which have not been superseded by any subsequent calculations until very recently The word characteristic as used in logarithm s first occurs in “ Briggs A r i thmeti ca l ogari thmi ca 1 6 2 4 ; the word mantissa was i n t ro du ced by J ohn Wallis in the Latin edition of his A l gebr a 1 6 93 p 4 1 and was used by L Euler in his I n tr odu cti o i n anal ysi n in 1 748 p 85 The onl y riv al of John Napier in the invention of logarith ms was the Swiss J oo s t B ii rg i ( 1 55 2 —1 6 3 He publishe d a table of logarith ms A r i thmeti s che u nd Geometri sche P r ogr ess tabu l en P rague 1 6 2 0 but he conceived the idea and constructed his table in dependently of Napier He neglected to have it published until Napier s logarithm s were know n and adm ired throughout Europe Among the various inventions of Napier to assist the m em ory of “ the student or calculator is N api er s rule of circular parts for the solution of S pherical right triangles I t is perhaps the happiest example of artificial m e m ory that is known Napier gives in the Des cr i pti o a proof of his rule ; proofs were given later by Johann Heinrich Lambert ( 1 7 6 5) and Leslie Ellis Of the four for “ m ulas for oblique S pherical triangles which are so m eti m es called N a pier s Analogies only two are due to Napier hi m self ; they are giv e n in hi s C on str u cti o The other t wo were added by B riggs in his an notations to the C on stru cti o A m od ification of Napier s logarith m s was m ade by J oh n S pe i d e ll a teacher of m athem atics in London who published the N ew L og a r i thmes London 1 6 1 9 containing the logarithm s of S ines tangents and secants Speidell did not advance a new theory He simply aimed to i mprove on N api er s tables by m aking all logarithm s posi tive To achie v e this en d he subtracted Napier s logarithm ic nu mbers 8 from 1 0 and then discarded the last two digits Napier gave l og si n 8 Subtracting this from 1 0 leaves 5 2 586 1 48 Speidell wrote l og s i n I t has been said that S peid el l s logarith ms 5 25 86 1 of 1 6 1 9 are logarithm s to the natural base e This is not quite true on account of co mplications arising from the fact that the logarith ms in Spei del l s table appear as i n tegr al nu mbers and that the natural trigonom etric values ( not printed in Sp ei del l s tables ) are likewise written as integral nu mbers If the last five figures in Sp ei del l s log then the l ogarith ms are ari thms are taken as deci m als (m antissas ) t he natural logar i th m s (with 1 0 a dd ed to e v ery negati v e character R M o t i z A m M th M thl y V l 9 5 p 22 , . , . . , , , ’ , ‘ . , ” “ . , ” , ’ , , , . , . . . , , , , , . ’ . ” ’ , . , , . ” ’ , . . ’ , , , , , , . . ’ ’ . . . ’ . . , ’ ’ ’ . , 1 . r , . a . on , o . 2 2, 1 1 , . 1 . A HISTORY OF M ATHE M ATICS 1 54 Third Table with the as the comm on r atio 1 69 Each column is a geom etric progression of . The . 69 terms 21 first or top nu mbers in colum ns the mselves constitute a geometric progression hav ing the rat the first top num ber being 10 the second 990 0 0 0 0 7 , ” , and so on The last nu mber in the 6 9th colu m n is 4998 60 9 40 34 Thus this Third Table giv es a series of nu mbers very nearly but 7 not exactly i n geom etrical progression and lying between 1 0 and “ Says Hutton these tables were found in the v ery nearly The m ost si mple m anner by little more than easy subtractions nu mbers are taken as the S ines of angles between 90 and Kine ma t i cal considerations yield hi m an upper and a lower li m it for the logarith m of a giv e n sine B y these lim its he obtains the logari th m “ of each nu mber in his Third Table To obtain _the logarithm s of sines between 0 and 30 Nap i er in dicates two methods By one of “ the m he co mputes log sin 6 by the aid of his Third S in d sin ( 90 Table and the form ula sin 2 A repetition of this process gives the logarith ms of S ines down to and so on Burgi s m ethod of computation was m ore primitive than N api er s “ In his table the logarith m s were printed in red and were called red nu mbers the antilogarith m s were in black The expressions r = I o n . . , , , . , ° ' ” . . ° ° . , ° . ’ ’ . n . where indicate the m ode of computation series is obtained by of that term p o l a t i on . and ro = o, addi n g Any term . bn u = 1, 2, of th e to the preceding term b _ the n P roceeding , 3, geom etric 1 1, 4 th part thus Burgi arrives at r = 2 30 2 70 0 2 2 and this last pair of nu mbers being obtained by inter , , . In the Appendix to the C on stru cti o there are described three m eth ods of co mputing logarith m s which are probably the result of the j oint lab ors of Napier and B riggs The first method rests on the successive extractions of fifth roots The second calls for square roots only Taking log and log find the logarithm of the m ean proportion between 1 and 1 0 There follows log x 10 log then log and so on Substantially this m ethod was i used by Kepler in his book on logari th m s of 1 6 2 4 and by V l ac q The third m ethod i n the Appen dix to the C on stru cti o lets log 1 = 0 log 1 0 = 10 and takes 2 as a factor 1 0 ti m es yielding a number composed of 30 1 0 2 9996 figures ; hence log . . . . - . . , , VIETA DESCARTES TO 1 55 ” A famous method of co mputing logarith ms is th e so called rad ix method I t requires the aid of a table of radices or nu mbers of the - . for m with their logarithms It The logarithm of a number is . found by resolving the nu mber into factors of the form ” then adding the logarith ms of the factors The earliest appearance “ of this method is in the anonym ous Appendix (very probably due 1 to O u g h t red) t o Ed w a rd Wright s 1 6 1 8 e d ition of N ap i er s D es cri pti o I t is fully d eveloped by Briggs who in his A ri thmeti ca l og ari thmi ca 1 6 24 gives a table of radices The m etho d has been frequently re 2 discovered and given in various form s A S light S im plification of Briggs process was gi ven as one of three m ethods by Robert Fl ow er in a tract The Radi x a n ew w ay of maki ng L ogari thms London 1 7 7 1 He di v ides a given number by a power of 1 0 and a S ingle digi t so as to reduce the first figure to 9 and then m ultipli es by a procession of ra dices until all the d igits beco m e nines The ra dix m etho d was re d iscovered in 1 7 8 6 b l Geor ge A tw ood ( 1 7 4 6 the inventor of Atwood s machine in A n ess ay on the A ri thmeti c of Factors and again by Z ecchi n i L eon el l i in 1 80 2 by Thom as M anning ( 1 7 7 2 scholar of Caius College Cambridge in 1 8 0 6 by Thomas Weddle in 1 84 5 Hearn in 1 8 4 7 and Orchard in 1 8 4 8 Extensions and v ariations of the radix m ethod have been published by P eter Gray ( 1 80 7 ? a writer on life contingencies Thom an A J Ellis ( 1 8 1 4 and others The three distinct methods of its application are due to B riggs Flower and Wed dle Another m ethod of co mputing common logarith m s is by the re = I = 10 ea t e d for m ation of geo m etric m eans If A then C B p V A B = 3 1 6 2 2 7 8 has the logarithm 5 D = V B C = 5 6 2 3 4 1 3 has the logarith m 7 5 etc P erhaps suggested by Napier s rem arks in the C on s tru cti o this m ethod was d eveloped by French writers of whom 3 — in 1 6 7 0 was perhaps the fi r s t O zan am Jacques Oz an am ( 1 6 40 1 7 1 7 ) is best known for his Recr ea ti on s mathéma ti qu es cl phy s i qu es 1 6 94 Still d iff erent d evices for the co mputation of logarith m s were i n vented by Brook Taylor John Long William Jones Roger Cotes An d rew Reid J am es D odson Abel 4 Burja and others . ’ ’ ’ . , , . , . ’ , , . , , . , . ” ’ , , , , , , . , , , . . . , . . . . , , . , ’ . . , , , . . , , . W L Gl ai sh e r , i n Quar terl y f ou r of M a th s , V ol 4 6 , 1 9 1 5 , p 1 2 5 2 For t h e de t ai l ed hi s to ry o f t hi s m e t hod co n su l t a l so A J E lli s i n P r oceedi n gs — of the Roya l S oc i ety ( L o n do n , V o l 3 1 , 1 88 1 , pp 3 98 4 1 3 ; S L u p to n , M a thema ti cal ’ — Ga ette, Vo l 7 , 1 9 1 3 , pp 1 4 7 1 5 0 , 1 7 0 1 7 3 ; C h H u t t o n 5 I n t r o d u c t i o n t o hi s M athemati cal Ta bl es ’ 3 S e e J W L G l ai sh er I n Q u ar terl y J ou r n al of P u re and A ppl M d th s , V o l 4 7 , 1 J . ’ . . ) z . . . . — . . . . . . . . . . 1 91 6 pp — 30 1 . . . . 2 49 ” Fo r d e t ail s see C h H u t t o n 3 I n t r o du c t i o n t o h i s M a thema ti ca l Ta bl es , al so t he “ En cycl opedi c des s c i ences mathé mati q u es , 1 90 8 ; I , 2 3 , T a b l es d e l o g ar i t h me s 4 ’ . . A H ISTORY O F M ATH EM ATICS 1 56 After the labor of computing logarithm s was practically over the facile methods of computing by infinite series came to be discovered Ja mes Gregory Lord William B rounk er ( 1 6 2 0 Nicholas M er cator ( 1 6 2 0 John Walli s and Ed mund Halley are the pioneer workers M ercator in 1 668 derived what amounts to the infinite series for log Transformations of this series yielded rapidly — converging results Wallis in 1 6 95 obtained 1 log I z) ( 5 2 = z+ § 2 + G Vega in his Thes au ru s of 1 7 94 lets z 1 /( 2y The theoretic view point of the logarith mwas broadened som ewhat during the seventeenth century by the graphic representation both in rectangular and polar co or d inates of a variable and its variable logarithm Thus were invented the logarith mic curve and the loga r i th mi c spiral I t has been thought that the earliest refere nce to the logarith m ic curve was m ade by the Italian Evangelista Torricelli i n a letter of the year 1 6 44 but P aul Tannery m ade it practically certain that Descartes knew the curve in Descartes described the log arithmic spiral in 1 6 3 8 in a letter to P M ersenne but does not give its equation nor connect it with logarithms He describes it as the curve which makes equal angles with all the radii drawn through the origin “ The name logarith mic S piral was coined by P i err e Va r i gn on in a paper presented to the P aris acade my in 1 7 0 4 and published in The m ost brilliant conquest in algebra during the six teenth century had been the solution of cubic and biquadratic equations All a t tempts at solving al gebraically equations of higher degrees rem aining fruitless a n ew line of inquiry—the properties of equations and their roots— was gradually opened up We hav e seen that Vieta had at t ai n ed a partial knowle dge of the relations between roots and c o J a cqu es P el eti er ( 1 5 1 7 a French man of letters poet efli c i en t s and m athem atician had observ ed as early as 1 558 that the root of an equation is a div isor of the last term In passing he writes equa tions with all term s on one S ide and equated to z ero This was done also by B uteo and Harriot One who extended the theory of equa tions somewhat further than Vieta was Al b e rt G ir ar d ( 1 590 ? a mathe matician of Lorraine Like Vieta this ingenious author ap plied algebra to geo metry and was the first who understood the use of negative roots in the solution of geom etric problem s He spoke of i m aginary quantities inferred by in duction that ev ery equation has as many roots as there are units in the num ber expressing its degree and first S howed how to express the su ms of their powers in term s of the c oefli c i en t s Another algebraist of considerable power was the English Th oma s H arr i ot ( 1 56 0 He acco mpanied the first colony sent out by Sir Walter Raleigh to Virginia Af ter having sur , . , . . . , , . . , . , , . ” . . , . , . , , . . , . , . , , . , , . . S ee G L o r i a B i bl i otheca ma th , 3 S , V ol 1 , 1 900 , p 7 5 ; L i n ter medi a i r e des mathémati ci ens , Vo l 7 , 1 900 , p 95 2 Fo r d e t a i l s a n d r e fe re n ce s see F C a j o r i , H i s to ry o f t he Exp o n e n t i al ' a n d Log a ri thmi c C o n c ep t s , A m M a th M on thl y, V o l 20 , 1 9 1 3 , p p 1 0 , 1 1 ’ 1 . . . , . ” . . . . , . . ‘ . . . . O F M ATHE M ATICS HISTORY A 1 58 by Z C L M Hence in des i gnating ratio I use not one point but two points which I use at the sam e tim e for division ; thus for your I write dy :x = dt :a; for dy is to x as dt is to a is indeed the sa me as dy d iv i d ed by x is equal to dt d ivided by a From this equa tion follow then all the r ul es of proportion This conception of ratio and proportion was far in advance of that in contempora ry arith m etics Through the aid of C hr i s ti an Wolf the dot was generally adopted in the eighteenth century as a symbol of m ultiplication P resu m ably Leibniz had no knowle dge that Harriot in his A r ti s an al yti cw pr a xi s 1 63 1 used a dot for multiplication as in aaa 3 bba = + 2 ccc Harriot s dot received no attention not even fro m Wallis O u g h t r ed and so m e of his English conte mporaries Richard N o r wood John Speidell and others were prominent in introducing abb re v i a t i on s for the trigono m etric functions : s s i or s i n for s i n e; s co or s i co for sine co mple m ent or cosi n e se for s ecan t etc O u gh t red did not use parentheses Term s to be aggregated were enclosed b e tween double c ol ons He wrote x/ (A +E ) thus wl q l— E : The two — d ots at the end were som eti m es o m itted Thus C :A +B E m eant 3 — (A +B E ) B efore O u gh t r e d the use of parentheses had been sug gested by Clavius in 1 6 0 8 and Girard in 1 6 2 9 In fact as early as _ ’ F w ‘ / 28 ID thus R v ( R 2 8 m en R 1 0 ) 1 55 6 Tartaglia wrote x where “ R v m eans radix universalis but he did not use parentheses in i n 1 di ca t i n g the product of two expressions P arentheses were used by I Er rar d de B ar l e — D uc Jacobo de Billy Richard Norwood Sam uel Foster nevertheless parentheses did not beco m e popular in algebra before the time of Leibniz and the B ernoullis I t is noteworthy that O ugh t red denotes 3— and 1 33 the approxi 7 ' . , , , , , , , . . . . , , . , ’ . . , . , ” , ‘‘ , , , . , . - . , . , . . , , . . , . - . . 1 , m ate ratios of the circumference to the diameter by the symbol , occurs in the S ’ it edition and I n the later editions of his Cl ovi s mathe mati cce O u g h t re d s n otation was a dopted and used extensively by Isaac B arrow I t was the forerunner of the notation 7r = first used by William Jones I n 1 70 6 in his S ynopsi s pal mari oru m ma thes eos London 1 70 6 p 2 6 3 L Euler first used 7r = 3 1 4 1 59 1 73 7 In his tim e the symbol m e t with general adoption O u gh t red stands out pro m inently as the in v entor of the circular and the rectilinear S lide rules The circular slide rule was described in print in hi s book the C i rcl es of P ropor ti on 1 6 3 2 His rectilinear slide rule was described in 1 633 in an A ddi ti on to the above work B ut O u gh tred was not the first to describe the circular slide rule in print ; this was done by one of his pupils Richard D elamain in 1 6 3 0 2 in a booklet entitled Gr ammel ogi a A b i tter controv ersy arose b e 1 64 7 ’ . . , , . , . . . . . , . , . , . , , , . G En est ro m i n B i bl i otheca mathemati ca , 3 S , V ol 7 , p 2 96 2 S ee F C aj o r i , Wi l l i a m O u ghtr ed, C h i c a g o a n d L on d on , 1 9 1 6 , p 46 1 . . . . . . . . . , VIETA TO D ESCARTES 59 tween Dela m ain and O ug h t red Each accused the other of having stolen the inv ention fro m him M ost probably each was an i n d ependent inventor TO the inventio n of the rectilinear slide rule O ug h t red has a clear title He states that he designed his sli d e rules as early as 1 6 2 1 The S li de rule was improv ed in England during the 1 seventeenth and eighteenth centuries and was used quite e xtensiv el y Som e of the stories told about O ug h tr ed are doubtless apocryphal as for instance that his econom ical wife denied him the use of a candle for study in the evening and that he died of joy at the Restoration after drinking a glass of sack to his M aj esty s heal th D e M organ “ hum orously rem arks It S hould be added by way of excuse that h e was eighty— S i x years old Algebra was now in a state of s ufficient perfection to enable Des cartes and o thers to take that importa nt step which form s one of the grand epochs in the history of m athem atics —the application of alge brai e analysis to define the nature and investigate the properties of algebraic curves In geometry the determ ination of the areas of curv ilinear figures was diligently studied at this period P au l G u l di n ( 1 5 7 7 a Swiss m athe matician of considerable note re di scov ered the following theorem published in hi S _C en tr obaryca which has been nam ed after hi m though first found i n the M athema ti cal C ol l ecti on s of P appus : The volu me of a solid of revolution is equal to the area of the g en er a t ing figure m ultiplied by the C ircu m ference described by the centre of grav ity We S hall see that this m ethod excels that of Kepler and Cav alieri in following a m ore exact and natural course ; but it has the disadvantage of necessitating the determination of the centre of grav ity which in itself m ay be a more diffi cult problem than the original one of finding the v olu m e Gul din made som e atte mpts to pro v e his theorem but Cavalieri pointed out the weakness of his de monstration was a native of Wii r temb e rg a n d i m Joh ann e s K e pl e r ( 1 57 1 —1 6 30 ) b ib ed Copernican principles while at the University of T ubi n g en His pursuit of science was repeate dly interrupted by war religious perse pecuniary e m barrassm ents frequent changes of resid ence c u t i on and family troubles In 1 60 0 he beca me for one year assistant to the Danish astrono mer Tycho B rahe i n the observatory near P rague The relation between the two great astronom ers was not always of an agreeable character Kepler s publications are v olum inous His first a t te mpt to explain the solar system was m ade in 1 596 when he thought he had discovered a curious relation between the five regular solids and the number and distance of the planets The publication of this pseudo discov ery brought him m uch fam e : At one tim e he tried to represent the orbit of M ars by the ov al curv e which we now write i n 3 = polar coordinates p 2 r cos 0 M aturer reflection and intercourse with Tycho Brahe an d G al i l eo l ed hi m to investigations and results . . . . . . , , , , “ ’ . ” , , , . , . . , . , , , , , . , . . , . , , , , . . , , ’ . . , . - . , 1 S ee F Caj ori , Hi s tory . f o the Logar i thmi c S lide Ru l e, N ew York , 1 90 9 . A HISTORY OF M ATHE M ATICS 160 wor thy of his genius Kepler s laws He enriched pure math e mati cs as well as astronomy I t is not strange that he was interested in the m athem atical science which had done him so much serv ice ; for “ if the Greeks had not cultivated conic sections Kepler could not 1 have superseded P tolemy The Greeks never dream ed that these curves would ever be of practical use ; Arist ae us and Apoll onius studied them m erely to satisfy their intellectual cravings after the ideal ; yet the conic sections assisted Kepler in tracing the march of the planets in their elliptic orbits Kepler m ade also extended use of logarith m s and decim al fractions and was enthusiastic in d iffusin g a knowledge of them At one time while purchasin g wine he was struck by the inaccuracy of the ordinary modes of d eterm ining the contents of kegs This led h im to the study of the vol um es of solids of rev olution and to the publication of the S tereometri a Dol i oru m in In it he deals first with the solids know n to Archimedes and 1615 then takes up others Kepler m ade wide application of an old but neglected idea that of infinitely great and infinitely small quantities Greek m athem aticians usually shunned this notion but with it modern mathe maticians co mpletely revolutioniz ed the science In comparing rectilinear figures the method of superposition was employed by the ancients but in comparing rectilinear and curvilinear figures wi th each other this m ethod failed because no addition or subtraction of rectilinear figures could ever produce curvilinear ones To meet this case they devised the M ethod of Exhaustion which was long and d ifficult ; it was purely syn thetical and in general required that the conclusion should be known at the outset The new notion of infinity led gradually to the invention of m ethods irnm easu rabl y m ore power ful Kepler conceived the circle to be composed of an infinite nu mber of triangles hav ing their comm on vertices at the centre and their bases in the C ircumf erence ; and the sphere to consist of an infinite nu mber of pyram ids H e appl i ed conceptions of this kind to the de term ination of the areas and volu mes of figures generated by curv es revolving about any line as axis but succeeded in solving only a f ew of the simplest out of the 84 problem s which he proposed for investi g a t i on in his S ter eometri a Other points of m athem atical interest in Kepler s works are ( 1 ) the assertion that the circu mference of an ellipse whose axes are 2 a and 2 b is nearly 7r a passage from which it has been i nk n ed (2) that Kepler knew the variation of a function near its m axim um value the assu mption of the principle of continuity (which to disappear ; (3) diff erentiates m odern from ancient geo m etry)when he shows that a parabola has a focus at infinity that lines radiating from this c ee c u s focus are parallel and have no other point at i n finity The S ter eometri a led Cavalieri an Italian Jesuit to the consideration ’ . . ” , . . , . , , . . . . , , . , , , . , , , . , . , ' . ‘ , . ’ , , , , . , 1 Will i am Wh ew ell Vol I , p 3 1 1 . . . , H i story f o the I nducti ve , S ci ences , 3 rd Ed . , N ew York , 1 8 58 , A HISTORY OF M ATHE M ATICS 62 There is an important curve not known to the ancients which now began to be studied with great z eal Roberval gave it the na me of “ trochoid P ascal the nam e of roulette Galileo the name of cy c l o id The invention of this cu rve see m s to be due to Charl es B ou vel l es who in a geo m etry publi shed in P aris in 1 50 1 refers to this cu r ve in connection with the problem of the squaring of the circle Galileo value d it for the graceful form it woul d give to arches in architecture He ascertained its area by weighing paper figures of the cycloid against that of the generating circle and found thereby the first area to be nearly but not exactly thrice the latter A m athematical determina t i on was made by his pupil Evan g el i s ta Torri c elli ( 1 6 0 8 who is more widely known as a physicist than as a m athem atician By the M ethod of Indivisibles he dem onstrated its area to be triple that of the revolving circle and pub l ished his solution This sam e quadrature had been e ffe cted a few y ears earlier ( about 1 6 3 6 ) by Roberval in France but his solution was not known to the Italians Roberval being a m an of irritable and violent disposition unjustly accused the m ild and am iable Torricelli of stealing the proof This accusation of pla giarism created so m uch chagrin with Torricelli that it is considered to have been the cause of his early death Vin c e n zo Vivi ani ( 1 6 2 2 another prom inent pup il of Galileo determined the tangent to the cycloid Thi s was accompli shed in France by Descartes and F ermat In France where geom etry began to be cultivated with greatest success Roberval F ermat P ascal e mployed the M ethod of Indivis i bl es and m ade new i mpro v e m ents in it G il e s P e r s o n e d e R o b e rval for forty years professor of m athematics at the College ( 1 60 2 of France in P aris clai med for hi m self the invention of the M ethod of Indivi sibles Since his complete works were not published until after his death it is difli c u l t to settle questions of priority M on tu cl a and Chasl es are of th e Opinion that he invented the m e thod independently of and earlier than the I talian geom eter though the work of the latter was published much earli er than Roberval s M arie finds it diffi cult to believe that the Frenchman borrowed nothing whatever from the Italian for both could not have hit independently upon the word I n di vi si bl es which is applicable to infinitely sm all quantities as con cei v ed by Cavalieri but not as conceived by Roberval Roberval and P ascal improved the rational basis of the M ethod of In divisibles by consi dering an area as m a d e up of an indefinite nu mber of rectangles instead of lines and a solid as composed of indefinitely sm all solids instead of surfaces Roberval applied the m ethod to the finding of areas volumes and centres of grav ity He e ffected the quadrature 1 m m m of a parabola of any degree y a x and also of a parabola y m We have already m entioned his qua drature of the cycloid a x Roberval is best known for his m ethod of drawing tangents which however was invented at the same tim e if not earlier by T orri c el l i , ” , ” . , “ , . . . , . , . , . . , , , . . , . . , , , , , . , . . , , ’ . , , , . , , , . , . , ‘ , “ “ n 11 . . , , , , , . VIETA D ES CARTES To 163 Torricelli s appeared in 1 6 44 under the title Oper a geometri ca Rober Som e of his special applications v a l gives the fuller exposition of it were published at P aris as early as 1 6 44 in M er se nn e s C ogi ta ta physi co Roberval presented the full develop m ent of the sub mathemati ca m A c e f e i on c es in 1 66 8 which published it to the French a O ec t d S y j in its M émoi r es This academy had grown out of scient ific m eetings held with M ersenne at P aris I t was founded by M inister Richelieu in 1 6 3 5 and reorganiz ed by M inister Colbert in 1 666 M ari n M er sen n e — rendered great services to science His polite and e n ( 1 588 1 6 4 8 ) gaging m anners procured him m any friends inclu ding D escartes and F erma t He encouraged scientific research carried on an ex tensiv e correspondence a n d thereby was the medium for the i n ter c ommu n ic a tion of scientific intelligence Roberv al s m ethod of drawing tangents is allied to Newton s prin c ip l e of fl uxi on s : Arch im edes conceived his spiral to be generated by a double m otion This idea Roberv al exten ded to all curves P lane curves as for instance the conic sections m ay be generated by a point acted upon by two forces and are the resultant of two m otions If at any point of the curve the resultant be resolv ed into its components then the diagonal of the parallelogram determ ined by them is the tan gent to the curve at that point The greatest difficulty connecte d wi th this ingenious m ethod consisted in resolv ing the resultant into components hav ing the proper lengths and directions Roberval did not always succee d i n doing this yet his new idea was a great step in advance He broke off from the ancient definition of a tangent as — a straight line hav ing only one point in comm on with a curve a defi n i ti on which by the m etho d s then available was not adapted to bri ng out the properties of tangents to curves of higher degrees ; nor e v en of curves of the second degree and the parts they may be made to play in the generation of the curves The subj ect of tangents receive d special attention also from F erma t D escartes and Barrow and reached its highest develop m ent after the invention of the differential calculus Fermat and D escartes d efined tangents as secants whose two points of intersection with the curve coincide ; B arrow considered a curve a polygon and called one of its sides produced a tangent A profound schola r in all branches of learning and a m athem atician of exceptional powers was P i e rr e d e F e r mat ( 1 6 0 1 He studied law at Toulouse and in 1 6 3 1 was m ade councillor for the parliament of Toulouse His leisure tim e was m ostly devoted to m athem atics which he stu died with irresistible passion Unlike D escartes and Fermat has left the im P ascal he led a quiet and unaggressive l i fe press of his genius upon all branches of mathem atics then known A great contribution to geom etry was his D e maxi mi s et mi ni mi s About twenty years earl i er Kepler had first observ e d that the incre m ent of a var i able as for instance the or di nate of a curv e is evan e sce n t for values very near a m axi m u m or a m in i m um value of the ’ . . ’ . ' S . . . . , . , , . ’ ’ . . , , , . , . . , . , . , , , . , . , . , . . , . . , , , , , A HISTORY OF M ATHE M ATICS 1 64 ariable D eveloping this idea F erma t obtained his rule for maxima an d minima He substituted x+ e for x in the given function of x and then equated to each other the two consecutive values of the function and div i d ed the equation by e If e be taken 0 then the roots of this equation are the v alues of x m aking the fun ction a maximum or a m inim u m F e rma t was in possession of this rule in 1 6 2 9 The main difference between it and the rule of the differential calculus is that it introduces the indefinite quantity e instead of the in fi nitely s mall dx F erma t m ade it the basis for his m ethod of d rawing tangents which inv ol v ed the determ ination of the length of the subtangent for a giv en point of a curve Owing to a want of explicitness in statement Ferm at s method of m axim a and m ini m a and of tangents was severely attacked by hi s great conte mporary D escartes who cou l d never be brough t to render due j ustice to his m erit In the ensuing dispute F erm a t found t w o z ealous d efenders in Roberval and P ascal the father ; whi le C M y dorge G D esargues an d Claude Hardy Supported D escartes Since F e rm a t intro d uce d the conception of infinitely small di ffer e n c e s between consecutive values of a function and arrived at the principle for fin ding the m axim a and m inim a it was m aintained by Lagrange Laplace and Fourier that F erma t may be regarded as the first in v entor of the diff erential calculus This point is not well taken as will be seen from the words of P oisson him self a Frenchman who rightly says that the differential calculus consists in a system of rules proper for finding the di fferentials of all functions ra th er than in the use which may be m ade of these infinitely s mall variations in the s o l u t io n of one or two isolated proble m s ) A conte mporary m athe m atician whose genius perhaps equalled that of the great F erma t was B l ai s e P as c al ( 1 6 2 3 He was born at Clerm ont in Au v ergne In 1 6 2 6 his father retired to P aris where he dev oted hi m self to teaching his son for he would not trust his educa tion to others Blaise P ascal s genius for geometry showed itself when he was but twel v e years old His fa ther was well skilled in m athe m aties but di d not wish his son to study it until he was perfect l y acquainted with Latin and Greek All m athem atical books were hidde n out of his sight The boy once asked his father what m athe “ m at i c s treated of and was answered i n general that it was the m ethod of m aking figures with exactness and of finding out what proportions they relati v ely had to one another He was at the same ti me forb i dden to talk any m ore about it or ever to think of it B ut his genius could not sub m i t to be confined within these bounds Start ing with the bare fact that m athematics taught the m eans of making figures infall i bly exact he e mployed his thoughts about it and with a piece of charcoal drew figures upon the tiles of the pave ment trying the metho d s of d raw i ng for example an exact circle or equ i lateral triangle He gave names of his own to these figures and then formed v . , . . , , . . . , . ’ , , , , , . , . , . , , . , , , , . , , , “ , ” , , . , , ’ . . , . . , , , , . . , . , , , . , M ATHE M ATICS A HISTORY OF 1 66 Huygens Wren and F erma t solved som e of the questions The chief disco v eries of C hri s toph e r Wr e n ( 1 6 3 2 the celebrated architect of S t P aul s Cathe d ral in Lon don were the rectification of a cycloidal arc and the determ ination of its centre of gravity F erma t found the area generated by an arc of the cycloid Huygens invented the c y c l oi dal pendulu m The beginning of th e seventeenth century witnessed also a revival of synthetic geo m etry One who treated conics still by ancient m e thods but who succeeded in greatly simplifying m any proli x proofs of Apoll o i n P aris a friend of D escartes nius was C l au d e M yd or g e ( 1 58 5—1 6 4 7 ) B ut it re m ained for G ir ar d D e s ar g u e s ( 1 593—1 6 6 2 ) of Lyons and for P ascal to leave the beaten track and cut o ut fresh paths They intro d u c e d the important m ethod of P erspective All conics on a cone with c i rcular base appear circular to an eye at the apex H en ce D e sarg u es and P ascal concei v ed the treatment of the conic sections as proj ections of circles Two i mportant and beautiful theorem s were given by D es “ argues : The one is ou the involution of the s i x points in which a transversal m eets a conic and an inscribed quadrangle ; the other is that if the vertices of two triangles S ituated either in S pace or in a plane lie on three lines m eeting in a point then their S ides m eet in three points lying on a line ; and conversely This last theore m has been employed i n recent tim es by B rian ch on C S turm G erg onn e an d P oncelet P oncelet m a d e it the basis of his beautiful theory of ho mol ogical figures We owe to D esargues the theory of involution and of transv ersals ; also the beautiful conception that the two ex t r emi t i es of a straight line m a y be considered as m eeting at infi nity a n d that parallels d i ff er fro m othe r pairs of lines only in having their points of intersection at infinity lH e r e— invented the epicycloid and showed its applicat i on to the construction of gear teeth a subj ect elaborated m ore fully later by La Hire P ascal greatly admired Desargues results saying ( in his E ss ai s pou r l es C on i qu es ) I wish to acknowle dge that I owe the little that I have discovered on this sub P ascal s and D esargues writings contained j ec t to his writings some of the fundam ental ideas of mo dern synthetic geom etry In P ascal s wonderful work on conics written at the age of S ix teen and now lost were given the theorem on the anharm onic ratio first found in P appus and also that celebrated proposition on the mystic hexagon “ known as P ascal s theore m viz that the oppos i te s i des of a hexa gon inscribed in a conic intersect in three points which are collinear This theore m form ed the keystone to his theory He him self said that from this alone he deduced over 40 0 corollaries e mbracing the conics of Apollonius and m any other results Less gi fte d than D es argues a n d P ascal was P h ili ppe d e l a H ir e ( 1 6 40 At first activ e as a pa i nter he afterward s d e v ote d him self to astronomy and m athe matics a n d beca m e professor of the Co l l ege de France in P aris He wrote three works on conic secti ons published in 1 6 73 1 6 7 9 and , , . ’ . , . . . . , , , . , , . , . ' . ” . , , , , , . . , , , . . , . , . ’ , , ” ’ ’ . , . ’ , , , ” , ’ , , . . . , . , , . , , VIETA TO D ES CARTES 167 es C on i ca e was best known The last of these the ec t i o n La S 5 Hire gav e the polar properties of circles and by proj ection transferred his polar theory from the circle to the conic sections In the c on struc tion of maps D e la Hire used globular projection in which the eye is not at the pole of the sphere as in the P tole maic stereographic pro j ec ti on but on the radius pro duced through the pole at a distance r sin 4 5 outside the sphere Globular projection has the advantage that everywhere on the map there is approxim ately the same degree of exaggeration of distances This m ode of projection was modified by his countryman A P arent D e la Hire wrote on roulettes on graphic methods epic y cloids c on choidsr md on m agic squares The labors of D e la Hire the genius of D esargues and P ascal uncovered several of the rich treasures of m o dern synthetic geom etry ; but owing to the absorbing interest taken in the analytical geom etry of D escartes and later in the di fferential calculus the subject was a l most entirely neglected until the nine t eenth century In the theory of numbers no new results of scientific value had been reached for over 1 0 0 0 years extending fro m the times of D iophantus and the H indus until the beginning of the seventeenth century B ut the illustrious period we are now consi dering produced m en who rescued this science from the real m of m ysticis m and superstition in which i t had been so long i mprisoned ; the properties of nu mbers bega n again to be stu died scientifically Not being in possession of t h e Hin d u indeter m inate analysis m any beautiful results of the B rahmi ns had to be r e discovered by the Europeans Thus a solution in integers of linear indeterminate equations was r e discovered by the Frenchm an B a c h e t d e M ézir i ac ( 1 58 1 who was the earliest noteworthy European D i opha n t i s t In 1 6 1 2 he published P r obl emes pl ai san ts ci dél ecta bl es qu i s e f on t par l es n ombr es and in 1 6 2 1 a Greek edition of Di ophan tu s with notes An interest in pri m e nu mbers is disclosed in the so called M ers en n e s nu mbers of th e form M p = —1 with p pri m e M arin M ersenne asserted in the preface to his 29 C ogi ta ta P hysi co M a thema ti ca 1 6 44 that the only values of p not greater than 2 5 7 which m ake M D a prim e are 1 2 3 5 7 1 3 1 7 1 9 Four mistakes have n ow been detecte d in 3 1 6 7 1 2 7 and 2 57 M erse n n e s classification v i z M 6 7 is compos i te ; M 6 1 M 8 9 and M I O7 are prim e M 1 8 1 has been found to be compos i te M ersenne gave in 2 8 4 96 8 1 2 8 2 3 5 50 33 6 1 6 44 also the first eight perfect nu m bers 6 In Eucl i d s El e 8 58 986 90 56 1 3 7 43 86 9 1 3 2 8 2 3 0 5 8 43 0 0 8 1 3995 2 1 2 8 men ts Bk 9 P rop 3 6 is g i v en the form ula for perfect num bers 1 1 P P P 2 The above eight perfect nu mbers where 2 1 is pri m e (2 are repro d uced by taking p= 2 3 5 7 1 3 1 7, 1 9 3 1 A ninth perfect nu m ber was found i n 1 8 8 5 by P S eelh off for which p= 6 1 a tenth in 1 9 1 2 by R E P owers for which p= 8 9 The father of the m o dern theory of numbers is F e rm at He was S O uncommunicative in di s position that he generally concealed his m ethods and m ade known 1 68 . , , . , , , ” “ . , , ° . . . . , ‘ , ‘ ‘ c , . , , , . , . , . , - . - . , ” . ’ ~ , . , - , , , , , , , , , , , , , . ’ . , , , . . , , , , , ’ , . , . , . , , “ ‘ - . , , , , , . . . . , . , , , . , A HISTORY OF M ATHE M ATICS 1 68 res ul ts only In some cases later analysts have been greatly pu zzled in the attempt of supplying the proofs Fermat owned a copy of B ach e t s Di ophantus in which he entered num erous marginal notes In 1 6 7 0 these notes were incorporated in a new edition of Di ophantus brought out by his son Other theore ms on numbers due to F ermat were publi shed in his Oper a vari a ( edited by hi s son ) and i n Walli s s C ommerci u m epi s tol i cu m of 1 6 58 Of the foll ow ing theorems the 1 first seven are found in the marginal notes : is i mpossible for integral values of x y and 2 when ( 1) hi s . . ’ . , , . , , ’ , . , n> 2 , , ” . This famous theorem was appended by Fermat to the problem of D iophantus II 8 : To divide a given square number into two squares “ Fermat s m arginal note is as foll ows : On the other hand it is im possible to separate a cube into two cubes or a biquadrate into two biquadrates or generally any power e xcept a square into two powers with the sam e exponent I have discovered a truly m arvelous proof of this which however the m argin is not large enough to contai n That Ferm at actually possessed a proof is doubtful N 0 general proof has yet been published Euler proved the theorem for n = 3 and n = 4 ; D irichlet for n = 5 and u = 1 4 G Lamé for n = 7 and K um m er for m any other values Repeatedly was the theorem m ade the priz e question of learned societies by the Academy of Sciences in The P aris in 1 8 2 3 and 1 8 50 by the Acade m y of B russels in 1 883 recent history of the theorem foll ows later A prim e of the form 4u + 1 is only once the hypo thenuse of a (2 ) right triangle ; its square is twice ; its cube is three times etc Ex a mple : . , ’ , ” , . . , . . . , . , . , . . , A prime of the form (3) can be expressed once and only once as the su m of two squares P roved by Euler A n um ber composed of two cubes can be resolved into two (4) other cubes in an infinite multiplicity of ways Every nu mber is either a triangular number or the sum of two 5) or three trian g ular n umbers ; either a square or the sum of two three or four squares ; either a pentagonal number or the sum of two three four or five pentagon al nu mbers ; sim ilarly for polygonal numbers in general The proof of this and other theorem s is promised by F erm at in a future work which never appeared This theorem is also given with others in a letter of 1 63 7 addressed to P ater 4u + 1 , . . , . , , , , , . . M er sen n e , , A S m any num bers as you please may be found such that the (6) . , square of each re mains a square on the addition to or sub traction from it of the sum of all the numbers . fu l l er hi s t o ri c al acco u n t o f F e rm a t s D i op han t in e t heo re ms an d p rob S ee l e m s , s e e T L H ea t h , Di opha n tu s of A l exa n dr i a , 2 E d , 1 9 1 0 , pp 2 6 7 3 2 8 a l so A n n a l s of M a themati cs , 2 S , Vol 1 6 1 1 87 1 8 , 1 9 1 7 , pp 1 For ’ a . . . . . . . . — — . . . 1 A HISTORY OF 70 M ATHE M ATICS factor of the form 4u + 1 From the above supposition it would follo w that 5 is not the sum of two squares—a conclusion contrary to fact Hence the supposition is false and the theorem is estab l ished F erma t applied this m ethod of descent with success in a large nu mber of theorem s By this method L Euler A M Legendre P G L Di ri ch let proved se v eral of his enunciations and many other nu merical propositions F erma t was interested in magic squares These squares to which the Chinese and Arabs were so partial reached the Occi d ent not l ater than the fifteenth century A m agic square of 2 5 cells was found by M Curtz e in a Ger man m anuscrip t of that ti m e The artist Albrecht “ D ii re r exhibits one of 1 6 cells in 1 5 1 4 in his painting calle d M ela n Choli e The abo v e na med B er n ha rd Fr eni cl e de B essy ( about 1 6 0 2 1 6 7 5) brought out the fact that the nu mber of m agic squares increased enormously with the order by writing do w n 8 8 0 magic squares of the or der four Ferm at gav e a general rule for finding the number of m agic squares of the order n such that for n = 8 this nu mber was but he seem s to hav e recogniz ed the falsity of his ru l e B achet de M ézi riac i n his P r obl emes pl ai s an ts cl dél ectabl es Lyon 1 6 1 2 gave a rule des terrasses for writ i ng down m agic squares of odd order Fr en icl e de B essy gave a process for those of 1 e v en order In the seventeenth century magic squares were studied by Antoine Arnauld Jean P re s t e t J O z anam ; in the eighteenth cen tury by P oignard D e la Hire J Sauveur L L P ajot J J Rallier des Ourm es L Euler and B enja m in Franklin In a letter B Franklin “ 2 said of his m agic square of 1 6 cells I m ake no question but you will read ily allo w the square of 1 6 to be the m ost m agically m agical of any m agic square ev er m a d e by any m agician A correspondence between B P as cal and P Fermat relating to a certain ga me of chance was the germ of the theory of probabilities of which som e anticipations are foun d in Cardan Tartaglia J Kepler and Galileo Che v alier de M ere proposed to B P ascal the funda “ 2 m ental P roble m of P oints to determ ine the probability which each player has at any given stage of the gam e of winning the game P ascal and F e rma t supposed that the players have equal chances of winning a S ingle point The former co mmunicated this proble m to F ermat who studied it with li v ely interest and sol v ed it by the theory of combinations a theory which was diligently stu died both by him and P ascal The calculus of probabilities engaged the attention also of C Huygens The m ost i mportant theore m reached by him was that if A has p chances of wi nning a su m a and q chances of winning a su m b then . . , . . . . . , . , . . , . . , , . . . , - . . , , , ” . , , , . . , , , , . , . , . . . . . , . . , , . . . , , ” . , . . , . , , . , , . . . , , , En cycl opedi c des s ci en ces math s , T I , V ol 3 , 1 90 6 , p 6 6 2 — I P a r i s 1 86 6 2 2 0 23 7 v r o m l t B l a i s e P a sc a l T S ee a l so I Oeu es c , , , pp , p e es de To d h u n te r , H i s tor y of the M a themati cal Theory of P r oba bi li ty, C a mb ri dg e a n d L o n do n , 1 86 5 , C h ap t er I I ’ 1 . . . . . . . . . . VIETA TO D ES CARTES he may expect to the win su 0 m 6 1 15 2 1 71 Huygens ga v e his results in . a treatise on probabili ty ( 1 6 which was the best account of the subj ect until the appearance of Jakob B ernoulli s A r s conj ectandi which containe d a reprint of Huygens treatise An absurd abuse of m athem atics in connection with th e probability of testi mony was made by J ohn C r ai g who in 1 6 99 concluded that faith in the Gospel so far as it depended on oral tradition expired about the year 80 0 and so far as it depended on written tradition it would expire in the year 3 1 50 Connected with the theory of probability were the investigations on mortal ity and insurance The use of tables of mortality does not seem to have been altogether unknow n to the ancients but the first na m e usually m entioned in this connection is Captain John Gr au nt who published at London in 1 6 6 2 his N atu ral an d P ol i ti cal Obs erva ti on s made u pon the bi l l s of mor tal i ty basing his de d uctions upon records of deaths which began to be kept i n London in 1 592 and were first intended to make known the progress of the plague Graunt was careful to publish the actual figures on which he based his conc l usions “ comparing him self when so doing to a S illy schoolboy com ing to say his lessons to the world ( that peevish and tetchie m aster)who brings a bundle of rods wherewith to be whipped for every m istake 1 he has co m mitted Nothing of marked i mportance was done after 1 Graun t until 1 6 93 when Ed m und Halley published in the P hi l o s ophi cal Tr an s acti on s ( London ) his celebrated m e m oir on the D egr ees ’ ’ . , . . , , . , , , ” , , , . f M or tal i ty of M an k i nd A ttempt to as cer ta i n the P r i ce of A n n u i ti es u pon Li ves To find the val u e of an annuity , m ultiply the C hance that the individual concerne d will be alive after n years by w i th o an . the present value of the annual paym en t due at the end of n years ; the n su m the results thus obtaine d for all values of n from 1 to the extrem e possible age for the life of that individual Halley considers also annuities on joint lives Am ong the ancients Archim edes was the only one who attained clear and correct notions on theoretical statics He had acquired fi rm possession of the idea of pressure wh i ch lies at the root of me c h an i c al science B ut his ideas slept nearly twenty centuries until the ti me of S S tevi n a n d G al il e o G al il e i ( 1 56 4 Stevin deter m i ned accura t el y the force necessary to sustai n a body on a plane inclined at any angle to the horizon He was in possession of a c om While Stevin inv estigated statics pl e t e doctrine of equilibriu m Gal i leo pursued principally dynam ics Galil eo was the first to abandon the idea usually attributed to Aristotle that bodies descend more q uickly in proportion as they are heav ier ; he established the first law of m otion ; determ ined the laws of falling bo dies ; and h avi ng obtained . . , . , . , . . . , , . , 1 I To dh u n t e r , H i s tor y . f o the Theory f o P roba bi l i ty, p p 3 8 , 4 2 . . A H ISTORY OF M ATHE M ATICS 1 72 a clear notion of acceleration and of the indepen dence of diff erent m otions was able to prove that proj ectiles move in parabolic curves Up to his tim e it was believ ed that a cannon ball moved forward at first in a straight line and then suddenly fell vertically to the ground Galileo had an understanding of cen tri fu gal f orces and gave a correct definition of momen tu m Though he formulated the fundam ental principle of statics ; known as the par al l el ogr am of f orces yet he did not fully recogniz e its scope The principle of virtual velocities was partly conceived by G u i d o Ub al do (died and afterwards more fully by Galil eo Galileo is the founder of the science of dynamics Am ong his con t e mporaries it was chiefly the novelties he detected in the sky that m ade h i m celebrated but J Lagrange clai m s that his astrono mical discoveries required only a telescope and perseverance while it took an extraor dinary genius to discover laws from phenom ena which we see constantly and of which th e true e xplanation escaped all earlier philosophers Galileo s dialogues on m echanics the Di scors i e demos tr azi on i ma tema ti che 1 6 3 8 touch also the subject of infinite aggregates The author displays a keenness of vision and an originality which was not equalled before the tim e of D edekind and Georg Cantor Salviati who i n general represents Galileo s own ideas in these dia 1 “ l og u e s says infinity and indivisibility are in their very nature i n comprehensibl e to us Simplicio who is the spokes man of Aris “ t o t el i a n scho l astic philosophy re marks that the infinity of points in the long line is greater than the infinity of points in the short line “ Then co m e the rem arkable words of Salviati : This is one of the diffi culties which arise when we atte mpt with our finite m in ds to discuss the infinite assigning to it those properties which we give to the finite and unlim ited ; but this I think is wrong for we cannot speak of infinite quantities as being the one greater or less than or equal to another We can on l y infer that the totality of all nu mbers is infinite and that the n u mber of squares is infinite and that the nu mber of the roots is infinite ; neither is the nu mber of squares less than the totality of all nu mbers nor the latter greater than the former ; and fi nally the attributes equal greater and l eS S are not app l icable to infinite but only to finite quantities O ne l i ne does not contain m ore or less or just as man y poi n t s as another e ac h l i n e contains an infinite nu m ber but From the time of Galileo an d D escartes to Sir W i ll i am Hamilton there was held the doctrine of the fi n i tu de of the hu man mind and its consequent in ability to conceive the infinite A D e M organ ridiculed this saying “ the argument a mounts to this who drives fat oxen should himself be fat Infin i te series which sprang into pro m i nence at the tim e of the . , - . , . , . . . . , , , ’ . , , . , . ’ ” , , , . ” , , . , , , , . , , , ‘ ’ ’ ‘ , ’ ‘ , , . ” ' ' , . , . . ” , , , . , ” S ee G al i l eo s Di a l og u es con cer n i n g two n ew S ci en ces , t ra n sl a t ed b y H e n ry C rew “ a n d Al fo n so d e S a l v i o , N ew Y o rk , 1 9 1 4, F i rs D ay, pp 30 3 2 1 ’ t — . . A 1 74 O F M ATHE M ATICS HISTORY D escartes considered m athe matical studies absolutely pernicious as a m eans of internal culture In a letter to M ersenne D escartes says : “ M D esargues puts me under obligations on account of the pains that it has pleased h i m to have in me i n that he S hows that he is sorry that I do not wish to study m ore in geometry but I have re sol v ed to quit only abstract geo metry that is to say the consideration of questions which s er ve onl y to exer ci se the mi nd and this in order to study another kind of geo metry which has for its obj ect the e xp l ana tion of the phenom ena of nature You know that all my ph y sics is nothing else than geo metry The years between 1 6 2 9 and 1 649 were passed by h im i n Holland in the study principally of physics and m etaphysics His residence in Holla nd Was during the m ost brilliant days of the D utch state In 1 63 7 he published his Di scou rs de l o M éthode containing a mong others an essay of 1 0 6 pages on geo metry His Geometri c is not easy reading An edition appeared subsequently with notes by his fr iend De B eau n e which were inten ded to re mov e the difficulties The Geometr i c of D escartes is of epoch m aking i mportance ; ne v ertheless we cann ot accept M ichel Chasles state ment that this work is pr ol es s i ne matre crea ta—a child brought into being without a m other I n part D escartes ideas are found in Apollonius ; the applicatio n of algebra to geo metry is found in Vieta G he tal di O u g h t red and e v en a mong the Arabs F e rma t D escartes contemporary advanced i deas on analytical geom etry akin to his own in a treatise entitled A d l ocos pl an os cl s ol idos i s agoge which howe v er was not published until 1 6 7 9 in Ferm at s Vari a oper a In D escartes Géométri e there is no syste matic dev elop ment of the m ethod of analytics The m ethod m ust be constructe d fro m iso l ate d state ments occurring in di ff erent parts of the treatise In the 3 2 geometric d ra w ings illustrating the text the a xes of coord inates are in no case explicitly set forth The treatise consists of three book s The first deals with p roble ms which can be constructed by the a id of the circle and straight line only The second book is on the “ nature of curved lines The third book treats of the construction of proble ms solid and more than solid I n the first book it is ma d e clear that if a proble m has a finite nu mber of solutions the final equation ob tained will have o nly one unknown that if the final “ equation has t w o or more unknowns the problem is not whol l y “ 1 If the final equation has two unkno w ns then since determined there is always an infinity of diff erent points which satisfy th e d e m and it is therefore required to recogniz e and trace the line on which To acco mplish this D escartes all of the m m ust be located (p . , . , , , , , , , ” . . , , . . , . . , . ’ ’ . , , . , , , ' , - , ’ . , ’ . . ” “ . . “ ” . ” . . , , , ” , . ” , . C J K eyser , M athemati cs , . — . 1 90 7 , pp 3 6 0 3 7 2 ’ 1 D esc a r t e s Géometr i e, ed B i bl i otheca ma thema ti ca , 3 S 191 2, . pp 20 . — 44 ; F . C aj o r i i n P opul ar S ci ence M on thl y, . We a re h ere g u ided by G En e st rom i n p 4 — l 1 2 0 2 43 ; V ol 1 2 , p p 2 73 , 2 74 ; Vo l 14, V o 1 4 , , pp n n l 1 2 1 2 43 , 3 2 9 , 33 0 a n b H i e l e i t e r i V o d y W 4 4 , pp p 35 7 , ’ . . . . . 1 886 , . . . . . . . . . . . D ES CARTES NEWTON TO 1 75 selects a straight l ine which he som eti mes calls a diam eter (p 3 1 ) and associates each of its points with a point sought in such a way that the latter can be constructed whe n the form er point is assumed as “ known Thus on p 1 8 he says J e c hoises une ligne droite co mm e A B pour rapporter a ses d ivers points tous ceux de cette l igne courbe EC Here D escartes follows Apollonius who related the points of a conic to the points of a dia meter by distances ( ordinates ) which m ake a constant angle with the diam eter and are determined in length by the positio n of the point on the dia meter This constant angle is with D escartes usually a right angle The n e w feature introduced by Descartes was the use of an equ ati on wi th mor e than one u n k n own so that (in case of two unknowns ) for any value of one unknown (ab scissa )the length of the other ( ordinate ) could be co mputed He uses the letters x and y for the abscissa and ordinate He makes it plain that the x and y may be represen t ed by other distances t han the ones selected by hi m (p that for instance the angle form ed by x and y need not be a right angle I t is noteworthy that Descartes and F e rma t and their successors down to the mid dle of the eighteenth century used oblique co ordinates m ore frequently than did later analysts I t is also note w orlthy that D escartes does not formally introduce a second a xis our y axis Such formal introduction is found in G Cra mer s I n tr odu cti on d l an al yse des l i gn es cou r bes al gébri qu es 1 750 ; earlier publications by de Gua L Euler W M ur d och and others contai n o nly occasional references to a y— axis The words abscissa ordinate were not used by D escartes In the strictly techni cal sense of anal ytics as one of the coordinates of a point th e word ordinate was used by Leibniz i n 1 6 94 but i n a less restricted sense such e xpressions as o rdi n a tim a ppl i ca tae occur m uch earl ier in F C o mman din u s and others The technical use of abscissa is observed i n the eighteenth century by C Wo l f and others In the “ m ore general sense of a d istance it was used earlier by B Cavalier i in his Indiv i sibles by S tef a no degl i A ngel i ( 1 6 2 3 a professor of m athe matics in Ro me and by others Leibniz introduced the word To guard aga inst certain current historical ; c oOrdi n a tae i n 1 6 92 “ errors we qu ote the following fro m P Tannery : One frequentl y attributes wrongly to D escartes the introduction of the convention of reckoning coordinates positiv ely and negati v ely in the sense in which we start the m fro m the origin The truth is that in this respect the Geometri c of 1 6 3 7 contains only certain re marks touching the interpretation of real or false (positive or negative ) roots of equations If then w e examine with care the rules given by D escartes in his Geometri c as well as his application of the m we notice that he adopts as a principle that an equation of a geometric locus is not vali d except for the angle of the coordinates ( quadrant ) in which it was established and all his contemporaries do likewise The extension of an equation to other angles ( quadrants ) was freely made in par ti cu . . ” , . , , . , . . , , . . . , , . , , . - . , ’ ’ . , - “ ” , , . “ . , . ” “ ” . , ” , “ . . ” . . . ‘ ” , . , . . , . . , , , . A 1 76 O F M ATHE M ATICS HISTORY lar cases for the interpretation of the negative roots of equations ; but while it served particular conventions (for e xample for reckoning distances as positive and negative )it was in reality quite long in co mpletely establishing itself and one cannot attribute the honor for it to any particular geom eter analytical geometry partly D escartes geo metry was called because unlike the synthetic geometry of the ancients it is actually a n al yti ca l in the sense that the word is used in logic ; and partly b e cause the practice had then already arisen of designating by the term a n al ys i s the calculus with general quantities The first important example solved by D e scartes in hi s geometry “ “ is the proble m of P appus ; v iz Given several straight li nes in a plane to find the locus of a point such that the perpendiculars or more generally straight lines at given angles drawn from the point to the given lines S hall satisfy the condition that the product of certain of them S hall be in a give n ratio to the product of the rest Of this celebrated proble m the Greeks solved only the special case when the nu mber of giv en lines is four in which case the locus of the point turns out to be a conic section By D escartes it was solv ed c om pl e t el y and it a fforded an excellent exa mple of the use which can be m ade of his analytical m ethod in the study of loci Another solution was give n later by Newton in the P ri nci pi a D escartes illustrates “ his analytical m ethod also by the ovals n ow nam ed after him cer taines ovales que vous verrez etre tres utiles pour la th éorie de la catoptrique These curves were studied by D escartes probably as early as 1 6 2 9 ; they were intended by him to serve in the construction of converging lenses but yielded no results of practical value In 1 the nineteenth century they received m uch attention The power of D escartes anal ytical m ethod in geom etry has been vividly set forth recently by L Bolt zmann in the rem ark that the form u l a appears at ti mes cleverer than the man who in v ented it Of all the problem s which he solved by his geom etry none gave him as great pleasure as his m ode of constructing tangents It was published earlier than the m ethods of F ermat and Roberval which were noticed on a preceding page D escartes m ethod consisted in first finding the norm al Through a given point x y of the curve he drew a circle which had its centre at the intersection of the norm al and the x— axis Then he imposed the condition that the circle cut the curve in two coincident points In 1 63 8 D escartes indicated in a letter that in place of the x y circle a straight line may be used This idea is elaborated by Fl ori mond de B eau n e in his notes to the 1 6 49 edition of D escartes Géométr i e In finding the point of intersection of the normal and x axis D escartes used the method of I ndeter mi n ate Coeffi ci en ts of which he bears the honor of invention Indeterm inate coeffi cients were e mployed by I 19 S ee G Lori a Ebene Cu rvou ( F S c hut te) 74 p , , ” . ’ , , , , , . ” . , , , , ” , . , , . , . . , ” , - , , . . , . ’ . . , . . ’ . , . , , . . , ’ . - , , . 1 . . , , 10 , . 1 . H ISTORY A 1 78 O F M AT H EM ATIC S of its beautiful properties and the controversies which their discovery occasioned Its quadrature by Roberval was generally considered a brilliant achieve ment but D escartes co mmented on it by saying that any one m oderately well versed in geom etry might ha v e done this He then sent a S hort demonstration of his own On Roberval s i n t i ma t i n g that he had been assisted by a knowledge of the solution D escartes constructed the tangent to the curve and challenged Roberval and F erm a t to do the sam e Fermat acco mplished it but Roberval never succeeded in solving this p roblem which had cost the genius of D escartes but a m oderate degree of attention The application of algebra to the doctri ne of curve d lines reacted favorably upon algebra A S a n abstract Science D escartes i mproved it by the introduction of the modern exponential notation In his “ 2 Géométr i e 1 6 3 7 he writes ao o n a pour m ultiplier a par s oi meme ; 3 pour l e m ultiplier encore une fois par a e t ainsi a l i nfi n i et a “ 3 3 Thus while F Vieta represented A by A c u b u s and Ste vin x 3 by a figure 3 within a s mall circle D escartes wrote a In his Geometri c he does not use negative and fractional exponents nor l iteral ex His notation was the outgrowth and an i mprovem ent of p on en t s notations e mployed by writers before him Nicolas C hu q u e t s m anu 3 1 script work L e Tri party en l a sci ence des n ombr es 1 4 84 gives 1 2 x 8 3 5 8 5 and r ox and their product 1 2 0 x by the symbols 1 2 1 0 1 2 0 respectiv ely C hu q u e t goes even further and writes 1 2 x and 7x 2 3 1 thus he represents the product of 8x and 7x by 56 J B urgi R eym er and J Kepler use Ro man nu m erals for the exponen I I 2 Thom as Harriot S imply tial symbol J Burgi writes 1 6x thus 16 . , . ’ . , , , . , . , . . , , ” , ” ’ . . , . , , . ’ . , , , , , ° , , . ‘ . . . , . . repeats the letters ; he writes in his A rti s an al yti coe praxi s " 2 1 0 2 4 aa + 6 2 54 a a 1 0 2 4 a + 6 2 54 a thus : a aaa D escartes exponent i al notation sprea d rap i dly ; about 1 6 60 or 1 6 7 0 the positive integral exponent h a d w o n an un d i sputed place in algebraic notation In 1 6 5 6 J Wallis S peaks of negative a n d fractional indices in his A r i thmeti ca i nfi n i toru m but he does not actually . , ’ ” “ . . , write _ 1 a for or a ’ /s , — 3 for x/a It was I Newton who in his fam ous . , . letter to H Oldenburg dated June 1 3 1 6 7 6 and containing his a n n ou n c em en t of the bino m ial theorem first uses negative and fractional exponents With D escartes a letter represented always only a positiv e nu mber I t was Johann H u dde who in 1 6 5 9 first let a letter stan d f o r negative as well as positive values D escartes also estab l ished so m e theore m s on the theory of equa tions Celebrate d is his rule of signs for determining the nu mber . , , , , . . . . 1 C hu q ue t ” . ’ s “ L e Tr ip a r ty , B u l l etti n o B on compag n i , V ol . 1 3, 1 8 80 , p . 7 40 . D ESCARTES TO NEWTON 1 79 of positiv e and negative roots He gives the rule after pointing out the roots 2 3 4 5 a n d the corresponding bino m ial factors of the 1— 2 3— equation x 4x 1 9x + 1 0 6 x 1 2 0 = 0 His exact words are as follo ws On c o nn oi t aussi de ceci combien il peut y avoir de vraies racines e t co mbien de fausses en chaque eq u a t i o n : a sa v oir i l y en peut a v oir et autant de v raies que les S ignes s y trouvent de fois etre c ha n g es e t autant de fausses qu il s trou e de fois eux ignes v d S y ou d eux S ig n es qui s e n t re suivent Co mm e en la derniere a cause 4 qui est u n change ment d u signe e n q u apres + x il y a 2 — e t apr es 1 9x i l y a + r o 6 x e t apres + r o 6 x il y a —1 2 0 sont qui encore d eux autres ch ange ments ou c onn oi t qu il y a tro i s vraies 3 2 racines ; e t une fausse a cause que les deux S ignes de 4x e t 1 9x s e n t re— sui v ent This state me n t lacks co mpleteness For this reason he has been frequently critici z ed J Wallis clai med that D escartes failed to notice that the rule breaks down in case of i maginary roots but D escartes does not say that the equation al w ays has but that it may have so m any roots D id D escartes recei v e any suggestion of his rule fro m earlier writers ? He m ight have received a hint from H Cardan whose re marks on this subj ect have been sum mariz ed by 1 G En e s t r6 m as follows : If m an equation of the secon d third or fourth degree ( 1 ) th e last ter m is negative then one variation of S ig n signifies one and only one positive root ( 2 ) the last term is positive the n t wo variations indicate either several positive roots or none Cardan does not consider equations ha v ing more than two variations G W Leibniz was the first to erroneously attribute the rule of signs to T Harriot D escartes was charged by J Wallis with availing himself without acknowledgment of Harriot s theory of equations particularly his m ode of generating equations ; but there see ms to be no goo d ground for the charge In m echanics D escartes can hardly be said to have advanced b e yond Gal ileo The l atter had overthrown the ideas of Aristotle on “ this subject and D escartes S i mply threw himself upon the enem y “ that had already bee n put to the rout His state ment of the first and second laws of motion was an improvem ent in form but his third law is false in substa n ce The m otions of bodies i n their direct i mpact was i mperfectly understood by Galileo erroneously giv en by D escartes an d first correctly stated by C Wren J Wall i s and C Huygens One of the most devoted pupil s of D escartes was the learned P ri n cess El i za beth daughter of Frederick V She applied the new analytical geo m etry to the so l utio n of the Apollon ian problem His second royal follower was Qu een C hri s ti n a the daughter of Gus tav us Adolphus She urged upon D escartes to com e to the Swe dish court After m uch hesitatio n he accepted the invitation in 1 6 49 . , , , ‘ - . . “ ’ ’ ’ , ’ . , ’ , , ’ . , , ’ . . . . “ , , , . . , . , , , , , . . . . . . . ’ , - , , . , . ” ” , . , . , . , . , . , , . ” . . , . . 1 B i bl i otheca mathema ti ca , 3 rd S . , V ol 7 , . 1 90 6 —7 , . p . 2 93 . A HISTORY OF M ATHE M ATICS 1 80 He died at S tockhol m one year later His life had been one long war fare against the prej udices of men I t is most re markable that the m a thematics and philoso phy of D escartes should at first have been appreciated less by his country m en than by foreigners The indiscreet temper of D escartes alienated the great contemporary French m athem aticians Roberv al F erma t P ascal They continued in in v estigations of their own and on som e points strongly opposed D escartes The univ ersities of France were under strict ecclesiastical control and did nothing to introduce his m athe matics and philosophy It was in the youthful universities of Holland that the eff ect of Cartesian teachi ngs was most immediate and strongest The only prominent French man who i mme diately followed in the footsteps of the great master was F l o ri mon d d e B eau n e ( 1 6 0 1 1 6 5 He was one of the first to point out that the properties of a curve can be deduced fro m the properties of its tangent This m ode of inquiry has been called the i nver se method of tangen ts He contributed to the theory of equations by consid ering for the first tim e the upper and lo w er limits of the roots of nu merical equations In the Netherlands a large nu mber of d istinguished m athe maticians were at once struck with ad miration for the Cartesian geo metry Fore most a m ong these are va n S chooten John de Witt van H eu rae t professor S l u z e and H u dde Fr an c i s c u s van S c hoo t e n ( died of m athe m atics at Leyden brought out a n edition of D escartes geom etry together with the notes thereon by D e B eaune His chief work is his Exerci tati on es M athemati cce 1 6 57 in which he applies the analyt i cal geom etry to the solutio n of m any interesting and d ifficult proble ms The noble hearted Joh ann d e Wi tt ( 1 6 2 5 grand pensioner of Holland celebrated as a states man and for his tragical end was an ardent geometrician He conceived a new and ingenious way of generating conics which is essentially the same as that by projective pencils of rays in m odern syn thetic geometry He treated the subj ect not synthetically but with aid of the Cartesian analysis R e n é F r an coi s d e S l u s e ( 1 6 2 2 — 1 6 8 5) and Joh ann H u dd e ( 1 633 1 7 0 4) m ade so m e i mprove m ents on D escartes and Ferm at s m ethods of drawing tangents and on the theory of maxim a and minima With H u dde we find the first use of three variables i n analytical geom etry He is the author of an ingenious rule for fin ding equal roots We 3 illustrate it by the equation x Taking an arith metical progression 3 2 of which the highest term is equal to the degree of the equation and m ultiplying each term of the equation respecti v ely by the correspon ding term of the progression we get 3— 2— 2— = 2x 8 x 0 or 3 x 2x This last equation is by one 3x d egree lower than the original one Find the G O D of the two equations This i s x —2 ; hence 2 is on e of the two equal roots Had there been no common divisor then the original equation woul d not . . . , , . , , . . . - . . . . , , , . , ’ , , . , , - . , , . , . . , ’ ’ . , . , . , , , , , . . . . , 1 A HISTORY OF M ATHE M ATI CS 1 82 and obtained a geometric series that was i nfi ni te How ever infinite series had been obtained before him by A l varu s Thomas a nati v e of Lisbon in a work L i ber de tri pl i ci motu and possibly by others B ut S t Vincent was the first to apply geom etric series to “ the Achill es and to look upon the paradox as a question in the s ummation of an infinite series M oreover St Vincent was the first to state the e xact tim e and place of overtaking the tortoise He spoke of the li mit as an obstacle against further advance similar to a rigid wall Apparently he was not troubled by the fact that in hi s theory the variable does not r ea ch its l im it His exposition of the “ Achi l les was favorably received by G W Leibniz and by writers over a century afterw ard The fullest account and discussion of Zeno s argu ments on m otion that was published before the nineteenth century was given by the noted French skeptical philosopher P i er r e B ayl e i n an article Zenon d El ée in his Di cti on n a i r e hi stori qu e et ad i nfi ni tu m . , , , ” . , , . . , . . , ” . , . . . . ’ ” ’ , , cr i ti qu e , The prince of philosophers in Holland and one of the greatest scientists of the seventeenth century was C h ri s tian H u yg e n s ( 1 6 2 9 1 69 a native of The Hague E m inent as a physicist and astronomer as well as m athe matician he was a worthy predecessor of Sir Isaac Newton He studied at Leyden under Fr a ns Va n S chooten The perusal of som e of his earliest theore ms led R D escartes to predict his future greatness In 1 6 5 1 Huygens wrote a treatise in which he pointed out the fallacies of Gregory S t Vincent on the subject of quadratures He hi mself gave a re markably close and convenient approxi m ation to the length of a circular arc In 1 66 0 and 1 663 he went to P aris an d to London In 1 6 6 6 he was appointe d by Louis XIV m e mber of the French Academ y of Sciences He was induced to rem ain in P aris from that time until 1 68 1 when he returned to hi s native city partly for consideration of his health and partly on ac count oi the revocation of the Edict of Nantes The m ajority of his profound discoveries were m ade with aid of the ancient geo metry though at ti mes he used the geo m etry of R D es cartes or of B Cavalieri and P Fermat Thus like his illustrious friend Sir Isaac Newton he al w ays sho w ed partiality for the Greek geom etry Ne w ton and Huygens were kind r ed min d s and had the greatest ad miration for each other Newton always speaks of hi m “ as the Sum mus H ug en i u s To the two curves ( cubical parabola and cycloid ) previously recti fi e d he adde d a third — the cissoid A French physician Clau dius P errault proposed the question to d eter mine the path in a fixed plane of a heavy point attached to one en d of a taut string whose other end m oves along a straight line in that plane Huygens and G W Leibniz studied this proble m in 1 6 93 generaliz ed it and thus worked out the , , . , , . . . . . . . . . , , . . , . . . , , , . ” , . . , . , , , . , , 1 2 H . Wi el ei tn e r S ee i n B i bli otheca ma themati ca , 3 F , B d 1 9 1 4 , 1 4 , p F C aj or i i n A m M ath M on thl y, V o l 2 2 , 1 9 1 5 , p p 1 0 9 1 1 2 . . , . . . . . . — . . 152 . . . D ESCARTES TO NEWTON ” tractrix Huygens solved geometry of the the problem of th e catenary determined the surface of the parabolic and hyperbolic conoid and disco v ered the properties of the logarith mic curve an d the solids generated by it Huygens De horol og i a os ci l l atori o (P aris 1 6 73) is a work that ranks second only to the P ri n ci pi a of Newton and constitutes h istorically a necessary introduction to it The book opens with a description of pendulum clocks of which Huygens IS the inventor Then follows a treatm ent of accelerated m otion of bodies fall ing free or sl iding on inclined planes or on given curves —cul m i n a ti n g in the brilliant discovery that the cycloid is the tautochronous curve To the theory of curves he added the important theory of “ evolutes After explaining that the tangent of the evolute is normal to the involute he applied the theory to the cycloid and showed by si mple reasoning that the evolute of this curve is an equal cycloid Then co mes the co mplete general discussion of the centre of oscillation This subject had been proposed for investigation by M M ersenne and discussed by R D escartes and G P Roberval In Huygens assumption that the common centre of gravity of a group of bodies oscillating about a horiz ontal axis rises to its original height but no higher is expressed for the first time one of th e most beautif ul principles of dynamics afterwards called the principle of the conserv ation of vi s vi va The thirteen theore m s at the close of the work relate to the theory of centrifugal force in circular motion 2 This theory aided Ne w ton in d isco v ering the l aw of gravitation Huygens wrote the first formal treatise on probability He pro posed the wave— theory of light and with great sk i ll applie d geom etry to its develop m ent This theory was long neglecte d but was revived and elaborated by Thomas Young and A J Fresnel a century later Huygens an d his brother i mproved the telescope by devising a better way of grin ding and pol i sh i ng lenses With m ore effi cient i n s tru m ents he d eterm ined the nature of Saturn s appendage and sol v ed other astronom ical questions Huygens Opu s cu l a pos thu ma appeared 1 . , , ’ . , . , . , , , ” . . , , . . . . . . . ’ , , , , , . . . . . . , . . . . ’ ’ . I n 1 70 3 . The theory of combinations the prim itive notions of which go back to ancient Greece received the attention of Wi l li am B u ckl ey of Ki ng s College Cambridge (d ied 1 5 and especially of Blaise P ascal who treats of it in his A r i thmeti cal Tr i a n gl e B efore P ascal thi s Triangle had been constructe d by N Tartaglia an d M Stifel Ferm at applied co mb i nations to the stu dy of probability The earliest m athe m atical work of Leibniz was his De a r te combi n a tor i a The subject was treated by John Wal l is in his A l gebra — was one of the m ost original ma th e ma t i Joh n Wal li s ( 1 6 1 6 1 70 3 ) c i an s of his day He was e ducated for the Church at Cambridge an d en , , ’ , . , . . . . . . . ) G L o ri a , Eben e C u r vou ( F S c h u tt e I I 1 9 1 1 , p 1 8 8 2 E D uhri n g , K r i ti sche Geschi chte der A ll geme i n en P ri nc i pi en der M echa n i k L e ip i g , 1 88 7 , p 1 3 5 1 . . z . . . , . . . A HISTORY OF M ATHE M ATICS 1 84 Holy Orders B ut his genius was e mployed chiefly in the study of mathe matics In 1 6 4 9 he w as appointed S av i l ia n professor of geo metry at Oxford He was one of the original m e mbers of the Royal Society which was founded in 1 6 6 3 He ranks as one of the world s greatest de 1 Walli s thoroughl y grasped the mathema t C ipherers of c ryptic writing ical m ethods both of B Cavalieri and R D escartes His C oni c S ecti ons is the earliest work in which these curves are no longer considered as sections of a cone but as curves of the second degree and are treated analytically by the Cartesian m ethod of c o ord inates In this work Wallis S peaks of D escartes in the highest term s b ut in his Al gebr a ( 1 6 8 5 Latin edition 1 6 9 he without good reason accuses D escartes of plag i ariz ing fro m T Harriot I t is interesti ng to observe that in his A l gebr a Wallis discusses the possibility of a fourth dimension “ Whereas nature says Wallis doth not admit of m ore than three dimensions it may justly see m very improp er to talk of (local ) a solid drawn into a fourth fi fth s i xth or further dim ension Nor can our fan si e im agine h ow there should be a fourth local dimen 2 The first to busy himself with the nu mber sion beyond these three of dimensions of space was P tole my Wall i s felt the need of a m ethod of representing i maginaries graphically but he failed to discover a 3 general and consistent representation He published Nasir— Eddin s proof of the parallel postulate and abandoning the idea of equi distance that had been e mployed without success by F C om ma n di n o C S C l a v io P A Cataldi and G A B ore l li gave a proof of his own based on the axiom that to e v ery figure there exists a S i milar figure 4 of arbitrary m agnitude The existence of si milar triangles was as su med 1 00 0 years before Wallis by Aga mis who was probably a teacher of Sim plicius We h av e a l ready m entioned else w here Wal l is s solution of the priz e questions on the cycloid which were proposed by P ascal The A r i thmeti ca i nfi n i tor u m published in 1 6 5 5 is his greatest work By the application of analysis to the M etho d of In d iv isibles he greatly increased the power of this instru ment for e ffecting quadratures He created the arith metical conception of a li mit by considering the successive values of a fraction for med in the study of certain ratios ; these fractional values steadi ly approach a li miting v alue so that the d iff erence becom es less than any assignable one and v anishes when the process is carr i e d to infinity He a dv ance d beyond J Kepler by making more extended use of the law of continuity and placing t er e d . . , . ’ . . . . . , , - . , , , , . , . . , , , , , ” . , . . , ’ . , . . . , . . . . , , , . , ’ . , . . , , , . , , ” . . D E S mi t h i n B u ll A m M a th S oc , Vol 2 4 , 1 9 1 7 , p 8 2 2 G En es t r Orn i n B i bli otheca ma thema ti ca , 3 S , V o l 1 2 , 1 9 1 1 1 2 p 8 8 ’ 3 S e e Wal l i s A l gebr a , 1 6 8 5 , p p 2 6 4 2 7 3 ; see al so En es t r Om i n B i bl i otheca mathe 269 mati ca , 3 S , V ol 7 , pp 2 6 3— 4 S ee al so F En g el u P S t ack e l , Theor i e der R B on o l a , op ci t , p p 1 2 1 7 Thi s t rea t is e P ar al l elli ni en von E u cl id bi s a uf Ga uss , L e i p ig , 1 8 95 , pp 2 1 3 6 n o f S ac c h e r i , a l so t h e e ss ays o f L amb e r an d Ta u r inus, n n G r a i m n l a t i o s t o e r a s v i es t g an d l e t t ers of G auss 1 . . . . . . . . . . . . — . , - . . . . . . - . . . . . . z . . . . — . t . . A HISTORY OF M ATHE M ATICS 1 86 responding to and the curves represented by the equations y 2 3 2 1 2 2 — — — = = = (1 y ( 1 x )y ( 1 x )y ( 1 x )etc are expressed in functions of the circum scribed rectangles havi ng x and y for their sides by the quantities forming the series x, . , , , , , 3 — x 1x 3 _ , 1 5 § x3+ x 5 7 1x + § x 1x etc x , x , When x = 1 these values becom e respectively . etc N ow 1 15 2 i — = since the ordinate of the circle is y ( 1 x )the exponent of which is 1 or th e m ean value between 0 and 1 the question of this quadrat ure reduce d itself to this If 0 1 etc oper ated upon by a certain law 1 4 8 — give 1 give when operated upon by the sam e 3 15 5 what will law ? He atte mpted to solve this by i n terpol ati on a _m ethod first brought into prominence by him and arrived by a highly complicated and difficult analysis at the following very remarkable expression : , 1, 3 , . , , , . , . , , , , , , , , " 71 2 He did not succeed in m aking the interpolation itself because he did not e mploy li teral or general exponents and could not conceiv e a series with m ore than one term and less than two which it seeme d to him the interpolated series m ust have The consideration of this dimc u l ty led I Newton to the discovery of the B inom ial Theore m This is the best place to S peak of that discovery Newton virtually assum ed that the sam e conditions which underlie the general ex pressions for the areas given above m ust also hold for the expression to be interpol ated In the first place he observed that i n each ex pression the first term is x that x i ncreases in odd powers that t e 3 3 3 h 3 signs alternate and and that the second term s 1x 1x 1x 1x are in arithm etical progression Hence the first two terms of the , , , . . . . . , , , , , m ust interpolated series be , , He nex t considered that the de x 3 no minators 1 3 5 7 etc are in arith m etical progression and that the coefli c i en t s in the num erators in each expre ssion a re the digits 0 of some power of the number 1 1 ; nam ely for the first expression 1 1 1 2 or 1 ; for the seco nd 1 1 or 1 1 ; for the third 1 1 or 1 2 1 ; for the 3 fourth 1 1 or 1 3 3 1 ; etc He then discovered that having give n the second digit ( call it m)the remaining digits can be found by con — — — m o m r m 2 t I n u al m u l ti pl I c a tI on of the term s of the ser i es , , , , . , , ‘ ’ , , , , , , , , , . , , , , etc . Thus if , m= 4 , then 4 . gives 6; 6 773 . —2 gives 4; D ESCARTES gi v es 1 second term is To NEWTON 18 Applying this rule to the required series since . , we hav e 3 m 7 t he 1 and then get for the succeeding , coeffi cients in the num erators respectiv ely - 1 “ , 1 111 1x hence the required area for the circular segm ent is x etc 1 3 1x ; 7 5 x 1 5 3 . 7 etc Thus he found the interpolated expression to be an infinite series instead of one having m ore than one term and less than two as Wallis believ e d it m ust be This interpolation suggeste d to Newton a mode 2 i — of expanding ( 1 x )or m ore generally ( 1 into a series He observed that he had only to o mit from the expression just found the denominators 1 3 5 7 etc and to lower each power of x by unity and he had the desired expression In a letter to H Oldenburg Newton states the theorem as follows :The ex traction (June 1 3 of roots is much shortened by the theorem , . , . , , , , , , . , . , , . . , n B Q+ — 2 17 111 , where A means the first term P B the second term C th e third term etc He verified it by actual m ultiplication but gave no regular proof of it He gave it for any exponent whatever but m a d e no dis tinction between th e case when the exponent is positive and integral and the others I t S hould here be mentioned that very rude beginnings of the bi nom ial theorem are found very early The Hindus and Arabs use d 2 3 the expansions of ( a + b)and (a + b)for extracting roots ; Vieta knew the expansion of but these were the results of S im ple multi plication without the discovery of any law The binomial coefficients for positive whole exponents were known to som e Arabic and Euro pean m athem aticians B P ascal derive d the coeffi cients from the “ m ethod of what is called the arithm etical triangle Lucas de Burgo M Stifel S S te v inus H B riggs and others all possessed s omething from which one would think the binomial theorem could “ have been gotten with a little attention if we did not know that such S imple relations were diffi cult to discover Though Wallis had ob ta ined an entirely n ew expression for 7r he was not satisfied with it ; for instead of a finite number of term s yield ing an absolute value it contained an infinite number approaching nearer and nearer to that value He therefore induced his friend Lor d B r ou n c k e r the first presi d ent of the Royal Society to investigate this subject Of course Lord B rou n c k e r did not find what they were after but he ob tained the following beaut iful equality , , n , , , . , . , . . . . ” . . , . , . , , , . ” , . , , , , . , . , , A H ISTO RY O F M ATH EMATICS 1 88 49 etc Continued fractions both ascending and descending appear to have been known alrea dy to the Greeks a nd Hindus though not in our present notation B rou n c k e r s e xpression gave birth to the theory of continued fractions Wallis m ethod of quadratures was diligently studied by his dis c ipl es Lord B rou n c k e r obtained the first infinite series for the area of the equilateral hyperbola xy= 1 between one of its asymptotes and 2+ . , , , ’ . . ’ . the ordi nates for and x= 1 x= 2 (London L ogari thmotechni a ; V IZ 1 668 , . 1 the area )of N i 1 1 M er cator col au s is often said 3 to conta i n the ser i es log 2 In 3 con real I ty I t tains the nu m erical values of the first few term s of that series tak ing a = 1 also a = 2 1 He adhered to the m ode of exposition which favored the concrete special case to the general form ula Wallis was the first to state M ercator s logarithm ic series in general symbols M ercator d e d uce d his results from the grand property of the hyper bola deduced by Gregory S t Vincent in B ook VII of his Opu s geo metri cu m Antwerp 1 6 4 7 : If parallels to one asym ptote are drawn between the hyperbola and the other asymptote so that the successive areas of the m ixtilinear qua drilaterals thus form ed are equal then the lengths of the parallels form a geom etric progression Apparently the first writer to state this theorem in the language of logarithm s was the B elgian Jesuit A lf ons A n ton de S aras a who defended Gregory S t Vincent against attacks m ade by M ersenne M ercator showed how the construction of logarithm ic tables could be reduced to the quadrature of hyperbolic spaces Following up som e suggestions of Wallis Wi l l i am N ei l succeeded in rectifying the cubical parabola and C Wr en in rectifying any cycloidal arc Gregory St Vincent i n P art X of h i s Opu s describes the construction of certain quartic cu rves often called virtual parabolas of S t Vincent one of which has a shap e 2 2 —2 = 4 — m uch l ike a lem niscate and in Cartesian c o ordinates is d (y x ) y Curves of this type are mentioned in the correspondence of C Huy gens with R d e Sluse and with G W Leibniz A prom inent English m athem atician and contemporary of Wallis was I s aac B arr ow ( 1 6 30 He was professor of m athematics in Lon don and then in Cambri dge but in 1 6 6 9 he resigned his chair , . . , . . ’ . . , , , , . , . . . , , . . . , , . , . . . , , . . , . Wallis in 1 68 and Edm und Halley in 5, B arrow gav e also the integral 1 64 7 M ATHE M ATICS A HISTORY OF 1 90 tan 0 d 9= log sec 0; B Cav al ieri in . ” established the i ntegral x dx by E Torricelli Gregory S t V i ncent 2 B P ascal J . . , . . Ja m es Gregory and , Sim il ar results were obtained . P . Fermat G , . P . Roberval and , N ewton to Eu l er I t has been seen that in France prodigious scientific progress was m ade during the beginning and m iddle of the seventeenth century The toleration which m arked the reign of Henry IV and Louis XIII was acco mpanied by intense intell ectual activity Extraordinary con fiden c e cam e to be placed in the power of the hu m an m ind The bold intellectual conquests of R D escartes P Fer mat an d B P ascal en riched m ath em atics with i mperishable treasures D uring the early part of the reign of Louis XIV we behold the sunset splendor of this glorious period Then followed a night of mental effe m inacy This lack of great scien t ific thinkers during the reign of Louis XIV may be due to the S imple fact that no great m inds were born ; but according to Buckle it was due to the paternalism to the spirit of dependenc e a n d subordination and to the lack of toleration which marked the policy of Louis XIV In the absence of great French thinkers Louis XIV surrounded him self by em inent foreigners O ROmer from Den m ark C Huygens from Holland D om in i c Cassini from Italy were the m athem atician s and astronomers a dorning his court They were in possession of a brilliant reputation before going to P aris Simply because they per formed scientific work i n P aris that work belongs no more to France than the disco v eries of R D escartes belong to Holland or those of J Lagrange to Ger m any or those of L Euler and J V P oncelet to Russia We m ust look to other countries than F ran c e f or the great scientific m en of the latter part of the seventeenth century About the tim e when Louis XIV assu med the direction of the French govern m en t Charles II beca m e king of England At this tim e England was extending her comm erce an d navigation and a d v an c i n g considerably in m ater i al prosper i ty A strong intellectual m o v e m ent took place which was unwittingly supporte d by the king The age of poetry was soon followed by an age of science and philos o phy In two successive centuries England produced Shakespeare and I Newton ! . . . . . , . , . . . , , , , , . , . . . , , , . . , . . , , . . . . . . , . . , . . S ee F C aj or i i n B i bli otheca mathema ti ca , 3 S , Vol 1 4 , 1 9 1 5 , pp 3 1 2 - 3 1 9 2 H G Z e u t h e n , Ges chi chte der M ath ( d e u t sc h v R M eye r , L eip ig , 1 90 3 , pp 2 5 6 ff 1 . . . . . . . . . . ) . . z . NEWTON To EULER 1 91 Germany still continued in a state of national degra dation The Thirty Years War had dism embered the e mpire and brutalized the people Yet this darkest period of Germany s history produced G W Leibniz one of the greatest geniuses of m odern times There are certai n focal points in history toward which the lines of past progress converge and fro m which rad iate the adv ances of the future Such was the age of Newton and Leibniz in the history of D uring fifty years preceding this era several of the mathematics brightest and acutest m athem aticians bent the force of their genius in a direction which finally led to the discovery of the infinites imal calculus by Newton and Leibniz B Cavalieri G P Roberval P F erma t R Descartes J Wallis and others had each contributed to So great was the adv ance m ade and so near was the new geo m etry their approach toward the invention of the infinitesimal analysis that both ] Lagrange and P S Laplace pronounced their countryman P F erm a t to be the first inventor of it The differential calculus therefore was not so m uch an individual discov ery as the grand result of a succession of discover i es by different m in d s Indeed no great discovery eve r flashed upon the mind at once and though those of Newton will influence mankind to the end of the world yet it must be “ adm itted tha t P ope s lines are only a poetic fancy : . ’ ’ . . . . , , . . . . , , . . . , . , . , , . , . . . , . , , . , , . ” , , ’ N ature an d Nature s l aw s lay h i d i n n ig ht ; ’ ‘ Go d sai d , Let Newton be , an d all was l i g ht ’ I s aac N e w ton ( 1 6 4 2 — was born at 1 727 shire , the sam e year in which Galileo died s mal l and weak that his life was despaired . ) Woolsthorpe in L incoln At his birth he was so of His m other sent him at an early age to a village school and in his twelf th year to the public school at Grantham A t first he see ms to have been very inattentiv e to his studies and very low in the school ; but when one day the little Isaac received a severe kick upon his sto m ach fro m a b oy who was above him he labored har d till he ran k e d higher in school than his antagonist From that tim e he continued to rise until he was the 1 head boy At Grantham Isaac showed a decided taste for m echan ical inventions He constructed a water clock a wind mill a carriage m oved by the person who sat in it and other toys When he had a t t ain e d his fifteenth year his m other took h i m ho m e to assist her in the m anagement of the farm but h is great dislike for farmw ork and his irresistible passion for study in d uced her to send h im back to Grantham where he re mained till his e ighteenth year when he en t ered Trinity College Ca mbridge Ca mbridge was the real b i rthplace bf Newton s genius So m e id ea of his strong intuiti v e powers may be drawn from the fact that he regarded the theorems of ancient geom etry as self ev ident truths and that without any pre li minary study he m ade h i m se l f m aster of D escartes Geometry He , . . , ‘ . . , , ‘ , . l . , - - . , , . , . , , , , , ’ . - , , ’ . , 1 D B r ew s te r , The M emo i rs . f o N ew ton , Edin b u rg h , V ol I , . 1 8 55, p 8 . . 92 . HISTORY OF M ATHE M ATICS A afterwards regarded thi s neglect of ele m entary geometry a mistake in his m athem atical studies and he expressed to Dr H P e mberton “ his regret that he had applied him self to the works of D escartes and other algebraic writers before he had consid ered the El emen ts of Euclid with that attention which S O e xcellent a writer deserves B esides R D escartes Geometry he studied W O ug h t red s Cl avi s J Kepler s Opti cs the works of F Vieta v a n S c ho o t en s M i scel l an i es I B arrow s L ectu res and the works of J Wallis He was particularly delighted with Wallis A ri thmeti c of I nfi n i tes a treatise fraught with rich and varied suggestions Newton had the good fortune of ha v ing for a teacher and fast friend the celebrate d D r Barrow who had been elected professor of Greek in 1 660 and was made L u casian professor of mathe m atics in 1 6 6 3 The mathe m atics of Barrow and of Wallis were the starting points fro m which Newton with a higher power than his masters moved onward into wider fields Wallis had ef f ec te d the quadrature of curves whose ordinates are expressed by any 2 — integral and positive power of ( 1 x ) We have seen how Wallis attemp ted but failed to interpolate between the areas thus calculat ed the areas of other curves such as that of the circle ; how Newton at tacked the proble m e ff ected the interpolation and discovered the B inom ial Theorem which aff orded a much easier and direct access to the quadrature of curves than did the m ethod of interpolation ; for even though the bino mial expression for the ordi n a te b e raised to a fractional or negativ e power the binomial could at once be expanded into a series and the quadrature of each separate term of that series could be e ffected by the m ethod of Wallis Newto n introduced the system of literal indices Newton s study of quadratures soon led hi m to another and most profound invention He himself says that in 1 6 6 5 and 1 6 6 6 he c on c eiv ed the m ethod of fl u xi o n s and applied the m to t he quadrature of curves Newton did not co mmunicate the in v ention to any of his friends till 1 6 6 9 when he placed i n the hands of Barro w a trac t e n titled De A n al ys i per E q u a ti on es N u mer o Termi n oru m I nfi n i tas which was sent by Barrow to John Collins who greatly ad mired it In this treatise the principle of fl uxion s though distinctly pointed out is on l y partially developed a ri d explained Supposing the abscissa to increase uniformly in proportion to the ti me he looked upon the area of a curve as a nascent quantity increasing by continued fl u xi on in the proportion of the length of the ordinate The expression which was obtained for the fl uxi on he expanded into a finite or infinite series of m ono mial term s to which Wallis rule was applicable Barrow urged Newton to publish this treatise ; but the m odesty of the author of which the excess if not culpable was certainly in the present i n 1 Had this tract stance very unfortunate prevented his compliance J h P l yf ai P rog ess Of t he M athemati cal and P hysi ca l S cien ces i n Eu . , . ” . . ’ ’ ’ , . , . ’ ’ , . , , . , . . ’ , . , . ' , . - . , ’ . , . , , ’ , , , , , . . ’ . . , , , . , , , . , . ’ . , . , o n a r, ” , , r pa di a B r i ta n ni ca , 7 th Edi tion . , A HISTORY OF M ATHE M ATICS 1 94 which ( time ) another space x b y I ncreasing with an uniform celerity x measures and exhibits as described : then 2 xx will represent the celerity by which the space y at the same mo ment of tim e proceeds to be described ; and con traryw i se “ B ut whereas we need not consider the time here any farther than it is expounded and m easured by an equable local motion ; and b e sides whereas only quantities of the sa m e kind can be compared to gether and also their velocities of Increase and decrease therefore in what follo w s I shall have no regard to ti me formally co n sidered but I Shall suppose so me one of the quantities proposed being of the same kin d to be increased by an equable fl u xi on to which the rest may be referred as it were to time ; and therefore by way of analogy it may not i mproperly receive the na me of tim e In this statem ent of Newto n there is contained his answer to the obj ection w hich has been raised against his m ethod that it introduces into analysis the foreign idea of m otion A quantity thus increasing by uniform fluxi on is what we now call an i ndepen dent variable Newton conti n ues : N ow those quantities which I consider as gradually and i n definitely increasing I S hall hereafter call fl u en ts or fl owi n g q u an ti ti es and S hall represent them by the final letters of the alphabet v x y and z; and the velocities by which every fluent is increase d by its generating m otion (which I may call fl u xi ons or simply velocities or celerities )I shall represent by the same letters pointed thus v x y z That is for the celerity of the quantity v I S hall put v and so for the celerities of the other quantities x y and z I shall put x y a n d z respectively I t m ust here be observ ed that Newton does not take the fl u xi on s the mselves infinitely sm all The “ m om ents of fl u x i on s a term introduced further on are infinitely s m all quantities These mom ents as defined and used in the M ethod of Fl u xi on s are substantially the d i fferentials of Leibniz D e M organ poi n ts out that no s m al l am ount of confusion has arisen fro m the use of the word fl u xi on an d the notatio n x by all the English writers previous to 1 70 4 excepting Newton and George Cheyne i n the sense 1 of an infinitely sm all increm ent S trange to say even in the C om mer ci u m epi s tol i cu m the words momen t and fl u xi on appear to be used as synon ymous Af ter show ing by examples how to solve the first problem Newto n proceeds to the demonstration of his solution The mom ents of flowi n g quantities ( that is their indefinitely small parts by the accession of which in infinitely sm all portions of time they are continually increased ) are as the velocities of their flowing or increas i ng “ Wherefore if the m oment of any one (a s x) be represented by the product of its celerity x into a n i nfinitely sm all quantity 0 (i e by , , , , . , , , , , , , , , , , , , . , . , . “ , , , , , , , , , , , , , . , , , ” , , , , , , . , . , , . , . , , , . , . , “ , , , , . , . D e M o rg a n , O n t he E a rl y H i s t o ry M agazi n e, N o v emb e r , 1 8 5 2 1 A . . of I n fin i t e sirn al s , . i n P hil osophi cal NEWTON )the moments of the others EULER To 1 95 will be represented by v0 yo 20 because v0 x0 yo and 230 are to each other as v x y and Now S ince the m o ments as x0 and yo are the indefinitely little accessions of the flo w ing quantities x a nd y by which those quantities are increased through the several indefinitely little intervals of tim e it follows that those quantities x and y after any in definitely small interval of tim e becom e x+ xo and y+y0 and therefore the equation which at all times indifferently expresses the relation of the flowing quantities will as well express the relation between x + x0 and y+ y0 as between x and y; so that x+ x0 and y+ y0 m ay be substituted in the sam e equation for those quantities instead of x and y Thus let 3— 2 3= — any equation x ax + axy y 0 be giv en and substitute x+ x0 for x and y+y 0 for y and there will arise x0 , v, , y, z, , , ' , , , , , , , , , , , , , , , , , . , , , , x 3 3 3 o + 3x x0 + 3xx0 xo + x 2 x axo xo + axy+ ayxo + ax0 y0 dx 2 2 ax 0 + a xyo —y3 —sy ro —syyoyo —y 0 “ Now by supposition x ax + axy y 0 which therefore being expunged and the rem aining term s being divid ed by 0 there will rem ai n 2 3 , , 3= , , , 2 3x x x+ ayx+ axy 3y y+3xxx0 3 3 — + x0 0 y0 0 = 0 2 2 ax xx0 + axy0 a 3yyyo . B ut whereas z ero is supposed to be infinitely little that it may r epr e sent the m o ments of quantities t he term s that are m ultiplied by it will be nothing in respect of the rest (ter mi n i i n com du cti pr o n i hi l o ; therefore I rej ect the m and there possu n t haberi cu m al i i s cal l al i ) remains , , , 3x x 2 x+ ayx+ axy 3y y 2 ax 2 0, as above in E xampl e I‘ Newton here uses i n fi n i t e simal s M uch greater t han g n the first problem were the difficulties en countered i n the sdII‘It i on of the second proble m involving as it does in verse operations which ha v e been taxing the skill of the best ana l ys t s since his tim e Newton gives first a S pecial solution to the second roble i which he resorts to a rule for which he has given no proof m n p I n the general solution of his second proble m Newton assu m ed homogeneity with respect to the fl u xi on s and then considered three when the equation contains two flu xi on s of quantities and ca ses : ( 1 ) but one of the fl uen t s ; ( 2 ) when the equation involves both the fl u en t s when the equation contains the flu as well as both the fl u xio n s ; (3 ) ents and the fluxion s of three or more quantities The first case is the . e , , , . . , . easiest since it requires s im ply the integration of dy d} f (x)to which , A HISTORY OF M ATHE M ATICS 1 96 k special solution is applicable The second case demanded nothing less than the general solution of a di ff erential equation of the first order Those who kn ow what e ff orts were afte rwards needed for the complete exploration of this field in analysis wil l not depre ciate Newton 5 work even though he resorted to solutions In form of in fin ite series Newton 5 thi rd case co mes now under the solution of partial differential equations He took the equation 2 x z+xy= 0 and succeeded In finding a particular integral of i t The rest of the treatise is devoted to the determination Of m axim a and m ini ma the radius of curvature of curves and o ther geom etrical applications of his fl uxion ary calcul us All this was done previous to the year 1 6 7 2 It must be observed that in the M ethod of Fl u xi on s (as well as in his De A n al ysi and all earli er papers) the m ethod e mployed by New ton is strictly i nfi n i tesirn al and i n substance like that of Leibniz Thus the original conception of the calculus in England as well as on the Continent was based on infi n i tesimal s The fundam ental principles of the fl uxion ary calculus w ere first given to the world in the P ri n ci pi a but i t s peculiar notation did not appear until publi shed in the second vol um e of Wall is A l gebr a in 1 6 93 The expositi on given in the A l gebr a was a contribution of Newton ; it rests on i n fi n i tesimal s In the first edition of the P ri nci pi a ( 1 6 8 7 ) the descrip tion of fluxi on s is l ikewise founded on i nfi ni t esimal s but in the second the foun d ation is som ewhat altered In B ook II Le mm a II ( 1 7 1 3) of the first e dition we read : Cave tam en i n tel l exeri s par ti cu l as hi s . . , ’ ’ . . . , , . . . , , , . , , ’ . . , . fi n i ta s . M omen ta q u am pri mu m fi n i tce , , magn i tu di n i s , desi n u n t a l i qu aten u s perpetu o eoru m sunt principia jamjam nas su n t momen ta Fi n i ri en i m repu gn at i n cr emen to vel decremen to I n t elli g en da centia fi n i taru m mag ni tud i n um In the es se . . second edition the two sentences whi ch we print in italics are replaced by the foll owing : “ P artic ul ar: fi ni tm non sunt mom enta sed q uantitates ip sas ex mo mentis g en i tw Through th e diffi culty of the phrases in bo th ex tracts this much distinctly appears that in the first m oments are infin i tely sm all quantities What else they are in the second is not 1 C lear In the Qu adr atu re of Cu rves of 1 70 4 the i nfinitely smal l quantity is completely abandoned I t has been shown that in the M ethod of Fl u xi on s Newton rej ected term s invol v ing the quantity 0 because they are i nfi nitely small compared with other terms This reasoning is unsatisfactory ; for as long as 0 is a quantity though ever so small this rej ection cannot be m ade w ithout aff ecting the result Newton seems to have felt this for in the Qu adr atu e of C u rves “ he remarked that in m athematics the m inutest errors are not to be neglected (errores quam m inimi in rebus ma th emat i cis non sunt contem nendi ) The early distinction between the syste m of Newton and Leibniz . ” . , , , . . , . , . , , . r , ” . 1 A De . M org an l oc , . ci t . , 1 85 2 . O F M ATHE M ATICS HISTORY A 1 98 apart by a sm al l angle fro m the tangent CH B ut when CK c o incides with CH and the lines CE E c cC reach their ultimate ratios then the points C and c accurately coincide and are one and the sam e Newton then adds that in mathematics the minutest errors are not to be neglected Thi s is plainly a re j ec ti on of the postulates of Leibniz The doctrine of infinitely small quantities is here renounced in a manner which would lead one to suppose that Newton had never held it himself Thus it appears that Newton s doctrine was diff erent in difl er en t periods Though in the above reasoning the Charyb dis of i nfi n i tesimal s is safely avoided the dangers of a Scyll a stare us in the face We are required to believe that a point m ay be consi dered a triangle or that a triangle can be inscribed in a point ; nay that three dissim ilar tri angles becom e S i milar and equal when they have reached their ulti m ate for m In one and the sa m e point In the introduction to the Qu adr atu re of Cu rves the fi uxi on of x is deter mined as follows In the sam e tim e that x by flowing becom es x+ 0 the power " x beco m es i e by the m ethod of infinite series 2 — n n 2 — — x +n o x + 0 x + etc . , , , , ” “ . . . . ’ . , , . , , , ” . . , . ” . n n , , 1 2 . 2 , and the increments 0 and no 1 n n + 2 are to one another as 1 " x ‘ 2- to ”+ ux ‘ 1 n 2 n 2 Let now the incre ments vanish and their last proportion will b e 1 to n x : hence the fl u x i on of the quantity x is to the fl u xi on of the — " quantity x as 1 : n ae “ The fl u xion of lines straight or curved in all cases whatev er as also the fl u xio n s of su pe rfi c i es angles and other quantiti es can be obtaine d in the sa m e m anner by the m ethod of prim e and ultimate ratios B ut to establ i sh in this way the analysis of infinite quantities an d to i n v est i gate pri m e and ultim ate ratios of finite quant i t i es nas ~ cent or ev anescent is i n har m ony with the geo m etry of the ancients ; a n d I ha v e en d eavored t o S how that in the m etho d of fl u x i on s it is not necessary to intro d uce into geo m etry infinitely sm al l quantities This mo d e of d ifferent i ating d oes not rem ove all the difficulties con n e c t e d with the subj ect When 0 beco m es nothing then we get the n ‘ , ” I I , , , , , , . , , ” , , , . , . r a tI O 0 n nx ‘ I , 0 t ch nee ds further e l u c I da t l o n . In dee d the , m ethod of Newton as delivered by hi m self is encu mbered with diffi culties , , NEWTON To EULER 9 and obj ections Later we S hall state B ishop B erkeley s obj ection to this reasoning Even among the ablest ad mirers of Newton there have been obstinate disputes respecting his explanation of hi s m ethod “ of prime and ultim ate ratios The so called me thod of limits is frequently attributed to New ton but the pure meth od of limits was never adopted by him as hi s method of constructing the calculus All he did was to establish in hi s P ri n ci pi a certain principles which are applicable to that me thod but which he used for a different purpose The first lemma of the first book has been m ade the foundation of the m ethod of limits “ Q uantities and the ratios of quantities which in any fini te tim e converge continually to equality and before the end of that tim e ap proach nearer the one to the other than by any given diff erence b e come u l tirn atel y equal In this as well as in the lemmas follow ing thi s there are obscurities and diffi culties Newton appears to teach that a variable quantity and its limit will ultimately coincide and be equal The full title of Newton s P r i n ci pi a is P hi l os ophi w N atu ral i s P r i n ci pi a M a themati ca I t was printed in 1 6 8 7 under the direction and at the expense of Edm und Halley A second edition was brought out in 1 7 1 3 with m any alterations and improvem ents and aecom It was sold out in a few pan i ed by a preface fro m Roger Cotes m onths but a pirated edition published in Am sterda m supplied the d e mand The third and last edition which appeared in England during Newton s lifetim e was published in 1 7 2 6 by Henry P e mberton The P r i n ci pi a consists of three books of which the first two constituting the great bulk of the work treat of the mathe matical principles of natural philosophy namely the laws and conditions of motions and forces In the third book is draw n up the constitution of the universe as deduced from the foregoin g principles The great principle under lying this m em orable work is that of universal gravitation The first book was completed on April 2 8 1 686 After the remarkably short period of three months the second book was finished The third book is the result of the next nine or ten m onths labors I t is only a sketc h of a m uch m ore extended elaboration of the subj ect which he had p lanned but which was never brought to com pletion The law of gravitation is enunciated in the first book Its discovery env elops the name of Newton in a halo of perpetual glory The cur rent version of the discovery is as follows : it was conj ectured by Robert Hooke ( 1 6 3 5 C Huygens E Halley C Wren I N ew ton and others that if J Kepler s third l aw was true ( its absolute accuracy was doubted at that tim e)then th e attraction betw een the earth and other m embers of the solar system varied i n vers ely as the square of the d istance B ut the proof of the truth or falsity of the guess was wanting In 1 6 6 6 Newton reasoned in substance that if r i represent the acceleration of gra ty on the surface of the earth v g ’ . ” . , . - , . , . , ” , , . , , . . ’ . , . , , . , . ’ . , , ' , , , . . . . , . , ’ . , . . . ‘ . , . , . . , ’ , , . , , . . , , , M ATHE M ATICS A HISTORY OF 200 be the earth s radius R the distance of the m oon fro m the earth T the tim e of lunar re v olution and a a degree at the equator then if the law is true ’ , , , , , , R 2_ T ' 71 4 _ _ 2 T or 2’ 1 80 a . The data at Newton s command gave R = 6 o 4r T= seconds but a only 6 0 instead of 6 9 1 English miles This w rong valu e of a rendered the calculated value of g smaller than its true value as known from actual m easure m ent It looked as though the l aw of inverse squares were not the true l aw and Newton laid the calculatio n aside In 1 6 84 he casually ascertai ned at a m eeting of the Royal Society that Jean P icard had m easured an arc of the m eridian and obtained a m ore accurate value for the earth s radius Taking the corrected value for a he found a figure for g which correspon ded to the known value Thus the law of inverse squares was verified In a scholiu m in the P ri n ci pi a Newton acknowle dged his indebted n ess to Huygens for the laws on centrifugal force e mployed in his calculation The perusal by the astrono m er Adam s of a great mass of u n pub l i shed letters and m anuscripts of Newton for m ing the P orts m outh collection (which re mained private property until 1 8 7 2 when its owner placed it i n the hands of the University of Cam bridge ) see m s to indicate that the d iffi culties encountered by Ne w to n i n the above calculation were of a diff erent nature According to Adam s Newto n s nu m erical veri fication was fairly complete in 1 6 6 6 but Newton had not been able to determ ine what the attraction of a spherical shell upon an ex ternal point would be His letters to E Halley S ho w that he did not suppose the earth to attract as though all its m ass were concentrated into a point at the centre He could not have asserted therefore that the assu m ed law of grav ity was verified by the figures though for long d istances he m ight have claim ed that it yielded close approxim ations When Halley vis i ted Ne w ton in 1 6 84 he requested Newton to deter mine what the orbit of a planet would be if the law of attraction were that of inverse squares Newton had solved a si m ilar problem for R Hooke i n 1 6 79 and replied at once that it was an ellipse Af ter Halley s visit Newton with P icard s n ew value for the earth s ra di us reviewed his early ca l culation a n d was able to S how that if the distances between the bodies i n the solar syste m were so great that the bo dies m ight be considered as points then their m otions were in accordance with the assu m ed law of gravi t a t io n In 1 6 8 5 he co mplete d his disco v ery by showing that a sphere whose density at any point depends only on the d istance from the centre attracts an external point as though its whole m ass were con c en t ra t e d at the centre Newton s unpublished m anuscripts in the P orts m outh collect io n show that he had worked out by m eans of fl uxi on s and fl u en t s hi s ’ . , , , . , . , . , ’ . , . . , . , ’ . , , . . . , , , . , . . , ’ ’ . , , ’ , , , . . ’ , , A HISTORY OF M ATHE M ATICS 20 2 by Albert Girard ta ke the explicit form as do also the general formul a d erived later by E Waring Newto n uses his formul ae for fix ing an upper lim it of real roots ; the su m of any even power of all the roots m ust exceed the same even power of any one of the roots He estab li shed also another lim it : A nu mber is an upper li m it if when sub stituted for x it gives to f (x) and to all its derivatives the sa me S ign In 1 74 8 Col in M aclauri n proved that an upper limit is obtained by adding unity to the absolute value of the large st negative c oefli ci en t of the equation Newton showed that in equations w ith real c o effi cients im aginary roots al w ays occur in pairs His inventive genius is grandly displaye d in his rule for determ ining the inferior li mit of the nu mber of im aginary roots and the superior limits for the number of positiv e and negative roots Though less expeditious than D es cartes Newton s rule always gives as close and generally closer limits to the number of positive and negative roots Newton did not prove his rul e Som e light was thrown upon it by George Campbell and Col in M aclaurin in the P hi l os ophi c al Tr an s acti on s of the years 1 7 2 8 and B ut no co mplete de m onstration was found for a century and a 1 72 9 half until at last Sylvester established a re markable general theorem which includes Newton s rule as a special case Not without interest is Newton s suggestion that the conchoid be adm itted as a curve to be used in geom etric constructions along with the straight line and circle since the conchoid can be used for the duplication of a cube and trisectio n of an angle—to one or the other of which every problem in v olving curves of the third or fourth degree can be reduced The treatise on M ethod of Fl u xi on s contains Newton s method of approxim ating to the roots of nu m erical equations Substantiall y the sam e explanation is given in his D e an al ysi per cequ ati on es nu mero ter mi n oru m i nfi n i tas He explains it by working one exa mple nam ely 1 3 the now fam ous cubic y 2y The earl i est printed account appeared in Wallis A l gebr a 1 6 8 5 chapter 94 Ne w ton assu mes that an approxim ate value is already known which d iffers from the true value by less than one tenth of that value He takes y= 2 and sub 3 2 = s t i tu t es y 2 + p in the equation which beco m es p + 6 p + 1 0 p Neglecting the higher powers of p he gets 1 op Taking he gets From he gets q = o o 54 + r and by the sa me process r = 0 0 0 0 4 8 53 F i nally y = 2 + 1 0 0 54 Newton arranges 5 147 his work in a paradigm He seem s quite aware that his m ethod m ay fail If there is d oubt he says whether p= 1 is sufficiently close to 2 the truth find p fro m 6p + r o p 1 = o He does not show that even th is latter m ethod will always ans w er By the sam e m ode of pro , . . . , , . , ‘ ‘ . , . , . ’ ’ , , , . . , , . , , , ’ . ’ , , . ’ . . , ’ , . , , - . , , . . . . . , , . . . , . , . , . ” Fo r q u ot a t io n s f ro m N ew t o n , see F C aj o r i , H i s t o ri ca l N o t e o n t he N e w t on R ap h so n M e t hod o f App roxi ma t io n , A mer M a th M on thl y, V o l 1 8 , 1 9 1 1 , pp 2 9 1 . . . . . NEWTON TO EULER 203 Newton finds by a rapidly converging series the value of y 3 3 3= — in terms of a and x i n the equation y + axy+ aay x 2 a o In 1 6 90 Joseph R aphs on ( 1 6 4 8 a fello w of the Royal Society of London p ublished a tract A n al ysi s wqu ati onu m u n i versal i s His m e thod closely resembles that of Newton The only diff erence is this that N ewton deriv es each successive step p q r of approach to the root fro m a n ew equation while R aph son finds it each time by substitution in the origi n al equation I n Newton s cubic R aphson 2 3 would not find the second correction by the use of x + 6 x + 1 0 x 1 = 0 but would substitute 2 1 + q in the original equation finding q He would then substitute 2 o g46 + r in the original equation 0 0 54 fin ding r R aph s on does not m ention 53 and so on Newton ; he evidently considered the difference suffi cient for his method to be classed independently To be e mphasiz ed is the fact that the process which in modern texts goes by the nam e of New ton s method of approxim ation is really not Newto n s m ethod but c e du re , , , . , , , . , . , , , , , , , ’ . , , . . , . , . . , ” ’ . ’ , , Raph so n ’ m odification s of it The f or m now so fa miliar . , f (a ) was (a ) a not used by Newton but was used by R aphso n To be sure Raphs on out i n full as poly does not use this notation ; he writes f (a ) and f (a ) It is d oubtful whether this m ethod S hould be nam ed after n omi al s Newton alone Though not identical with Vieta s process it re se mbles Vieta s The chief diff erence lies in the d ivisor used The divisor is m uch simpler and easier to compute than Vieta s divisor Raphs on s version of the process represents what J Lagrange recogniz e d as an advance on the schem e of Ne w ton The m ethod is “ “ 1 plus S imple que celle de Newton P erhaps the na m e Newton R aph s o n m ethod would be a designation m ore nearly representing the facts of history We m ay a dd that the solution of nu m erical equations was considered geom etrically by Thom as B aker in 1 6 84 “ and E dmund Halley in 1 6 8 7 but i n 1 6 94 Halley had a very great desire of doing the sam e in numbers The only difference betwe en Hall ey s and Newton s own m ethod is that Halley solves a quadratic equation at each step Newton a linear equation Halley m odified also certain al gebraic expressions yielding approxim ate cube and fif th roots give n i n 1 6 9 2 by the French man Thomas Fan tet de L agny I n 1 7 0 5 and 1 7 0 6 Lagny outlines a m ethod of di fferences ; ( 1 66 0 1 7 such a m ethod less syste matically developed had bee n previously if a b c explained i n England by John Collins B y this m ethod _ are in arith m etical progression then a root m ay b e foun d app roxi m ately from the first second and higher diff erences of f ( a) f (b) ' . , , ’ . , ’ . , ’ . . ’ , ’ . . ” ” . . . ” , . ’ ’ . , , , - , , . , , , , , f (a) , , ” , , Newton s M ethod of Fl u xi on s contai ns also gram wh i ch enable d hi m in an equation f (x , ’ , 1 L ag rang e , R es o l u ti on des , eq u al . nu m . , 1 , , Newto n s parallelo = 0 to find a ser i es y) 7 98 , N o t e ’ , V , p . 1 38 . A HISTORY OF M ATHE M ATICS 4 in powers of x equal to the variable y The great utility of this rul e lay in its determ ining the f or m of the series ; for as soon as the law was k n own by which the e xponents in the series v ary then the e xpansion could be effected by the m ethod of indeterm inate coefficients The rule is stil l used in determining the infinite branches to curves or their figure at m ultiple points Newton gave no proof for it nor any clue as to how he discovered it The proof was supplied half a century 1 later by A G K astner and G Cram er independently In 1 704 was published as an appendix to the O pti cks the E nu merati a l i nearu m terti i ordi n i s which contains theore ms on the theor y of curv es Newton divi d es cubics into seventy tw o S pecies arranged in larger groups for which his co mmentators have supplied the nam es “ “ genera and classes recogniz ing f o urteen of the form er and seven of the latter He overlooked six S pecies dem anded by his ( or four) principles of classification and after w ards added by J S tirling Wil liam M urdoch ( 1 7 54 and G Cram er He enunciates the r e “ m arka ble theorem that the five S pecies which he nam es divergent parabolas give by their p rojection every cubic curve whatever AS a rule the tract con tains no proofs I t has been the subj ect of frequent conjecture how Newton de d uced his results Recently we have gotten at the facts since m uch of the analysis used by Newton and a few additional theorems hav e been discov ered am ong the P ortsm outh papers An account of the four holograph m anuscripts on this sub jcet has been published by W W Rouse B all in the Tr a n s acti ons of the L ondon M a thema ti ca l S oci ety ( vol xx pp 1 0 4 It is inter esting to observe how Newton begins his research on the classification of cubic curves by the algebraic m ethod but finding it laborious attacks the p roblem geometrically and after w ards returns again t o analysis Space d oes not perm it us to do m ore than m erely mention Newton s prolonged researches in other departm ents of science He con ducted a long series of experim ents in optics and is the author of the corpus c u l ar theory of light The last of a nu mber of papers on optics which he contributed to the Royal Society 1 6 8 7 elaborates the theory “ of fits He explained the decomposition of light and the theory of the rainbow By him were invented the reflecting telescope and the sextant (afterwards r e invented by Thom as Godfrey of P hila 2 delphia and by John Hadley)He d educed a theoretical e xpression for the velocity of sound in air engaged in experi ments on chem istry elasticity m agnetism and the l aw of cooling and entered upon geo logical speculations D uring the two years following the close of 1 6 92 Newton su ff ered . , , . , . , . ' . , . . . , - , , , - . ” , , , . , . , . . . , . . , . . , . . . , , , , , . ’ . ” , . , , . . - . , , , , , . , 1 S G u n t h er , Vermi schte U n ters uchu ngen . 1 8 76 , 2 pp 1 36 - 1 87 p 42 . Ges chi chte d math . . F C aj or i , Teac hi n g . . . z ur a nd H i s tory of M a themati cs i n the U S . . Wi s s . , z L eip i g ’ Wa s h i n g ton , 1 8 90 , A HISTORY OF M ATHE M ATICS 206 went to London and re mained there fro m January till M arch He there becam e incidentally acquainted with the m athe matician John P ell to who m he explained a m ethod he ha d found on the su mm ation of series of nu mbers by their diff erences P el l told h im that a similar form ula had been published by Gabriel M outon ( 1 6 1 8—1 6 94)as early as 1 6 70 and then called his attention to N M ercator s work on the rectification of the parabola While in London Leibniz ex hi bi t ed to the Royal Society his arith m etical m achine which was S im ilar to B P ascal s but m ore e ffi cient and perfect After his re turn to P aris he had the leisure to study m athe m atics m ore syste m at i cal l y With in d o mitable energy he set about re m o ving his ig n o rance of higher m athe matics C Huygens was his principal master He studied the geo metric works of R D escartes H on orari us Fabri Gregory S t Vincent and B P ascal A careful st udy of infinite series led hi m to the discovery of the following expression for the ratio of the C ircu mference to the dia meter of the circle previously discovered by J ames Gregory : , . , . ’ , . . , . , ’ . , . , . . . . . . , . , , . , —+ . 77 1 = I z s I +s l l r s etc . This elegant series was found in the same way as N M ercator s on the hyperbola C Huygens was highly pleased with it and urged him on to new invest i gations In 1 6 73 Leibniz derived the seri es ’ . . . . a r e tan x = x —1 x 3 + 1x 3 from which m ost of the practical m etho ds of computing 7T have been obtained This series had been previously disco v ered by Ja mes Gregory and was used by A br aham S ha r p ( 1 6 5 1 —1 74 2 )under i n In 1 7 0 6 s t ru c t i o n s fro m E Halley for calculating i t to 7 2 places — John M achi n ( 1 6 80 1 7 professor of astronomy at Gresha m Col lege in London obtained 1 0 0 places by using a n expression that is obtained from the relation . , . . , — 4 4 are tan —arc tan 2 11 , by substituting Gregory s infinite series for ar e ta n 1 and a re tan 1 1g — m i i 2 M achin s for ula was used I n 1 8 74 by W l l am S han ks ( 1 8 1 1 88 2 ) for computing to 70 7 places Leibniz entered into a detailed study of the quadrature of curves and thereby became inti mately acquainted with the higher m ath Am ong the papers of Leibniz is still found a manuscript ema ti cs on quadratures written before he left P aris in 1 6 7 6 but which was never printed by him The m ore important parts of it were e mbodied in articles published later i n the A cta er u di tor u m In the study of Cartesian geometry the attention of Leibniz was ’ . ’ . . , , . . NEWTON TO EULER 20 7 drawn early to the direct a n d inverse proble ms of tangents The direct proble m had been sol v ed by D escartes for the si mplest curves only ; while the inverse had co mpletely transcended the power of his analysis Leibniz investigated both proble ms for any curve ; he — constructed what he called the tri an gu l u m char acteri s ti cu m an infinitely s mall triangle between the infinitely small part of the curve coinciding with the tangent and the diff erences of the ordinates and abscissas A curve is here considered to be a polygon The tri angu l u m char acter i sti cu m is si m ilar to the triangle for m ed by the tangent the ordinate of the point of contact and the sub tangent as well as to that between the ordinate norm al and sub norm al It was e mployed by I Barrow i n Englan d but Leibniz states that he obtained it from P ascal From it Leibniz observed the connection e xisting between the direct and inverse proble ms of tangents He saw also that the latter could be carried back to the quadrature of cu rves All these results are contained in a m anuscript of Leibniz written in 1 6 7 3 O n e mode used by h im i n e ffecting quadratures was as follows : The rectangle form ed by a sub normal p and an elem ent a (i e infinitely s mall part of the abscissa) is equal to the rectangle form ed by the ordinate y and the elem ent l of that ordinate ; or in symbols pa = yl _B ut the summation of these rectangles from z ero on gives a right triangle equal to half the square of the ordinate Thus usin g Cavalieri s no ta t i on he gets . . , . . , - , , - . . , , , . . . . , - . . . , ’ . , , o B ut a = o mn mn p . ’ y = om n o mn . . l; o . yl =y 2 1 2 ( omn m eaning omni a all ) . . , hence mn l o mn l . . This equation is especially interesting since it is here that Leibniz first introduces a n ew notation He says : I t will be useful to write , “ . for writes mn o th e . , as l for mn l , o . that is the , su m of the l ’ S ”he then ; equation thus : Fro m this he deduced th e S implest integrals such as , Since the sy mbol of su mm ation raises the d im ensions , cluded that the opposite calculus or that of diff erences , he con d, would A HISTORY OF M ATHE M ATICS 20 8 lower them Thus if . then l = ya , , ya d l The symbol d was at first placed by Leibniz In the denom inator because the lowering of the power of a term was brought about in ordinary calculation by division The m anuscript giving the abov e is dated October 2 9th This then was the m e morable day on which the notatio n — of the n ew calculus cam e to b e a notation which contributed enor mou sl y to the rapid gro w th and perfect develop m ent of the calculus Leibniz proceeded to apply his n ew calculus to the solution of certain proble ms then grouped together u n der the name of the In v erse P roble m s o f Tangents He found the cubical parabola to be the solution to the following : To find the c u rv e in which the sub norm al is reciprocally proportional to the ordinate The correctness of his solution was tested by him by applying to the result the m ethod of tangents of B aron R en e Fra n goi s de Sluse ( 1 6 2 2 1 6 8 5) and reason ing backwards to the original supposition In the solution of the , . , , , , . . ' . - . third problem he changes his notation from x d to the now usual nota tion dx I t is worthy of rem ark that i n these investigations Leibniz nowhere explains the S ignificance of dx and dy except at one place . , , a In m arg i nal note : Idem est dx x et d , id est differentia inter duas , proxim as Nor does he use the term difi er en ti al but al w ays differ en ce Not till ten years later in the A cta eru di tor u m did he give further explanations of these symbols What he aim ed at principally was to d eterm i ne the change an expression undergoes when the sym x . , . , , . or d is placed before it . It m ay be a consolation to students wrestling with the elem ents of the differential calculus to know that 2 it required Leibniz considerable thought and attentio n to determ ine whether dx dy is the sa m e as d (xy)and , dx dy j the sam e as df After . y considering these questions at the close of one of his manuscripts he conclude d that the expressions were not the sam e though he could not give the true value for each Ten days later i n a m anuscript xdy dated November 2 1 1 6 7 5 he found the equation ydx = dxy — giving an expression for d (xy)which he observed to be true for all curves He succeed ed also in eliminating dx fro m a diff erential equation so that it contained only dy and thereby led to the solution “ of the problem under consideration B ehold a most elegant way C J G h d t E td ck g d h h r n A l ysi s Hal l e 8 55 p 5 h 8 48 C J G h d t E td k g d r D ifl enzi l g d ch L ei b i z H al l , , , . , , , , . , , , . 1 . er . . . , n e un er o e e na . , 1 12 . , . ' 2 pp ar 2 5, er . 41 . ar , n ec un e er a rec nun ur n , e, 1 , A HISTORY OF M ATHE M ATICS 2 10 by Leibniz to Tschi rn hausen during a controversy which they had had on this subject Fearing that Ts chi rnh au sen might claim as his own an d publish the notation and rules of the differential calculus Leibniz d ecide d at last to m ake public the fruits of his inventions In 1 684 or nine years after the new calculus first dawned upon the m ind of Leibniz and nineteen years after Ne w to n first worked at fl uxi on s and three years before the publicatio n of Newton s P ri n ci pi a Leibniz published in the A cta eru di toru m his first paper on the differ He was unwilling to give to the world all his treasures en t i al calculus but chose those parts of his work which w ere most abstruse and least perspicuous This epoch m aking paper of only S ix pages bears the “ title : Nova me thodu s pro maxi mi s e t m inim is i t emq u e t an g en tib u s qu a nec frac tas nec irrationales quantitates moratur e t S ingulare pro illis calculi genus The rules of calculation ar e briefly stated without proof and the meaning of dx and dy is not m ade clear P rinter s errors increased the diffi culty of comprehending the subj ect It has been inferred fro m this that Leibniz him self had no definite Are dy and dx finite or infinitesi m al a n d settled ideas on this subj ect quantities ? At first they appear i n deed to have been taken as finite when he says : We now call any line selected at random dx then we designate the line which is to dx as y is to the sub tangent by dy which I S the d i fference of y Leibn iz then ascertains by his calculus in what way a ray of light passing through two di ff erently refracting m edia can trav el easiest fro m one point to another and then closes h i s article by giv ing his solution in a few words of F de B e au n e s proble m T w o years later ( 1 6 86 )Leibniz published in the A cta er u di tor u m a paper containing the rudi m ents of the integral calculus The quantities dx and dy are there treated as i n finitely s mall He S howed that by the use of his notation the properties of curves could be fully expressed by e q u a ti on s Thus the equation . , , , . , , ’ , , , , . , . , ” e , , . , . ’ . . , , , , - , , . , , , , ’ , . , . . . , . — / x zx x 2 y + characteri zes the cycloi d The great invention of Leibniz now m ade public by his articles in the A cta eru di toru m m a d e little impression upon the m ass of m athe m a t i c i an s In Germ any no one co mprehen ded the n ew calculus except Ts chi r nh a u s en who re mained indiff erent to it The author s statem ents were too S hort and succinct to make the calculus generally un derstood The first to take up the study of it were two fore i gners the Scotch m an J ohn C r a i g and the Swiss Ja k ob (Ja mes ) B ern ou l l i The latter wrote Leibniz a letter in 1 6 8 7 wi shing to be initiated into the m ysteries of the n ew analysis Leibniz was then travelling abroad so that this letter rem ained unanswered till 1 6 90 Jam es B ernoulli 1 . , , . ’ . , . , . , , . , . 1 C J G e rh a rd t , Gesc hi chte der M athemati k i n Deu tschl a nd , M u n ch e n , . p . I 59 . . 1 8 7 7, NEWTON TO EULER 21I succee ded meanwhile by close application in uncovering the secrets of the differential calculus without assistance He and his brother John prov ed to be mathem aticians of exceptional power They app l ied the mselves to the new science with a success and to an ex tent which Leibniz made Leibniz declare that it was as m uch theirs as his carried on an ex tensive correspondence with the m as well as with other mathem aticians In a letter to John B ernoulli he suggests a mong other things that the integral calculus be improved by reducing i n The integra t eg r al s back to certain funda m ental irreducible for m s tion of logarithm ic expressions was then studied The writings of Leibniz contain m any innovations and anticipations of since pro m nent methods Thus he m ade use of variable param eters laid the foundation of a n al ysi s i n s i tu introduced in a manuscript of 1 6 7 8 the notion of determ inants (previously used by the Japanese )in his e ffort to simplify the expression arising in the elim ination of the u n known quantities from a set of linear equations He resorted to the device of breaking up certain fractions into the s u m of other fractions for the purpose of easier integration ; he e xplicitly assu med the prin S ingular solution c i pl e of continuity ; he ga v e the first instance of a and laid the foun dation to the theory of envelopes in two papers one of which contains for the first time the term s co ordi nate and axes of co or di n ates He wrote on osculating curves but his paper contained the error (pointed out by John B ernoulli but not a dmitted by Leibniz ) that an osculating circle will necessarily cut a curv e in four consecutive points Well known is his theore m on the n th diff erential c oefli c i en t of the product of two functions of a variable Of his m any papers o n mechanics so m e are valuable while others contain grave errors Leibniz introduced I n 1 6 94 the use of the word f u n cti on but not i n the modern sense Later in that year Jakob B ernoulli used the word in the Leibniz ian sense In the appendix to a letter to Leibniz dated July 5 1 6 98 John B ernoulli uses the word in a m ore nearly m odern “ sense : earum [appl i ca taru m] q u aec u n q u e fu n c ti o n e s per alias appl i catas P Z e xpress es In 1 7 1 8 John B ernoulli arri v es at the definitio n of function as a quantity composed in any manner of a variable and any constants (O n appelle ici fonction d une grandeur variable une quantité co mpos ée de quelque maniere que c c soit de cette gran 1 deur variable e t de constantes ) Leib n iz m ade i mportant contributions to the notation of mathe Not only is our notation of the diff erential and integral ma t i c s calculus due to him but he used the S ign of equality i n writing pro portions thus a :b = c :d I n Leibni z ia n m anuscripts occurs for “ 2 Says similar and for equal and S im ilar or congruent , , , . . . , . , , . . , . , , , . ” , , - - . , , . . , . , , . . , , , . ” ’ , . . . ” , . ” z . S ee M C an to r , op c i t , V ol I I I , 2 Ed 1 90 1 , pp 2 1 5 , 2 1 6 , 4 5 6 , 4 5 7 ; E nc ycl o pedi c des sci ences ma thémati q u es , Tome I I , Vo l I , p p 3 5 2 S ee al so J Trop fk e , L ei bn i , Wer k e E d G erh ar d t , 3 F o l g e , B d V , p 1 5 3 op c i t , V ol I I , 1 90 3 , p 1 2 1 . . . . . . , ‘ z . . . . . . . — . . . . . . . M ATHE M ATICS A HISTORY OF 212 ” “ E B J ourdain Leibniz himself attributed all of his ma the ma ti cal discoveries to hi s i mprove ments in notation B efore tracing the further develop m ent of the calculus we shall S ketch the history of that long and bitter controversy be tw een English and Continental m athem aticians on the invention of the calculus The question was did Leibniz invent it independently of Newton or was he a plagiarist ? We must begin with the early correspondence betw een the parties appearing in this dispute Newton had begun using his notation of fl u xi on s in In 1 6 6 9 I B arrow sent John Collins Newton s tract De A n al ysi per equ ati on es etc The first visit of Leibniz to London e xtended fro m the r 1 th of Jan uary until M arch 1 6 7 3 He was in the habit of comm itting to writing i mportant scientific comm unications received from others I n 1 8 90 C J Gerhardt discovered in the royal library at Hanover a sheet of 3 m anuscript with notes taken by Leibniz during this journey They are headed O b serv a ta P hil osophi ca in itinere Anglicano sub i n i ti um anni 1 6 73 The shee t is divi ded by horiz ontal lines into sections The sections giv en to C hymi c a M ec han i c a M agnetica Botanica Anatomica M edica M iscellanea contain extens i ve m em oranda while those devoted to m athem atics have very few notes Under Geo m etrica he says only this : Tangentes o m niu m fi g u raru m F i g u rar um We sus g eom e t ri ca r u m exp li c a t i o per m o t u m p u n c ti in m oto lati p ec t fro m this that Leibni z had read Isaac B arrow s lectures Ne w ton is referre d to only under Optica Evidently Leibniz did not obtain a knowle dge of fl uxi on s during this visit to London nor is it claimed that he did by his opponents Various letters of I Newton J Collins and others up to the b e ginnin g of 1 6 7 6 state that Newton inv ented a method by which tan gents coul d be drawn without the necessity of freeing their equatio ns from irrational terms Leibniz announced in 1 6 74 to H Oldenburg then secretary of the Royal Society that he possessed very general analytical m ethods by which he had found theore m s of great im portance on the quadrature of the circle by m eans of series In answer Oldenburg stated Newton and James Gregory had also discovered metho ds of quadratures which e xtended to the circle Leibniz de sired to have these m ethods communicated to him ; and Newton at the request of Oldenburg and Collins wrote to the form er the cele b ra t ed letters of June 1 3 and October 2 4 1 6 7 6 The first contained the Binomial Theorem and a variety of other m atters relating to infi nite series and quadratures ; but nothing directly on the m ethod of P 1 . . . , . . , , . ’ . . , , . , . . . . . , , , , , , , , . . . ’ . . , . . . , , , , . . , , , , . . , , , , . P E B Jou rdai n , The N a tu r e of M athemati cs , L o n do n , p 7 1 2 J Edl e ston , Cor res ponden ce “of S i r I saac N ewt“on a nd P r of essor Cotes , L on don , and F l u xi on s C omm erc i um Ep i s toli c u m i n 1 8 50 , p xxi ; A D e M o rg an , t h e P en ny C ycl ope di a “ 3 L e i b n i i n L o n don i n S i t u ngs ber i chte der K P reuss i schen C J G e rh ard t , A cademi c d Wi ssensch zu B er l i n , Feb , 1 8 9 1 1 . . ” . . . . . . . . z . . . z . . . M ATHE M ATICS A HISTORY OF 2 14 ace to a volu me of his works that the calculus di ffe ren tial i s was N ew ton s m ethod of fi ux i o n s which had been com municated to Lei bniz in the Oldenburg letters A review of Wallis works in the A cta er u di tor u m for 1 6 96 re minded the reader of Newton s own ad m issio n in the scholiu m above cited For fifteen years Leibniz had enjoyed unchallenged the honor of being the inventor of his calculus B ut i n 1 6 99 Fati o de Du i l l t er — a Swiss who had settled in England stated i n a m athe 1 6 6 ( 4 17 mat i cal paper presented to the Royal Society his convictio n that 1 Newton was the first i n ventor ; addi n g that whether Leib n iz the second in v entor had borrowed anything fro m the other he would leave to the judg m ent of those who had see n the letters and manu scripts of Newton This was the first distinct insinuatio n of plagiar i sm It would see m that the English m athematicians had for some time been cherishing suspicions unfavorable to Leibniz A feeling had doubtless long prevailed that Leib niz during his second visit to Lon don in 1 6 7 6 had or m ight have see n a mong the papers of Joh n Collins Newton s A n al ysts per a qu ati on es etc which contained ap plications of the fi u xi ona ry m ethod but no syste matic develop ment or e xplanation of it Leibniz certainly did see at least part of this tract D uring the week spent in London he took note of whatever i n terested h im a m ong the letters and papers of Collins His m e mo randa disco v ered by C J Gerhardt i n 1 8 49 i n the Ha n over library 1 fill two sheets The one bearing on our question is headed E xcerpta de A n al ys i per aeq ua tion es nu mero ter ex t rac t a t u N e w t on i M s c minoru m i n fi n i t as The notes are very brief e xcepting those De r es ol u ti on e cequ a ti on u rn a ecta r u rn of which there is a n al most c o m fl This part was evidently n ew to him If he exa mi n ed p l e t e copy Newton s entire tract the other parts did not particularly i mpress him Fro m it he see m s to have gained nothi n g pertaining to the i n By the previous introductio n of his ow n a l fi n i t e s imal calculus ~b h m m i or t he had ade greater progress t h a n g y what ca me to his knowle dge i n London Nothing m athe matical that he had recei v ed engaged his thoughts i n the i mm ediate future for on his way back to Holland he co mposed a lengthy dialogue on m echanical subjects Fatio de D u i ll ie r s insinuations lighted up a fla me of discord which a whole century was hardly suffi cie n t to e xtinguish Leibniz who had never contested the priority of Newton s discovery and w ho appeared to be quite satisfied with Newton s adm ission in his scholiu m now appears for the first time i n the controversy He m ade an a n i mated reply i n the A cta eru di tor u m and co mplained to the Royal Society of the injustice done him Here the affair rested for so m e ti me In the Qu adr atu re of Cu rves published 1 7 04 for the first time a for mal expositio n of the m ethod a n d notation of fl u xi on s was m a d e public I n 1 7 0 5 appeared a n u m ” L i b iz i Lo d l c it C J G e ha d t ’ ’ . , ’ , . ' . , , , , . , , , , . . . , , ’ , , . , , . . , ’ . . . ” . . . , , . . ’ , . . . , . ’ , . ’ , ’ , . . , . , , . 1 . . r r “ , e n n n on , o . c . NEWTON EULER TO 215 favorab l e revie w of this i n the A cta erudi toru m stating that Newton uses and al w ays has used fl u xio n s for the di ff erences of Leibniz This was considered by Ne w ton s friends an i mputation of plagiaris m o n th e part of their chief but this interpretation was al w ays strenuously resisted by Leibniz J ohn K ei l l ( 1 6 7 1 professor of astrono my at Oxford undertook with m ore z eal tha n j udgment the defe n ce of Newton In a paper inserted in the P hi l os ophi cal Tr an sacti ons o f 1 7 0 8 he clai m ed that Ne w to n was the first inventor of fl ux i on s and “ that the sa m e calculus was afterw ard published by Leibniz the name and the m ode of notation being changed Leibniz complained to the secretary of the Royal Society of bad treat ment and requested the interference of that body to induce K e ill to disavow the i n tentio n of imputing frau d John K eil l was not m ade to retract his accusation ; o n the contrary was authoriz ed by Newton and the Royal Society to explain and d efen d his state ment This he did i n a long letter Leibniz thereupon complained that the charge was n ow more ope n tha n before and appealed for j ustice to the Royal Society and to Ne w ton himself The Royal Society thus appealed to as a j udge appointed a co mmittee which collected a nd reported upon a large mass of d ocu m ents —m ostly letters fro m and to Ne w ton Leib n iz Wallis Colli n s etc This report called the C ommerci u m epi s tol i cu m appeared i n the year 1 7 1 2 and agai n i n 1 7 2 2 and 1 7 2 5 with a Recensio prefixed and a ddi tional notes by K e ill The final co n clusion i n the “ C ommer ci u m epi s tol i cu m was that Ne w ton was the first inventor B ut this was not to the point The question w as not whether Ne w to n was the first inventor but whether Leibniz had stolen the m ethod The co mmittee had not form ally ventured to assert their belief that Leibniz was a plagiarist I n the follo w ing se n tence they insinuated that Leibn iz did take or m ight have taken his method fro m that of “ Newton : And we find no m ention of his (Leib n iz s ) havi n g any other Difi er en ti al M ethod than M ou ton s before his Letter of 2 1 s t of Ju n e 1 6 77 which was a year after a Copy of M r N ew ton s Letter of the r o t h of D ecember 1 6 7 2 had been sent to P a ri s to be co mm unicated to him ; and about four years after M r C ol l i n s began to co mmunicate that Letter to his Corresponde n ts ; i n which Letter the M ethod of Fl u xi on s was suffi ciently des c ri b d to any intelligent P erson About 1 8 50 it was show n that what H Olde n burg se n t to Leibniz was not Newton s letter o f D ec 1 0 1 6 7 2 but only excerpts fro m it which o mitted Newton s m ethod of drawi n g tangents a n d coul d not possibly convey an idea of fl u xi on s Oldenburg s letter was fou n d a mong the Leibniz ma n uscripts i n the Royal Library at Hano v er a n d was published by C J Gerhardt i n 1 846 1 848 1 849 and 1 8 5 and again later , . ’ , . , . , ” , , . . , . . , . , , , , , . , , , , , ” . . . . , . , ’ ’ , ’ , , . , , . ” ’ . . ’ . , , ’ ’ . , . . , , . S ee Essa ys on the Lif e an d Wor k of N ew ton b y A u g u s t u s D e M o rg a n , e di t ed , w i th n o t es an d a pp e n d i ces , b y P hil i p E B Jo u r d a i n , C hi c a g o a n d L o n do n , 1 9 1 4 Jo ur dain g i ves on p 1 0 2 t he b i b l io g rap hy o f t he p u b l i ca t i o n s o f N ew to n an d L e ib ni 1 . . . . z . A HI STORY OF M ATHE M ATI CS 2 16 M oreover published the C orrespondence it beca m e known that the of S i r I s aac N ew ton a n d P r of ess or C otes Royal Society in 1 7 1 2 had not one but two parcels of Collins One parcel contained letters of Ja m es Gregory and Isaac Newton s letter “ of D ec 1 0 1 6 7 2 in full ; the other parcel which was m arked To Leibnitz the 1 4 th of June 1 6 7 6 About M r Gregories remains contained an abridgm ent of a part of the contents of the first parcel with nothing but an allusion to Newton s method d escribed in his letter of D ec 1 0 1 6 7 2 In the C ommer ci u m epi stol i cu m Newton s letter was printed in full and no mention was m ade of the existence “ of the second parcel that was marked To Leibnitz Thus the C ommer ci u m epi s tol i cu m conveyed the i mpression that Newton s u m curtailed letter of D ec 1 0 1 6 7 2 had reached Leibniz in which fl uxi on s “ was suffi ciently described to any intelligent person while as a m atter of fact the method is not described at all in the letter which Le i bniz received Leibniz protested only i n private letters against the proceeding of the Royal Society declaring that he would not answer an argu m ent so weak J ohn B ernoulli in a letter to Leibniz which was published later in an anonym ous tract is as decide dly unfair towards Newton as the friends of the latter had bee n towar d s Leibniz John K eil l replied and then Newton and Leibniz appear as m utual accusers in se v eral letters addressed to third parties I n a letter dated April 9 1 716 and sent to Antonio S chi n el l a Conti ( 1 6 7 7 an Italian priest then residing in London Leibni z agai n rem inded Newton of the ad m ission he ha d m ade i n the scholium which he was n ow desirous of disav owing ; Leibniz also states that he al w ays believ ed Newton but that seeing h i m connive at accusations which he m ust have known to be false it was natural that he (Leibniz ) should begin to Newton did not reply to this letter but circulated som e r e d oubt marks am ong his friends which he publishe d i m m ediately after hearing of the death of Leibniz Nove mber 1 4 1 7 1 6 This paper of Newto n gives the following explanatio n pertaining to the scholiu m i n question : He [Leibniz ] pretends that in my book of principles I allowed hi m the in v ention of the calculus di ff eren t ial i s i n dependently of my own ; and that to attribute this inventio n to myself is co n trary to m y knowledge there av o w ed B ut in the paragraph there referred unto I do not find one word to this purpose I n the third e d ition of the P r i n ci pi a 1 7 2 6 Newto n o m itted the scholiu m and substituted in its place another in which the nam e of Leibniz does not appear National pr id e and party feeling long prevented the adopt i on of impartial opini ons in England but n ow it is generally ad m itted by , when J Edlesto n in . 1 8 50 , , , . ’ , . , , ” , , , , . , ’ ’ . , . . ’ , . ” , , . , . , , , . , , . , , , , , , . , . , , , ” . . , , . , , We B B i o t a n d F L e fo r t s e di ti on o f t h e C ommer ci u m epi s tol i c u m, P a r i s , 1 8 5 6 , w hi c h e xh i b i t s a l l the a l t e ra t io n s ma d e i n t h e d i ff e ren t rep r i n t s o f t hi s ’ p u b l i c a t io n an d r e p ro d u c es a l so H O l den b u rg s l e tt e r t o Le i bn i o f J u l y 2 6 , 1 6 7 6 , a n d o ther i mp or t an t d oc u me n t s b eari ng o n t h e c on t rov er sy re c o mm e n d J . ’ . . z . . A HI STORY OF M ATHE M ATIC S 2 18 attention It was again proposed in 1 7 1 6 by Leibniz to feel the pulse of the English mathem aticians This may be considered as the first defiance proble m professedly aimed at the English Newton solved it the same evening on which it was delivered to him although he was m uch fatigued by the day s work at the m int His solution as published was a general plan of an investigation rather than an actual solution and was on that account criticised by Johann B ernoulli as being of no value B rook Taylor undertook the defence of it but ended by using very r ep re h en si bl e language Johann B ernoulli was not to be outdone in i n civ ility and m ade a bitter reply Not long afterw ards Taylor sent an open defiance to Continental m athematicians of a proble m on the integration of a fl u xi on of co mplicated form which was known to very few geo meters in England and supposed to be beyond the power of their adversaries The selection was injudicious for J ohann B ernoulli had long before explained the m ethod of this and similar integrations I t serv ed only to display the skill and augm ent the triu mph of the followers of Leibniz The last and m ost unskil ful challenge was by John K eill The problem was to find the path of a projectile in a m ed iu m which resists proportional ly to the square of the velocity Without first m aking sure that he himself could sol v e it K eil l bol dly chall enged Johann B ernoulli to produce a solution The latter resol v ed the question in very short tim e not on l y for a resistance proportional to the square but to any power of the velocity Suspecting the weakness of the adversary he repeate dly off ered to send his solution to a confidential person in London provided K eil l would do the sam e K eill never m ade a reply and Johann Bernoulli 1 abused him and cruelly exulted ov er him The explanations of the funda m ental principles of the calculus as giv en by Newton and Leibniz lacked clearness and rigor For that reason it m e t with opposition from several quarters In 1 6 94 B ern hard N i eu w en tij t ( 1 6 54— 1 7 1 8) of Holland denied the existence of differentials of higher orders and objected to the practice of neglecting infinitely s mall quantities These obj ections Leibniz was not able to meet , . . . ’ , . , , , , , . , . . , . , . . . . , . , . , , , , . . , . , . . satisfactorily . In his reply he said the value of dr _ dx in geom etry could be expressed as the ratio of finite quantities In the interpretation 2 of dx and dy Leibni z vacillated At one ti m e they appear i n his wr i tings as finite lines ; then they are called infinitely s mall quantities a n d again q u an ti ta tes i n as s i gn a bi l es which spring fro m q u a n ti tates ass i gn a bi l es by the law of continuity In this last presentation Leibni z approached nearest to Newton . . , , , . ”i . John P l ayfai r , P rog re s s of th e M at hema ti cal an d P hy si c al S ci en ce s n En cycl opcedi a B r i tan n i ca , 7 t h Ed , co n t i n u ed i n t h e 8 th E d b y S i r John L e sli e ’ 2 C o n su l t G Vi v an ti , I l con cetto d I nfi n i tesi mo S aggi o s tor i co N uo va edi ion e N ap ol i , 1 90 1 1 “ . . . . . z . . ' NEWTON EULER TO 9 In England the principles of fl uxi on s were boldly attacked by — B r k l e y 1 the eminent metaphysician in i s h o eor e e e 68 B G ( g 5 17 p_ a publication called the A n al yst He argued with great acute ness contending among other things that the fun da mental idea of supposing a finite ratio to exist betw een terms absolutely evanescent “ the ghosts of departed quantities as he called the m—was absurd and unintelligible B erkeley claimed that the second a nd third fi uxi o n s were even m ore m ysterious than the first fl u xi on His c on tention that no geo m etrical quantity can be exhausted by division is “ in consonance with the claim m ade by Zeno in his dichoto my and the claim that the actual infinite cannot be realiz ed M ost m odern readers recogniz e these contentions as untenable B erkeley declared as axiom atic a lemm a involving the shifting of the hypothesis : If x receives an increm ent i where i is expressly supposed to be some quantity then the i n crement of x divided by i is found to be n x + " n (u x If n o w you take i = 0 the hypothesi s i s s hif ted i+ and there is a m anifest sophis m in retaining any result that was ob t ai n ed on the supposition that i is not z ero B erkeley s le mma fou n d no favor a mong English m athe maticians until 1 8 0 3 when Robert Woodhouse openly accepted it The fact that correct results are obtaine d in the di fferential calculus by incorrect reasoning is explained by Be rkeley o n the theory of a co mpensation of errors This theory was later ad v anced also by Lagrange and L N M Carnot The publication of B erkeley s A n al ys t was the m ost spectacular m athe ma t i cal event of the eighteenth century in England P ractically all B ritish discussions of fl uxi on al concepts of that tim e involve issues raised by B erkeley B erkeley s object i n writing the A n al ys t was to show that the principles of fl u xi o n s are no clearer than those of Chris “ t ia n i ty He referred to a n infi d el m I t h e ma t i c i an ( E d m und Halley ) 1 of whom the story is told that when he j es ted concerning theological “ questions he was repulsed by Newton with the re m ark I have studied these things ; you have not A friend of B erkeley when on a be d of sickness refused spiritual consolation because the great m athe m aticia n Halley had convinced h i m of the inconceivability of the doctrines of Christianity This induced B erkeley to write the , , , , ” , . . ” , . . ” , n , , " I , 2 ‘ , ’ . . ” . . . . . ’ . ’ . ” . , , ” , , . , , , . A n al yst . — ( 1 6 84 1 750 ) Replies to the A n al yst were published by Ja mes J of Tri nity College Cambridge under the pseudonym of P hi l al e thes C an tab rig ie n si s and by J ohn Wal ton of D ublin There followed several rejoi nders J u ri n s d efence of Newton s fl uxi on s did not meet the approval of the mathe matician B e n j ami n R o b i n s ( 1 70 7 and later in In a Journal called the Republ i c/e of L etter s (Londo n) the Wor k s of the L ea r n ed a long and acri monious controversy was carried on bet w ee n Juri n and Rob i n s an d later betw ee n Juri n and Henry P emberton ( 1 6 94 the editor of the third editio n of u ri n ” , . ’ ’ . , , , , 1 M ach M echa n i cs , 1 90 7 , — 8 pp 4 4 4 49 . . A H ISTO RY O F M AT H E M ATI C S 2 20 New ton s P ri n ci pi a The question at issue was the precise m eaning of certain passages in the writings of Ne w ton : D id Newton hold that “ there are variables which reach their lim i ts ? Jurin answered Yes ; “ Robins and P emberton answered No The debate betw een Jurin and Robins is important in the history of the theory of limits Though holding a narrow vie w of the concept of a lim it Robins deserves credit for rej ecting all infinitely s mall quantities and giving a logically quite coherent presentation of fi u xion s in a pamphlet called A D i scou rs e ’ . ” ” . . , c on cer ni n g the N atu r e an d C er tai n ty of S i r I s aac N ew ton s M ethods of ’ M acl au r i n s Fl u xi on s , 1 7 4 2 , m ark the top ’ This and notch of mathe m atical rigor reached during the eighteenth century in the exposition of the calculus B oth before and after the period of eight years 1 834—1 84 2 there existed during the eighteenth century in Great B ritain a m ixture of Continental and British conceptions of the new calculus a superposition of B ritish symbols and phraseology upon the older Continental concepts Newton s notation was poor and Le i bniz s ph i losophy of the calcul u s was poor The mix ture r epr e sented the temporary survival of the least fit of both syste ms The subsequent course of events was a superposition of the Leibniz ian notation and phraseology up o n the li mit concept as developed by Newton Jurin Robins M aclaurin D Al emb er t and later writers In France M i chel Rol l e for a ti m e rej ected the differential calculus and had a controversy with P V ar ig n on on the subj ect P erhaps the m ost powerful argu m ent in favor of the new calculus was the con sistency of the results to which it led Fam ous is D Al emh er t s advice “ to y oung students : Allez en avant e t la foi vous vien dra Am ong the m ost vigorous prom oters of the calculus on the Conti nent were the B ernoullis They and Euler m ade B asel i n Swi tz erland fa mous as the cra dle of great m athem atic i ans The fam ily of B er n ou l li s furnished in course of a century eight m e m bers who dist i n athem atics We subjoin the following g en ea g ui sh ed the m selves in m logical table N i col au s B ern ou l l i the Father Fl u xi on s , 1 73 5 . , . , , , ’ . ’ . . - ’ , , , . , . . ” ’ ’ . . , . . . , — 1 6 54 1 7 0 5 J ak ob J oh ann , N i col au s N i col au s , 1 6 8 7 Dan i el , —7 59 1 J ohan n , . 1 667 —1 748 1 726 N i col au s , 1 6 95— — l D ani e , 1 7 0 0 1 7 8 2 1 7 90 J ohan n , 1 7 1 0 — 1 — 8 4 4 7 1 J a k ob, 07 1 — 7 59 7 8 9 1 celebrated were the two brothers Jakob (Jam es) and Johann and Daniel the son of John Jakob a n d Johann were staunch (John ) friends of G W Leibni z and worked han d in han d wi th him J ak ob — m n g inter was born in B asel B eco i J B e r o l l i 1 1 0 m a e s n u 6 ) ( 54 7 5) ( M ost , , . . . . . A 222 HI STORY OF M ATHE M ATI C S theore m If where the letters are integers and t = r + s is expanded by the bino m ial theore m then by taking n large enough the ratio of u ( denoting the su m of the greatest term and the to the sum of the re n prece d ing terms and the n following ter ms ) maining term s m ay be m ade as great as we please Letting r and s be proportional to the probability of the happe n i n g and failing of an event in a single trial then i t corresponds to the probability that i n n t trials the nu mber of times the event happens will lie bet w een n (r 1 ) “ and n (r + both i n clusive B ernoulli s theorem will ensure hi m a 1 permanent place in the history of the theory of probability P ro m i ne n t conte mporary workers on probability were M ont mort in France and D e M oivre in England In D ece mber 1 9 1 3 the Acade my of “ Sciences of P etrograd c el eb ra t ed the bicentenary of the law of large nu mbers Jakob B ernoulli s A rs conj ectandi having been p ublished at Basel i n 1 7 1 3 Of his collected works in three volu mes one was printed in 1 7 1 3 the other t w o i n 1 744 — B r J oh an n ( Jo h n ) e n o u lli ( 1 66 7 1 748) was initiated into m athe m at ic s by his brother He after w ards visited France where he m e t Nicolas M alebranche Giovanni Dom enico Cassini P de _L ahi re P For ten years he occupied the V ar ig n on and G F de l H o spi ta l mathe matical chair at Groni n ge n and the n succeeded his brother at Basel He was one of the m ost e n thusiastic teachers and m ost suc c e ss fu l original investigators of his ti me He was a m e mber of al most every learned society i n Europe His co n troversies were al most as nu merous as his discoveries He was ardent in his frie n dships but unfair m ean and violent toward all who i n curred his dislike —eve n his own brother and son He had a bitter dispute with Jakob on the isoperi metrical proble m Jakob convicted him of several paralogis ms After his brother s death he atte mpted to substitute a disguised solu tio n of the form er for an incorrect one of his own Johann ad mired the merits of G W Leibniz and L Euler but was bli n d to those of I Newton He i mm ensely enriched the i n tegral calculus by his labors A mong his discoveries are the exponential calculus the line of s w iftest descent and its beautiful relation to the path described by a ray passing through strata of variab l e de n sity In 1 6 94 he e xplai n ed in a letter to l H ospi tal the method of evaluating the indeterminate ’ n ou ll i s , , . , ” ’ . . . ” , , / ’ , . , , . , . , , . , , . ’ . . , . . . . . , , , . . . ’ . , . . . , . . . , , . ’ 0 He treated trigonometry by the analytical m ethod , studied caustic curves and trajectories Several ti mes he was given priz es by the Academy of Science in P aris Of his sons N i c ol au s and D an i el were appointed professors of mathem atics at the sam e ti me i n the Acade my of S t P etersburg The former soon died in the prim e of life ; the latter returned to B asel i n 1 7 33 where he assu m ed the chair of experim e n tal philosophy His . . , . . . , 1 1 To dh u n ter , Hi story . f o Thear . f o P r ob , p 7 7 . . . NEWTON TO EULER 23 first mathe matical publication was the solution of a differential equa tion proposed by J F R i c ca t i He wrote a work on hydrodynamics He was the first to use a suitable notation for inverse trigono metric functions ; in 1 7 2 9 he used AS to represent arcsine ; L Euler in 1 7 3 6 1 used At for arctangent Daniel B ernoulli s investigations on prob ability are re markable for their boldness and originality He pro posed the theory of moral expectati on which he tho ught would give results more i n accordance with our ordinary notio n s than the theory of mathemati cal pr obabi l i ty He applies his m oral expec tation to the P etersburg proble m : A throws a coi n i n the air ; if head s o called appears at the first thro w he is to receive a shilling fro m B if head d oes not appear until the second thro w he is to receive 2 shillings if head does not appear until the third throw he is to receive 4 S hillings and so on : required the expectation of A B y the mathe matical theory A s expectation is infinite a paradoxical result A given sum of m oney not being o f equal i mportance to every m an account should be taken of r el ati ve values Suppose A starts with a s um a then the moral expectation i n the P etersburg proble m is finite according to D aniel B ernoulli when a is finite ; it is 2 when a = o about 3 when The P etersburg problem was discussed a = 1 0 about 6 whe n a = by P S Laplace S D P oisson and G Cram er D aniel B er n oulli s m oral expectation has beco m e classic but no one ever m akes use of it He applies the theory of probability to insurance ; to determine the m or tality caused by s m all pox at various stages of life ; to deter m ine the nu mber o i survivors at a given age fro m a give n nu mber of births ; to determ ine how m uch inoculation lengthens the average duration of life He S howed h o w the di fferential calculus could be used in the theory of probability He and L Euler enjoyed the ho n or of hav ing gained or shared no less tha n ten pri zes fro m the Acade my of Sciences in P aris Once while travelling with a learned stranger “ who asked his nam e he said I am D aniel Bernoulli The stra n ger could not believe that his co mpanio n actually was that great celebrity “ and replied I am Isaac Newton J oh ann B e rn o u l l i ( born 1 7 1 0 ) succeeded his father i n the professor ship of m athe matics at Basel He captured three priz es (o n the cap stan the propagatio n of light and the m agnet) fro m the Acade my o f Sciences at P aris N i c ol au s B e rn o u ll i (bor n 1 68 7) held for a ti me the mathe matical chair at P adua which Galileo had once filled He p ro v ed . . . . . . ’ . . , ” . “ - , , , . ’ , . , , . , , , , , ’ . . . , . . . , . - . . . . ” , , , . ” , . . , , . . —= — 2 2 1 74 2 In that 5 A 3 A Joh ann B e r n ou l l i (born 1 7 44 )at the age btau Su at of nineteen was appointed astronom er royal at B erlin and after wards d irector of the m athe matical d epart m ent of the Aca d e m y H is brother Ja kob took upon him self the duties of the chair of e xp e r i , . G En e s t rom i n B i bl i otheca ma thema ti ca , V ol 6 , pp 3 1 9— 3 2 1 ; Vo l 2 I To dhu n ter , Hi s t of the Theor of P r ob , p 2 20 1 . . . . . . . . . . 1 4, p . 78 . A HISTORY OF M ATHE M ATIC S 24 physics at B asel previously perform ed by his uncle J akob and later was appointed m athem atical professor in the Academy at St P etersburg Brief m ention will n ow be m ade of some other ma thematicians belonging to the period of Newton Leibniz and the elder B ernoullis a pupil of G u illa u m e F ran coi s An toi n e l H O S pi tal ( 1 6 6 1 Johan n B ernoulli has already been m entioned as taking part i n the challenges issued by Leibniz and the B ernoullis He helped pow er fully i n m aking the calculus of Leibniz better known to the m ass of m athematicians by the publication of a treatise thereon the A n al ys e This contai n s the m ethod of find ing des i nfi n i men t peti ts P aris 1 6 96 the li miting value of a fraction whose two terms tend to w ard z ero at the sam e ti me due to Johann B ernoulli Another z ealous French ad v ocate of the calculus was P i e rr e Var ig n on ( 1 6 54 I n M em de P a ri s Ann ée M D CCIV P aris 1 7 2 2 he follows Ja B ernoulli in the use o f polar co ordinates p and w Letting x = p and y = l w the equations thus changed represent wholly di fferent m“ m = curv es For instance the parabolas x a y beco me Fermatia n Jo s e ph S a u ri n ( 1 6 59—1 73 7 ) solved the delicate proble m of S pirals how to determine the tangents at the m ultiple poi n ts of algebraic I n 1 7 1 7 issued an ele m entary cur v es \ Fr an cms N1col e ( 1 6 83 1 758 ) treatise o n finite differences i n which he finds the su m s of a consider able nu m ber of interesting series He wrote also on roulettes par ti c u Also interested i n l a rl y S pherical epicycloids and their rectification finite differences was P i err e Raym o n d d e M o n tmo rt ( 1 6 7 8 His chief writings on the theory of probability ; served to stim ulate his more distinguished successor D e M oivre M ontmort gav e the first general solution of the P roble m of P oints J e an P a u l d e G u a — gave the de monstration of Descartes rule of signs n ow 1 1 ( 7 3 1 7 8 5) gi v en i n books This skilful geo m eter wrote in 1 7 40 a work o n analyt ical geo m etry the obj ect of which was to S ho w that most investiga t ions on curves could be carried on with the analysis of D escartes quite as easily as with the calculus He shows how to fi n d the tangents asymptotes and various singular points of curves of all degrees and proves by perspective that several of these points can be at infinity M ich e l Roll e ( 1 6 5 2 — is the author of a theore m nam ed after h im 1 7 1 9) That theore m is not found in his Tr ai tad al gébre of 1 6 90 but occurs in his M ethode pou r r és ou dre l es egali tez P aris The na m e “ — of Rolle s theorem was first used by M W D rob i sch ( 1 8 0 2 1 8 96 ) Leipzig in 1 834 and by Giusto B el l av i ti s in 1 846 His A l gebre contains his m ethod of cascades In an equation in 7)which he has trans form ed so that its signs becom e alternately plus and minus he puts v= x+ z and arranges the result according to the descending powers when equated to z ero are of x The coeffi cients of x x m ental , , . . , , . ’ , . , . , , . , . , , , , - . , . , , . . - . . , . , . , , . , ; ’ , . , . , , , . . ’ , ” ’ , , ” “ . . ‘ . . ” n , . S ee F C aj o ri o n t he hi s t o ry 3 r d S , V o l I I , 1 9 1 1 , pp 3 0 0 3 1 3 1 — . . . . o . , ‘ l , f Roll e , ’ s Theorem i n B i bl i otheca ma themati ca , A HI STORY OF M ATHE M ATIC S 2 26 correct T sc hi rn hau s en concluded that in the researches relating to the properties of curves the calculus might as well be dispensed with After the death of Leibniz there was in Germany not a S ingle mathe mat i c ian of note Ch ri s ti an Wolf ( 1 6 7 9— 17 professor at Halle was a mbitious to figure as successor of Leibniz but he forced the ingenious ideas of Leibniz into a pedantic scholasticism and had the unenviable reputation of having presented th e elements of the arith metic algebra and analysis developed since the time of the Renais sance in the form of Euclid — of course only in outward for m for into the S pirit of the m he was quite unable to penetrate ( H Hankel ) The conte mporaries and im mediate successors of Newton in Great Britain were men of no mean merit We have reference to R Cotes B Taylor L M aclaurin and A de M oivre We are told that at the “ death of R o g er C ot e s ( 1 6 8 2 Newton exclaimed If Cotes had lived we m ight have k n ow n some thi ng I t was at the request of Dr B entley that R Cotes undertook the publication of the se gond edition of Ne w ton s P r i n ci pi a His m athem atical papers were pub li shed after his death by Robert S m ith his successor in the P l u mbia n professorship at Trinity College The title of the work H a rmoni a M en su rar u m was suggested by the following theore m contained in it : If on each radius vector through a fi xed point 0 there be taken a point R such that the reciprocal of OR be the arith metic m ean of the reciprocals of OR ] OR then the locus of R will be a straight line In this work progress was m ade in the application of logarithm s and the properties of the circle to the calculus of fl u en ts To Cotes we owe a theore m in trigono metry which depends on the form ing of — factors of x I In the P hi l os ophi cal Transa cti on s of London pub li sh e d 1 7 1 4 he develops an i mportant form ula reprinted I n his H ar mon i a M en su r aru m which I n m odern notation is i gb = log s i n cp Usually this form ula IS attributed to L Euler Cotes studied “ 2 = z the curve p 0 a to which he gave the nam e lituus Chief among the ad mirers of Newton were B Taylor and C M aclaurin The quar rel between English and Continental m athematicians caused them to work quite independently of their great contemporaries across the Channel B roo k T aylo r ( 1 68 5— was interested in m any branches of 1 73 1 ) learning and in the latter part of his life engaged m ainly in religious and philosophic S peculations His principal work M ethodu s i n cre — men toru m di r ecta cl i n ver sa London 1 7 1 5 1 7 1 7 added a new branch to mathem atics now called finite diff erences of which he was the inventor He m ade many i mportant applications of it particularly to the study of the form of m ovem ent of vibrating strings the r edu c tion of which to mechanical principles w as first attempted by h i m “ This work contains also Taylor s theore m and as a S pecial case of it what is now called M ac l au ri n s Theorem Taylor di scovered his theorem at least three years before its appearance in print He , . . , ' , , , , ” , , . . . . , . , , . ” , . , . , . . . ’ . , . , , , , , , . . n , . , , , . . . . , . . . . , . ” , , , , , , , . , ” ’ , , ’ , . . . NEWTON EULER TO 7 gave it in a letter to John M achin dated July 2 6 1 7 1 2 I ts i mportance was not recognize d by analysts for o v er fifty years until J Lagrange poin ted out its power His proof of it does not consider the question of conv ergency and is quite worthless The first more rigorous proof was given a century later by A L Cauchy Taylor gave a singular solution of a di fferential equation and the m ethod of finding that solution by di fferentiation of the di ff erential equation Taylor s work contains the first correct explanation of astronom ical refraction He wrote also a work on linear perspective a treatise which like his other writings su ff ers for want of fulness and clearness of expression At th e age of twenty three he gave a rem arkable solution of the prob l em of the centre of oscillation published in 1 7 1 4 His claim to priority was unj ustly disputed by Johann B ernoulli In the P hi l o “ s ophi cal Tr an s acti on s Vol 3 0 1 7 1 7 Taylor applies Taylor s series to the solution of num erical equations He assu m es that a rough = 0 has been found approxi mation a to a root of f (x) Let and x = a + s He expands by his theorem discards all powers of s above the second substitutes the values of k k k and then solves for s By a repetition of this process close approximations are secured He m akes the importa nt observation that his method solves also equations involving radicals and transcendental functions The first appl i cation of the Newton Raph so n process to the solution of transcendental equations was made by Thom as Si mp son in his Ess ays on M a thema ti ck s London 1 740 The earliest to suggest the m ethod of recu rri ng seri es for finding roots was D ani el B ern ou l l i ( 1 70 0 — who in 1 7 2 8 brought the 1 78 2) quartic to the form then selected arbitrarily four numbers A B C D and a fifth E thus also a six th by the sa me recursion formula F = aE + bD + cC + eB and so on If the last two nu mbers thus found are M and N then x = M + N is an appro xi mate root D aniel B ernoulli giv es no proof but is aware that there is not always convergence to the root This m ethod was perfected by Leo n hard Euler in his I n tr odu cti o i n an al ysi n i nfi ni toru m 1 748 Vol I Chap 1 7 and by Joseph Lagrange in Note VI of hi s Res ol u ti on des equ ati ons n u méri qu es Brook Taylor in 1 7 1 7 expressed a root of a quadratic equation in the form of an infinite series ; for the cubic Fran goi s Nicole did sim i l arl y in 1 7 38 and Clairaut in 1 7 46 A C Clairaut i n serted the process i n his El emen ts d al gébre Thom as Simpson determ ine d roots by r e version of series in 1 743 and by infinite series in 1 74 5 M arquis d e Courtivro n ( 1 7 1 5— also expressed the roots in the for m of i n 1 7 8 5) 1 finite series while L Euler devoted several articles to this topic At this time the matter of convergence of the series did not receiv e . , , . , . . , . . . ’ . . , , . , - . , ” . ’ . , , , . , ” , ’ , . , , . , . , , . . . , . , , , , , , , , . , , . . , . , , . , . . . . ’ . . . , 1 p . Fo r 212 . r efe ren ces see . F C aj or i , i n C ol or ado C ol l eg e P u bl i cati on , G en e r al S e ri es 5 1 , . A HI STORY OF M ATHE M ATIC S 2 28 proper att en tion except in som e rare instances James Gregory of Edinburgh i n his Ver a ci r cu l i cl hyperbol ce qu adr atu r a first used the terms conv ergent and d iv ergent series while Wil l ia m B ro u n c k er gav e an argu m ent which a m ounted to a proof of the con vergence of his series noted above C oli n M a c l au ri n ( 1 6 98 — 1 746 ) was elected professor of mathematics at Aberdeen at the age of nineteen by competitiv e exam ination and in 1 7 2 5 succeeded Jam es Gregory at th e Univ ersity of Edinburgh He enj oyed the frien dship of Newton and i nspired by Newton s disco v eries he published in 1 7 1 9 his Geometr i a Organi ca containing a new and re m arkable m ode of generating co n ics know n by his nam e “ and referring to the fact wh i ch becam e know n later as Cram er s th paradox that a curve of the n order is not always determ ined by points that the number may be less A second tract De Li n ea r u m g eometr i c a r u m pr opr i eta ti bu s 1 7 2 0 is re m arkable for the elegance of its d em onstrations I t is based upon two theorem s : the first is the theorem of Cotes ; the second is M acl au ri n s : If through any point 0 a line be drawn m eeting the curve in n points and at these points tangents be drawn and if any other line through 0 cut the curve in R 1 R 2 etc and the system of n tangents in r l r g etc , . ” , ” “ , . , , , . ’ , , , , , ” , ’ , . , , , , . ’ , , , then , . , , . , This and Cotes theorem are generaliz ations of ’ 2 theorem s of Newton M aclaurin uses these in his treatm ent of curves of the second and third degree culm inating in the remarkable theorem that if a quadrangle has its v ertices and the two points of intersection of its opposite sides upon a curv e of the third degree then the tangents He de d rawn at two opposite vertices cut each other on the curve So m e du c e d in d epen d ently B P ascal s theore m on the hexagra m of his geom etrical results were reached independently by Wi l l i am B r ai k en r i dge ( about 1 7 0 0 — after a clergym an in Edinburgh The follow ing is known as the B ra ik en ri dg e M aclaurin theorem : If the sides of a polygon are restricted to pass through fixed points while all the vertices but one lie on fixed straight lines the free vertex M ac l au ri n s m ore general d escribes a conic section or a straight line state ment (P hi l Tr an s 1 73 5) is thus :If a polygon m ov e so that each of its sides passes through a fixed point and if all its summ its excep t one describe curv es of the degrees m n p etc respectively then the free summ it m oves on a curve of the d egree 2 mnp which reduces to mn p when the fixed points all lie on a straight line M ac “ laurin was the first to write on pe dal curves a nam e due to Olry T e rq u em ( 1 7 8 2 M aclauri n is the author of an A l gebra The object of his treatise on Fl u xi on s was to found the doctrine of fl u xion s on geom etric d emonstrations after the m anner of the ancients and thus by r i gorous exposition answer such attacks as B erkeley s that The Fl u xi on s contained for th e doctrine rested on false reasoning . , , . ’ . . ” . “ - , ’ . . . , , , , , . , ” , . , . , ’ , , . HI STORY A 2 30 O F M ATHE M ATIC S to the hyperbola His work on the theory of probability surpasses anything done by any other ma them atician except P S Laplace His principal contributions are his i nvestigations respecting the D uration of P lay his Theory of Recurring Series and his e xtension of the value of Daniel B ernoulli s theorem by the aid of S tirling s 1 theorem His chief works are the D octri n e of Chances 1 7 1 6 the M i s cel l an ea A n al yti ca 1 7 30 and his papers in the P hi l os ophi cal Tr an sacti on s Unfortunately he did not publish the proofs of his results in the doctrine of chances and J Lagrange more than fif ty years later found a good exercise for his skill in supplying th e proofs A generaliz ation of a problem first stated by C Huygens has re “ c ei v ed the nam e of D e M o ivr e s P roble m : Given n dice each having f faces d eterm ine the chances of throwing any give n num ber of points It was solved by A de M oivre P R de M ontm ort P S Laplace and others D e M oivre also generaliz ed the P roblem on the D uration of P lay so that it reads as follows :Suppose A has m counters and B has n counters ; let their chances of winning in a single gam e be as a to b; the loser in each gam e is to give a counter to his adversary : required the probability that when or bef ore a certai n nu mber of games has been pl ayed one of the players W ill have won all the counters of his ad v ersary D e M o iv re s solution of this problem constitutes his m ost substantial achieve m ent in the theory of chances He e mployed in his researches the m ethod of ordinary finite differences or as he called it the m ethod of recurrent series A fam ous theory involving the notion of inverse probability was ad vanced by Thomas B ayes I t was published in the London P hi l o s ophi ca l Tr a n s acti on s Vols 53 and 54 for the years 1 7 6 3 and 1 76 4 after the death of B ayes wh i ch occurred i n 1 7 6 1 These researches originated the discussion of the probab i lities of causes as inferred from observed e ffects a subject developed m ore fully by P S Laplace Using m odern symbols Bayes fund am ental theore m may be sta ted 2 thus : If an event has happened p tim es and failed q ti m es the probability that its chance at a si n gle trial lies bet w een a and b is . . . , . , ’ ’ . , , , , . , . . . ’ , , . . . , . , . . . , , , ’ . . , , . . , . , . , . , . . ’ , , x? — q x 1 ( ) ( 1 — )d x ? ” x . A m em oir of John M ichell On the probable P arallax and M ag ni tude of the fixed Stars in the London P hi l os ophi cal Tr an sacti on s Vol 5 7 I for the year 1 76 7 contains the fa mous argu m ent for the existence of design drawn from the fact of the closeness of certain stars like the P leiad es We m ay take the six brightest of the P leia d es and supposing the whole num ber of those stars which are equal in splendor to the faintest of these to be about 1 50 0 we shall , , , , . . , , , , , I To dhu n t er , A H i s tor y of the M athemati cal Theor y a n d L on don , 1 86 5 , pp 1 3 5 1 93 2 I To d hu n te r , op ci t , p 2 9 5 1 — . . . . . . . . , f o P roba bili ty, C amb ri dg e E ULER LAGRANGE AND LAP LACE 31 , find the odds to be near to 1 that no s ix stars out of that nu mber scattered at rando m in the whole heavens would be w ithin so small a distance from each other as the P leiades are , , , , ” , , . and Eu l er , L agr an ge, L apl a ce the rapid development of mathema tics during the eighteenth century the leading part was taken not by the universities but by the academies P articul arly prominent were the academies at B erlin This fact is the more singular because at that time an d P etrograd Germany and Russia did not produce great m a t hematicians The academ ies received t heir adornment mainly from the Swiss and French I t was after the French Revolution that s chools gained their ascendancy over academ ies D uring the period from 1 7 30 to 1 8 20 S w itz erland had her L Euler ; France her J Lagrange P S Laplace A M Legendre and G M onge The m ediocrity of French m athem atics which marked the tim e of Louis XIV was now foll owed by one of the very brightest periods of all history England on the other hand which during the u np ro d u c t i v e period in France had her Newton could n ow boas t of no great m athem atician E xcept young Gauss Germ any had no great na m e France now waved the m athematical sceptre M athematical studies am ong the English and German people had su n k to the lowest ebb Am ong them the d irection of original research was ill chosen The form er adh ered with e xcessive partiality to ancient geo m etrical m ethods ; the latter produced the co mbinatorial school which brought forth nothing of great value The labors of L Euler J Lagrange and P S Laplace lay in higher analysi s a n d this they developed to a wonderful degree By them analysis cam e to be completely sev ere d fro m geo m etry D uri ng the preced i ng period the effort of m athe m aticia n s not only in England but to som e extent eve n on the continent had been directe d to w ard the solution of problem s clothed in geom etric garb and the results of calc ul ation were usually reduced to geom etric form A change now took place Euler brought about an em ancipation of the analytical calculus from geo m etry and established it as an i n depen dent science Lagrange and Laplace scrupulously adhered to this separati on B ui l d ing on the broad foundation laid for higher analysis a n d m e Euler with m atchless fertility of c h an i c s b y Newton and Leibni z m ind erected an elaborate structure There are few great ideas pur sued by succee ding analysts which were not suggeste d by L Euler or of which he d id not share the honor of invention With perhaps less exuberance of inventi on but with m ore co mprehensive genius and profoun der reasoning J Lagrange d evelope d the i n finitesim al calculus and put analyt i cal m echan i cs into the for m i n which we now know i t P S Lapla ce appl i e d the calculus a n d m echan i cs to the elaboration In , , . , . . . . . , . , . . , . , . , . . . , , . , . . . . , . . , . . , . . , . , , , , , . . . . ' , , . , . . , , , , , . . . . A HI STORY OF M ATH E M ATIC S 232 of the theory of universal gra vita tion and thus largely extending and supplem enting the labors of Newton gave a full analytical discussion of the solar system H e also wrote an epoch marking work on P rob abil ity Am ong the analytical branches created during this period are the calculus of Variations by Euler and Lagrange Spherical Har m on i cs by Legendre and Laplace and Elliptic Integrals by Legendre Comparing the growth of analysis at thi s time wi th the growth d uri ng the time of K F Gauss A L Cauchy and recent m a the ma ti c i an s we observe an i mportant diff erence D uri ng th e form er period we witness m ainly a develop ment with reference to form P lac ing al m ost implicit confidence in results of calculation ma themati c i an s did not always pause to discover rigorous proofs an d were thus led to general propositions so me of which have since been found to be true in only special cases The Combinatorial School In Germany carried this tendency to the greatest extreme they worshipped form alis m and paid no attention to the actual contents of form ulae B ut in recent tim es there has been added to the dex terity in the formal treatm ent of problems a much needed rigor of demonstration A good example of this increased rigor is seen in the present use of i n finite series as compared to that of Euler and of Lagrange in his earlier works The ostracism of geo m etry brought about by the m aster m inds of this period could not last perm anently Indeed a n ew geom etric school sprang into existence in France before the close of this period J Lagrange would not perm it a single diagram to appear in his M eca n i qu e an al yti qu e but thirteen years before his death G M onge published his epoch m aking Géometri e descri pti ve L e o nh ar d Eul e r ( 1 7 0 7—1 783 ) was born in B asel His father a m inister gave him his first instruction in m athem atics and then sent hi m to the University of B asel where he becam e a favorite pupil of Johann B ernoulli In his nineteenth year he composed a dissertatio n on the m asting of ships which received the second priz e from th e French Acade m y of Sciences When Johann B ernoulli s two sons Daniel and Nicolau s went to Russia they induced Catharine I in 1 7 2 7 to invite their friend L Euler to S t P etersburg where D aniel in 1 733 was assigned to the chair of mathem atics I n 1 7 3 5 the solving of an astronom ical problem proposed by the Academy for which several e minent m athem aticians had dem anded som e m onths time was achieved in three days by Euler with aid of improved m e thods of his own B ut the eff ort threw h im into a fever and deprived him of the use of his right eye With still superior m ethods this sam e problem 1 The despotism of was solved later by K F Gauss in one hour ! Anne I caused the gentle Euler to S hrink from public a ff airs and to d evote all his t im e to science After his call to B erlin by Frederick the , , , - . . , , . , . . . , . , , . . , , , . , . - . , , . - , , , . . . , , . ’ . , . , , . , ’ . , . , , , , , , , . . . , , ’ , . . . . . 1 W . S ar t ori u s Wal ter sh au sen , Gauss , zu m Gedachtn i ss , Leip z ig , 1 8 56 . A HISTORY OF M ATHE M ATICS 234 but also the B eta and Gamma Functions and other original investi M ethodu s i n ven i endi l i n eas t i a on s ; g maxi mi mi n i mi ve pr opri etate am ount of m athem atical genius cu rvas which displaying an S eldo m rivall ed contained his researches on the calculus of v ariations to th e invention of which Euler was led by the study of th e researches of Johann and Jakob B ernoulli One of the earliest problem s bearing on this subj ect was Newton s solid of revolution of least resistance reduced by him in 1 6 8 6 to a diff erential equation (P ri n ci pi a Bk II Sec VII P rop XXXIV Scholiu m )Johann B ernoulli s problem of the brachistochrone sol v ed by h im in 1 6 97 and by his brother Jakob in the same year stim ulated Euler The study of isoperim etrical curves the brachistochrone in a resisting m ediu m and the theory of geodesics previously treated by the elder B ernoullis and others led to the creation of this new branch of m athem atics th e Calculus of Variations His method was essentially geom etrical which m akes the solution of the simpler proble m s very clear Euler s Theori a gauden tes , 1 744 , , , . ’ , , . , . , ’ . , . , . , , , . , , , , . , ’ . motu u m pl an eta ru m et Theor i a motu u m l u n ae, metar u m, Theor i a motu s l u n ar, 1 74 4 , co 1 7 53 , are his chief works on astronom y ; S es et de 1 772 , l ettr es a u n e pr i n cesse d A l l emagn e su r qu el qu es suj ets de P hysi q u e P hi l os ophi e, 1 7 7 0 , was a work which enj oyed great popularity We proceed to mention the principal innov at i ons and inv entions “ of Euler In his I n tr odu cti o ( 1 74 8 every analytical expression in x , i e every expression m ade up of powers , logarith m s , trigono m etric ’ . ” ) . ” functions etc is called a function of Som etim es Euler used ” another d efin ti on of function namely the relation between and expresse d in the —plane by any curve drawn freehand libero ” m anus duetu In m odified form these two rival definitions are . . “ . , x , i , x x . y , “ y , 1 . , traceable in all later history Thus Lagrange proceeded on the i dea in v olved in the first definition Fourier on the idea involved in the second Euler treated trigonometry as a branch of analysis and consistently treated trigonom etric values as ratios The term trigonom etric function was introduced in 1 7 7 0 by Georg S i mon K l u gel ( 1 73 9—1 8 1 2 ) 2 of Halle the author of a m athematical dictionary Euler d eveloped and system atiz ed the m ode of writing trigonom etric form ulas taking for instance the S inus to tu s equal to 1 He simplified form ulas by the S imple expedient of designating the angles of a triangle by A B C and the opposite S ides by a b c respectively Only once before have we encountered this S imple device I t was used in a pamphlet pre pared by Ri Rawl i n s on at Oxford so m etim e between 1 6 5 5 and This notat i on was re i ntroduce d sim u l taneously with Euler by Thomas Simpson in England We m ay add here that in 1 734 Euler use d the “ notation f (x) to indicate function of x that the use of e as the F Kl e i El m t m th m tik v hoh S t ndp k te a s I L eip z ig 9 8 p 43 8 . , . ” “ . . , , , . , , , , , , , . . . - . , 1 n, . 2 M C an t o r . 3 en ar e , p o . . e a . . un a V o l I V , 1 90 8 , p 4 1 3 N a tu r e, V ol 94 , 1 9 1 5 , p 6 4 2 ci t S ee F C aj ori i n a . , . . . . . . u . , , , 1 0 , . . E UL ER LAGRANGE AND LAP LACE 235 , symbol for the natural base of logarith m s was introduced by him in that in 1 7 50 he used S to denote the half su m of the sides of a “ triangle that i n 1 7 55 he introduced 2 to signify su mmation that in 1 7 7 7 he used i for a notation used later by K F Gauss We pause to rem ark that in Euler s ti m e Th o ma s S i mps o n ( 1 7 1 0 an able and self taught English m athem atician for m any years professor at the Royal M ilitary Acade m y at Woolwich and author of several text books was active in perfecting trigonom etry as a science His Tri gon ometry London 1 748 contains elegant proofs of two b) : B) fo rm ulas for plane triangles (a + b) c = cos %(A :s i n § C and (a —B ) c = s i n %(A : cos %C which have been ascribed to the Ger m an as who develope d them t ron om er K arl B r and an M al tw ei de ( 1 7 7 4 m uch later The first formula was given in di fferent notation by I Newton in his Un i versal A ri thmeti qu e; both form ulas are given by Fr i edr i ch Wi l hel m O ppel in E ul er laid down the rules for the transform ation of c o— ordinates in space gave a m etho dic analytic treatment of plane cur v es and of surfaces of the second order He was the first to discuss the equation of the second degree in three variables and to class ify the surfaces represented by it By criteria analogous to those used in the classi fi ca ti o n of conics he obtained five species He de v ised a m ethod of sol v ing biquadratic equations by assu ming x = x/ i with the hope that it would lead him to a general solution of algebraic equations The m ethod of elim ination by sol v ing a series of linear equations ( invented independently by E B éz ou t) and the m etho d of elim ination by sym m etric functions are due to him Far reaching are Euler s researches on logarithm s Euler d efined logarithm s as 3 exponents thus abandoning the old view of logarith m s as term s of an arith m etic series in one to one correspondence with ter m s of a geom etric series This union between the exponential and logar i th mic concepts had taken place so mewhat earlier The possibility of de fining logarith m s as e xponents had been recogniz ed by John Wallis in 1 6 8 5 by Johann B ernoulli in 1 6 94 but not till 1 74 2 do we find a syste matic exposition of logarith ms based on this idea I t is giv en in the introduction to Gardi ner s Ta bl es of L oga r i thms London 1 7 4 2 “ This introd uction is collected wholly fro m the papers of W i lliam Jones Euler s influence caused the ready adoption of the new defi n i tion That this view of logarithms was in every way a step in advance has been doubted by som e writers Certain it is that it i nvol v es i n ternal diffi culties of a serious nature Euler threw a stream of light upon th e subtle subject of the logarithm s of negativ e and im aginary numbers In 1 7 1 2 and 1 7 1 3 this subj ect had been discussed in a ” - , , . . . ’ - , , - . , , , , , , . . , . , . . , . . . , ’ . , - - . . ‘ , . , ’ , ” , . ’ . . . . . —9 4 G En est rom , B i bl i otheca ma thema ti ca , V ol 1 4 , 1 9 1 3 2 A v B rau n m ii hl , op ci t , 2 Teil , 1 9 0 3 , p 93 ; H mathema ti ca , 3 S , V ol 1 4 , pp 3 4 8 , 34 9 3 10 2 S ee L E ul er , I n tr odu cti o, 1 7 4 8 , C h ap V I , 1 . . . . . . . . . . . . . . . . . p 81 Wi el e i t n e r i n B i bl i otheca 1 . 1 , . . O F M ATHE M ATIC S H I STO RY A 2 36 correspondence between G W Leibniz and Johann B ernoul li L eib n iz m aintained that since a positive logari th m corresponds to a nu mber larger than unity and a negative logarith m to a positive number less than unity the logarith m of 1 was not really true but i magin ary ; hence the ratio havi ng no logari thm is itself imaginary M oreover if there really existed a logarith m of then hal f of it 1 — would be the logarithm of 1 a conclusion which he considered absurd The statements of Leibniz involve a double use of th e term imaginary :( 1 ) in the sense of non — existent ( 2 ) in the sense of a number of the typ e x/ T I Johann B ernoulli m aintained that 1 has a logarithm Since dx : x = dx : —x there results by integration — = = lo l log (x) og x) the logarith m ic curve ; y g x has therefore two branches symm etrical to the y= axis as has the hyperbola The corre spo n d en c e between Leibniz and Johann B ernoulli was first published in 1 74 5 In 1 7 1 4 Roger Cotes developed in the P hi l os ophi cal Tran s acti on s a n i mportant theore m which was republished in his H a r mon i a men su r aru m In m odern notation it is i ¢ = log (cos ¢ + t si n (b) In the exponential form it was discovered again by Euler i n 1 748 Cotes was aware of the periodicity of the t rig o n om e t ri c functions Had he applied this idea to his formula he m ight have anticipated Euler by m any years in show ing that the logarithm of a number has an infinite nu mber of d ifferent values A second discussion of the logarithm s of negative numbers took place in a correspondence b e tween young Euler and his revered teacher Johann B ernoulli in th e x) years 1 7 2 7 B ernoulli argued as before that log x = l og — Euler uncovered the diflfic ul ti es and inconsistencies of his own and Bernoulli s views without at that tim e being able to a dv ance a satisfactory theory He showed that Johann B ernoul li s expression 1 . . . , , , . , , , , . , - . . , , . , . . . . , . , , , . , ’ , , , ’ . 4 v i ? Be which is in compatible with B ernoulli s claim that log tween 1 7 3 1 and 1 74 7 Euler m ade steady progress i n the m astery of relat i ons involving im aginaries In a letter of Oct 1 8 1 740 to / \ = = Johann B ernoulli he stated that y 2 cos x and y e e ’ . . x , I , - , 2 were both integrals of the d iff erential dy =0 + y 2 equation 22 and were equal to each other Euler knew the corresponding expression for B oth expressions are given by hi m in th e M i scel l an ea B er ol i n en si n x He gave the s i a 1 7 4 3 and aga i n in his I n tr odu cti o 1 7 4 8 Vol I 1 0 4 value 1 7 V 57 6 3 as early as 1 7 4 6 in a letter to Chris tian Goldbach ( 1 6 90 but makes no reference here to the i n . . , , , , , . . 1 , “ H istory l t the Expo n en t i a an d L og ari hmi c C on cep t s , — o t l 2 1 1 t o n hl V 0 i ca n M a h M , y, 9 3 , p p 39 4 2 2 S ee F C aj o r i i n A m M a th M onthl y, V ol 2 0 , 1 9 1 3 , pp 44 4 6 1 S ee F C aj o ri . , . . . . of . . . . . — . A mer A HI STORY OF M ATHE M ATIC S 2 38 G W Leibniz nor J akob and J ohann B ernoulli had entertained any serious doubt of the correctness of the expression 1+ — o r Gu i d G a ndi ( 1 6 7 1 1 74 2 ) of P isa went so far as to conclude from this that In the treatment of series Leibniz ad v an c ed a m etaphysical m ethod of proof which held sway over the 1 minds of the elder B ernoullis and e v en of Euler The tendency of that reasoning was to j ust ify results which seem highly absurd to followers O f Abel and Cauchy The looseness of treatm ent can best be seen from examples The v ery paper in which Euler cautions against divergent series contains the proof that . . , . . . 1 1 as follows 0 n +n 2 + — I f . n it l “ —7 hese added gi e ero has no hesitation to write 1 0 an d no one objected to such results excepting N i c ol a u s B ernoulli the nephew of Johann an d Jakob Strange to say Euler finally succee d e d in converting N i c ol au s B ernoulli to his own erroneous views At the present tim e it is diffi cult to believe that Euler S hould — have confi dently written si n qS—z S i n S in 3 2 2 4 sin but such examples aff ord str iking illustrations of the want of 0 scientific basis of certain parts of analysis at that ti m e Euler s proof of the bino mial form ula for negative and fractional exponents which was widely reproduced in elem entary text books of the nineteenth century is faulty A re m arkable developm ent due to Euler is what he nam ed the hypergeo m etric series the su mm ation of which he observed to be depen dent upon the integration of a linear diff erential equation of the second order but it rem aine d for K F Gauss to point out that for special values of its letters this series represented nearly all functions then known Euler gave in 1 7 7 9 a series for arc tan x di fferent from the series of Jam es Gregory which he applied to the form ula 7r = 2 0 arc tan 1+ 3 8 arc tan 7 9 used for computing The series was published in 1 7 98 Euler reached re markable results on the summ ation of the reciprocal powers of the natural nu mbers In 1 73 6 he had found the s u m of the 2 reciprocal squares to be 7r /6 and of the reciprocal fourth powers to In an article of 1 743 which until recently has been gen be 2 Euler finds the su ms of the reciprocal e v en powers er al l y ov erlooked of the natural numbers u p to and inclu di ng the 2 6 th power Later he S howed the connection of coeffi cients occurring in these sum s with B ernoullian num bers due to Jakob B ernoulli th e Eul er d eveloped the calculus of finite differences in the first chapters t v z . Eu l er , , . , . , ’ . , - , . , , , . , . , . , , . . , ‘ , . ” . R R e i ff , Geschi chte der U n end l i chen Rei hen , T u b i n g en , 1 8 8 9 , p 6 8 — 2 l o l i n t t S 8 1 0 t e c k e B i bl i o t h ca m a h e m a i ca V P S a , 9 7 8 , pp 3 7 60 , 3 , 1 . . . . . . . — . . EUL ER LAGRANGE AN D , LA P LACE 2 39 of his I nsti tu ti on es cal cu l i difieren ti al i s and then deduced the differen tial calculus from it He established a theorem on hom ogeneous func tions known by his name and contributed largely to the theory of diff erential equations a subject which had received the attention of I Newton G W Leibniz and the B ernoullis but was still unde v el oped A C Clairaut Alexis Fontaine des B ertins ( 1 70 5 a n d L Euler about the sam e ti me observed criteria of integrability but Euler in addition showed how to e mploy the m to determ ine i n t eg ra t i n g factors The principles on which the criteria rested involve d som e degree of obscurity Euler was the first to make a systematic study of S ingular solutio n s of differential equatio n s of the first order I n 1 7 3 6 1 7 56 and 1 7 6 8 he considered the two paradoxes which had puzzled A C Clairaut : The first that a solution may be reached by differentiation instead of integration ; the second that a singular solution is not contained in the general solution Euler tried to es t abl i sh an a pr i ori rule for determ ining whether a solution is containe d in the general solution or not Stim ulated by researches of Count de Fagnano on elliptic integrals Euler established the celebrated addition theorem for these integrals He i n vented a new algorith m for continued fractions which he employed in the solution of the indeterm inate equation ax+ by= c We n ow kno w that sub tantially the sa m e solution of this equation was given 1 0 0 0 ye ars e arlier by the H indus Euler gave 6 2 pairs of a m icable nu mbers of which 3 pairs were previously know n : one pair had been di s covered by the 1 P ythagoreans another by F e rmat and a third by D escartes By giving the factors of the nu mber when n = 5 he pointed out that this expression di d not always represent prim es as was supposed “ by P F e rma t He first supplied the proof to Ferm at s theore m and to a second theorem of F erma t which states that every pri me of the form 4n + 1 is expressible as the s u m of two squares i n one and “ only one way A third theorem Ferm at s last th eorem that x +y = z has no integral solution for values of n greater than 2 was prov ed by Euler to be correct when n = 4 and n = 3 Euler di s cov ere d four theorem s which taken together m ake out the great law of qua dratic reciprocity a l aw independently discovered by A M 2 Legen dre In 1 73 7 Euler showed that the s u m of the reciprocals of all prim e nu mbers is log (l og thereby initiating a line of research on the distribution of prim es which is usually not carried back further tha n 3 to A M Legen dre In 1 74 1 he wrote on partitions of nu mbers pa r ti ti o n u me roru m In 1 7 8 2 he published a discussion of the problem of 3 6 o ffi cers of s ix d ifferent grades and fro m six different regi ments who are to be placed , . , , , . . , . . . , , . , . , . . . , . . , , . . , - . , s . , . , . , , , ’ . . , , ” ’ . n n , , n , , . . , . . c . . e oo . , S ee B i bl i otheca mathemati ca , 3 S V ol 9 p 2 6 3 ; V ol 1 4 pp 3 5 1 — 3 54 2 L eip ig , O sw al d B a u m g a r t U eber das Q u ad r ati sche Rcc i pr oci tats g es etz 3 G En e s tr Om in B i bl i otheca mathema ti ca , 3 S , V o l 1 3 , 1 9 1 2 , p 8 1 1 . . , . . , . , . z ' , . . . . . . . . 1 885 . A HI STORY OF M ATHE M ATIC S 2 40 in a square in such a way that in each row and colu m n there are six offi cers all of diff erent gra des as well as of diff erent regi ments Euler thinks that no solution i s ob ta inable when the order of the square is of the form 2 m od 4 Arthur Cayley in 1 890 reviewed what had been written ; P A M ac M ahon solved it in 1 9 1 5 I t is called the problem “ of the Latin squares because Euler in his notation used n lettres latines Euler enunciated and proved a well known theorem giving the relation between the nu mber of vertices faces and edges of cer tain pol yhedra which however was known to R D escartes The powers of Euler were directed also towards the fascinating subj ect of the theory of probability in whi ch he solved som e diffi cult proble ms Of no little i mportance are Euler s labors in analytical m echanics “ Says Whewell : The person who did mos t t o give to analysis the generality and symmetry which are now its pride was also the person 1 He worke d out who made m echanics analytical ; I m ean Euler the theory of the rotation of a body around a fixed point established the general equations of m otion of a free body and the general equation of hydrodynam ics He solved an imm ense num ber and variety of m echanical problem s which arose in his m ind on all occasions Thus “ on reading Virgil s l i nes The anchor drops the rushing keel is staid he could not help inquiring what would be th e ship s m otion in such a case About the sam e tim e as D aniel B ernoulli he published the P r i n ci pl e of the Con s erva ti on of A r eas and defended the principle of least action advanced by P M aup er tiu s He wrote also on tides and on sound Astronomy owes to Euler the m ethod of the variation of arbitrary constants By it he attacked the problem of perturbations explain i n g in case of two planets the secular variations of eccentric i ties nodes etc He w as one of the first to take up with success the theory of the m oon s m otion by giv ing approxi mate solutions to the proble m of three bodies He laid a sound basis for the calculation of tables of the m oon These researches on the m oon s m otion which captured two prizes were carried on while he was blind with the assistance of his sons and two of his pupils His M echani ca s i ve motu s sci enti a Vol I 1 73 6 Vol II 1 74 2 is in the language of a n a l yti ce expos i ta “ Lagrange the first great work in which analysis is applied to the science of m ovem ent P rophetic was his study of the m ovements of the earth s pole He showed that if the axis around which the earth rotates is not coincident w ith the axis of figure the axis of rotation will re v ol v e about the axis of figure in a pre d ictable period On the assu mption that the earth is perfectly rigid he showed that the period is 30 5 days The earth is now known to be elastic From observ ations taken in 1 884—5 . , . . . ” . “ . , , , - , . , , , , , . . , . ’ . ‘ ” , . , , . ” . , , ’ , , , ’ . ” “ . , . . . , , , , ” . , ’ . ’ , . , , . , , . , . , , , , . ’ . , . . , . 1 W Whew ell . 1 8 58 , p 363 . . , H i story f o the I ndu cti ve S ci en ces , 3 rd E d . , Vo l . I , N ew York , A HI STORY OF M ATHE M ATIC S 2 42 m ission to the Academy of Sciences In 1 754 he was m ade per manent secretary of the French Acade my D uring the last years of his life he was m ainly occupied with the great French encyclop aedia which was begun by D enis D iderot and himself D Al emb er t declined i n 1 7 6 2 an invitation of Catharine II to undertake the e d ucation of her son Frederick the Great pressed him to go to B erlin He m ade a visit but declined a perm anent residence there In 1 743 appeared his Tr ai té de dyn ami qu e founded upon the important general principle bearing his nam e :The impressed forces are equivalent to the eff ective forces D A l emb er t s principle seem s to have been recogniz ed before h i m by A Fontaine and I n som e m easur e by Johann B ernoulli and I Newton D Al emb er t gave it a clear m ath ematical for m and made num erous applications of it I t enabled the la w s of m otion an d the reasonings depending on them to be represen t ed in the m ost general form in analytical language D Al emb er t applie d it in 1 744 in a treatise on the equilibrium and m otion of fluids in 1 746 to a treatise on the general causes of winds which obtained a priz e from the B erlin Academy In both these treatises as also I n one of 1 7 4 7 d iscussing the fa m ous proble m of vibrating Chords he was led to partial differ He was a leader a mong the pioneers in the study of en ti al equat i ons . . , ’ . , , . . . , , ’ ’ . , . ’ . . . f ’ . , , , , , . , . 2 2 such equations To the equation . of vibrating chords he gave as 7 2 33 1 $ 2 2, aris ing in the problem general solution —at) the , 1 , , and showed that there is only one arbitrary function if y be supposed to vanish for x = 0 an d x = l Daniel B er n oulli starting with a par t i c u l ar i n tegral g i ven by B rook Taylor showed that this differential equation is satisfied by the trigonom etric series , . , , = a S In y — cos 7r x - l . — sin +B 7rt - l 2 7r x . l c os 2 7r t and claimed this expression to be the m ost general solution Thus “ Daniel B ernoulli was the first to introduce F ou ri e r s series into physics He claim ed that his solution being compoun d ed of an i n finite nu mber of tones and overtones of all poss i ble intensities was a general solution of the proble m Euler den i ed its generality on the groun d that if true the doubtful conclusion would follo w that the above series represents any arb i trary functio n of a variable These doubts were dispelled by J Fourier J Lagrange proceeded to find the su m of the above ser i es but D A l emb er t obj ected to his 1 process on the ground that it involved div ergent series A m ost beautiful result reached by D Al emb e rt with a i d of his principle was the co mplete solution of the problem of the precess i on of the equinoxes which had baffled the talents of the best m i nds . ’ , . , , . , , . . . . ’ , . , ’ , , . , 1 R R e i ff , . p o . ci t . , I I A b sc hn i tt . . EULER LAGRANGE AND LAP LACE 2 43 , He sent to the F rench Academ y in 1 7 4 7 on the sa me day with A C Clairaut a solution of the proble m of three bodies This had become a question of universal interest to m athe maticians i n which each v ied to outdo all others The proble m of two bodies requiring the d eter m ination of their m otion when they attract each other with forces in v ersely proportional to the square of the distance betwee n “ them had been co mp l etely sol v ed by I Newton The proble m of three bodies asks for the motion of three bodies attracting each other according to the law of gra v itation Thus far the co mplete solution of this has transcen d ed the power of analysis The general di fferential equations of m otion were stated by P S Laplace but ” the difficulty arises i n their integration The solutions giv en at that ti me are m erely convenient m ethods of approxi mation in special cases when one body is the sun disturbing the m otion of the moon around the earth or where a planet m oves under the influence of the sun and another planet The m ost important eighteenth century researches on the proble m of three bo dies are due to J Lagrange In 1 7 7 2 a priz e was awarded hi m by the P aris Acade m y for his E ssa i su r l e pr obl eme des tr oi s cor ps He shows that a co mplete solution of the proble m requires only that we know every mo m ent the sides of the triangle form ed by the three bodies the solution of the triangle d epe n ding upon t w o di fferential equations of the second order and one differential equation of the third He found particular solutions when the triangles remain all si m ilar In the discussion of the m eaning of negative quantities of the fundam ental processes of the calculus of the logarith m s of co mplex numbers and of the theory of probability D A l emb e r t paid so m e attention to the philosophy of m athe m atics In the calculus he favored the theory of lim its He looked upon infinity as nothing but a limit which the finite approaches without ever reaching it His criticisms were not al w ays happy When stude n ts were halted by “ the logical difficulties of the calculus D Al emb e r t would say Alle z en avant e t la foi vous viendra He argued that when the prob ability oi an event is v ery s mall it ought to be taken 0 A coin is to be tossed 1 0 0 times and if head appear at the last trial and not before 100 A shall pay B 2 crow ns By the ordinary theory B S hould giv e A which should not be argues D Al e mb e rt b e 1 cro w n at the start cause B will certainly lose This v iew was taken also by Count de B u ff on D Al emb ert raised other obj ections to the principles of probability The naturalist Comte de B ufi on ( 1 70 7 wrote an E ssai d a r i thméti qu e mor al e 1 7 7 7 In the study o i the P etersburg proble m he let a child toss a coi n 2 0 84 ti mes which produced 1 0 0 5 7 crowns ; there were 1 0 6 1 gam es which produced 1 crown 494 which produce d 1 2 crowns and so o n He was one of the first to e mphasiz e the d esir . , . . , , . , ” , . . . , . . . , . , , . . . . , . . , , ’ , , . . . ” . ’ , , . , . , , , . ’ , , , . ’ . . . , ’ - , . , , , . 1 Fo r re feren c es , see I T o d hu n t e r , H i s tor y . f o Theor y f o P r oba bil i ty, p 3 4 6 . . A HI STORY OF M ATHE M ATIC S 2 44 ability of verifying the theory by actual trial He also introduced what is called local probability by the consideration of problems that require th e aid of geometry Some studies along thi s line had — h n r t t been carried on earlier by Jo A bu hn o ( 1 6 58 1 73 5) and Thomas Simpson in Englan d Count de B uff on derived the probability that a needle d ropped upon a plane ruled with equidistant parallel lines will fall across one of the lines The probability of the correctness of judgments determined by a m ajority of votes was exam ined m athem atically by Jean — A n toi n e His general conclusions N i col as C a r i tat de C ond or cet ( 1 74 3 are not of great im portance ; they are that voters m ust be enlightened 1 men in order to ensure our confidence in their decisions He held that capital punishm ent ought to be abolished on the ground that however large the probability of the correctness of a single decision there will be a large probability that In the course of many decisions 1 som e innocent person will be condemne d Al e xi s C l au d e C l a ir au t ( 1 7 1 3 1 7 6 5) was a youthful prodigy He read G F de l H ospi tal s works on the infinitesimal calculus and on conic sections at the age of ten In 1 7 3 1 was published his Recher ches s u r l es c ou r bes a dou bl e cou r bu r e which he had ready for the press when he was six teen It w as a work of remarkable elegance and se cured his admission to the Academy of Sciences when still under legal age In 1 73 1 he gave a proof of the theorem enunciated by I Newton that ev ery cubic is a projection of one of five divergent parabolas Clairaut form ed the acquaintance of P i er re L ou i s M orean de M au per — s ti u ( 1 6 98 1 7 whom he acco mpanied on an expedition to Lapland to m easure the length of a degree of the m eridian At that tim e the shape of the earth was a subj ect of serious disagree m ent I Newton and C H u yg en s h a d concluded from theory that the earth was flat tened at the poles About 1 7 1 2 Jea n Domi n i qu e Cassi n i ( 1 6 2 5—1 7 1 2 ) — m easured an arc exten d ing and his son J acqu es C ass i n i ( 1 6 7 7 1 7 56 ) from D unkirk to P erpignan and arrived at the startling result that the earth is elongated at the poles To decide between the conflicting opinions m easurements were renewed M aup er ti u s earned by his “ work in Lapland the title of earth flat ten er by disproving the Cassinian tenet that the earth was elongated at the poles and showing t hat Newton was right On his return in 1 743 Clairaut published a work Theori e de l a figu r e de l a Ter r e which was based on the results of C M aclaurin on homogeneous ellipsoi ds I t contains a rem arkable theorem nam ed after Clairaut that the s u m of the fractions ex press i ng the ellipt i c i ty and the I ncrease of gravity at the pole 15 equal to 2 —t imes the fraction expressing the centr i fugal force at the equator the unit of force being represente d by the force of grav ity at the equator This theorem is independent of any hypothes i s with respect to the law of densities of the successiv e strata of the earth It em I T dh n t Hi t y f Theor y f P r b C h p ter 7 . . . , , , . . , , , . . ’ ’ . . . , . . . , ' . . . . . . - . . ” . , , , . , , , . . , , 2 , . . 1 . o u er , s or o o o . , a 1 . A HI STORY OF M ATHE M ATIC S 246 ” To the emperor s fur ther question how he attained this mastery he “ said L i ke the celebrated P ascal by my own self In his Cos mol ogi cal L etters he m ade som e remarkable prophecies regarding the stellar system He entered upon plans for a m athe mati cal symbolic logic of the nature once outlined by G W L eibniz In m athem atics he m ade several discoveries which were ex tended and overshadowed by his great contemporaries His first research on pure m athem atics develope d in an infinite series the root x of the m equation x + px = q Since each equation of the form m can be reduced to x + px = q in two ways one or the other of the two resulting series was always found to be convergent and to give a value of x Lam bert s results stim ulated L Euler who extended the m ethod to an equation of four term s and particularly J Lagrange = 0 can be expressed who found that a function of a root of a by the series bearing his nam e In 1 7 6 1 Lambert comm un i cated to the B erlin Academy a m em oir (published in which he pro v es rigorously that W is irrational I t is given in simplified form in Note IV 2 of A M Legen dre s Geometri c where the proof is exten d e d to 71 " Lambert proved that if x is rational but not z ero then ne i ther e nor tan x can be a rational nu mber ; s i nce tan 1r /4 = 1 it follows that ’ , , , . , . . . . . . , , ’ . . , . , , . . ’ . . . , , , , 7r 4 or 7T cannot be Lambert s proofs rest on the express i on r a t Ion al . ’ 1 for e as a continued fraction giv en by L Euler w ho in 1 7 3 7 had sub 2 There were at this s t a n t i al l y shown the irrational i ty of e and e tim e so m any circle squarers that i n 1 7 7 5 the P aris Aca de m y found it necessary to pass a resolution that no m ore solutions on the qua drature of the circle should be exam ined by its offi cials This resolution ap plied also to solutions of the duplication of the cube and the trisection of an angle The con v iction had been growing that the solution of the squaring of the circle was impossible but an irrefutable proof was not discovered until over a century later Lambert s Fr eya P er s pecti ve 1 7 59 and 1 7 7 3 contains researches on descriptive geom etry and enti tle him to the honor of being the forerunner of M onge In his e ff ort to sim pl i fy the calculation of com etary orbits he was led geom etrically to som e rem arkable theorem s on conics for instance thi s : If in two ellipses having a co mm on m ajor axis we take t w o such arcs that their chords are equal and that also the su m s of the ra di i vectores d rawn respectively from the foci to the extrem i ti es of these arcs are equal to each other then the sectors form ed in each ellipse by the arc an d the two ra dii vectores are to each other as the 2 square roots of the parameters of the ell i pses La mbert elaborate d the subject of hyperbolic functions wh i ch he designated by si n h x cosh x etc He was however not the first to . . . . , ’ . , , , . , , “ , , ” , , . , , . R C A rc hib al d i n A m M a th M on thl y, V o l 2 M C hasl es, Geschi chte der Geometr i e, 1 8 39 , p 1 . . . . . , , 21, . . 1 9 1 4, 1 83 . p . 2 53 . EULER LAGRANGE AND LAP LACE 247 , introduce them into trigonometry That honor falls upon Vi n cenzo 1 Ri oca ti ( 1 7 0 7 a son of Jacopo R i cca ti In 1 7 70 Lam bert published a 7 place table of natural logarith ms for nu mbers 1 —1 0 0 In 1 7 78 one of his pupils J ohann K arl S chu l ze published ex tensive tables which included the 4 8 place table of nat ural logarithms of prim es and many other numbers up to which had been computed by the D utch artil lery offi cer Wolf r am A feat even more remarkable than Wolfram s was the computation of the common logarith ms of numbers 1 —1 0 0 and of all prim es from 1 0 0 to 1 1 0 0 to 6 1 places by A br aha m S har p of Yorkshire who was some time assistant to Flam steed at the English Royal Observatory They were published in Sharp s Geometry I mprov d 1 7 1 7 — o L a n d e n 1 1 was an English m athem atician whose h n J ( 7 9 1 7 90 ) writings se rved as the starting point of investigations by L Euler J Lagrange and A M Legendre Landen s capital discovery con t ai n ed in a me m oir of 1 7 5 5 was that every arc of the hyperbola is immediately rectified by m eans of two arcs of an ellipse In his residual analysis he attem pted to obviate the m etaphysical d iffi c u l ti es of fl u xi on s by a d opting a purely algebraic m etho d J La grange s C al cu l des Fon cti ons is based upon this idea Lan d en S howed ho w the algebraic expression for the roots of a cubic equation could be deriv ed by application of the differential and integral calculus M ost of the tim e of this suggestive writer was S pent in the pursuits of active l ife Of influence in the teaching of m athe m atics in England was C ha rl es H u tton ( 1 73 7 for many years professor at the Royal M ilitary Academ y of Woolwich In 1 7 8 5 he published his M athemati cal Tabl es and in 1 7 95 his M a themati cal and P hi l osophi cal D i cti on a ry the best work of its kind that has appeared i n the English language His El emen ts of C on i c S ecti on s 1 7 8 9 is re m arkable as being the first work in which each equation is rendered conspicuous by being printed in 2 a separate line by itself It is well known that the Newton Raphso n m ethod of appr oxim a tion to the roots of nu merical equations as it was handed do w n from the sev enteenth century lab ored un d er the defect of insecurity in the process so that the successive corrections did not always yield results converging to the true value of the root sought The rem oval of this defect is usually attributed to J Fourier but he was anticipated half a century by J Raym M ou rrai l l e i n his Tr ai té de l a r es ol u ti on des equ a ti on s en gen er al M arseille e t P aris 1 7 6 8 M ou r r a ill e was for fourteen years secretary of the acade m y of sciences in M arseille ; later he becam e m ayor of the city Unlike I Newton a n d J Lagrange M ou rrai ll e and J Fourier introduced also geo m etrical cons i d erations M ou rrail l e concluded that security is insured if the first appro xim ation . . - . , , - . , ’ , , , , . ’ ’ . , - , . ’ . . . , , ” “ , . . . . ’ . . . , . , . , , . - , , , . . . , . , , . . M C an tor op 2 M C an t or , op . . , . , . . . ci t . ci t 1 . . . , , Vol I V , V ol I V , . . 1 90 8 , p 41 1 1 90 8 , p 46 5 . . . . A HI STORY OF 2 48 M ATHE M ATIC S is so selected that the curve is convex toward the axis of x for th e interval between a and the root He shows that this condition is 1 suffi cient but not necessary In the eighteenth century proofs were giv en of D escartes Rule of Signs which its discoverer h ad enunciated without de monstration G W Leibniz had pointe d out a line of proof but did not actually — r ea 1 J n P es t e t 1 published at P aris in his give it In 6 7 5 ( 6 4 8 1 6 90 ) E l emen s des ma théma ti qu es a proof which he afterwards acknowledged to be insuffi cient In 1 7 2 8 J ohann A n dreas S egn er ( 1 70 4—1 7 7 7 ) pub l i sh e d at Jena a correct proof for equations ha v ing only real roots In 1 7 56 he gav e a general d em onstration based on the consid eration that m ult iply i ng a pol ynom ial by (x —a )increases the num ber of var i ations by at least one Other proofs were given by Jean P au l de I s aa c M i l n er Fr i edr i ch Wi l hel m S tubn er Gu a de M al ves a . , . ’ . . . , . . . , . ' A br aha m Gotthelf K as tn er Gr u n er t K F Gau ss ber of pos i tive roots falls short , Wari n g Edw ard J . A . Gauss showed that if the n u m of the nu mber of v ar i at i ons i t d oes so by an even nu mber E Laguerre later extende d the rule to poly a n d to i n n om i al s with fractional and inco mm ensurable exponents 2 finite series I t was established by D e Gua de M alves that the absence of 2 m successive terms indicates 2 m im aginary roots while the absence of 2 m+ 1 successiv e term s in di cates 2 m+ 2 or 2 m i magin ary roots according as the two term s between which the deficiency occurs hav e like or unl i ke signs Edw a r d W a rin g ( 1 7 3 4— 1 7 98 ) was born in Shrewsbury studied at M agdalene College Cambridge was senior wrangler i n 1 7 5 7 and He published M i s L u cas ia n professor of m athe m atics since 1 7 6 0 c el l a n ea a n al yti ca in 1 7 6 2 M edi tati on es al gebr ai cw in 1 7 7 0 P r opr i eta ti s a l gebr ai car u m cu rva r u m in 1 7 7 2 and M edi ta ti on es a n al yti cce in 1 7 7 6 These works contain m any new results but are diffi cult of co mpre h en s i o n on account of his brevity and obscurity of exposition He is said not to ha v e lectured at Cambridge his researches be i ng thought u nsuited for presentation in the for m of lectures He a dm itted that he ne v er heard of any one in England outsid e of Cam bridge who had read an d understoo d his researches In his M edi ta ti on es al gebra i cce are som e n ew theorems on nu mber Forem ost am ong these is a theorem di scovered by his friend John and univ ersally known as Wilson s theorem Wi l son “ Waring gives the theore m known as Waring s theorem that eve ry i nteger is either a cube or the su m of 2 3 4 5 6 7 8 or 9 cubes either or 1 9 fourth powers ; th i s has a fourth power or the su m of 2 3 nev er yet been fully dem onstrate d Also without proof is giv en the theore m that e v ery even integer is the su m of two primes and every . . . , , . , . , , . , , , , . , , . , , . , . , , . . ” ” ’ ’ . , , , , , , , , , , . S ee F C aj o ri i n B i bl i otheca ma thema ti ca , 3 rd S , V ol 1 1 , 2 Fo r re fe re n ces t o t he p u bl ic a t i o n s o f t he se w r i t e rs , see F Coll ege P u bli cati on , G e n er al S e ri es N o 5 1 , 1 9 1 0 , p p 1 8 6 , 1 8 7 1 . . . . 19 1 1 , . . . pp . 132 —1 3 7 . C aj o r i i n Col or ado O F M ATHE M ATI C S HI STORY A 50 points or singu lar li nes planes etc at i nfi nity occasion the with draw a l to i nfinity of certain of t he intersection points ; and this at a 1 tim e when the nature of such S ingularities had not been dev eloped Lou i s Ar b og as te ( 1 759—1 80 3) of Alsace was professor of m athe m a ti c s at S trasburg His chief work the C al cu l des Deri vati on s 1 8 0 0 gives the m ethod known by his nam e by which the successive coeffi c i en t s of a develop m ent are derived from one another when the ex pression is complicated A D e M organ has pointed out that the true nature of derivation is differentiation accompanied by integration In this book for the first time are the sym bols of operation separated , , . , , ” . , . , , , . . . from those of quantity dr The notation n for is due to him (E M ari a G ae tan a Agn e s i ( 1 7 1 8— 1 7 99) of M ilan distin g uished as a linguist mathem atician and ph ilosopher filled the mathematical chair at the University of B ologna duri ng her father s sickness A g n e si was a so m na mbulist Several tim es it happened to her that she went to her stu dy while in the som nambulist state m ade a light and solv ed som e problem she had left incomplete when awake In the m orning she was surprised to find the solution carefully worked 2 out on pape r In 1 748 she published her I n sti tu zi oni A n al i ti che “ which was translated into English in 1 80 1 The witch of Ag n esi “ 2 = 2 or Versiera is a cubic curve x y a (a —y) treated in Ag n esi s I n 2 ~ 2 3 = s ti tu zi on i but given earlier by P Ferm at in the form ( a x ) y a The curve was discussed by Guido Grandi in his Qu adr atu r a ci rcu l i et hyper bol ce In two letters from Grandi to P isa 1 7 0 3 and Leibniz in 1 7 1 3 q rves resembling flowers are discussed ; in 1 7 2 8 Grandi published at Florence his Fl or es geometri ci He considered curves in a plane of the type p = r sinn w and also curves on a sphere Recent studies along this line are due to B odo Habenicht E W Hyde H Wi el ei tn er The leading eighteen th century historian of m athe matics was J e a n — Et i e n n e M on tu cl a ( 1 7 2 5 1 7 99) who published a H i s toi re des mathe mati qu es in two volu m es P aris 1 7 58 A second edition of these two volumes appeared in 1 7 99 A third volu me written by M on tu cl a was partly printed when he died ; the rest of it was seen through the press by the astronomer Jo s e ph J er Ome l e Fran goi s d e L al an d e who prepared a four th volum e m ainly on the history of ( 1 73 2 4 astronomy one of the greatest m ath e J o s e ph L ou i s Lag r an g e ( 1 73 6 m a ti cian s of all tim es was born at Turin and d ied at P aris He was of French extraction His father who had charge of the Sardinian . . , , , , ’ . . , , , . ” , . ” . ’ - . , . , , , , . . . . , , . , , . , . , , , . - . , . Whi t e i n , B u l l A m M ath S oc , V ol 1 5 , 1 909 , p 33 1 ’ 2 L I n ter méd i a i r e des ma théma ti ci en s , Vo l 2 2 , 1 9 1 5 , p 2 4 1 3 G L ori a , E ben e C u r ven ( F S c h ii t t e , I , 1 9 1 0 , p 7 9 ’ 4 For d e t ai l s o n o t h e r m a t hema t i c a l hi s t o ri an s , se e S G u n t her s C an to r , op c i t , V o l I V , 1 90 8 , pp 1 — 36 1 H S . . . . . ) . . . . . . . . . . . . . . . . . c hap t er in E UL ER LA G RAN G E AN D , military LAP LACE chest was once wealthy but lost all he had in speculation Lagrange considered this loss his good fortune for otherwise he might not have made m athematics the pursuit of his life While at the college in Turin his genius did not at once take its true bent Cicero and Virgil at first attracted him more than Archimedes and Newton He soon came to ad mire the geo metry of the ancients but the perusal of a tract of E Halley roused his enthusiasm for the anal ytical method in the d evelop m ent of which he was destined to reap undying glo ry He now applied hi mself to mathematics and in his seventeenth year he becam e professor of mathem atics in the royal mili ta ry academy at Turin Without assistance or guidance he entered upon a course of study which in two years placed him on a level with the greatest of his contemporaries With aid of his pupils he established a society which subsequently developed in to the Turin Academy In the first five volum es of its transactions appear m ost of his earlier papers At th e age of nineteen he comm unicated to L Euler a general m ethod “ of dealin g with isoperimetrical problem s know n n ow as the Cal cui us of Variations This comm anded Euler s liv ely ad m iration and he courteously withh eld for a tim e fro m publication so m e researches of his own on this subj ect so that the youthful Lagrange m ight com Lagrange did quite pl e t e hi s investigations and clai m t he inv ention as m uch as Euler tow ards the creation of the Calculus of Variations As it came from Euler it lacked an analytic foundation and this Lagrange supplied He separated the principles of this calculus fro m geom etric considerations by which his predecessor had derived them Euler had assum ed as fixed the lim its of the integral i e the extrem ities of the curve to be determ ined but Lagrange rem oved this re striction and allowed all c o ordinates of the curve to vary at the sam e “ tim e Euler introduced in 1 7 66 the nam e calculus of variations and did m uch to improve this science along the li n es m arked out by Lagrange Lagrange s investigations on the calculus of variations were published in 1 7 6 2 1 7 7 1 1 7 88 1 7 97 1 8 0 6 Another subject engaging the attent i o n of Lagrange at Turin was the propagation of sound In his papers on this subj ect in the M i s cel l an ea Tau r i n en s i a the young m athe m atician appears as the critic of I Newton and the arbiter between Euler and D Al emb e r t By considering only the particles which are i n a straight line he reduced the problem to the sam e partial d iff erential equa t ion that represent s the motions of vibrating strings Vibrating strings had been discussed by Brook Taylor J ohann B ernoulli and his son D aniel by D Al emb e r t and L Euler In solvi ng the partial diff erential equations D Al emb er t restricted him self to f unctions which can be expanded by Taylor s series while Eu l er thought that no restriction was necessary that they could be arbi t ra ry discontinuous The proble m was taken up wi th great skill by Lagrange who introduce d new points of view but decide d in fav or of . , , , . . . , . , . , . . . . . , ’ , . , . . , . . . , . , ” - . , ’ . , , , . , . , ’ . . , , . , ’ . . , ’ , ’ , , , . , Q , A HI STORY O F M ATHE M ATIC S 2 52 Euler Later de Condorcet and P S Laplace stood on the side of D A l emb er t S ince in their judgm ent so m e restriction upon the arbi t r ary functions was necessary From the m odern point of view neither D A l embe r t nor Euler was wholly in the right : D Al emb er t insisted upon the needless restriction to functions with a l imitless number of derivativ es while Euler assum ed that the diff erential and 1 integral calculus could be applied to any arbitrary function I t now appears that Daniel B ernoulli s claim that his solution was a general one (a claim disputed by D A l emb er t J Lagrange and L Euler) was fully j ustified The problem of vibrating strings s timu lated the growth of the theory of expansions according to trigonom etric functions of m ultiples of the argum ent H B urkhardt has pointed out that there was also another line of growth of this subj ect namely the growth in connection with the problem of perturbations where L Euler started out with the develop m ent of the reciprocal distance of two planets according to the cosine of m ultiples of the angle b e tween their radii v ec t o ri s By constant application d uring nine years Lagrange at the age of twenty S ix stood at the su mm it of European fam e B ut his intens e studies had seriously weakened a constitution nev er robust and though his physicians in duced him to take rest and exercise his nervous syste m nev er fully recovered its tone and he was thenceforth subject to fits of m elancholy In 1 7 6 4 the French Academy proposed as the subject of a priz e the theory of the libration of the m oon I t dem ande d an explanation on the principle of universal grav itation why the m oon always turns with but slight v ariations the sam e phase to the earth Lagrange secured the priz e This success encouraged the Aca dem y to propose f or a priz e the theory of the four satellites of Jupiter — a problem of S ix bodies m ore diffi cult than the one of three bo d ies previously treated by A C Clairaut D A l emb er t and L Euler Lagrange over cam e the diffi culties by m ethods of approximation Twenty four years afte rwards this subj ect was carrie d further by P S Laplace Later astrono m ical investigations of Lagrange are on com etary per t u rb a t i on s ( 1 7 7 8 and 1 7 8 His researches a n d on Kepler s proble m on the problem of three bo dies has been referred to previ ously B eing anxious to m ake the personal acquaintance of leading m athe mat i ci an s Lagrange visited P aris where he enjoyed the stim ulating delight of conversing with A C Clairaut D Al emb er t de Condorcet the Abb é M ar i e and others He had planned a visit to London but he fell dangerously ill after a dinner in P aris and was compel led to return to Turin In 1 7 6 6 L Euler left B erlin for S t P etersburg and he pointed out Lagrange as the only man capable of filling the place . . . , ’ , . ’ ’ ' , . ’ ’ , . . . . . , , . . , , - . , , , , . , . , , . , . , , ’ . . , . . , - . . . . ’ . . , , ’ . . , , , . , , , . . . , . Fo r de t ai l s see H B u rk ha r d t s E n twi ckl u n g en n a ch os ci l l i r end en Fu n k ti on en u n d I n tegr a ti on der D ifi er en ti a l gl ei chu n g en d cr ma themati s che n P hys i k L ei p i g , Thi s i s an e xha ust i ve a n d v a l u a b l e hi s tory o f t hi s t op i c 1 90 8 , p 1 8 ’ 1 . . . . . z A HI STORY OF M ATHE M ATIC S 2 54 self evident Other proofs of this were given by J R Argand K F Gauss and A L Cauchy In a note to the above work Lagrange uses Fermat s theore m and certain suggestions O f Gauss in eff ecting a com m algebraic solution of any bino ial equation l e t e p In the B erlin M émoi res for the year 1 7 6 7 Lagrange contributed a paper S u r l a r esol u ti on des equ ati on s nu meri qu es He explains the separation of the real roots by substituting for x the term s of the progression 0 D 2 D where D m ust be less than the least dif ference between the roots Lagrange suggested three ways of com puting D : One way in 1 7 6 7 another in 1 7 95 and a third in 1 798 The first depends upon the equation of the squared differences of the roots of the giv en equation E Waring before this had derived this i m portant equation but in 1 7 6 7 Lagrange had not yet seen Waring s writings Lagrange fin ds equal roots by computing the highest com m on factor between f (x) and f (x) He proceeds to develop a new mode of approxi m ation that by continued fractions P A Cataldi had used these fractions in extracting square roots Lagrange enters upon greater deta i ls in his A ddi ti on s to his paper of 1 7 6 7 Unlike the older m ethods of approxim ation Lagrange s has no cases of failure Cette m éthode me laisse ce m e semble rien a d ésirer yet though theoretically perfect it yields the root in the form of a con t i n u ed fraction which is un d esirable in practice While in B erlin Lagrange published several papers on the theory of nu mbers In 1 7 6 9 he gav e a solution i n integers of indete rm inate equations of the second d egree which resembles the Hin d u cyclic “ me thod ; he was the first to prove in 1 7 7 1 Wilson s theore m enun c i a t ed by an English m an John Wilson and first published by E Waring in his M edi ta ti on es A l gebr ai cce; he inv estigated in 1 77 5 under f what conditions t 2 and i 5 1 and 3 hav ing been discussed by L Euler ) are quadratic resi dues or non resi dues of odd prim e n um bers q ; he prov e d in 1 770 B achet de M éz i riac s theorem that every integer is equal to the s u m of four or a less number of squares He proved Ferm at s theorem on x + y = z for the case n = 4 also F e r 2 2= 2 m at s theorem that if a + b c then ab is not a square In his m em oir on P yramids 1 7 73 Lagrange m ade considerable use of determ inants of the third order and dem onstrated that the square of a determ inant is itself a determ inant He never however dealt explicitly and directly with determ inants ; he siIn pl y obtained acci d enta lly identities which are now recogniz ed as relations between determ inants Lagrange wrote m uch on d ifferential equations Though the sub j ec t of contemplation by the greatest m a them aticians (L Euler D A l emb e r t A C Clairaut J Lagrange P S Laplace )yet m ore than other branches of m athem atics do they resist the system atic application of fi xed m etho d s a n d princ ipl es The subject of S ingular s olutions which ha d been taken u p by P S Laplace in 1 77 1 a n d 1 7 7 4 - . . . , . . . . , . ’ . ’ ’ . , , , , , . . , . . ’ , . ’ . , . . . . ” . ’ , . , , , , , . ” . , ’ , : , , , . , z z :: - . , ’ , ’ n . , , n fl , , ’ , . , , , , , , . . . . , ’ , . . , . . , . , . , . . , EULER LAGRANGE AND LAP LACE 2 55 , was investigated by Lagrange who gave the derivation of a S ingular solution from the general solution as well as from the diff erential equation itself Lagrange brought to vie w the relation of singular solutions to envelopes Nevertheless he failed to rem ove all mystery surrounding this subtle subj ect An inconsistency in his theorem s caused about 1 8 70 a complete reconsideration of the entire theory of singular solutions Lagrange s treatment is given in his C al cul des — Fon cti ons Lessons 1 4 1 7 He generaliz ed Euler s researches on tota l differential equations of two variables and of the nin th order ; he gav e a solution of partial differential equatio n s of the first order (B erl i n and spoke of their singular solutions ex M emoi rs 1 7 7 2 and tending their solution i n M emoi rs of 1 7 7 9 and 1 78 5 to equations of any number of variables The M emoi r s of 1 7 7 2 and 1 7 74 w ere refi ned — m m in certain points by a young athe atician P aul Charpit 1 7 8 4) whose m ethod of solution was first printed in Lacroix s Trai té du cal cu l 2 Ed P aris 1 8 1 4 T II p 54 8 The discussio n on partial differential equations of the second order carried on by D Al emb ert Euler and Lagrange has already been referred to in our a ccoun t of . . , . ’ . ’ . , , , , . ’ , . . , , , , . . . ’ , , , , D A l emb er t Wh ile in B erlin , ’ . Lagrange wrote the M écani qu e A nal yti qu e the greatest of his works (P aris From the principle of vi rtual velocities he deduced with aid of the calculus of variations the whole system of m echanics so elegantly and harm oniously th at it may fi tly “ be calle d in Sir Willia m Rowan Ham ilton s words a kind of sc i en t ifi c poem It is a most consu mm ate example of analytic generality “ Geom etrical figures are nowhere allowed On n e trouvera point de figures dans cet ouvrage (P reface )The two divisions of m echanics —statics and dynamics—are in the first four sections of each carried out analogously and each is prefaced by a historic S ketch of principles Lagrange formulated the principle of least action In their orig inal form the equations of m otio n involve the c o ordinates x y z of the diff erent particles m or dm of the system B ut x y z are in general not independent and Lagrange introduced in place of them any variables 5 Il f) whatever determ ining the position of the point at “ the time These generaliz ed c o ordinates may be taken to be inde pendent The equations of m otion may now assu m e the form , , , , ” , ’ , . . ” . . . , . ‘ - , , . , l , c , , , , , ” , - . , , . d dT di or when E p respect to f p ’ , , , , 75 7 ( — dT 8? L “ P are the partial diff erential of one and the sa m e functio n d dT dT d V — E ff L “ c oefli c i en ts V, then w it h the form E The latter is par excel l en ce the Lagrangian form of the equations of motion Wi th Lagrange originate d the rem ark that m echanics may ' dt dé . O F M ATHE M ATI C S HI STORY A 2 56 be regarded as a geom etry of four dim ensions To hi m falls the honor of the introduction of the potential into dynamics Lagrange was anx ious to have his M écani qu e A n al yti q u e published in P aris The work was ready for print in 1 7 86 but not till 1 7 88 could he find a publisher and then only with the condition that after a few years he would purchase all the unsold copies The work was edited by A M Legendre After the death of Frederick the Great men o f science were no longer respected in Germ any and Lagrange accepted an inv itation of Louis XVI to m igrate to P aris The French queen treated him with regard and lodging was procured for h im in the Louv re B ut he was sei z ed with a long attack of melancholy which d estroyed his taste for m athem atics For two years his printe d copy of th e M e — can i qu e fresh fro m the press the work of a quarter of a century lay unopened on his desk Through A L Lavoisier he became i n ter es t ed in che m istry which he found as easy as algebra The disastrous crisis of the French Revolution aroused hi m again to ac t i v i ty About this time the young and acco mplished daughter of the astronomer P C Le monnier took compassion on the sad lonely L agrange and insiste d upon m arrying him Her dev otion to him constituted the one tie to life which at the approach of death he fo u nd it hard to break He was m ade one of the commissioners to establish weights and m easures having units founded on nature Lagrange strongly favored the decim al subdiv ision Such was the m oderation of Lagrange s character and such the universal respect for him that he was retained as presid ent of the commission on weights and m easures e v en after it had been pu rifi ed by the Jacobins by striking out the nam es of A L Lav oisier P S Laplace and others Lagrange took alarm at the fate of Lav oisier and planned to return to B erlin but at the estab l i shme n t of the E col e N or mal e in 1 7 95 in P aris he was induced to accept a professorship Scarcely had he tim e to eluci date the fou n da tions of arithm etic and algebra to young pupils when the school was closed His additions to the algebra of L Euler were prepared at this tim e In 1 797 the E col e P ol ytechn i qu e was founded with Lagrange as one of the professors The earliest triumph of this institution was the restoration of Lagrange to analysis His m athe matical activity burst out anew He brought forth the Thear i e des f on cti ons an al yti qu es L egon s su r l e cal cu l des f on cti ons a treatise on the sa me lines as the preceding and the Res ol u ti on des equ ati on s n u meri qu es which includes papers published m uch earlier ; his m em oir . . . , , . . . . , , . , . . , , . . ” . “ , , . . . . , , . . . ’ . , , . , . . . . , , , , . , . . , . . . . , , N ou vel l e méthode pou r s er i es , ’ publi shed r és oud r e 1 7 70 , l es equ ati on s l i tter al es par l e moyen des ’ gives the notation however much earlier in a part of a memoir for by dill dx ’ which occurs Fran goi s Davi e t de HI STORY A 2 58 O F M ATHE M ATIC S derivatives as it was call ed has been generally abandoned He introduced a no ta tion of hi s own but it was inconvenient and was abandoned by h im in the second edition of his M ecani qu e in which he used in fi n i tesim al s The primary object of the Theari e des f on cti ons was not attained but its secondary results were far reaching I t was a purely abstract mode of regarding functions apart from geo m etrical or m echanical considerations I n the further develop m ent of higher analysis a functio n becam e the leading idea and Lagrange s work may be regarded as the sta rti ng point of the theory of functions as dev eloped by A L Cauchy G F B Riem ann K Weierstrass and others The first to doub t the rigor of Lagrange s exposition of the calculus were A bel B u rj a ( 1 7 5 2 —1 8 1 6 ) of B erlin the two P olish m athe m aticians and the B ohemian H Wr on s ki and J B S n i ad ecki ( 1 7 5 6 B B ol zan o who were all me n of li m ited acquaintance and influence I t rem ained for A L Cauchy really to in itiate the period of greater . , , , , ’ , ' . - . , , . . ’ , - . . , . . . , . , . ’ , . . . . , . . rIg or . . Instructive is C E P icard s characteriz ation of the tim e of La grange : I n all this period especial ly in the second half of the eight e en th century what str i kes us with ad m iration and is also so m ewhat confusing is the extrem e i mportance of the applications realiz ed while the pure theory appeared still so ill assured One perceives it when certain questions are raised like the degree of arbitrariness i n the integral of vibrating chord s whi ch gives place to an interm inable and inconclusive discussion Lagrange appreciated these i n suffi c i en ci es when he published his theory O f analytic functions where he strov e to give a precise foundatio n to analysis One cannot too m uch adm ire the m arvellous presentim ent he had of the rOl e which th e functions which with him we call analytic were to play ; but we may confess that we stand astonished before the demonstration he b e l i ev ed to hav e given of the possibility of the develop m ent of a function 1 in Taylor s series In the treatm ent of infinite series Lagrange displayed in his earlier writings that laxity com m on to all m athem aticians of his time ex c ep ti n g N i col a u s B ernoulli II and D A l emb er t B ut his later articles m ark the beginning of a period of greater rigor Thus in the C al cu l des f on cti ons he gives his theorem on the lim its of Taylor s theorem La grange s mathem atical researches extended to subj ects which have not been mentioned here—such as probabilities finite differences ascending continued fractions elliptic integrals Everywhere his wonderful powers of generaliz ation and abstraction are mad e manifest In that respect he stood without a peer but his great contemporary P S Laplace surpasse d h i m in practical sagacity Lagrange was content to leave the application of his general results to othe rs and so me of the m ost important researches of Laplace (particularly those ’ . . “ , , , , . , . , . , , ” ’ . , ’ . . , ’ . ’ , , . , . , , . . . , , 1 Congress f o A r ts an d S ci en c e, S t L o u i s , . 1 90 4 , V ol I , p 5 0 3 . . . , EUL ER LAGRANGE , LAP LACE AN D 2 39 on the velocity of sound and on the secular acceleration of the moon) are imp l icitly contained in Lagrange s works Lagrange was an extrem ely m odest m an eager to avoid co n tro v er sy and even ti mid in conversation He spoke in tones of doubt “ and his first words generall y were Je n e sais pas He would never allow his portrait to be taken and the only ones that were secured were sketched without his knowledge by persons attending the meet ings of the Institute P i e rr e S i m o n Lapl a c e ( 1 749— 1 8 2 7) was born at B eaumont en Auge i n Norm andy Very little is known of his early life When at the height of his fame he was loath to speak of his boyhood spent in pov erty His father was a s mall farm er So me rich neighbors who recogniz ed the boy s talent assisted him in securing an education As an extern he attended the m ilitary school i n B eaum ont where at an early age he beca me teacher of m athe m atics At eighteen he went to P aris arm ed with letters of recomm endation to D Al emb er t who was then at the height of his fam e The letters rem ained unnoticed but young Laplace undaunted wrote the great geom eter a letter on the principles of m echanics which brought the following en thusiastic response : You needed no introduction ; you have recommended your self ; my support is your due D A l emb er t secured him a p ositio n at the Ecol e M i li tai re of P aris as professor of mathematics H is future was n ow assured and he entered upon those profound researches which brought hi m the title of the Newton of France With won derful mastery of analysis Laplace attacked the pending problems in the application of the l aw of gravitation to celestial motions D ur ing the succeeding fifteen years appeared most of his original contri butions to astronom y His career was one of almost uninterrupted prosperity In 1 7 84 he succeeded E B éz ou t as examiner to the royal a rtillery and the following year he becam e m ember of the Academ y of Sciences He was m ade president of the B ureau of Longitude ; he ai ded in th e introduction of the decim al syste m and taught w ith J Lagrange ma thematics i n the E col e N ormate When during th e Revolution there arose a cry for the reform of everything even of the calendar Laplace suggested the adoption of an era beginning with the year 1 2 50 when ac c ordin g to his calculation the m ajor axis of the earth s orbit had bee n perpendicular to the equinoctial line The year was to begin with the vernal equinox and the z ero m eridian was to be located east of P aris by degrees of the centesim al division of the quadrant for by this m eridian the beginning of his proposed era fell at m idnight B ut the rev olutionists rej ected this schem e and m ade the start of the n ew era coincide with the beginning of the 1 glorious French Republic Laplace was justly adm ired throughout Europe as a most sagacious ’ . , , ” . , , . , . - - . . , . . ’ . , . ’ , , . , , , , ” ’ . . ” , . , , . . . . . , . , , . , . , , , , ' , , , ’ . , , . , . 1 R u dol f Wo l f , Geschi chte der A s l ron omi e, M unch e n , 1 8 7 7, p 334 . . A HI STORY OF M ATHE M ATIC S 2 60 p rofound scientist but unh appily for his reputation he strove not only after greatness in science but also after political honors The political career of this e minent scientist was stained by servility and suppleness After the 1 8 th of B rum aire the day when Napoleon was m ade emperor Laplace s ardor for republi can principles suddenly gave way to a great devotion to the e mperor Napoleon rewarded this devotion by giving him the post of m inister of the interior but “ dism issed him after six m onths for incapacity Said Napoleon La place n e saisissait aucune question sous son véritable point de v u e ; il cherchait des subtilit és partout n av ai t que des id ées probl emati q u e s e t portait en fi n l e sp r i t des i n fi n im en t petits j usque dans l a dmi n i s t ra tion D esirous to retain his allegiance Napoleon elevated hi m to the Senate and bestowed various other honors upon him N ever the less he cheerfully gave his voice i n 1 8 1 4 to the dethrone ment of his patron and hastened to tender his services to the B ourbons thereby earning the title of m arquis This pettiness of his character is seen in his writings The first edition of the S ysteme du monde was dedi c a t ed to the Council of Five Hundred To the third volu m e of the M ecan i qu e C el es te is prefix ed a note that of all the truths contained in the book the one most precious to the author was the declaration he thus m ade of gratitude and devotion to the peace maker of Europe After this outburst of affection we are surprised to find in the ed i tions of the Theari e a n al yti qu e des probabi li tés which appeared after the Restoration that the original dedication to the e mperor is suppresse d Though supple and servile in politics it m ust be said that in religion and science Laplace never m isrepresented or concealed his own con vi c t i on s however distasteful they m ight be to others In m athem atics and astronomy his genius shines with a lustre excelled by few Three — great works did he give to the scientific world the M écani qu e C el este the E xposi ti on du systeme du monde and the Theori e an al yti qu e des probabi l i tes B esides these he contributed important m emoirs to the French Academ y We first pass in brief review his astronom ical researches In 1 773 he brought out a paper in which he proved that the m ean m otions or m ean distances of planets are invariable or m erely subj ect to s mall periodic changes This was the first and m ost i mportant step in his 1 attempt to establish the stability of the solar system To I Newton and also to L Euler it had seemed doubtful whether forces so nu mer ous so variable in position so diff erent in intensity as those in the solar system could be capable of maintaining perm anently a con dition of equilibriu m Newton was of the opinion that a powerful hand m ust intervene from tim e to tim e to repair t h e derangem ents occa s i on ed by the m utual action of the d i ff erent bodies This paper was the begin n i ng of a series of profound researches by J Lagrange and an d , , , . , . , ’ , . , . , ’ , , ” ’ ’ . , . , , . . . ’ , - . . , ’ , . , , . . , , , ’ . . . . . . . , , , , . . 1 D . Repor t, F . J A rag o . 1 8 74 . , Eu l ogy on L ap l ac e , ” t ran sl a ted by B . . P ow e l l , S mi ths on i a n A HI STORY OF M ATHE M ATI C S 262 — of celestial m otions treating particularly of m otions of com ets of our moon and of other satellites The fif th volum e opens with a brief history of celestial m echanics and then gives in appendices the results of the author s later researches The M ecani qu e C él este was such a master piece and so co mplete that Laplace s immediate suc The general part of c essor s were able to add co mparatively li ttle the work was translated into Germ an by Johann K arl B u r khardt — 1 and appeared in B erlin 0 1 80 2 1 8 0 N a tha n i el B owdi tch ( 7 73 — 1 brought out an edition in Engli sh with an extensive com ( 773 1 83 8 ) — m enta ry i n B oston 1 8 2 9 1 839 The M écan i qu e C el es te is not easy reading The diffi culties lie as a rule not so m uch in the subject itself as in the want of verbal explanation A complicated chain of reasoning receives often no explanation whatever J B B iot who assisted Laplace in revising the work for the press tells that he once asked Laplace som e explanation of a passage in the book which had been written not long before and that Laplace S pent an hour en deavor ing to recover the reasoning which had been carelessly suppressed ” m m l i the re ark est facile de voir Notwithstanding the i por I w th tant researches in the work which are due to Laplace him self it naturally contains a great d eal that is d rawn fro m his predecessors It is in fact the organiz ed result of a century of patient toil B ut Laplace frequently neglects properly to acknowle dge the source fro m which he draws and lets the reader infer that theorem s and formul a: due to a pred ecessor are really his own We are told that when Laplace presented Napoleon with a copy “ of the M écan i qu e Cel este the latter m ade the rem ark M Laplace they tell m e you hav e written this large book on the syste m of the universe and have never even m entioned its Creator Laplace is said to have replied bluntly Je n avais pas besoin de cette hy o th és e— la This assertion taken literally is i mpious but may it p not have been inten d ed to conv ey a meaning som ewhat diff erent from its literal one ? I Newton was not able to explain by his law of gravitation all questions arising in the m echanics of the heavens Thus being unable to show that the solar syste m was stable and suspecting in fact that it was unstable Newton expresse d the opinion that the special intervention from time to tim e of a powerful hand was necessary to preserve order Now Laplace thought that he had proved by the law of grav itation that the solar system is stable and in that sense may be said to have felt no necessity for reference to the Al mighty We now proceed to researches which belong m ore properly to pure m athem atics Of these the m ost conspicuous are on the theory of probability Laplace has done more towards advancing this subject than any one other in v est i gator He publ i she d a series of papers the m ain results of which were collecte d in his Theori e a n al yti qu e des r obabi l i tes 1 8 1 2 i 1 8 20) The thir d e d tion consists of an introduction ( p , , . , , ’ ’ . ’ - , , . . , , , . , . , , . . . , . , , “ , , . , , . . , , , . , , , . , ” . ” “ ’ , . , , , . . , , , , , . , . . . . , ’ ’ , . EULER LAGRANGE AN D , LAP LACE 2 63 and two books The introduction was published separately under the title E ssai phi l osophi qu e su r l es pr obabi l i tés and is an ad mirable and masterly exposition without the aid of analytical form ul a of the principles and applications of the science The fir st book contains the theory of generating functions which are appli ed in the second book to the theory of probability Laplace gives in hi s work on p robabi l i ty hi s me thod of approxi mation to th e values of definite integrals The solution of linear diff erential equations was reduced by him to definite i ntegrals The use of parti al d ifference equations was introduced into the study of probability by him about the same time as by J Lagrange One of the most importa nt parts of the work is the application of probability to the method of lea st squares which is shown to give the m ost probable as well as the most convem i en t results Laplace s work on probabili ty is very diffi cult reading particularly the part on the method of least squares The analytical processes “ are by no means clearl y established or free fro m error N 0 one was more sure of giving the result of a nalytical processes correctly and no one ever took so little care to point out the various s ma l l con siderations on which correctness depends (D e M organ ) Laplace s comprehensiv e work contains all of his own researches and m uch derived from Other writers He giv es m asterly expositions of the P roblem of P oints of Jakob B ernoulli s theore m of the problem s ta ken from B ayes and Count de B u ff on In this work as in his M écani qu e C el este Laplace is not in the habit of giving due credit to writers that 1 preceded hi m A D e M organ says of Laplace : There is enough originating from him self to m ake any reader wonder that one who could so well aff ord to state what he had taken fro m others should have set an example so dangerous to his own clai ms Of Laplace s papers on the attraction of el l ipsoids the m ost im portant is the one published in 1 7 8 5 and to a great extent reprinted in the third volum e of the M écan i qu e C el este I t gives an exhaustive treatment of the general problem of attraction of any ellipsoid upon a particle S ituated outside or upon its surface Spherical harm onics or the so called Laplace s coeffi cients constitute a pow erful analytic engine in the theory of attraction in electricity an d m agnetism The theory of spherical harmonics for two di mensions had been previously given by A M Legendre Laplace failed to m ake due ack n ow l edg m ent of this and there existed in consequence between the two “ great men a feeling more than coldness The potential function V is m uch used by Laplace and is S how n by h im to satisfy the partial . - , , . , , , . ' . . . . , . ’ , . . , ” ’ . . ’ , , . , . . ” , . ’ , , . ” ’ - , . , , . ” . . , , , , , . , —17 7 , 2 diff erential equation 5 V hat 1 2 1 A D e M or g an , A n E ssay p I I o f A pp e n di x I 1 . . . , . 2 5 V 3 on 2 a V ?a 0. This is know n as Laplace s P r oba bi li ti es , L on do n , ’ 1 838 ( d at e of P r e fac e ) A HI STORY OF M ATHE M ATIC S 2 64 equation and was first giv en by hi m in the more complicated form whi ch it assu m es in polar co ordinates The notion of potential was however not introduced into analysis by L aplace The honor of t hat achievement be l ongs to J Lagrange Regarding Laplace s equation P E P icard said in 1 90 4 : Few equations have been the object of so many works as this celebrated equation The conditions at the limits may be of divers forms The simplest case is that of the calorifi c equilibriu m of a body of which we m ainta in the elements of the surface at given temperatures ; from the physical point of view it may be regarded as evident that the temperature continuous wi thin the interior since no source of heat is there is determined when it is given at the surface A m ore general case is that where the temperature may be giv en on one portion wh ile there is radiation on another portion These questions have greatly contributed to the orientatio n of the theory of partial diff erential equations They have called attention to types of deter mi n at i on s of integrals which would not hav e presented themselves 1 in remaining at a point of view purely abstract Am ong the m inor discoveries of Laplace are his m ethod of solving equations of the second third and fourth degrees his memoir o n singular solutions of di fferential equations his researches in finite differences and in determ inants the establishm ent of the e xpansion theorem in determ inants which had been previously given by A T V an dermon de for a sp ecial case the deter m ination of the co mplete integral of the linear differential equation of the second order In the M écani que C él este he m ade a generali z ation of Lagrange s theorem on the develop m ent of functions in series known as Laplace s theorem Laplace s investigations in physics were quite extensive We m en tion here his correction of Newton s form ula on the velocity of sound in gases by taki ng into account the changes of elasticity due to the heat Of compression and cold of rarefact ion ; his researches on the theory of tides ; his m athe m atical theory of capillarity ; his explanation of astronom ical refraction ; his formul a for m easuring heights by the barom eter Laplace s writings stand out in bol d contrast to those of J Lagrange in thei r lack of elegance and symm etry Laplace looked upon mathe ma ti cs as the tool for the solution of physical problems The true result being once reached he devoted little tim e to explaining the various steps of his analysis or in polishing his work The last years of his life were spent m ostly at Arcueil in peaceful retirem ent on a country place where he pursued his studies with his usual vigor until his death He was a great adm irer of L Euler and would often “ say Lise z Euler lisez Euler c est notre m ai tre a tous The latter part of the eighteenth century brought forth researches on the graphic representation of im aginaries all of which remained , - . , , . . . ’ . , . . . , , . , , . ” . , . , , , , , . . , . ’ ’ . ’ . ’ . ’ . . . , . , - , . . , ’ , . , , , 1 Congr ess f o A r ts an d S ci en ce, S t L ou i s , . 1 90 4 , V ol I , p 50 6 . . . A HI STORY OF M ATHE M ATIC S 2 66 the Aca demy of Sciences on M arch 1 9 1 7 91 by a committee con sisting of J C Borda J Lagrange P S Laplace G M onge de Con dorce t This subdivision is found in the Fran coi s Cal l et ( 1 744—1 798) logarithm ic tables of 1 795 and other tables published in France and Germany Nevertheless the decimal subdivision of the quadrant did 1 not then prevail The com m ission composed of B orda Lagrange Laplace M onge and Condorcet decided upon the ten m ill ionth part of the ear th s quadrant as the primitive unit of length The leng th of the second s pendulum had been under consideration but was finally rejected because it rested upon two dissimilar elem ents gravity and tim e In 1 799 the m easurem ent of the earth s quadrant was completed and the m eter established as the natural unit of length Al e xan dre Th eoph i l e Van d ermon d e ( 1 7 3 5— 1 7 96 ) studied music during his youth in P aris and advocated the theory that all art rested u pon one general law through which any one could becom e a c om poser with the aid of m athem atics He was the first to giv e a con n e c t ed and logical exposition of the theory of determ inants and may therefore almost be regarded as the founder of that theory He and J Lagrange originated the m ethod of co mbinations in solving equations A dri e n M ar i e L e g e n dre ( 1 7 5 2 — 1 8 33) was educated at the Col l ege M azarin in P aris where he began the study of m athem atics under Abb é Joseph F ran coi s M arie ( 1 73 8 His m athem atical genius secured for him the position of professor of m athematics at the mili ta ry school of P aris While there he prepared an essay on the curv e described by projectiles thrown into resisting m edia (ballistic curve) which captured a priz e o ff ered by the Royal Academy of B erlin In 1 7 8 0 he resigned his position in order to reserve m ore ti m e for the study of higher mathem atics He was then m ade m ember of several public comm issions In 1 7 95 he was elected professor at the Norm al School and later was appointed to some m inor govern m ent positions O w ing to his timidity and to Laplace s unfriendliness toward him but few important public offices comm ensurate with his abili ty were ten dered to h im As an analyst second only to P S Lap l ace and J L agrange Legen dre enriched mathem atics by i mportant contributions mainly on elliptic integrals theory of numbers attraction of ellipsoids and least squares The most im portant of Legendre s works is his Foncti ons el l i pti q u es issued in two volu m es i n 1 8 2 5 and 1 8 2 6 He took up the subj ect where L Euler John Landen and J Lagrange had left it and for forty years was the only one to cultivate this new branch of analysis until at last C G J Jacobi and N H Abel steppe d in with 2 a dm irable new discoveries Legendre imparted to the subj ect that , . . . , . , , , . . , . , . . , , - , ’ . ’ , , , ’ . . - ' , . , , , . . . , . , . . . . ’ , . , . . , . , , , , ’ . , . , . . , . , . , . . . . 1 pp . For de t ai l s , 1 38 —1 6 3 se e R M eh m k e i n J . ahres b . z d d M a th Verei n i g u ng , L ei p i g , . . . 1 900 , . M El i e de B e au mon t , S mi thson i a n Repor t, 1 8 6 7 2 . . M emo i r of L eg en dre . T r an sl a t ed by C A A l exan d e r, . . EULER LAGRANGE AND LAP LACE 67 , connection and arrange ment which belongs to an independent science S tarting with an integral d epen ding upon the square root of a poly nom ial of the fourth degree in x he S howed that such integrals can be brought back to three canonical forms designated by F and . , , He also undertook the prodigious task of calculating tables of arcs of the ellipse for diff erent degrees of amplitude and eccentricity which supply the m eans of integrating a large number of diff erentials An earlier publication which contained part of his researches on elliptic functions was his C al cu l i n tegr al in three volum es ( 1 8 1 1 1 8 1 6 in which he treats also at length of the two classes of definite integrals named by him E u l eri a n He tabulated the values of log I (p) for values of p betw een 1 and 2 One of the earliest subj ects of research was the attraction of sph e roi ds which suggested to Legendre the function P " nam ed after him His m em oir was presented to the Academ y of Sciences in 1 7 8 3 The researches of C M acl aurin and J Lagrange suppose the point a t tracted by a spheroid to be at the surface or within the spheroid but Legendre showed that in order to d eterm ine the attraction of a spheroid on any external point it suffi ces to cause the surface of ano ther spheroid described upon the sam e foci to pass through that point Other m e moirs on el lipsoids appeared later In a paper of 1 7 88 Legen d re published criteria for distinguishing between m axim a and m inima in the calculus of v ariations which were show n by J Lagrange i n 1 7 97 to be i n sufli c i en t ; this matter was set right by C G J Jacobi in 1 83 6 The two household gods to which Legendre sacrificed with ever renewed pleasure in the silence of his closet were the elliptic functions and the theory of numbers His researches on the latter subject together with the nu m erous scattered fragm ents on the theory of num bers du e to his predecessors in this line were arranged as far as possible into a system atic whole a n d publishe d in two large quarto volum es entitled Thear i e des n ombr es 1 8 30 B efore the publication of this work Legendre had issued at d ivers tim es prelim inary articles Its crowning pinnacle is the theorem of quadratic reciprocity pre v i ou sl y in d istinctly given by L Euler without proof but for the first 1 tim e clearly enunciated an d partly proved by Legendre While acting as one of the comm issioners to connect Greenwich and P aris geodetically Legendre calculated the geodetic triangles in France This furnished the occasio n of establishing form ula an d theorem s on geodesics on the treatment of the S pherical triangle as if it were a plane triangle by applying certain corrections to the angles and on the m ethod of least squares published for the first tim e by hi m without d e monstration in 1 80 6 , . , , . ‘ . , . , . . . , . . , ‘ . . . . . . , , , , . , . , . , . , . , , , , . 1 O B au m g ar t , Ueber . aas Quadrati sche z R eci pr oci l a l s g cs etz, L e ip ig , 1 88 5 . A HI STORY OF M ATHE M ATIC S 2 68 Legendre wrote an El emen ts de Géometri e 1 794 which enjoyed great popularity being generally adopted on the Continent and in the United States as a substitute for Eucli d This great modern rival of Eucli d passed through num erous e ditions ; som e containing the ” 2 elements of trigonometry and a proof of the irrationality of 71 and 71 “ With prophetic vision Legendre remarks : I l est mem e probable que l e nom bre 7r n est pas mem e comp ris dans les i r ra ti on ell e s algébriques c est a— di re qu il n e peut pas etre la racine dune équation algébrique d un nombre fi n i de term es dont les c oefi c i en t s sont ra ti on el s M uch attention was given by Legendre to the subj ect of parallel lines In the earlier editions of the El emen ts he m ade direct appeal to the “ senses for the correctness of the parallel axio m He then attempted “ to dem onstrate that axiom but his proofs did not satisfy even him self In Vol XII of the M em oirs of the Institute is a paper by Legendre containing his last attempt at a solution of the problem Assum ing space to be infinite he proved satisfactorily that it is i m possible for the su m of the three angles of a triangle to exceed t w o right angles ; and that if there be any triangle the s u m of whose angles is two right angles then the sam e m ust be true of all triangles B ut in the next step to S how that this s u m cannot be less than two right angles his demonstration necessarily failed If it could be granted that the su m of the three angles is always equal to two right angles then the theory of parallels could be strictly d e duced Another author who made contributions to elem entary geom etry was the Italian L orenzo M ascheron i ( 1 750 He publ i shed his 1 Geometri a del compass o (P avia 1 7 97 P alerm o 1 90 3 ; French editions by A M Carette appeared in 1 7 98 and 1 8 2 5 a Germ an edition by All constructions are m ade with a pair of J P Gruson in co mpasses but without restriction to a fixed radius He proved that all constructions possible with ruler and compasses are possible with compasses alone I t was J V P oncelet who proved in 1 8 2 2 that all such construction are possible with ruler alone if we are given a fixed circle with its centre in the plane of construction ; A Adler of Vienna proved in 1 8 90 that these constructions are possible with ruler alone whose e dges are parallel or whose e dges converge in a point M asch eron i clai m ed that constructions with co mpasses are m ore accurate than those with a ruler Napoleon proposed to the French m athe ma ti ci an s the problem to divide the circu m ference of a circle into four equal parts by the co mpasses only M ascheroni does this by applying the radius three tim es to the circu mference ; he obtains the arcs A B B C C D ; then A D is a diameter ; the rest is obvious E W Hobson (M ath Gazette M arch 1 1 9 1 3) a n d others have shown that all Euclidean constructions can be carried out by the use of compasses alone ’ , , , . ’ . ’ , ’ - ” ’ ’ . ” , ” - . . , . . , . , , . , . , , . , , . , , . . . . , . . . , . . , . , . - , . . , . . , , . 1 Vo l A l ist . 1 9, of M ascheron i 19 1 2, p 92 . . s w r i t i ng s i s g i ve n i n L I n ter médi ai r e des mathéma ti ci ens , ’ A HI STORY OF M ATHE MA TIC S 2 70 tions are form ed by giving each fraction a negativ e coeffi cient in an equation for its nu merator taken positively and for its deno minator the su m of the positive coeffi cients preceding it if moreover unity is added to each fraction thus formed then the largest nu mber thus obtainable is larger than any root of the equation In 1 8 2 2 A A Vene a French ofli cer of engineers S howed :If P is the largest negative c oefli c i en t and if S be the greatest coeffi cient among the positive term s which precede the first negative term then will P + S + I be a superior limi t Fourier took a prominent part at his home in promoting the Revo l u ti on Under the French Revolution the arts and sciences seem ed for a tim e to flourish The reform ation of the weights and m easures was planned with grandeur of concep tion The Normal School was created in 1 795 of which Fourier becam e at first pupil then lecturer His brilliant success secured hi m a chair in the P olytechnic School the duties of which he afte rw ards quitted along with G M onge and C L B erthollet to acco mpany Napoleon on his ca mpaign to Egypt Napoleon founded the Institute of Egypt of which J Fourier becam e secretary In E g ypt he engaged not only in scientifi c work but dis charged i mportant poli tical functions After his return to France he held for fourteen years the prefecture of Grenoble D uring this period he carried on his elaborate investigations on the propagation of heat in soli d bodies published in 1 8 2 2 in his work entitled L a Theor i e A n al yti qu e de l a Chal eu r This work m arks an epoch in the histo ry of both pure and applied m athem atics I t is the source of all moder n m ethods in m athem atical physics i nvol v ing the i n tegration of partial diff erential equations in problem where the boundary values are s fixed ( boun d ary value problem s P roble m s of this type involv e L Euler s second definition of a function in which the relation is not necessarily capable of being expressed analytically This concept of a function greatly influenced P G L D irichlet The g em of “ F ou ri er s great book is F ou ri er s series By this research a long controversy was brought to a close and the fact recogniz ed that any arbitra ry function (i e any graphically given function ) of a real variable can be represented by a trigonom etric series The first announcement of this great discovery was m ade by Fourier in 1 80 7 , , , , . , . . , , , . . . . , . , , . , . . . , . , , . ; . . , . . “ ” ’ - ’ . . . ’ . . . ’ - . , . . . , n before the French Academy bn cos )represents nx coefficients an = . The trigonom etric series the function p( )i < x S n n xdx , )for qb (x and b7, = a) 2 (a,, eve ry value of sin x, n x+ if be equal to a similar the in The weak point in F o u r i er s analysis lies in his failure to prove generally that the tr i gonom etri c series actually converges to t e g ra l ’ . EULER LAGRANGE AN D , LAP LACE 2 7: the value of the function William Thomson (l ater L ord Kelvi n ) “ says that on M ay 1 1 840 (when he was only six teen ) I took Fourier out of the University L ibrary ; and in a fortnight I had mastered i t gone righ t th ro ugh it Kelvin s whole career was in fl uenced by “ F ouri er s work on hea t of which he said it is diffi cult to say whether their uni q uel y original quality or their transcendant interes t or their perennially importa nt instructiveness for physical science is most 1 to be p raised Clerk M a xwell pronounced it a grea t ma thematical In 1 8 2 7 F ourier succeeded P S Lapla ce as president of the poe m council of the P olytechnic School About th e time of B udan and Fourier i mporta nt devices w ere invented in I taly and England for the solution of num erical equations The I talian scientific society in 1 80 2 off ered a gold m edal for improve ments in the solution of such equations ; it was awarded in 1 80 4 to P aolo R ufli n i With aid of the calculus he develops th e t heo ry of transforming one equation into another whose roots are all di m in ished 2 by a certain constant Then follows the m echanism for the practical computer and here Ruffi ni has a device which is simpler than Horner s scheme of 1 8 1 9 and practically identical with what is now known as Horner s procedure Horner had no knowledge of Ruffi ni s m em oir Nor did either Horner or R ufli n i kno w that their m ethod had been given by the Chinese as early as the thirteenth century Horner s first paper was read before the Royal Society J uly 1 1 8 1 9 and pub l ish ed in the P hi l osophi cal Tr an s acti on s for 1 8 1 9 Horner uses L F A A rb og aSt s derivatives The moder n reader is surprised to find that Horner s exposition involves very intricate reasoning which is in m arked contrast with the S imple and ele mentary explanations found in modern texts P erhaps this was fortunate ; a simpler treatm ent m ight have prevented publication in the P hilosophical Transactio n s “ As it was much de m ur was made to the insertion of the paper The “ elementary character of the subject said T S Davies was the professed objection ; his recondite m ode of trea ting it was the profess ed passport for its ad mission A second article of Ho m er on his m ethod was refused publication in the P hilosophical Transactions and ap m r ed i n 1 7 6 5 in the M a thema ti ci a n after the death of Ho er a ea ; p third article was printed in 1 8 30 Both Ho mer and Ruffi ni explained their m e thods at first by higher analysis and l ater by elem en ta ry al gebra ; both o ffered their m ethods as substitutes for the old process of root extraction of nu mbers R ufli n i s paper was neglected and forgotten Horner was fortunate in finding two in fluential champions — — of Belfast and A of his m ethod John Radford Young ( 1 7 99 1 88 5) D e M organ The R uffi n i Horner process _has been used widely in England and the United States less widely in Germ any Austria and . ” , , ’ - . ’ , , , , ” , , . . . . . , . . . ’ , ’ ’ . . ’ . , , , . . . . ’ . ’ . ” , ” . . . , , . . , , . ’ - . . . - . , , S P Thomp so n L ife of Wi l l i a m Thoms on , L o n do n , 1 9 1 0 , pp 1 4 , 6 89 2 S ee F C a o r i x i ma t i o n a n ti c ip a ted b y R u ffi n i , j , H o rn er s m e t hod o f app ro— A m M a th S oc 2 d S , V ol 1 7 , 1 9 1 1 , pp 409 4 1 4 1 . . . ’ . . . . . . . . . B u ll . A HI STORY OF M ATHE M ATIC S 2 72 I taly and not at all in France In France the Newton Raphson 1 m ethod has held al m ost undisputed sway Before proceeding to the origin of m odern geom etry we shall speak briefly of the introduction of higher analysis into Great B ritain This took place during the first quarter of the last century The B ritish began to deplore the very s mall progress that science was m aking in England as co mpared with its racing progress on the Continent The first Englishman to urge the study of continental writers was Robert — Woodhou se ( 1 7 73 1 8 2 7 ) of Caius College Cambridge In 1 8 1 3 the Analytical Society was form ed at Cambridge This was a s mal l club established by George P eacock John Herschel Charles Babbage a n d a few other Ca mbridge students to pro m ote as it was hu m orously expressed by B abbage the principles of pure D i sm that is the Leibniz ian notation in the calculus against those of dot— age or of the Newtonian notation This struggle ended in th e introduction - , . . . . . ” “ . , . , , , ” , - , , , . into Cambridge of the notation to the exclusion of the fl ux ion al nota tion y This was a great step in advance not on acco unt of any great superiority of the Leibniz ian over the Newtonian notation but because the adoption of the form er opened up to English students the v ast storehouses of continental discoveries Sir William Thom son P G Tait and som e other m odern writers find it frequently con Herschel P eacock and B abbage v en i en t to use both notations translated in 1 8 1 6 from the French S F Lacroix s briefer treatise on the d i fferential and integral calculus and added in 1 8 20 two volu mes of exa mples Lacroix s larger work the Tr ai l e du cal cu l “ difi ér en ti el et i n tegr a l first contained the term di fferential coeffi cient “ and definitions of definite and indefinite integrals I t was one of the best an d most extensive works on the calculus of that tim e “ Of the three founders of the Analytical Society P eacock afterw ards did m ost work in pure m athem atics B abbage becam e famous for his i n v ention of a cal culating engine superior to P ascal s It was nev er finished owi ng to a m isunderstanding with the governm ent John Herschel the em inent a n d a consequent failure to secure funds astronom er displayed his m astery ov er hi gher analysis in m em oirs comm unicated to the Royal Society on new app l ications of m athe mat i cal analysis and in articles contributed to c yc l op a dias on light on m eteorology and on the history of m athe m atics In the P hilo 1 sophical Transactions of 1 8 1 3 he introduced the notation si n x —1 2 2 for arcsi n x ar ctan x He wrote also l og x cos x tan x for l og (l og x)cos (cos x) but in this notation he was anticipated by Heinrich B u rm an n of M annhei m a partisan of the c om 1 8 1 7) bi n at ory analysis of C F Hindenburg in Germ any F ef s d f ther d e tai l see C l r d C l l g P bl i cati o Ge n al S e i s ’ . , , . , . , . , . , ’ , , . . , ” , ’ ' ” . , ’ , . ” . , . ’ . , , , . , , , . , ‘ , , , , , , , - , . 1 or r e r en ce an ur . . , o o a o o e e u n, er r e A HI STORY OF M ATHE M ATIC S 2 74 undisputed supre macy It was reserv ed for the genius of G M onge to bring synthetic geom etry in the foreground and to open up new avenues of progress His Géométr i e descr i pti ve marks the beginning of a wonderful develop m ent of modern geom etry Of the two leading problems of descriptive geometry the one—to — represent by drawings geometrical m agnitudes was brought to a — h m M high degree of perfection before t e ti e of onge ; the other to solve proble m s on figures in space by constructions in a plan e —had recei v ed considerable attention before his ti m e His most noteworthy predecessor in descriptive geometry was the French man Amedee F ra n goi s F réz i er ( 1 6 8 2 B ut it re mained for M onge to create descriptive geo metry as a di sti n ct branch of science by imparting to it geometric generalit y an d elegance All problem s previously treated in a special an d uncertain m anner were referred back to a few general principles He intro d uced the line of intersection of the horiz ontal and the v ertical plane as the axis of projection By revolving one plane into the other around this axis or ground line m any advantages 1 were gained G as par d M o n g e ( 1 7 4 6 —1 8 1 8 ) was born at B eaune The constru o tion of a plan of h i s nat i v e tow n brought the boy under the notice of a colonel of engineers who procured for him an appointm ent in the college of eng i neers at M ez ieres B eing of low birth he could not recei v e a commiss i on in the army but he was permitted to enter the annex of th e school where surveying an d drawing were taught O b serv ing that all the O perations connected with the construction of p l ans of fortification were conducte d by long arithm etical processes he subs t ituted a geom etrical m ethod which the comm andant at first refused e v en to look at ; so short was the tim e in which it could be practised that when once exam ined i t was recei v e d with avidity M onge d eveloped these m etho d s further and thus created his d es cr i p tive geom etry Owing to the riv alry between the French m il i tary schools of that time he was not perm itte d to divulge his n ew m e tho d s to any one outsi de of this institution In 1 76 8 he was made professor of m athem atics at M ez i eres In 1 7 80 when convers i ng with two of his pup i ls S F Lacroix an d S F Gay de Vernon in P aris he was obliged to say Al l that I hav e here done by calculation I could have done with the ruler and compasses but I am not allowed to reveal these secrets to you B ut Lacroix set him self to exam ine what the secret could be d iscovere d the processes an d published the m I n 1 7 95 The m ethod was publ i shed by M onge him self in the sam e year first in the form in which the shorthand writers took dow n his lessons give n at the Norm al School where he had been elected professor and then again in re vised form in th e Jou r n al des écotes n or mal es The next — e dition occurre d in 1 7 98 1 7 99 After an ephe m eral existence of only four m onths the Norm al School was clo sed in 1 7 95 In the sam e year t ll d C h i ti Wi L h b hd D G m t i c L e ip z i g 8 84 p 2 6 . . , . . , . . . . - , . . , . , , . , , , . , , . , . . , . . , . , . , , ” , . , , . , , , , , . . . 1 r s an en e r, e r uc er ars e en en eo e r , , 1 , . . EULER LAGRANGE LA P LACE AN D , 2 75 the P olytechnic School was opened in the establishing of which M onge took acti v e part He taught there descriptive geometry un til his departure from France to accompany Napoleon on the E g yptian campaign He was the first president O f the Institute of Egypt M onge was a z ealous partisan of Napoleon and was for that reason deprived of all his honors by Louis XVIII This and th e destruction of the P olytechnic School preyed heavily upon his mi nd He did not long surv i v e this insult M onge s num erous papers were by no means confined to descriptive geom etry His analytical discoveries are hardly less remarkable He introduced into analytic geomet ry the m ethod ic use of th e equation of a line He made important contributions to sur faces of the second degree ( previously studied by C Wren and L Euler ) and discovered between the theory of surfaces and the integration of partial d iffer e n t i al equations a hidden relation whi ch threw new light upon both subjects He gave the diff erential of curves of curvature esta blished a general theory of curvature and applied it to the ellipsoid He found that the validity of S olutions was not im paired when imaginaries are involved a mong subsidiary quantities Usually attributed to M onge are the centres of si militude of circles and certain theorem s 1 which were however probably kno w n to Apollonius of P erga M onge published the following books : S tati cs 1 7 8 6 ; A ppl i cati on s de l al gebr e The last a l a geometri e 1 80 5 ; A ppl i ca ti on de l a n al y se a l a geometri c tw o contain most of his m iscellaneous pap ers M onge was an inspiring teacher an d he gathered around hi m a large circle of pupils a mong which were C D upin F S ervoi s C J B rian chon Hachette J B B iot and J V P once l et J ea n B apti s te B i ot ( 1 7 7 4 professor at the Coll ege de France in P aris cam e in contact as a young man with Laplace Lagrange and M onge In 1 80 4 he ascended with Gay Lussac in a balloon They proved that the earth s magnetism is not appreciably reduced in intensity in regions above the earth s surface B iot wrote a pop ular book on analytical geometry and was activ e in m athem atical physics and geodesy He had a controv ersy wi th Arago who championed A J Fresnel s wave theory of light B iot was a man of strong individuali ty and great influence Ch ar l e s D u pi n ( 1 7 84 for many years professor of mechanics in the Conservatoire des Arts e t M étiers in P aris published in 1 8 1 3 an important work on Dével oppements de geometri c in which is i ntro d uc ed the conception of conj ugate tangents of a point of a surface “ 2 and of the indicatrix I t contains also the theorem known as D u pin S theorem Surfaces of the second d egree and descriptive geom , . . . . , , . . . ’ . . . . . , . , . , . , , . , ’ , ’ ’ , . . , , , . , . . . , . , . , . . . , . , , - . ’ ’ . . . . ’ . . , , ” ’ , . . 1 R C A r chib al d i n A m M a th M on thl y, V o l . 161 . . . . 2 2, 191 5, — 1 2 ; V ol 6 pp . . G i n o L o r i a , D i e H a u ptsachl i s ten Theori en der Geometr i c 1 888 , p 49 2 . . . 23 , pp . 1 59 ( F S c h ut t e)L e ipz ig . , , O F M ATHE M ATIC S HI STORY A 2 76 were successfully studied by J ean N i col as P i erre H ochette ( 1 76 9 who be ca m e p rofessor of descriptive geometry at the P oly technic School after the departure of M onge for Rome and Eg yp t In 1 8 2 2 he published hi s Tr ai té de g éométri e descri pti ve D escriptive geom etry which arose as we have seen in technical schools in France was transferred to Germany at the foundation of technical schools there G Schreiber ( 1 7 99 professor in Karls ruhe was the first to spread M onge s geometry in Germany by the 1 — publica tion of a work thereon in 1 8 2 8 1 8 2 9 In the United S tates descriptive geo m etry was introduced in 1 8 1 6 at the M ilitary Academy in West P oint by Claude Croz et once a pupil at the P olytechnic 2 School in P aris Croz et wrote the first English work on the subj ect — z r t La ar e N i ch o l a s M ar gu e i e C arn ot ( 1 7 53, 1 8 2 3)was born at Nolay in B urgundy an d educated in his native province He entered the army but continued his mathe m atical studies and wrote in 1 7 84 a work on m achines containing the earli est proof that kinetic energy is lost in collisions of bodies Wi th the advent of the Revolution he threw him self into politics and when coalesced Europe in 1 793 l aunched against Fr ance a m illion sol diers the gigantic task of or g an iz i n g fourteen arm ies to m eet th e ene m y was achieved by hi m He was banishe d in 1 7 96 for opposing Napoleon s cou p d etat The refugee went to Geneva where he issued in 1 7 97 a work still tre quently quoted entitled Refl exi on s s u r l a M étaphysi qu e du C al cu l I nfi ni tes i mal He declared hi mself as an irreconcilable enemy of kings After the Russian campaign he off ered to fight for France though not for the em pire On the restoration he was exiled He died in M agdeburg His Geométri e de posi ti on 1 80 3 and his Essay on Tr ansvers al s 1 80 6 are i mportant con tributions to m odern geometry While G M onge revelled m ainly in three dim ensional geom etry Carnot co n fined him self to that of two By his e ffort to explain the “ meaning of the negative S ign in geo m etry he established a geom etry “ of position which however is diff erent from the Geometrie der Lage of to day He invented a class of general theorem s on pro j e c tiv e properties of figures which have since been pushed to great extent by J V P oncelet M ichel Chasles and others 3 “ Thanks to C arn o t s researches says J G D arb oux the con c ep t i on s of the inventors of analytic geo m etry D escartes and F erma t retook alongside th e infinitesim al calculus of Leibniz and Newton the place they had lost yet should never have ceased to occupy With his geom etry said Lagrange speaking of M onge this dem on of a man wi ll m ake him self imm ortal While in France th e school of G M onge was creating m odern e t ry . . , , , , . . . ’ , , . . . , , , , . , , , , . ’ ’ . , , , ’ , ” . , ’ . . , . . ’ , . , , . , - . , . ” , , , - . , . . . , , ’ . . , , , , . ” , , , , . . 1 2 pp . 3 C F . . Wi en er , C aj o ri , 1 14, ci t p 36 Teachi ng and Hi s tor y p o . . . . f M athema ti cs in U S o . . , 1 17. Congress f o A r ts a nd S ci en ce, S t L o u i s , . 1 90 4 , V ol . 1, p 53 5 . . Wa shi ng ton , 1 8 90 , THE NINETEENTH AND TWENTIETH CENT URIES I n trodu cti on N EVE R more z ealously and successfully has mathematics been cultivated than during the nineteenth and the present centuries Nor has progress as i n previous periods been confined to one or two countries While the French and Swiss who during the preceding epoch carried the torch of progress have continued to develop ma the m a t ic s with great success from other countries whole armies of en thu s i as t i c workers have wheeled into the front rank Germ any awoke from her lethargy by bringing forward K F Gauss C G J Jacobi P L D irichlet and hosts of m ore recent men ; Great B ritain produced her A D e M organ G Boole W R Hamilton A Cayley J J Sylvester besides champions who are still living ; Russia entered the arena with her N I L ob achevs ki ; Norway with N H Abel ; I taly with L Crem ona ; Hungary with her two B olyais ; the United S tates with B enja m i n P eirce and J Willard Gibbs H S White of Vassar College estim ated the annual rate of increase in m athem atical publication from 1 8 70 to 1 90 9 and ascertained the periods betwee n these years whe n diff erent subj ects of research r e 1 Taking the Jahrbu ch ii ber di e Fort c ei v ed the greatest e m phasis s chr i tte der M a themati k published since 1 8 7 1 ( founded by Carl Ohrt m ann ( 1 83 9— 1 88 5) of the Konigliche Realschule in B erlin and S ince 1 8 8 5 under the chief editorship of E m il Lampe of the technische Hochschule in B erlin )and also the Revu e S emes tri el l e published since 1 8 93 ( un d er the auspices of the M athe m atical Society of Am sterda m) he counted the nu mber of titles and in som e cases also the number of pages fille d by the reviews of books and articles devoted to a certain subj ect of research and reached the following approximate results : The total annual pub licat i on double d during the forty years ; (1) D uring these forty years 30 % of the publication was on applied (2) m athem atics 2 5 % on geo m etry 2 0 % o n analysis 1 8 % on algebra Geo m etry dominated by P l ii ck er 7 % on history and philosophy ; 3 ) his brilliant pupil Klein Clifford and Cayley doubled its rate of production from 1 8 7 0 to 1 890 then fell off a third to regain m ost of its loss after 1 8 99 ; Synthetic geom etry reached its m axi mum in 1 88 7 and then declined during the following twenty years ; the a mount of anal ytic geometry al w ays exceeded that of synthetic geometry the . , , . , , , . . . . , . . , , . . . . . . , , . . , . , , . . . . . . . . . , . , , , , , , , , , , ” , , , , , , , , , H S Wh i t e , F or ty Y ears F l uc t u a t i on s i n M a t hema t i c al R esea r ch , N S , V o l 4 2 , 1 9 1 5 , pp 1 0 5 1 1 3 ’ 1 . . . — . . . . S ci ence, INTRODUCTION 2 79 excess being most pronounced since 1 88 7 ; (4 ) Analysis which takes i t s rise equally fro m calculus fro m the algebra of i maginaries fro m the intuitions and the critically refined develop ments of geom etry and from abstract logic : the common servant and chief ruler of the other branches of m athem atics shows a trebling in forty years reaching “ its first m aximu m in 1 890 probably the culmination of waves set in m otion by Weierstrass and Fuchs in B erlin by Riemann in G ot tingen by Hermite in P aris M ittag L effi er in S tockh ol m D ini and B rioschi in I taly ; before 1 88 7 m uch of the growth of analysis is due to the theory of functions which reaches a maximu m about 1 8 8 7 with a sweep of the cu rve upward again after 1 900 due to the theory of integral equations and the influence of Hilbert ; ( 5) Algebra i n cluding series and groups experienced during the forty years a steady gain to 2 5 times its original output ; the part of algebra relating to algebraic form s invariants etc reached i ts acme before 1 8 90 and then declined most surprisin gly ; ( 6 ) D ifferential equations increased “ in amount S lowly but steadily from 1 8 70 under the combined i n fl u en ce of Weierstrass D arb ou x and Lie showing a slight decline “ in 1 886 but followed by a marked recovery and advance during the publication of lectures by Forsyth P icard G ou rsa t and P a in l ev é ; The m athem atical theory of electricity and m agnetis m rem ained ( 7) less than one fourth of the whole applied m athe m atics but rose after 1 8 7 3 steadily toward one — fourth by the labors of Clerk M axwell W Thom son (Lord Kelvin ) and P G Tait ; ( 8) The constant shifting of m athematical investigation is du e partly to fashion The progress of m athem atics has been greatly accelerated by the organiz ation of m athem atical societies issuing regular periodicals The leading societies are as follows : L ondon M athema ti cal S oci ety organiz ed in 1 86 5 L a s oci eté mathémati qu e de Fr ance organiz ed in 1 8 72 Edi n bu rgh M athemati cal S oci ety organi z ed 1 883 C i rcol o ma te mati co di P al ermo organiz ed in 1 88 4 A meri can M athemati c al S oci ety organized in 1 888 under the nam e of N ew Y or k M athemati cal S oci ety Deu ts che M a thema ti k er and changed to its present nam e in Verei n i gu ng organi z ed i n 1 8 90 I ndi a n M a themati cal S oci ety organiz e d in 1 90 7 S oci edad M etemati ca Espaii ol a organiz ed in 1 91 1 M a themati cal A ssoci ati on of A mer i ca organiz ed in 1 9 1 5 The nu mber of m athem atical periodicals has enorm ously increased 2 According to Felix M ii ll er there were d uring the passed century up to 1 70 0 only 1 7 periodicals containing m a them atical articles ; there were in the eighteenth century 2 1 0 such p eriodicals in the nineteenth century 950 of them , , , , ” , , , , ” , - , , , , , , ~ , , . , , , ” , , , - , , . , . . . . ’ , , , , , , , . . , , , , , . C on su l t Thom as S F i sk e s addre ss i n B u ll A m M ath S oc , Vo l 1 1 , 1 90 5 , p 2 38 D r Fi sk e hi mself w a s a l eade r i n t h e org an i a t i on o f t he S oc i e ty 2 J a hres b d deu ts ch M a them Ver ei n i g u ng , V o l 1 2 1 90 3 , p 4 3 9 S e e al so G A M il l er i n H i stori cal I ntroducti on to M athemati cal Li teratu r e, N ew Y ork , 1 9 1 6 , C haps I , I I ’ 1 . z . . . . . . . . . . . . . . . . , . . . . A HI STORY OF M ATHE M ATIC S 2 80 A great stim ulus toward m athe matical progress have been the international congresses of mathe maticians I n 1 889 there was held in P aris a Congres international de bibliographie des scie nces ma th e mat i q u es In 1 8 93 during the Colu mbian E xposition there was held in Chicago an International M athem atical Congress B u t by c om m on agree m ent the gathering held in 1 8 97 at Zurich Switz erland is “ called the first international mathe matical congress The S econd was held in 1 900 at P aris the third in 1 90 4 at Heidelberg the fourth in 1 90 8 at Rom e the fifth in 1 91 2 at Ca mbridge in England The obj ect of these congresses has been to promote friendly relations to give re v iews of the progress and present state of di fferent branches of m athem atics and to d iscuss m atters of term inol ogy and bibliography One of the great c o operative enterprises intended to bring the results of m odern research in digested form before the tech nical reader is the E n cykl opadi e der M athemati schen Wi ssen schaf ten the publica tion of which was begun in 1 8 98 under the editorship of Wi lhel m Fr an z M eyer of KOn in e rg P ro m inent as joint editor was H ei n ri ch B u r k 1 9 1 4) of Zurich l ater of M unich In 1 90 4 was begun the hardt ( 1 8 6 1 — publication of the French revised and enlarged e dition under the — u e l of the University of Nancy editorship of J l s M o k ( 1 8 57 1 9 1 4) A S regards the productiveness of modern writers Arthur Cayley 1 “ said in 1 88 3 : I t is diffi cult to give an idea of the vast e xtent of m odern m athem atics This word extent is not the right one :I mean — extent crowded wi th beautiful detail not an extent of m ere uni formity such as an objectl ess plain but of a tract of beautiful country seen at first in the distance but which will bear to be ra mbled through and studied in every detail of hillside and valley stream rock wood and flower I t is pleasant to the m athe matician to think that in his as in no other science the achie v e ments of every age re main posses sions forever ; new discoveries seldom disprove older tenets ; seldom is anything lost or wasted If it be asked wherein the utility of som e modern extensions of mathematics lies it m ust be acknowle dged that it is at present diffi cult to see how som e of them are ever to becom e applicable to questions of comm on life or physical science B ut our inability to do this S hould not be urged as an argument against the pursuit of such studies I n the first place we know neither the day nor the hour when these abstract develop ments will find application in the m echanic arts in physical science or in other branches of m athematics For example the whole subj ect of graphical statics so useful to the practical em metri c der L age W R g i n eer was m ade to rest upon v o n S ta u d t s Geo Hami lton s principle of varying action has its use in astrono my ; complex quantities general integrals and general theorem s in inte g ra t i o n offer advantages in the study of electricity and magnetis m . . , , . , , , , . , , , . , , . - ' , . . , . , ‘ ’ . , , , , , , , . , , . , . . , , . , , , ’ ’ , , ’ . . “ , , . A r t hu r C ayl ey , I n au g u ral Addre ss b efo re t he B r i t i sh A s so c i at i on , por t, p 2 5 1 . . 1 8 83 , Re A HI STORY OF M ATHE M ATI C S 2 82 of positive construction Chemistry in a modern spirit is stretching out into m athem atical theories ; Will ard Gibbs in his m emoir on the equilibriu m of chem ical systems has led the way ; and though his way is a path which chem ists find strewn w i th the thorns of analysis his work has rendered incidentally a real service in co ordinating experim ental results belonging to physics and to chem istry A new and generaliz ed theory of stati stics is bein g constructed and a school has grow n up which is applying the m to biological phenom ena Its activity howe ver has not yet me t with the sympathetic goodwill of all the pure biologists ; and those who remember the quality of the discussion that took place last year at Cambridge between the biom e t ri c i an s and so m e of the biologists will agree that if the new school should languish it w ill not be for want of the tonic of criticism The great characteristic of m odern m athe matics is its generaliz ing tendency Nowadays little weight is giv en to isolated theorem s says J J Syl v ester except as a ff ording hints of an unsuspected n ew sphere of thought like m eteorites detached from so m e undiscovered planetary orb of speculation In m athe m atics as in all true sciences no subj ect is considered in itself alone but always as related to or an outgrowth of other things The develop m ent of the notion of continuity plays a leading part in m odern research In geom etry the principle of continuity the idea of correspondence and the theory of proj ection constitute the fundam ental m odern notions Continuity asserts itself in a m ost stri king way in relation to the circular points at infinity in a plane In algebra the m odern idea finds expression in the theory of linear transform ations and invariants and in the recognition of the value of ho mogeneity and symm etry 1 H F B aker said i n 1 9 1 3 that with the aid of groups a complete theory of equations which are soluble algebraically can be given B ut the theory of groups has other applications The group of interchanges am ong four quantities which leave unaltered the product of their six diff erences is exactly sim ilar to the group of rotations of a regular tetrahe dron whose centre is fix ed when its corners are inter changed am ong them selves Then I m ention the historical fact that the prob l em of ascertaining when that well known diff erential equa tion called the hypergeom etric equation has all its solutions expressible in finite term s as algebraic functions was first sol v ed in connection For any linear differential equation it is w ith a group of si milar ki nd of primary importance to consider the group of interchanges of its solutions when the independent variable starting from an arbitrary point m akes all possible excursions returning to its initial value There is howev er a theory of groups diff erent from those so far referre d to in which the variables can change continuously ; this alone is most extensiv e as m ay be j u dge d from one of its lesser applications the familiar theory of the invariants of quantics M oreov er perhaps . , , , , , , , , . , . , , ” , , . . , . . , ” , . , , , , . , . , , . . , . . . , . . , . - , . , , , , . , , , , . 1 Repor t B ri ti sh A ss ’ n ( B i rming ham) , 19 13, L on don , , 19 1 4, p 371 . . INTROD UCTION the most masterly of the analytical discussions of the theory of geom etry has been carried through as a particular application of the theory of such groups If the theory of groups illustrates how a unifying plan works in mathem atics beneath the bewildering d etail the nex t m atter I refer to well sh ows what a wealth what a grandeur of thought may spring from what see m slight beginnings Our ordinary integral calculus is well nigh powerless when the result of integration is not expressible by algebraic or logarith m ic functions The attem pt to extend the possibilities of integratio n to t he ca se when the function to be inte grated involves the square root of a polynom ial of the fourth order led first after many eff orts to the theory of doubly periodic functions To day this is m uch simpler than ordinary trigono metry and even apart from its applications it is quite incredible that it S hould ever again pass fro m being a m ong the treasures of civiliz e d man Then at first in uncouth form but now clothed with delicate beauty ca me the theory of general algebraical integrals of which the influence is spread far and wide ; and with it all that is systematic in the theory of plane curves and all that is associated with the con After this cam e the theory of multiply c ep t i on of a Riemann surface periodic functions of any nu mber of variables which though still ve ry far indeed fro m being complete has I have always felt a m aj esty of conception which is unique Q uite recently the idea s evolve d in the previous history have prompted a vast general theory of th e classification of algebraical surfaces according to their essential prop 3 e r t i e s which is opening endless n ew vistas of thought The nineteenth century and the beginning of the twentieth century constitute a period when the very foundations of m athem atics have bee n r e exam ined a n d when fundam ental principles have been worke d 1 “ out anew Says H F B aker : I t is a constantly recurring need of science to reconsid er the exact i mplication of the term s e mploye d ; and as num bers and functions are ine v itable in all m easurem ent the precise m eaning of number of continuity of infinity of limit an d so on are fundamental questions These notions have m any p i tfalls I may cite the construction of a function which is continuous at all points of a range yet possesses no definite di fferential coeffi cient at any point Are we sure that hu man nature is the only co n tinuous variable in the concrete world assum ing it be continuous which can possess such a vacillating character ? We could take out of our life all the moments at which we can say that our age is a certain number of years and days and fractions of day and still have appreciably as long to live ; this woul d be true however often to whatever exactness we named our age provided we were quick enough in nam ing it These inqu i ries have been associated also with the theory of those se ri e s w hi ch Fourier used so boldly and H F B k er l c ci t , p 3 6 9 ” . “ , , , . - . , - , , - . , , , , . , , , , . , , , , , . ” , - . - . . . , , , , , . , . , . , , , , , , , , , . , 1 . . a , o . . . . A H I STO RY O F M ATHE M ATIC S 2 84 so wickedly for the conduction of h eat Like all discoverers he took much for granted P recisely h o w m uch is the problem This proble m has led to the precision of what is meant by a function of real variables to the question of the uniform convergence of an infinite series as you may see in early papers of S tokes to n ew form ulation of the conditions of integration and of the properties of m ultiple integ rals and so on A n d it rem ains still incompletely solved Another case in which the suggestions of physics have caused grave disquiet to the mathem aticians is the problem of the variation of a definite integral N 0 one is likely to underrate the grandeur of the aim of those who would deduce the whole physical history of the world from the single principle of least action Everyone must be interested in the theorem that a po t en t i al function with a gi v e n value at the boundary of a volum e is such as to render a certain i n B ut in that pro t eg ral representing say the energ y a m inim u m portion one desires to be sure that the logical processes e mployed are free from obj ection And alas ! to deal only with one of the earliest problem s of the subj ect though the finally sufficient con ditions for a minim um of a si mple integral see m ed settled long ago and could be applied for exa mple to Newton s celebrated problem of the soli d of least resistance it has since been shown to be a general fact that such a proble m cannot have any definite solution at all And although the principle of Thomson and D irichlet which relates to the potential proble m referred to was expounded by Gauss and accepted by Riemann and re mains to day in our standard treatise on Natural P hilosophy there can be no doubt that in the form in which it was originally stated it proves j ust nothing Thus a n ew inv estigation has been necessary into the foundations of the principle There is another problem close l y connected with this subj ect to which I would allude : the stabil i ty of the solar syste m For those who can m ake pronounce m ents in regard to this I have a feeling of envy ; for their m ethods as yet I have a quite other feeling The interest of this problem alone is s ufli c i en t to j ustify the craving of the P ure M athem atician for powerful m ethods and unexceptionable rigour There are others who view this struggle for absolute rigor from a 1 “ diff erent angle Horace Lamb in 1 90 4 spoke as follows : a traveller who refuses to pass over a bridge until he has personally tested the soundness of every part of it is not likely to go very far ; something m ust be risked even in M athe matics I t is notorious that even in this real m of exact thought discovery has often been in advance of strict logic as in the theory of i maginaries for exa mple and in the whole provi nce of analysis of which F ou ri er s theorem is a type 2 “ Says M axi m e B Och er : There is what may perhaps be cal led the . , . , . . , , , , . . . . , , , , , . , , , . , , ’ , , , . , , , , - , , , . , . , , . , , . ” . . . , ‘ ’ , ” , , ’ , . A dd res s b efor e S ec t i on A , B ri t i sh A ss n , i n C amb ri dg e , 1 90 4 2 M axime B ocher i n Con gr ess of A r ts a nd S ci ence, S t L o u i s , 1 90 4 , V ol I , p 4 7 2 1 ’ . . . . . ' A HI STORY OF M ATHE M ATIC S 2 86 independently G Frege have been able to make a rather S hort list of logical conceptions and principles upon which i t would seem that all exact reasoning depends B ut the validity of logical prin c i p l e s m ust stand the test of use and on this point we may never be sure Frege and B ertrand Russell independently built up a theory of arith m etic each starting with apparently self evident logical prin c ipl es Then Russell discovers that his principles applied to a very general kind of logical cl as s lead to an absur di ty There is evident need of reconstruction somewhere After all are we m erely making successive appr oxi mati ons to absolute rigor ? 1 “ A B Ke mpe s definition is as fol lows : M athematics is th e science by which we investigate those characteristics of any subj ect m atter of thought which are due to the conception that it consists of a nu mber of di ff ering and non diff ering individuals and pluralities 2 Ten years later M axim e B ocher m odified Kempe s definition thus : “ If we have a certain class of obj ects and a certain class of relations and if the only questions which we investigate are whether ordered groups of t hose obj ects do or do not satisfy the relations the results of the investigation are called m athem atics B ocher re marks that if we restrict ourselves to exact or deductive mathe matics then Ke mpe s definition beco mes coextensive with B P eirce s B ertrand Russell in his P ri n ci pl es of M a themati cs Cambridge 1 90 3 regards pure mathe matics as consisting exclusively of dedu c “ tions by logical principles from logical pri n ciples Another def inition given by Russell sounds paradoxical but really expresses th e extre m e generality and extrem e subtleness of certain parts of m o d ern “ m athem atics : M athe matics is the subj ect in which we never kno w 3 what we are talking about nor whether what we are saying is true Other definitions along si milar lines are due to E P apperi tz G I tel son and L C ou tu ra t . , ” . , . - , . , . , . , ’ . . ” - . ’ , , . , ’ ’ . . ” , , , , . , ” . . . . S yntheti c Geometry The confli ct between synthetic and analytic m ethods in geometry whi ch arose near the close of the eighteenth century and the beginning of the nineteenth has n ow com e to an end Neither S ide has com e out victorious The greatest strength is found to lie not in the sup pression of either but in the friendly rivalry between the two and in Lagrange prided the sti m ulating influence of the one upon the other himself that in his M ecani qu e A n al yti qu e he had succeeded in avoiding all figures ; but since his tim e m echanics has received much help from geometry M odern syn thetic geo metry was created by several investigators about the same tim e I t seem ed to be the outgrow th of a desire for . , . , , . . . P r oceed L ondon M ath S oc , V ol 2 6 , 1 89 4 , p 1 5 2 M B oc her , op ci t , p 4 66 3 B R u s se ll i n I n ter n ati on a l M on thl y, V o l 4 , 1 90 1 , p 8 4 1 . . . . . . . . . . . . . . . SYNTHETI C G EO M ETRY 287 general methods which S hould serve as threads of Ariadne to guide the student through the labyrinth of theorems corollaries porisms and proble ms Synthetic geom et ry was first cultivated by G M onge L N M Carnot and J V P oncelet in France ; it then bore rich fruits at the hands of A F M ob i us and Jakob S teiner in Germany an d Switz erland and was finally developed to still higher perfection by M Chasles in France v on S ta udt in Germany and L Crem ona in Italy J e an Vi ctor P on c e l e t ( 1 7 88 a native of M etz took part in the Russian campaign was abandoned as dead on the bloo dy field of K rasn oi and taken prisoner to S ara toff D eprived there of all books and reduced to the rem embrance of what he had learned at the Lyceum at M etz and the P olytechnic School where he had studied with predilection the works of G M onge L N M Carnot and C J B r ian ch on he began to study m athem atics from its ele ments He entered upon original researches which afterwards m ade h im i l lus trio n s While in prison he did for mathe matics what B unyan did for literature —produced a m uch read work which has re mained of great value dow n to the present tim e He returned to France in 1 8 1 4 and in 1 8 2 2 publ i shed the work in question entit l ed Tr ai té des P ropri etés proj ecti ves des figu r es In it he investigated the properties of figures which remain unaltered by proj ection of the figures The projection is not e ff ected here by parallel rays of prescribed direction as with G M onge but by central projection Thus perspective proj ection used before him by G D esargues B P ascal I Newton and J H Lambert was elevated by him into a fruitful geom etric m ethod P oncelet form ulated the so called pr i n ci pl e of con ti n u i ty which asserts that properties of a figure which hold when the figure varies accor ding to definite laws wi ll hold also when the figure assum es som e li miting position “ 1 “ could not content him self with P oncelet S ays J G D ar b o ux the insuffi cient resources furnished by the m etho d of projections ; to attain i maginaries he created that famous principle of continuity which gave birth to such long discussions between hi m and A L Cauchy Suitably enunciated this principle is excellent and can render great serv ice P oncelet was wrong in refusing to present it as a S imple consequence of analysis ; and Cauchy on the other hand was not w il ling to recogniz e that his own obj ections app l icable with out doubt to certain transcendent fi gures were without force in the applications m ade by the author of the Tr ai té des propri etes proj ec ti ves J D G erg onn e characteriz ed the principle as a valuable instrument for the d iscovery of new truths which nevertheless di d 2 not make stringent proofs su per fluou s By this principle of geom etric , , , . . . . . , . . , . . , . , , . . , , . , , , . . , . . , . . , . . - , . , ’ , , . . , . . , . , , . , . . , . , . - , . . . , , . . . , . , , , , ” . ’ . ’ . , . Con gr ess of A r ts and S ci ence, S t L ou i s , 1 90 4 , V ol I , p 5 39 2 E K ot t er , Di e En twi ck el u n g der syn theti schen Geometri c S ta vdt, L e i p i g , 1 90 1 , p 1 2 3 1 . . z . . . . . von M onge bi s f au A HI STORY OF M ATHE M ATIC S 2 88 continuity P oncelet was led to the consideration of points and li nes which vanish at infinity or b ec omé im aginary The inclusion of such ideal points and lines was a gif t which p ure geom etry received from analysis where i maginary quantities behave m uch in the sam e way as real ones P oncelet elaborated som e i deas of D e L ahi r e F S ervoi s — m D r o n n e into a regular ethod the me thod of r e cipr o G e and J g cal polars To him we owe the P rinciple of D uality as a consequence of reciprocal polars As an independent principle it is due to G erg on n e D a rb o u x says that the significance of the principle of duality which “ was a little vague at first w as sufficiently cleared up by the dis c u s s i on s which took place on this subj ect between J D G e rg o n n e It had the advantage of making J V P oncelet and J P l ii ck er correspond to a proposition another proposition of wholly diff erent “ aspect This was a fact essentially new To put it in evidence G e rg o nn e invented the syste m which since has had so much success of m e moirs printed in double colum ns with correlative propositions in j uxtaposition (B arboux ) Jo s eph D i az G e r g onn e ( 1 7 7 1 —1 8 59) was an offi cer of artillery then professor of m athem atics at the l yceum in N i mes and later professor at M ontpelli er He solved the Apollonian P roblem and claim ed superiority of analytic m ethods over the synthetic Thereupon P oncelet pub l ished a purely geo m etric solution G erg on n e and P once let carried on an intense controversy on the priority of discovering the principle of duality No doub t P oncelet entered this field earlier wh i le G erg on n e had a deeper grasp of the principle Some geom eters particularly C J B ri an c hon entertaine d doubts on the general val id ity of the principle The controversy led to one new result namely G erg on n e s considerations of the cl ass of a curve or surface as well 1 as its order P oncelet wrote m uch on applied mechanics In 1 83 8 the Faculty of Sciences was enlarged by his election to the chair of m echanics J G D arb ou x says that presented in opposition to analytic geom etry the m ethods of P oncelet were not favorably r eceived by the French analysts B ut such were their importance and their nov elty that without delay they aroused from di v ers sides the M any of these appeared in the A nn al es m ost profound researches de ma thema ti qu es published by J D G erg on n e at N i m es from 1 8 1 0 to 1 83 1 D uring over fifteen years this was the only j ournal in the worl d devoted exclusively to m athe matical researches G erg onn e collaborated often against their will with the authors of the m em oirs sent hi m rewrote them and som etim es m ade them say m ore or less than they would have wished G e rg onn e having becom e rector of the Academ y of M ontpel lier was forced to suspend in 1 83 1 the publication of his journal B ut the success it had obtained the taste for research it had contribute d to d evel op had comm enced to bear . , . . . , , . . . . ‘ , . . , . .. . . . . , , , ” . , . . . . , , . . . , , , . , ’ , . . . . , . , . ” , , , . ’ . , . . . “ , , , , , . , . , , 1 E K ott er , . p o . ci t . , pp . 1 60 —64 1 . A 2 96 H I STORY OF M AT H E M ATIC S ” the greatest geometrician since the J ak ob S te in er ( 1 7 96 time of Euclid was born in U tzen dorf in the Canton of B ern He di d not learn to write till he was fourteen At eighteen he became a pupil of P estalo zz i Later he studied at Heidelberg and B erlin When A L C rell e started in 1 8 2 6 the celebrated mathem atical journal bearing his nam e S teiner and Abel becam e leading con t ri b u t or s Through the influence of C G J Jacobi and others the chair of geom etry was founded for hi m at B erlin in 1 8 34 This posi tion he occupied until his death which occurred after years of bad heal th In 1 83 2 Steiner p ublished his S ystemati sche En twi ckel u ng der A b “ han gi gk ei t geometri scher Ges tal ten von ei n ander in which is uncovered th e organism by which the most diverse phenom ena (Erschei nu ngen ) in the world of space are united to each other Here for the first time is the principle of duality introduced at the outset This book and von S tau dt s lay the foundation on which synthetic geo metry in its later form rested The researches of French m athe m aticians cul m ina ti n g in the rem arkable creations of G M onge J V P oncelet and J D G erg on n e suggested a unification of geom etric processes “ This work of uncovering the organis m by which the m ost different forms in the world of space are connected with each other this ex posing oi a s mall num ber of very simple fundamental relations in which the sche me reveals itself by which the whole body of theore m s can be logically and easily developed was the task which S teiner 1 “ assu m ed Says H Hankel : In the beautiful theorem that a conic section can be generated by the intersection of two proj ective pencils ( and the dually correlated theorem referring to proj ective ranges) J S teiner recogniz ed the fundam ental principle out of which the innu m erable properties of these rem arkable curves follow as it were automatically wi th pl ayful ease Not only did he fairly complete the theory of curves and surfaces of the second degree but he m ade great advances in the theory of those of higher degrees In the S ystemati sche En tw i ck el u ngen ( 1 8 3 2 ) S teiner directed atten tion to the complete figure ob tained by joining in every poss ible way s ix points on a c onic and showed that in this h exag ramm u m m ys t i c u m “ “ the 6 0 P ascal lines pass three by three through 2 0 points ( Steiner points which lie four by four upon 1 5 straight lin es P l ucker J P l ii ck er had sharply criticiz ed S teiner for an error that had crept into an earlier state m ent ( 1 8 2 8 ) of the last theorem Now Steiner gave the correct state ment but without acknowledgment to P l ii ck er Further properties of the h exag rammu m mys t i c u m are due to T P Kirkm an A Cayley and G Sal mon The P ascal lines of three hexa gons concur in a new point Kirk m an There are 6 0 Kirk m an po i nts Correspon ding to three P ascal lines which concur in a Steiner point there are three Kirk m an points which lie upon a straight . , . . . . . , , , . . . . , . , . ” , . . , ’ . , . . . . , . , . , ” , . . , ” . , , . , . ” . , . . , . , . . . . , 1 H H an k e l , El emente der P r oj ecti vi schen Geometr i c, . 1 8 75 , p . 26 . . SYNTHETI C GEO M ETRY 2 9: ” line Cayley line There are 2 0 Cayley lines which pas s four by “ four through 1 5 Sal mon points Other new properties of the mystic 1 hexagon we re obtained in 1 8 7 7 by G Veronese an d L Cre mona In S teiner s hands synthetic geometry m ade prodigious progress New discoveries followed ea ch other so rapidly that he often did not take tim e to record their demonstrations In an article in Gr el l e s Jou r n al on A l l gemei n e Ei gen s chaf ten A l gebr ai scher C u rven he gives without proof theorems which were declared by L O Hesse to be “ like Fermat s theorem s riddles to the present and future genera tions Analytical proofs of som e of them hav e been given S ince by others but L Crem ona finally pro v ed them all by a synthetic m ethod S teiner discovered synthetically the two pro minent properties of a surface of the third order ; v iz that it contains twenty seven straight lines and a pentahedron which has the double points for its vertices and the lines of the Hessian of the given surface for its edges This subj ect will be discussed more fully later S teiner m ade investigations by synthetic m ethods on m axima and minima and arri v ed at the solution of problems which at that time surpassed the analytic power of the calculus of variations I t will appear later that his reasoning on this topic is not always free from criticism 2 S teiner generaliz ed M alfa tti s prob l em Gi ovann i Fr ancesco M al — of the university of Ferrara in proposed t h e a tt i 1 1 1 8 0 1 8 0 ( ) 7 7 3 3 f problem to cut three cylindrical holes out of a three sided pris m in such a w ay that the cylinders and the prism have the sam e altitude and that th e volume of the cylinders be a maximu m This problem was reduced to another n ow generally known as M alfa tti s problem : to inscribe three circles in a triangle so that each circle will be tangent to two sides of the triangle and to the other two circles M alfatti gave an analytical solution but Steiner gave without proof a construction remarked that there were thirty two solutions generaliz ed the problem by replacing the three lines by three circles and solved the analogous problem for three dimensions This general problem was sol v ed analytically by C H Schellbach ( 1 80 9—1 8 9 2 ) and A Cayley and by R F A C l eb sch with the aid of the addition theorem of elliptic 3 functions A simple proof of S teiner s construction was given by A S Hart of Trinity College D ublin in 1 8 56 Of interest is S teiner s paper Ueber di e geometri schen C ons tru cti onen . . . . ’ . ’ . . . ’ , . , . . - . . . , . . ’ . , , - , . ’ , . , , - , , . . . . . . . ’ . . . , . , ’ , , fii hr t mi ttel s au s ge der ger aden L i n i e u nd ei n es K r ei s es f es ten in which he shows that all quadratic constructions can be eff ected with the aid of only a ruler provided that a fixed circle is drawn once for all It was generally known that all linear constructions could be eff ected by the ruler without other aids of any kind The case of , . . , G S al mo n , C on i c S ecti on s , 6 t h Ed , 1 8 7 9 , N o t e s , p 3 8 2 2 K a r l F i n k , A B r i ef Hi s tor y of M a thema ti cs , t ra n sl b v W W B em an S mi t h , C h i ca g o , 1 900 , p 2 5 6 3 A Wi t t s t ei n , zu r Geschi chte des M a lf a tti s chen P robl ems , N o r dli n g e n , 1 . . . . . . . and D E . ’ . . 1 8 78 . . . A HI STORY OF M ATHE M ATI C S 292 cubic constructions calling for the determination of three unk nown elem ents (poi nts) was worked out in 1 86 8 by Lu dwi g H erman n K or 1 90 4 ) tu m ( 1 8 3 6 — of B onn and Stephen S m ith of Oxford in two r e searches which received the Steiner priz e oi the B erlin Academy ; it was shown that if a conic (not a circle ) is given to start with then all such constructions can be d one w ith a ruler and compasses Fran z — of B reslau demonstrated in 1 895 that these cubic London ( 1 8 6 3 1 9 1 7) constructions can be e ffected with a ruler only as soon as a fi xed 1 cubic curv e is once drawn 2 F B u tzb erg er has recently pointed out that in an unpublished manuscript Steiner disclosed a knowledge of the principle of inver sion as early as 1 8 2 4 In 1 84 7 Liouville called it the transformation by reciprocal radii After S teiner this transform ation was found in depen dently by J B el l av i ti s in 1 83 6 J W S tubbs and J R Ingram in 1 84 2 and 1 843 and by William Tho m son (Lord Kelvin ) in 1 84 5 Steiner s researches are confined to synthetic geom etry He hated analysis as thoroughly as J Lagrange disliked geom etry S teiner s Gesa mmel te Wer ke were publishe d in B erlin in 1 8 8 1 and 1 88 2 — s e s 1 M ich e l Ch a l ( 7 93 1 880 ) was born at Epernon entered the P oly technic School of P aris in 1 8 1 2 engaged afterwards in business which he later gave up that he m ight devote all his tim e to scientific pursuits In 1 84 1 he becam e professor of geodesy and m echanics at the Ecole “ polytechnique ; later P rofesseur de G éométrie sup érieure a la F ac u l te He was a volu minous writer on geom etrical des Sciences d e P aris subjects In 1 83 7 he published his ad mirable A per gu hi stori qu e s u r l or i gi n e et te dével oppemen t des méthodes en g eometri e containing a history of geo metry and as an appendix a treatise sur deu x principes g én éraux de la Science The A per gu hi s tor i qu e is still a standard historical work ; the appendix contains the general theory of H omog and of duality (Reciprocity )The na me du al i ty r aphy ( Collineation ) is due to J D G erg onn e Chasles introduced the term a nhar moni c l tni ss and to Cli ff ord s ra ti o corresponding to the Ger man D oppel ver ha Chasles an d J S teiner elaborated independently the c r oss r a ti o m odern synthetic or proj ective geo met ry Nu m erous original m e moirs of Chasles were published later I n the Jou rn al de l Ecol e P ol ytechni qu e He gav e a reduction of cubics different from Newton s in this that the fi v e cu rves from which all others can be proj ected are sym metrical with respect t o a centre In 1 86 4 he bega n the publication in the “ C omptes r en du s of articles in which he solves by his method of “ characteristics and the principle of correspon dence an immense number of problem s He d eterm ined for instance the nu mber of intersect i ons of two curves in a plane The m ethod of characteristics contains the basis of enu m erati v e geo m etry As regard s Chasles use of i maginaries J G D arboux says : Here , , , . , . . , . . . , . . . . , . ’ . ’ . . - . , , , . , . . ’ ’ ’ , , ” , . . . . . ' ’ , - . . . ’ . ’ , , . ” ” , . , , , . . ’ , J a hr es b d d M a th Ver ei n i g u n g , V ol 4 , p 2 B u l l A m M ath S oc l 2 0 , 1 9 1 4, p 4 1 4 , Vo 1 63 1 . . . . . . . . . . . . . . . . , A HI STORY OF M ATHE M ATIC S 2 94 The labors of Chasles and Steiner raised synthetic geom etry to an honored and respected position by the side of analysis — r h r i s t i a n o t a u d t 1 K ar l G eo g C v nS was born in Rothen ( 7 98 1 86 7 ) burg on the Tauber and at his death was professor in Erlangen His great works are the Geometri c dcr L age N ii rn b e rg 1 84 7 and his — B ei tr age zu r Geometri c der L age 1 8 56 1 8 6 0 The author cut loose from algebraic form ul a and from m etrical relations particularly the anha rm onic ratio of J Steiner and M Chasles and then created a geo metry of position which is a complete science in itsel f independent of all m easure m ents He S hows that proj ective pr operties of fi g ures have no dependence whatever on m easure ments and can be estab “ lish ed without any m ention of the m In his theory of throws or Wii rfe he even gives a geo metrical definition of a number in its rel ation to geo metry as d etermining the positio n of a point Gu stav K ohn of the University of Vienna about 1 894 introduced the throw as a fu ndam ental concept un derl ying the proj ective properties of a geom etric configuration such that according to a principle of duality of this geome try throws of figures appear in pairs of reciprocal throws ; figures of reciprocal throws form a complete analogy to figures of equal throws Referring to Vo l i S ta u dt s num erical c o ordinates defined without introducing distance as a fundamental idea A N “ Whitehead said i n 1 90 6 : The establish m ent of this result is one of the triu mphs of m odern m athe m atical thought The B ei tr age contains the first co mplete and general theory of i maginary points lines and planes i n proj ective geo metry R epre se n t a t i on of an i maginary po int is sought in the co mbination of an in v olution with a determ inate direction both o n the real line through the point While purely proj ective v on S taud t s m ethod is inti mately related to the proble m of representing by actual points and 1 li n es the imaginaries of analytical geom etry Says Kotter : Staudt “ was the first who succeeded i n subjecting the im aginary elem ents to the fundam ental theorem of projective geom etry thus returning to analytical geom etry the present which in the hands of geo metri c i an s had led to the m ost beautiful results Von S tau dt s geo metry of position was for a long tim e disregarded m ainly no doubt because his book is extre mely condensed An i mpulse to the study of this subj ect was given by C u l man n who rests his graphical statics upo n the work of von Staudt An interpreter of von S taudt was at last found in Theodor Reye of Strassburg who wrote a Geometri c der L ag e in 1 8 6 8 The graphic representation of the imaginaries of analytical geom e t ry was syste m atically undertaken by C F M axi mi l i en M a r i e ( 1 8 1 9 who worked how ever o n entirely d iff erent l i nes fro m those of v on Staudt Another in d ependent attemp t was made i n 1 8 93 by F H Loud of C ol orado C ol l eg e . , , . , , , , . , . ” , . , , . , ” “ . , . , , , ’ - , . ” , . , . , , ’ , . . ” , ’ . , , , . , . , . . . , , . . , . . ‘ 1 E K ott er , . p o . ci t . , p . 1 23 . , . . SYNTHETI C GEO M ETRY 2 95 Synthetic geo m etry was studied with m uch success by Lu i gi Cr e who was born in P avia and becam e in 1 860 pro m o n a ( 1 8 30 fessor of higher geo m etry in B ologna in 1 8 6 6 professor of geom etry and graphical s tatics in M ilan i n 1 8 7 3 professor of higher m athematics and director of the engineering school at Ro m e He was influe nced by the writings of M Chasles later he recogniz ed v on S ta u d t as the true founder of pure geom etry A mem oir of 1 8 66 on cubic surfaces secured half of the Steiner priz e fro m B erlin the other half being awarded to Ru dolf Sturm t hen of B rom berg Crem ona used the m etho d of enu m eration with great e ffect He wrote on plane cu r ves on surfaces on birational transform ations of plane and soli d space The birational transform ations the simplest class of which is now “ called the Cremona transformation proved of i mporta nce not only in geo metry but in the analytical theory of algebraic functions and integrals I t was developed m ore fully by M N Other and others 1 Beyond the H S White comm ents on this subj ect as follows : linear or proj ective transform ations of the plane there were known — the quadric inversions of Ludwig I mm anuel M agnus ( 1 7 90 1 86 1 ) of B erlin changing lines into conics through three funda menta l points and those exceptional points into singular lines to be discarded Cre mona described at once the highest ge n eraliz ation of these trans fo rmations one to— one for all poi n ts of the plane except a finite set of fundamental points He found that it m ust be m e diate d by a net of rational curves ; any two intersecting in one variable point and in fixed points ordinary or m ultiple which are the funda mental poi n ts and which are the mselves t ran form ed into s i ngular rational curves of the sa m e orders as the indices of m ultiplicity of the points When the fundam ental points are enu m erated by classes according to their se v eral in d ices the set of class nu mbers for the in verse transform ation is found to be the sam e as for the direct but usually related to d i ffere n t indices Tables of such rational nets of l o w orders were m ade out by L Crem ona and A Cayley and a wide n ew vista seem ed opening ( such indeed it was and is ) when si m u l tan eou sl y three invest i gators announced that the m ost general Cre m ona transform ation is equivalent to a succession of qua dric transformations of M agnus s type This seem ed a cli m ax and a set back to certain expectations Cre mona s theory of the trans form ation of curves a nd of the correspondence of points on cu rves was extended by him to three di m e n sions There he showed how a “ great variety of particular transform ations can be constructed but anything l ike a general theory is still in the future Ruled surfaces surfaces of the second order space curves of the third order an d the general th eory of surfaces received m uch attention at his hands He was interested in map d rawi ng wh ich had engaged the attention of R Hoo ke G M ercator J Lagrange K F Gauss and others For , , . , . . , . , . , . . ” , , , , . . . “ . . , . , - , . , , , . , , . . . ” ’ . - , , ’ . . ” , . - , ~ , , . - , . , . , 1 B ul l A m . . , . M ath S oc , V ol . . . . . . 24, 1 9 1 8 , p . 24 2 . A 2 96 HI STORY O F M ATH EM ATIC S a one one correspondence the surface must be unicursal and this is suffi cient L Crem ona is associated with A Cayley R F A C l eb sch 1 M N Ot her and others in the develop m ent of this theory Cre mona s writings were translated into Ger man by M axi mi l i an Cu rtze ( 1 8 3 7 p rofessor at the gym nasiu m in Thorn The Opera matemati che di L u i gi Cremon a were brought a t M ilan in 1 9 1 4 and 1 9 1 5 One of the pupils of Crem ona was G i ovan ni B atti s ta G u cci a ( 1 8 55 He was born in P alermo and studied at Rome under Cremona In 1 8 8 9 he becam e ex traordinary professor at the Un iv er si ty of P al ermo in 1 8 94 ordinary professor He gave m uch attention to the study of curves and surfaces He is best known as the founder in 1 8 84 of the Ci r col o ma temati c o di P al ermo and director of its Rendi con ti The society has becom e i nternational and has been a po w erful stimulus for mathem atical research i n Italy K ar l C u l man n ( 1 8 2 1 professor at the P ol yt echn i c u m in Z u rich published an epoch m aking work on Di e gra phi s che S ta ti k Zurich 1 86 4 which has rendered graphical statics a great rival of analytical statics B efore C u l mann B arthel emy Edou ard Cou si n cry ( 1 7 90— 1 8 51 ) a civil engineer at P aris had turned his attention to the graphi cal 2 calculus but he m ade use of perspective and not of m oder n geom etry C u l mann is the first to undertake to present the graphical calculus as a symm etrical whole holding the sam e relation to the new geom e t ry that analytical m echanics does to higher analysis He m akes use of the polar theory of reciprocal figures as expressing the relation between the force and the funicular polygons He deduces this rela tion without leav ing the plane of the two figures B ut if the polygons be regarded as proj ections of lines in space these lines m ay be treated as reciprocal elem ents of a N ull sys tem This was done by Cl erk M axw el l in 1 86 4 and elaborated further by L Cremon a The grap hi cal calculus has been applied by O M ohr of D resden to the elastic line for continuous spans H en ry T Eddy ( 1 844 then of the Rose P olytechnic Institute n ow of the University of M innesota gives graphical solutions of proble m s on the m axim u m stresses in bridges “ under concentrated loads with aid of what he calls reaction poly gons A standard work L a S tati qu e gr aphi qu e 1 8 74 was issued by M aurice Lev y of P aris D escriptive geom etry [ reduced to a science by G M onge in France and elaborated further by his successors J N P H achette C Du pi n — of P aris Ju l cs de l a C ou rn er i e of P aris ] Theodor e Ol i vi er ( 1 7 93 1 8 53 ) was soon studied also in other countries The French directed their attention m ainly to the theory of surfaces and their curvature ; the — of Karls Germ ans and Swiss through Guido Schreiber ( 1 799 1 8 7 1 ) - , . . . . , . . , ’ . . . . . ’ . , . , . . - , , , , ’ . ’ - , , . , , , . . ” . , . . . , . . . , , ” , , , . , . , . . , . . , , . , . , 1 2 79 P roceedi n g s f o the Roy . S oc . f o L on don , V ol 75 , L on don , 1 90 5 , pp . 2 77 . B o i s , Gr aphi cal S tati cs , N ew York , dc N omogr a phi e, P a ri s , 1 899 , p 5 2 . A . J ay d u . . 1 8 75 , p . x x xn ; M d O cag ne , Tr ai té ’ . O F M ATHE M ATIC S HI STORY A 2 98 and centroid of a triangle are collinear lying on the Euler line H C Gossard of the Unive rsity of Oklahom a showed in 1 9 1 6 that the three Euler lines of the triangles form ed by th e Euler line and the sides taken by twos of a given triangle form a triangle triply per sp ec t i v e with the giv en triangle and having the sa m e Euler line Con “ nine point circle the spi c u ou s a m ong the new develop m ents is the discovery of which has been erroneously ascribed to Euler A m ong the several independent discoverers is the English m an B enj ami n —1 8 8 who proposed in L e b ou rn s M athema ti cal Re os i tor B eva n 3 ) y y p I 1 8 1 80 4 a theore m for proof which practically gives us the nine po int circle The proof was supplied to the Reposi tor y I P art 1 p 1 43 by John B u tterw orth who also proposed a problem solv ed by hi mself and John Whi tl ey; from the general tenor of which it appears that they knew the circle in question to pass through all nine points These nine points are explicitly m entioned by C J B ri an chon and J V P oncelet i n G erg on n e s A n n al es of 1 8 2 1 In 1 8 2 2 K arl Wi l hel m Feu cr bach ( 1 8 0 0 professor at the gym nasium i n Erlangen published a pamphlet in which he arrives at the nine point circle an d proves the theorem known by his nam e that this circle touches the incircle and the three exc i rc l es The Germ ans call it F eu erb ach s Circle The last independent discoverer of this re markable circle so far as known is T S Davi es in an article of 1 8 2 7 in the P hi l osophi cal M agazi n e II 2 9—3 1 Feuerbach s theorem was e x tended by A ndr ew fellow of Trinity College D ublin w ho S ea rl c H a r t ( 1 8 1 1 S howed that the circles which touch three given circles can be dis tributed into sets of four all touched by the sam e circle In 1 8 1 6 A u gu s t L eopold Cr el l e published in B erlin a paper dealing wi th certain properties of plane triangl es He showed how to deter mine a point 0 inside a triangle so that the angles ( taken in the same order) form ed by the lines joining it to the vertices are equal In the adjoining figure the three m arked angles are equal If the construction is m ade so that angle Q A C = Q C B = O B A then a second point is obtained The study of these new B Q angles and new points led C rel l e to exclaim : It is indeed wonderful that so s imple a figure as the triangle is so inexhaustible in properties How m any as yet unknown proper ties of other figures m ay there not be ! Investigations were m ad e — also by K ar l Fri edri ch A ndr eas J acobi ( 1 7 95 1 8 5 5)of P for ta and som e of his pupils but after his d eath in 1 8 55 the whole m atter was forgotten In 1 8 75 the subject was again brought befor e the m athematical public by Henri B rocard ( 1 84 5 whose re searches were followed up by a large num ber of investigators in France England and Germ any Unfortunately the nam es of geom etrician s which have been attached to certain re markable points lines and “ , . . . ' , , , . - , . , ’ , , , , . . , , , , , , . . . ’ . . . , , - - , , ” ’ . ' , . , . . , ’ , , . , , . . , . . ’ ’ ’ , ' . . ” , , , . , . , , G EO M ETRY SYNTH ETI C 2 99 ” circles are not always the names of the men who first studied their properties Thus we speak of B rocard points and B rocard angles but historical research brought out the fact in 1 8 8 4 and 1 886 that these were the points and lines which had been stu die d by A L “ The Brocard Circle is Brocard s own C re l l e and K F A Jacobi creation In the triangle AB C let ( 2 and Q be the first a n d second B rocard point Let A be the intersection of B 9 and C Q ; B of ” “ . “ , , , , ” ” . . . “ . . . ’ . ’ , ’ ' ’ . and C O and A O The circle passing through A “ C is the B rocard circle A B C is B rocard s first triangle “ Another lik e triangle A B C is called B rocard s second triangle " " The points A B C together with Q Q and two other points lie in the circu mference of the B rocard circle In 1 8 73 Emi l e L emoin e ( 1 840 the editor of l I n ter medi ai re des mathémati ci en s called attention to a particular po i nt within a plane triangle which has been variously called the Le moine point sym m edian point and Grebe point nam ed after E rn s t Wi lhel m G rebe — of Kassel If CD is so drawn 1 8 0 ( 4 1 8 7 4) as to m ake angles a and b equal then one of the two lines AB and CD is the an ti el of the other with reference to ra l l C a p the angle O Now OE the bisector of AB is the medi an and OF the bisector of the anti parallel of AB is called the sym medi an ( abbreviated fro m symetri qu e dc l a médi an c)The point of concurrence of the three symm edian s in a triangle is called — of Univ ersity College School in Lon er 1 2 T u c k 8 after Robert ( 3 1 90 5) — of M 1 8 don the symm edian point John S turgeon ackay ( 43 1 9 1 4 ) E dinburgh has pointed out that some of the properties of this point brought to l i ght since 1 8 73 were first d i scovered previously to that AO ’ B , ’ . ’ ’ ' ” , ’ . ’ ’ ’ , , , ’ . ’’ ’’ ’ , , . ” , . ’ ” ” , ’ ” “ , , , . , . , . , , , - , ’ . ” , , . , , A H I STOR Y O F M AT H EMATI CS 30 0 date The anti parallels of a triangle which pass through its sym m edian point m eet its S ides in s ix points which lie on a circle call ed “ “ the second Lemoine circle The firs t Le moine circle is a special “ “ case of a Tucker circle and concentric with the B rocard circle “ The Tucker circles may be thus defined Let D F = FE = ED let m oreover the follow ing pairs of lines he anti parallels to each other : AB and ED B C and FE CA and D F ; then the six points “ D D E E F F li e on a Tucker circle Vary the length of the equal anti parallels and a family of Tucker circles is obtained Allied to these are the Taylor circles due to H M Taylor of Trinity College Cambridge “ Still different types are the M ackay circles and the N eu b erg circles due to Joseph Neuberg ( 1 840 of C Luxe mburg A syste matic treatise on this topic Di e B r ocardschcn Gebi l de was written by Albrecht E mm erich B erlin 1 8 91 Of the al most i n nu m erable m ass of new theorem s on the triangle and circle a great nu m ber is given in the Tr eati se on the Ci rcl e a nd the S phcr c Oxford 1 9 1 6 written by J L Coolidge of Harvard University Since 1 88 8 E Le moine of P aris developed a system called g eome t rog raphi c s for the purpose of nu m erically co mparing geo m etric con s t r u c t i on s with respect to their S im plicity Coolidge calls thes e “ the best known and least undesirable tests for the s implicity “ of a geo m etrical construction ; A E mch declares that they are hardly of any practical value in so far as they do not indicate how to S i mp l ify a construction or how to m ake it m ore accurate A n ew theore m upon the circum scribed tetraedro n was propounded in 1 8 97 by A S B ang and proved by J ob Gehrke The theore m is : Opposite edges of a circum scribed tetraedron subtend equal angles at the points of contact of the faces which contain them I t has bee n the starting point for extended developments by Fran z M eyer J 1 N eub erg and H S White - . ” ” ” , ” , ” . . ’ ’ ’ . , - , ’ ’ ’ , , ’ ’ , , . - ’ , ” , , , . . . , . , ” , . , , . , , , , , . , . . . , ' , . ” . ” , . . . . . . - . , . . . Li n k moti on - The generation of rectilinear motion first arose as a practical prob l em in the design of stea m engines A close approxim ation to such “ m otion is the parallel m ot i on d esigned by Jam es Watt in 1 78 4 : In a freely j ointe d qua d rilateral AB CD with the S ide AD fi xed a point M on the side B C m oves in nearly a straight line The equa “ tion of the curv e trace d by M so meti mes called Watt s curve was first derived by the French engineer Fr an goi s M ari e dc P rony ” . , , ” . ’ , , , 1 B ul l A m M ath S oc . . . . , V ol . 1 4 , 1 90 8 , p . 2 20 . A HI STORY OF M ATHE M ATIC S 30 2 The barrister at law Alfred B ray Ke mpe of London showed in 1 8 7 6 that a link m otion can be found to describe any given algebraic curve ; he is the author of a popular booklet H ow to dr aw a S trai ght Li n e London 1 8 7 7 Other articles of note on this subj ect were prepared by Sam uel Roberts Arthur Cayley W Woolsey Johnson V Lig u in e of th e University of Odessa and G P X Koenigs of the Ecole P oly technique I n P aris The dete rm ination of the linkage with m inim um nu mber of pieces by which a given curve can be described is still an unsolved problem , - , , . , , , . . . , . , . . . — P a r al l el L i n es , N on Eu cl idean Geometry and Geometry of n Di mensi on s D uring the nineteenth century very re markable generali zations were m ade which reach to the v ery root of two of the oldest branches — of m athem atics elem entary algebra and geom etry In geom etry the axio m s have been searched to the bottom and the con c l u si o n has bee n reached that the defin ed b y Eucli d s axio m s is not the only possible non m i c t o ry space Euclid prov ed “ that if a straight line falling on two other straight lines m ake (I 2 7 ) the alternate angels equal to one another the two straight lines shall be parallel to one another B eing unable to prove that i n every other case the two lines are not parallel he assu med this to be true in “ what is now generally called the 5th axio m by som e the 1 1 th or “ the 1 2 th axio m Simpler and m ore obvious a xiom s have been advanced as sub “ As early as 1 6 6 3 John Wallis of O xford recommen d ed : To s t i t u t es any triangle another triangle as large as you please can be drawn which is S imi lar to the giv en triangle G S acche ri assu m ed the ex i s t en c e of two si m ilar unequal triangles P ostulates si m ilar to Wallis hav e been proposed also by J H Lam bert L Carnot P S Laplace m l e f A C Clairaut assu es the existence of a rectangle ; D e b o u J W Bolyai postulated that a ci rcle can be passed through any three points not i n the sam e straight line A M Legen dre that there e xisted a finite triangle whose angle — s u m is two right angles J F Lorenz and Legendre that through every point within an angle a line c a n be drawn i n t eresc t i n g both sides C L D odgson that in any circle the inscribed equilateral quadrangle is greater than any one of the seg m ents which lie outside it B ut probably the S i mplest is the ass u mp tion m ade by Joseph Fenn in his e dition of Eucli d s El emen ts Dub — m m lin 1 7 69 and again sixteen years later by Willia Ludla ( 1 7 1 8 1 vicar of Norton and adopted by John P layfair : Two straight lines which cut one another can not both be parallel to the sam e straight 1 line It is noteworthy that this axiom is distinctly stated in P r oc l u s s note to Eucli d I 3 1 B ut the m ost nu m erous e ff orts to re move the supposed defect in , . , , ’ . - . , ” , ” . , ” , . . . , ” , , , . . ’ , . . . . . . , . . , . , . . . , . . , . , . . . ’ , , , “ , ” . ’ , 1 , . T L H ea t h , The Thi r teen B ook s . . f o E ucl i d s El emen ts , V ol I , p ’ . . 2 20 . SYNTHETI C GEO M ETRY 39 3 Euclid were a ttempts to prove the parallel postulat ri es of espera te but fru i tl ess en deal q r the hol d i dea the m i n s of sev e ral f riath éma ti c i an s tha t a geo m etry m ight be built u p — th e : a l l e xio m While A M Legendre till a S pai l e n déa Y Of ed tO establish the axio m by rigid proof L ob a ch evsk i brought out a publication which assu med the contradictory of that axiom and which was the first of a series of articles destined to clear up Oh sc u r i t i es in the funda m ental concepts and greatly to extend the field of geo m etry N i ch ol au s I van ovi ch L ob a ch e vs k i ( 1 7 93— 1 8 56 ) was born at M a karic i in N i zhn i at Kasan and fro m 1 8 2 7 to 1 846 was professor and rector of the University of Kasan His views on the foundation of geom etry were first set forth in a paper laid before the physico mathem atical depart m ent of the University of Kasan in February 1 8 2 6 This paper was never printed and was lost His earliest publication was in the Kasan M cssengcr for 1 8 2 9 and then in the Gel ehr te S chrif ten der Uni versi tat K asan 1 83 6 —1 83 8 under the “ title N ew Ele ments of Geo metry w i th a complete theory of P ar allels B eing in the Russian language the work remained unknown to foreigners but even at hom e it attracted no notice In 1 840 he pub l i shed a brief state m ent of his researches in B erlin under the title Geometr i sche Un tersu chu n gen zu r Theor i e der P aral l el l i n i cn Loba “ c h e vsk i constructed a n i maginary geom etry as he called it wh ich _ “ has b eéITdé scrib ed by W K :Clifford as quite simple m erely Eu c lid withou t the vicious assum ption A re m arkable part of this geo m etry is this that through a point an indefinite number of lines can be drawn l i A si m ilar in a plane none of which n the sa m e plane n e i g i v en_ _ k temfi i f geom et ry was deduced independentl y by the B olyais i n sy “ Hungary who called it absolute geo metry was born in S z ekler Land Wo lf g an g B olyai de B ol ya ( 1 7 75— 1 8 56 ) Transyl v ania After studying at Jena he went to Gottingen where he bec ame intimate with K F Gauss the n nineteen years old Gauss used to say that B olyai was the only man who fully understood his views on the m etaphysics of m athem atics B olyai beca m e professor at the Reformed College of M aros V as arhely where for forty seven years he had for his pupils m ost of the later professors of Tran syl vania The first publications of this remarkable genius were dramas and poetry Clad in old tim e planter s garb he was truly original in his private life as well as in his m ode of thinking He was extre m ely m odest No m onu m ent said he should stand over his grave only an apple tree i n m emory of the three apples ; the t w o of Eve and P aris w hich m ad e hell out of earth and that of I Ne w ton which elevated 1 the earth again into the circle of heavenly bodies His son J oh ann d F S h mid t Joh A d m L be zw ei er g i h r M t hema t ik , - i fi ' _ . ' . . ’ , , , . , , . - . , . , , , , , . , . , , , . ” ' ' . , , , . , ” ~ , . . , - , . , , . . . , . - - , . ’ - . , . , . , , - , , . , , . 1 c . Wolfg an g 1 90 1 w ) , B o l ya i us v on e n un ’ ar sc B ol ya , Gr u ner t s A rchi v, i n B u dapest t t as an a rc hi ec e . e a 1 86 8 . , er an n F r an z S chmi d t un (182 7 A HI STORY OF M ATHE M ATIC S 3 04 B olyai hirn sel f was educated for the army and dist i n g uished as a profound m athe matician an impassioned violin— player and an expert fencer He once accepted the challenge of thirteen O ffi cers on condition that after each duel he m ight play a piece on his violin and he vanquished them all The chief m athematical work of Wolf gang B olyai appeared in — 2 two volum es 1 83 1 833 entitled Ten tamen j u ven tu tem s tudi os am i n i n tr odu ccndi I t is followed by an ap cl emen ta ma thes eos pu r a Its twenty six pages make the p en dix com posed by his son Johann nam e of Johann B olyai im m ortal He published no thing else but he l eft behind one thousand pages of manuscript While L ob ach ev sk i enjoys priority of publication it may be that Bolyai developed hi s system som ewhat earlier Boly ai S atisfied hi m — self of the non contradictory character of his new g eom et ry on or be fore there Is som e doub t whether Lob achev sk i had reached this point in 1 8 2 6 Johann B olyai s fa ther se em s to have been the only person in Hungary who really appreciated the m erits of his son s work For thi rty fi v e years this appendix as also L ob ach ev sk i s researches rem ained in al most entire oblivion Finally Richard Baltz er of the Univ ersity of Giessen in 1 86 7 cal led attention to the won derful researches In 1 86 6 J H oii el translated L ob achev sk i s Geometri sche Un ter In 1 8 6 7 appeared a French translation of s u chu n g en into French Johann Bolyai s A ppendi x In 1 891 George B ruce Halsted then of the University of Texas rendered these treatises easily accessible to American readers by translations brought out under the titles of Bolyai s T h e S c i en ce A bs ol u te of S pa ce and N L ob ach evs ki s Geo J metr i cal R es ear ches on the Theory of P ar al l el s of 1 840 The Russian and Hungarian mathematicians were not the only ones to who m p a n g e ome try suggested itself A copy of the Tentamen reached K F Gauss the elder Bolyai s form er roo mmate at G ottingen a n d this Nestor of Ger man m athe maticians was surprised to disco v er in it worked out what he hi mself had begun long before only to leav e it afte r hi m I n hi s papers As early as 1 7 92 he had started on researches of that character His letters S how that In 1 7 99 he was trying to prove a pr i or i the reality of Euclid s syste m ; but so m e ti me within the next thi rty years he arrived at the conclusion reached by L ob achevski “ and Bolyai In 1 8 2 9 he wrote to F W B essel s tating that hi s con v i c t i on that we cannot found geo metry co mpletely a pr i or i has b e “ come if possible still firm er and that if nu mber is m erely a product of ou r m ind S pace has also a r eal i ty beyond our m ind of whi ch w e cannot fully foreordain the laws a pr i or i The term n on Eu cl i dean t h e f i s f l i m se s of It is surprising that m t r y is due to Gauss eo e _ r p g non Euclid ean geom etry were had I n the eighteenth _centu ry Ger on a J esuit father of M ilan i n 1 733 wrote n i mo S a ccher i ( 1 6 6 7 ' ( 1 80 2 , ' , , . . , , , . - . . , . , . h l g - H ’ ' . ’ ’ - , . . , , , . ’ . . ’ . , , ’ ’ . . . . ’ . . , , , . . ’ . ” , , . . , , ' , . m . - . , A H I STORY O F M AT H E M ATIC S 3 06 contemporary researches on parallel lines due to A M Legendre in France The researches of K F G auss N I L ob achev sk i and J Bolyai have been considered by F Kl ein as c on s ti t u ti rig the first p eriod I n the histo ry of non Euclidean geometry It is a period I n which the syhth et i c m eflI Od s of elementary g eom etry were in vogue The second period e mbraces the researches of G F B Riemann H Hehn holt z S Lie and E B eltra m i and e mp l oys the m ethods of diff erential geometry It was in 1 8 54 that Gauss heard from his pupil Riemann a marvellous dissertation whi ch considered the foundations of g eome try fro m a new point of view Riem ann was not fa miliar with Lo b achev ski and Bolyai He developed the notion of n ply extended magni tude and the m easure relations of which a manifoldness of n dimensions is capable on the assu mption that every line may be measured by every other Rie mann applied his ideas to space He taught us to disti n guish between f infin i t e extent Acco rdi ng to hi m we have I n our m ind a m ore general notion of space i c a notion of non Euclidean space but we learn by axpe r i en ce that our physical space is if not exactly at least to a high degree of approxim ation Euclidean space Riemann S profound dissertation was not published until 1 8 6 7 when it appeared in the Gotti ngen A b B efore this the idea of n dim ensions had suggested itself ha ndl u ngen under various aspects to P tolemy J Wallis D A l emb er t J Lagrange m and H G Grass ann The idea of ti me as a fourth di P l ii k e r c J men si on had occur red to D Al emb er t and Lagrange About the sa m e ti me wi th Rie m ann s paper others were published from the pens of This period marks the beginning H H el mhol tz and E B el tr ami — of lively discussions upon this subj ect So me writers J B ell avi ti s for e xample—were able to see in non Euclidean geo metry and n dirn en s i on al space not hi ng but huge caricatures or diseased out growths of mathe matics H Hel mholt z s article w as en t i tl ed That sachen w el che der Geometr i c zu Gr u nde l i egen 1 8 6 8 and contained many of the ideas of Riemann Helmholt z popul ariz ed the subj ect in lectures and in articles for various m aga zines Starting with the idea of congruence and assuming the free m obility of a rigid body éfid the return unchanged to its original position after rotation about an axis he proves that the square of the line elem ent 15 a homogeneous function of the second degree in the diff erentials Hel mholtz s investigations were carefully exam ined by S Lie who red uced the Riemann Hel mholtz problem to the following for m : To determ ine all the continuous groups in space which in a boun ded region have the property of displacements There arose three types of groups . . . . . . . , . c ' . - . . . . . , . . . , , . , , . - . - , , ” . . ‘ ‘ . . - . , . , , , ’ . , ’ , . ’ . , . , . . , . , , . ’ . ’ , . . . . . , - , ' ’ . . , , , . . , , , ’ . . - , , . , S om merv ill e i s t he au thor o f a B i bli ography of n on E ucl idea n g eometr y i n cl udi ng the theor y of para ll el s , the f ou ndati on s of geometry, and space of n di mens i on s , L o n don , - 19 1 1 1 . D M Y S o mm erv il l e , . . . op ci t . . , p . 1 95 . SYNTHETIC GEO M ETRY 30 7 which characteri ze the three geo metries of Euclid of N I L obach ev 1 ski and J B olyai and of F G B Rie mann Eu g e ni o B e l trami ( 1 83 5 born at Cremona wa s a pupil of F Brioschi ? H e was professor at Bologna as a colleague of L Cremo n a Betti at P av ia as a c o worker w ith F a t P isa as an associate of E C a sora t i and since 1 8 9 1 at Ro m e where he S pent the last years of his career uno degli illustri maestri dell analisi in Italia Beltrami w rote in 1 868 a classical paper S aggi o di i n ter pr etazi on e del l a g eometri a n on en cl i dea (Gi or n which is a nalytical ( and lik e di M atem se v eral other papers S hould be m entioned elsew here were we to adhere to a strict separation between synthesis and analysis ) He reached the b rilliant and surprising conclu sion t hat in part t he the OremS of non Euclidem g eome try find thei r fr eal ization u pon surfaces of con stant neg at ive curvature H e studi ed also surfaces of constant posi tive curvatur e and e nded with the interesting theorem t hat the spac e o f constant positi v e curvature is contained in the space of con sta nt negative curvat u re These researches of B eltrami H Helmholtz and G F B Riem ann cul minated in the conclusion that on sur faces of constant curvature we may have three geo metries the non Eucli d ean on a surface of constant negative curvature the spheri cal On a sur face of constant positive cur vature and the Eucl idean geo metry on a surface of z ero cu rvature The three g e o me t r i es do not contra dict each oth er but are me mbers of a system a geo m etrical trinity The ideas of hyper S pace were brilliantly ex poun ded and popularised in England by Cl ifford William Ki n g d on Cl iffor d ( 1 84 5—1 8 79) was b orn at E xeter edu c a t ed at Tri n ity College , C ambridge and fro m i 8 7 1 until his death professor of applied mathematics in University College L ondon His premature death left incomplete several brilliant researche s which he had entered upon Am ong these are his paper On Cl assificati on of L oci and his Theor y o Gr aphs n the C a n on i cal He wrote articles O f Form a nd Di ss ecti on of a Ri eman n s S u rf a ce on B i qn a ter n i on s and an incomplete work on the El emen ts of Dyn ami c He gave exact “ meaning in dynamics to such fam iliar words as spin twist “ “ sq ui rt whi rl The theor y of polars o f _c urves and surface s was generaliz ed by him and by Reye H i s cl assifi c a ti on of loci 1 8 7 8 b eii In en erab s t udy of cu rves Wa s an introduction to the study i o f_ e n si on a l S pace in a di rec t ip n ainly proj ective Th i s study i m ; _ ni m has been continued since chi efly by G Veronese of P adua C Segre of Turin E Bertini F A schi er i P Del P e zz o of Naples Beltrami s researches on non Euclidean geom etry were followed in 1 8 7 1 by important investigations of Felix Klein resting upon Cayley s S i xth M emoi r on Qu a nti cs 18 59 The develop m ent of geom e t ry in the first half of the nineteenth century had led to the separation L i e Th ar i der T nsf ormati on sgru ppen Bd III L ei pzi g 1 893 pp 4 3 7 5 43 ; . , . , . . . . . , " . . , - . , . ” , ’ . , , - . . , , , . ' " w - , . , , ‘ , “ ' ‘ . . , . . , . , - , ' , . , , - . . , , ' , . , " . . ’ , ” ” , ” . , ” , , _ . . , g , , ‘ . " " . , , . . , . , . . ’ - , , , ’ . , 1 e , B on o l a , p o . e ci t . , ra p . 1 54 . - , . , , , . A HI STORY OF M ATHE M ATIC S 3 8 0 of this science into two parts : the geomet ry of position or descriptiv e geo metry which dealt with properties that are unaff ected by proj e c t ion and the geo m etry of m easure m ent in w hi ch the funda mental notions of di stance angle etc are changed by proj ection Cayley S S i xth M emoi r brought these strictly segregated parts together again by his definition of distance between two points The question whether i t is not possible so to e xpress the metrical properties of figures that they will not vary by proj ection (or linear transformation ) had been sol v ed for special projections by M Chasles J V P oncelet and E Laguerre but it re mained for A Cayley to give a general solution by defining the distance between two points as an arbitrary constant m ultiplied by the logarith m of the anharmonic ratio in which the line joining the two points is divided by the fundamental quadric These researches applying the principles of pure projective geo metry m ark t h e third period in the develop m ent of non Euclidean geo m etry Enlarging upon this notion F Klein S howed the independence of projecti v e geo m etry fro m the parallel axio m and by properly choosing th e law of the m easure m ent of d i stance deduced fro m proj ecti v e geom etry the spherical Euclidean and pseudospherical geom etries nam ed by h im respectively the elliptic parabolic and hyperbolic geom etries This suggestiv e i n vestigation was followed up by nu m er ous writers particularly by G B attaglini of Naples E d O v i dio of Turin R de P aolis of P isa F A sc hi e ri A Cayley F Lin d emann of M unich E Schering of Gottingen W Story of Clark University H S ta hl of T ubingen A Voss of M unich H om ersh am Cox A B uch 1 heim The notion of parallelis m applicable to hyperbolic S pace was the only extension of Euclid s notion of pa rallelis m until Cli fford dis covered i n elliptic S pace straight lines which possess m ost of the prop e r t i e s of Euclidean parallels but di ffer fro m the m in being skew Two lines are right (or left ) parallel if they cut the sam e right (or left) generators of the absolute Later F Klein and R S Ball m ade extensiv e contributions to the knowle dge of these lines M ore re c en t l y E Stu dy of B o n n J L Coolidge of Har v ard University W Vogt of Hei delberg and others hav e been studying this subject The m e thods e m ployed hav e been those of analytic an d synthetic geom etry 2 as well as those of d iff erential geo metry and vectorial analysis The geo metry of n dimensions was stud ied along a line mai n ly m etrical by a host of writers a mong who m may be m entioned Simon N ew c omb of th e Johns Hopkins Univ ersity L S chl afl i of B ern W I Stringham — 1 of the Univ ersity of California W Killing of M unster 8 ( 4 7 1 90 9) — T Craig of the Johns Hopkins Ru dolf Lipschitz ( 1 83 2 1 90 3 ) of B onn R S Heath of B irm ingha m and W Kill ing in v estigate d the k i nem at i cs Regular sol i ds in n dim ens ional space a n d m echanics of such a S pace — i were studied by Str ngham Ellery W D avis ( 1 8 5 7 1 9 1 8)of th e , ’ , , , . . . . . , . , . , . , , - . . , - , , , , , , . ’ , . . , . , , , . . , . . , . , . , , . , , . . ’ , . , . . . . . . , . . , . . . , ' , , . . . , . . . , . , . . - . . , 1 G Lo r i a , Di e ha npts a chl i chs ten Theor i en der Geometr i e, B u l l A m M a th S oc , V ol 1 7 , 1 9 1 1 , p 3 1 5 . . . . . . . . 1 888 , p . 10 2. A HI STORY OF M ATHE M ATIC S 3 10 A n al yti s ch Geometr i s che En twi ckl u n gen in two volum es Therein he adopted the abbreviated notation [ used before hi m I n a more restricted way by Etienne B ob il l i er ( 1 797 professor of m echanics at Chalons sur M arne] and avoided the tedious process of algebraic elim ination by a geom etric consideration In the second volume the principle of duality is form ulated analytically With h im duality and homogeneity found e xpression already in his system of c o ordinates The ho mogenous or trilinear system used by him is m uch the same as the c o ordinates of A F M ob i u s I n the i d entity of analytical opera tion and geom etric construction P l ii c k er looked for the source of his e e e ri e contains a roofs The s t e m er n a l t i s c h n m t 1 83 5 S d A G o p y y complete classification of plane curves of the third order based on the nature of the points at infinity The Theari e der A l gebrai schen Cu rven 1 8 39 contains besides an enu m eration of curves of the fourth ord er the analytic relations betw een the ordinary singularities of plane “ curves know n as P lucker s equations by which he was able to “ explain P oncelet s parad ox The discovery of these relations is “ says A Cayley the m ost i mportant one beyond all comparison in the entire subj ect of m odern geom etry The four P lucker equa tions have been e xpressed in di fferent form s Cayley studied higher singularities of plane curves M W Haskell of the University of California in 1 91 4 S howed from the P l ucker equations that the m aximu m num ber of cusps possible for a curve of order m is the ( except when m is 4 and 6 i n which g reatest integer i n m (m case the m aximu m nu mber is 3 and and that there is always a self dual curve with this m aximu m num ber of cusps Certain interrelations of the various geom etrical researches of the first half and mi ddle of the nineteenth century are brought out by 1 “ J G D arb ou x in the following passage : While M C hasles J Steiner and later v on Staudt were intent on constituting a riv al doctrine to analysis and set in so m e sort altar against altar J D G erg onn e E B ob illi er C Sturm an d above all J P l ii ck er per f ec te d the geom etry of R D escartes and constituted an analytic sys t em in a m anner adequate to the disco v eries of the geo m eters I t is to E B ob ill i er and to J P l ii ck er that we owe the m ethod called a br i dged n ota ti on B ob ill i er consecrated to it so m e pages truly n ew in the last volu mes of the A n n al es of G erg on n e P l ii ck er comm enced to develop it in his first work soon followed by a series of works where are established i n a ful ly conscious m anner the foundations of the m odern analytic geom etry It is to him that we owe tangential co ordinates trilinear c o or dinates employed with ho m ogeneous equa tions and finally the e mploym ent of canonical form s wh ose val i dity was recogniz ed by the m ethod so deceptive so m etim es but so fru i t ful cal led the en u mer ati on of con s ta n ts In Germ any J P l ii c k er s researches m e t with no favor His m ethod - . - , . . - . - . . . . , , , . , ” , , ” ’ ’ , . . , , ” , . . . , . . , . , - . . . . , , , . , , , . . . , . , . , , . . . . . . , . - , , , ” , , , . ’ . 1 Congr ess f o . A r ts a nd S ci ence, S t L o u i s , . 1 9 04 , Vo l 1, pp 5 4 1 , 5 4 2 . . . ANAL YTI C GEO M ETRY 311 was declared to be unproductive as compared with the synthetic m ethod of J Steiner and J V P oncelet ! His relations with C G J Jacobi were not altogether friendly S teiner once declared that he woul d stop writing for Cr el l e s Jou rn al if P lucker continued to con 1 tribute to i t The result was that m any of P l ii c k er s researches were published in foreign journals and that his work cam e to be better known i n France and England than in his native country The charge was also brought against P l ii ck er that though occupying the chair of physics he was no physicist This induced him to relinquish m athe m atics and for nearly twenty years to devote his energies to physics I mportant discoveries on Fresnel s wa ve s urface m agnetis m spectru m analysis were m ade by him B ut towards the close of his — — m life he returned to his first love athe matics and enriched it with n ew discoveries By consid ering S pace as m ade up of lines he created “ a n ew geom etry of space Regarding a right line as a curv e i n volving four arbitrary param eters one has the whole system of lines “ in space B y connecting the m by a single relation he got a co mplex “ of lines ; by connecting the m with a twofold relation he got a con His first researches on this subj ect were laid before g r u e n cy of lines the Royal Society in 1 8 6 5 His further investigations thereon ap p e ared i n 1 8 6 8 i n a posthu m ous work entitled N eu e Geometri e des . . . . . . . ’ ’ . , . , . , , ’ - , , . - . , , ” . ~ . ” , , . , . . Rau mes gegr un det ' f di e B etr achtu n g der ger aden Li n i e ’ Klein P l ii ck e r s analysis lacks au al s Kou mel e edited by Felix the elegance found in J Lagrange C G J Jacobi L O Hesse and R F A C l e b s ch For m any years he had not kept up with the progress of geo m etry so that m any invest igations in his last work had already receiv e d m ore general treatm ent on the part of others The work co ntaine d nev ertheless m uch that was fresh a n d origi n al The theory of complexes of the second degree left unfinished by P l ucker was continued by Fel ix Klein who greatly e xtended and supplem ented the ideas of — h l S m aster — i d tt e s Lu w g O o H s e ( 1 8 1 1 1 8 74) was born at Konigsberg and stu died at the university of his nativ e place under F W B essel C G J Jacobi F J R i c hel o t and F Neu m ann Ha v ing taken the doctor s d egree i n 1 84 0 he beca m e docent at K onigsberg and in 1 8 4 5 e x t ra or di n a ry professor th ere A m ong his pupils at that ti m e were H ei n ri ch Du r ege ( 1 8 2 1 — of P rague Carl Neum a n n R F A C l eb sc h 1 8 93 ) G R Kirchho ff The K onigsberg period was one of great activity for Hesse Eve ry new discovery increased his z eal for still greater achievem ent His earliest researches were on surfaces of the second order and were partly synthetic He solved the proble m to construct any tenth point of such a surface when n ine points are giv en The analogous problem for a conic had been solv ed by P ascal by m eans of the hexagra m A difficult proble m confronting m athem at i c i ans of this tim e was that of el im i nati on J P l ucker had seen that the men t, . . . , . . . , . . . , . . , . , . , , , , . , . , . . . . ’ , . . , . . , , . , , . . . . . , . . . , . . . . . 1 A d D ro n k e , J . u l i us P l uck er , B o nn , ‘ 1871 . A HI STORY OF M ATHE M ATI C S 12 m ain adv antage of his special m ethod in analytic geom etry lay in the avoidance of algebraic elimination Hesse however showed h ow by determ inants to make algebraic elim ination easy In his earl ier results he was anticipate d by J J Sylvester who published his dialytic These advances in algebra Hesse m ethod of eli m ination i n 1 840 applied to the analytic study of curves of the third order By linear substitutions he reduced a form of the third d egree I n three variables to one of only four terms an d was led to an i mportant determ inant inv ol v ing the second d i fferential coeffi cient of a form of the third “ d egree called the Hessian The Hessian plays a lea d ing part in the theory of invariants a subj ect first studied by A Cayley Hesse sho w e d that his determ inant give s for every curve another curv e such that the double points of the first are points on the second M any of the r Hessian Sim i larly for surface s ( C r el l e m ost i mportant theorem s o n curves of the third or der are due to Hesse He d eterm i ne d t h e curve of the 1 4 th order which passes through the 5 6 points of contact of the 2 8 b i tangents of a curv e of the fourth order His great m e m oir on this subj ect ( C r ell e 1 8 55) was published at the sam e tim e as was a paper by J Steiner treating of the sam e subj ect Hesse s incom e at Konigsberg had not kep t pace with his growi ng reputation Hardly was he able to support himself and family In 1 8 5 5 he accepted a m ore lucrative position at Halle and in 1 8 5 6 one at Heidelberg Here he rem ained until 1 8 6 8 when he accepted a 1 At Heidelberg he revised posi tion at a technic school In M unich and enlarged upon his previous researches and published I n 1 8 6 1 his . , , . . . , . . , , ” “ . , ” . , . . ” , “ , . , . , - . , . . ’ . . , . , . , Vor l es u n gen ti ber di e A n al yti s che Geometr i e des R au mes , i ns bes on der e M ore elementary works soon followed uber Fl a chen 2 Or dn u ng “ While in Heidelberg he el aborated a principle , his U eb er trag u ng s princip Accordi ng to thi s , there corresponds to every point in a ” . . . . . plane a pair of points in a line and the proj ective geo metry of the plane can be carried back to the geo metry of points in a line The researches of Plii ck er and Hesse were continued in England by A Cayley G Sal mon and J J Sylvester I t m ay be premised here that amon g the early writers on analytical geom etry in England was J ame s B oo th ( 1 80 6 whose chief results are e mbo di ed in hi s Tr eati se on S ome N ew Geometr i cal M ethods and J a m e s M a c C u l l a g h who was professor of natural p hi losophy at D ublin ( 1 80 9 and made som e valuable discoveries on the theory of quadrics The influence of these m en on the progress of geom etry was insign ificant for the interchange of scientific results between di fl er en t nat i ons w as not so complete at that tim e as m ight have been desired In further illustration of this we m ention that M Chasles in France elaborated subjects whi ch had previ ously been disposed of by J Steiner in Ger many and Steiner publ i shed researches which had been gi ven by , . . , . , . . . , , . , . . , . , 1 ' G u s ta v B a u er , Ged achtn i ssr ede f au Otto Hess e, M un ch en , 1 88 2 . 3 A HI STORY OF M ATHE M ATIC S 14 had shown how elliptic functions could be advantageously applied to M alfa t ti s problem The idea involved therein vi z the use of higher transcendentals in the study of geom etry led hi m to his great est di scoveries Not o nl y did he apply Abelian functions to geom etry but con v ersely he drew geom etry into the servi ce of Abelian functions C l eb s ch made liberal use of determ inants His study of curves and surfaces began with the determination of the points of contact of lines which m eet a surface in four consecutive points G Salm on had pro v ed that these points lie on the intersection of the surface with a — deri v ed surface of the degree 1 1 n 2 4 but his solution was gi v en in i nconvenient for m C l eb sc h s investigation thereon is a most beautiful piece of analysis The representation of one surface upon another (Fl achen abbi l du ng) so that they have a ( 1 1 ) correspondence was thoroughly studied for the first ti me by C l eb s c h The representation of a S phere on a plane is an old proble m whi ch drew the attention of P tole my Gerard M er cator J H La mbert K F Gauss J L Lagrange Its i mportance in the construction of m aps is obvious Gauss was the first to represent a surface upon anothe r w ith a view of more easily arriving at its properti es J P l ucker M Chasles A Cayley thus represente d on a plane the geom etry of quadric surfaces ; C l eb s ch a n d L Crem ona that of cubic surfaces Other surfaces have been stu died in the same way by recent writers particularly M ax N other of Erlangen A ng el o of Ro m e Fel i x Kl ei n Georg H L K or ndorf er A r men a n te ( 1 844—1 8 7 8 ) of Naples H G Z eu then of Cope nhagen E ttor e C apor al i ( 1 8 5 5—1 8 8 6 ) A funda mental question which has as yet received only a par tial a n swer is this :What surfaces can be represented by a ( 1 1 ) correspond ence upon a given surface ? This and the analogous question for curves was stu died by C l eb sch Higher correspon dences between surfaces hav e been investigated by A Cayley and M 1 Nother I m portant bearings upon geometry has Riemann s theory of birational transfor m ations The theory of surfaces has been stu died by J os e ph i P professor at the Sorbonne in ar s Jea n Al fr e d S erre t ) 5 — of D ublin Wi l l i a m Gaston Da r bou x of P aris J ohn C as ey ( 1 8 2 0 1 8 9 1 ) — — n r t r r h of D ublin e i i h S b e 1 8 2 of H c c Rober ts ( 1 8 1 7 1 88 3 ) ( 9 1 8 92 ) B reslau El wi n B r u n o C hri stofi el ( 1 8 2 9 professor at Zurich later at S trassburg Chri stoffel wrote on the theory of potential on minim al surfaces on the so called transfor mation of Christoff el of i sothermic surfaces on the general theory of curved surfaces His researches on surfaces were ex tended by Ju l i u s Wei ngarten 1 83 6—1 9 1 0 ) of the University of F r ei b u rg and H a n s von M angol dt of Aachen in A S we shall see m ore ful ly later surfaces of the fourth order 1 88 2 were investigated by E E Ku mmer and Fresnel s wave surface stu di ed by W R Ham i lton is a part i cular case of Kummer s quartic 1 surface with sixteen double points and sixteen S ingular tangent planes C l e b sc h ’ . . , , , . . , . . . , ’ . . , , , . , . . , , . , . . . . . - . . , . , . , . . , . , , . , , . , , . . . , . . . ’ . , , , ' , , , ‘ , . " - , , . , , , . ’ . . - , , ’ . , . . , 1 A C ayl ey , I nau g u ral A dd ress , . 1 88 3 . ANALYTIC GEO M ETRY 315 P ro m inent in these geometric researches was J ean G as ton Da r b o u x ( 1 84 2 He was born at Nim es found ed in 1 8 70 w i th the — collaboration of Gu i l l a u me J u l es H oitel ( 1 8 2 3 1 886 ) of B ordeaux and J u l es Tan n ery the B u l l eti n des s c i en ces ma théma ti q u es et as tr on omi qu es and was for half a cent ury conspicuous as a teacher In 1 900 he becam e permanent secreta ry of the P aris Academy of Sciences in which position he was succeeded after hi s death by E mil P icard B y his researches D arb oux enriched the synthetic analytic and i n fi n i t esi mal geo metries as well as rational m echanics and analysis He wrote L egons su r l a theori e gen er al e des su rf aces et l es appl i cati on s — t r i u es du cal cu l i nfi n i tes i mal é o m e P aris 88 1 g 7 1 8 96 and L egons su r q l es systemes or thogon au x ct l es coor donn ees cu r vi l i gn es P aris 1 8 98 He investigated t riply orthogonal ystem s of surfaces the deformat i on of surfaces and rolling of applicable surfaces infi nitesimal deforma tion spherical representation of surfaces the develop m ent of the moving axes of co ordinates the use of i magina ry geo m etric elem ents 1 the use of isotropic cylinders and dev el opab l es ; he introduced p entaspherical coordi nates “ Eisenhart says : B arbou x was a strong ad vocate of the use of i maginary el em ents in the study of geo metry He believ ed that their use was as necessary in geometry as in analysis He has been i m pressed by the success with which they have been e mployed in the sol ution of the problem of m inimal surfaces Fro m the very beginning he m ade use in his papers of the isotropic line the null sphere ( the isotropic cone ) and the general isotropic dev elopable In his first m emoir on orthogonal systems of surfaces he S howed that the envelope of the surfaces of such a system when defined by a S ingle equati on is an isotropic developable D ar b o u x gi v es to E douard C om the credit of being the first to apply the consi dera b escu re ( 1 8 1 9— P) tions of kine matics to the study of the theory of surfaces with the consequent use of m oving c o or dinate axes B ut to D arb o u x we ar indebted for a realiz ation of the power of this m ethod and for its D ar b o u x s ability was systematic development and exposi tion based on a rare co mbination of geo metrical fancy and analytical power He did not sympathi z e with those who use only geo metrical reasoning in attacking geom etrical problems nor with t hose who feel that there is a certain vi rtue in adhering strictly to analytical proc esses In common with M onge he was not content with dis but fel t that i t was equally important to make di sciples c ov er i es Like thi s di stinguished predecessor he developed a large group of geometers including C Guichard G Koenigs E C o ss era t A D e m oulin G Tzi t z ei ca and G D emar t r es Their brilliant researches a re the best tribute to his teachi ng P roceeding to the fuller consi deration of recent de v elop m ents w e , , , , . , . , , . , ’ ’ ’ , , , . , , s , , , , - , , . . . . , . , , . - . , ’ . . , . . , . , , . , . , . ” . , , . . . , ’ ” A m M a th M on thl y, V o l 2 4 1 0 1 7 p 3 54 S ee L P E i sen h ar t s C o n t r i b u t io n t o G eome t ry i n B ull A m M a th S oc , V ol 2 4 , 1 9 1 8 , p 1 . . . ’ . , , . . . . . . . . . “ D a rb o u x 2 2 7. ’ s A 31 6 H I STORY or M AT H E M ATIC S quote from H F B aker s address before the International Congress 1 held at Ca mbridge in 1 9 1 2 : The general theory of Higher P lane Cur ves would be impossible without the notion of the genus of a curve The inv estigation of Abel of the nu mber of independent i n t eg ral s in ter m s of which his integral su m s can be e xpressed m ay thus be held to be of paramount importance for the general theory This was further e mphasi z ed by G F B Riem ann s consideration of the no tion of birational transformation as a fundamental principle After thi s two streams of thought were to be seen First R F A C l eb s ch remarked on the existence of invariants for surfaces analogous to the genus of a p l ane curve Thi s number he defined by a double integral ; it was to be unaltered by birational transformation of the surface B ut C l eb sc h S idea was carried on and developed by M Noether also A B rill and Noe ther elaborated in a g eom etrical form the results for plane curv es which had been ob tained with t ran s c en dental consi derations by N H Abel and G F B Riemann Then the geo meters of Italy took up N o ether s work with very remark able genius and carried i t to a high pitch of perfection and clear ness as a geome t rical theory In connection therewith there arose the i mportant fact which does not occur in N oe ther s papers that it is necessary to cons i der a surface as possessing two genera ; and the nam es of A Cayley a n d H G Zeuthen S houl d be referred to at this stag e B ut at this tim e another stream was running in France E P icard was develop i ng the theory of Riemann integrals—S ingle integrals not double integrals— upon a surface How long and laborious was the task m ay be j udged fro m the fact that the publica tion of P icard s book occupied ten years—and may even then have seemed to m any to be an artificial and unproductive i mitation of the theory of algebraic integrals for a curve In the light of s ub s e quent events P icard s book appears likely to remain a permanent landmark in the history of geometry For now the two strea m s the purely geo metrical in Italy the transcendental in France have united The results appear to me at least to be of the gr eatest i m portance The work of E P icard in question is the Thear i e des fon cti on s al gébri q u es de deu x var i abl es i ndépendan tes which was brought out in conj unction with Georges Si mar t between the years 1 897 and ’ . . “ . . ’ . . . . . . . . , . . ’ . . . . . . . . . ’ ‘ , . ’ , , . . . . . . . , ’ . ’ , . , , , . ’ . . , 1 90 6 . H F Baker proceeds to the enumeration of some indivi dual r e s u l t s : Gui d o Caste l nuovo of Rom e has shown that the deficiency of the characteristic series of a linear system of curves upon a surface can not exceed the di ff erence of the two genera of the surface F ederig o Enriques of Bologna has completed this result by show ing that for an algebraic syste m of curves the characteristic series is complete Upon this resul t and upon E P icard s theory of integrals of the second . . . . ’ . , P r oceed of the 5 th I n ter n C on gr ess , V ol I , C a mb r i dg e , 19 1 3 , p 4 9 Fo r m o r e d e t a il , c o n s u l t H B B a k e r i n t he P r oceed of the L on don M a th S oc , V o l 1 2 , 1 9 1 2 1 . . . . . . . . . . . . A HI STORY OF M ATHE M ATIC S 1 3 8 ” theory of cubic surfaces This w a S don e later also by L Cre mona and R Stur m between whom in 1 866 the S teiner pri z e was di vided An elegant notation w as invented by Andrew Hart but the notation which has me t with general adopti on was advanced by L S chl afli of B er n i n 1 8 58 i t is that of the double S ix S chl afli s double six theorem “ proved by him and by m any others S ince is as follows : Gi v en fi ve l ines a b c d e whi ch m eet the sa m e straight line X ; then m ay any four of the five lines be intersected by another li ne Suppose that A B C D E are the other lines intersecting (b c d e)(c d e a ) and (a b c d) respectively T hen A B C D E (d e a b)(e a b c ) will all be me t by one other straight line x L S c hl afli first considered a division of the cubic surfaces into species in regard to the reality of the 2 7 lines His final classification was adopted by A Cayley In 1 8 7 2 R F A C l eb sc h constructed a “ m odel of the di agon al s u rf ace with 2 7 real lines w hi le F Klein es t ab l i sh ed the fact that by the principle of continuity all form s of real surfaces of the third order can be deri v ed fro m the particular surface ha ving four conical points ; he exhibited a co mplete set of models of cubic surfaces at the World s Fai r in C hi cago in 1 8 94 In 1 86 9 C F Geiser showed that the projection of a cubic surface from a point upon i t on a plane of proj ection parallel t o the tangent plane at that i c cur v e ; and that every quartic cur v e can be generate d oint is a quart p “ i n this way The theory of var i eti es of the third order says A Henderson that is to say curved geom etric form s of three dim en sions contained in a Space of four di mensions has been the subject of a profound m e moir by C or r ado S egr e ( 1 88 7) of Turin The depth and fecundity of thi s paper is evinced by the fact that a large pro portion of the propositions upon the plane quartic and i ts bi ta ng en t s P ascal s theore m the cubic surface and i ts 2 7 lines Ku m m er s sur face and i ts configuration of sixteen singular points and pla n es and on the connection between these figures are derivable fro m propositions relating to Segre s cubic variety and the figure of si x points or spaces fro m which i t S prings Other investigators into the properties of thi s beautiful and i mportant locus in space of four dim ensions and som e of its consequences a re G Castelnuovo and H W Richmond In 1 86 9 C Jordan first proved that the group of the problem of the trisection of hyperelliptic functions of the fi rst order is isomorphi c with th e group of the equation of the 2 7 th degree on which the 2 7 l ines of the general surface of the thir d deg r e e depend In 1 88 7 F Klein sketched the e ffectiv e reduction of the one problem to the other while H M aschk e H B urkhardt and A Witting completed the work outlined by Klein The Galois group of the equation of t he 2 7 lines was investigated also by L E Dickson F Kuhnen H Weber E P ascal E K a s n e r a n d E H M oore Surfaces of the fourth ord er ha v e been studied less thoroughly than those of the third J S teiner worked out properties of a surface of the ' . . . . , , . ’ , . , , , , , . , , , , , , , , , , , , , ” , , , , , , , . , , , , , , , . . . , . . . . . . , ” ’ . . . , , . , . , , , . , ’ ’ , , , , ’ , . ” . . . . “ . ” , ' . . , . . , . , . . , . . . . . . , . . , . , ANALYTI C GEO M ETRY 319 fourth order in 1 844 when he was on a journey to Italy ; that sur face bea rs this na m e and later received the attention of E E Kumm er 1 In 1 8 50 Thom as Weddle remarked that the locus of the vertex of a quadric cone passing through six given points is a quartic s urface and not a twisted cubic as M Chasles had once stated A Cayley gave a symm etric equation of the surface in 1 86 1 Thereupon Chasles in 1 8 6 1 showed that the locus of the vertex of a cone whi ch di vides six given segm ents harmonically is also a quartic surface ; thi s more general surface was identified by Cayley with the Jacobian of four q uadrics the Wedd l e surface corresponding to the case in which the four quadrics ha v e S ix co mmon points P roperties of the Wed dle sur face were stu died also by H B ateman The plane section of a We ddle surface is not an arbitrary quartic cur v e but one for which an invariant vanishes Frank M orley proved that the curve contains an 6 i nfini ty of configurations B where it is cut by the lines on the sur face In 1 863 and 1 8 6 4 E E Ku mmer entered upon an intensive study of surfaces of the fourth order Noted is the surface named after him which has 1 6 nodes The various shapes it can assum e have been stu died by Karl Rohn of Leip zig I t has received the attention of m any m athem aticians inclu d ing A Cayley J G D a rb ou x F Klein 2 H W Richm ond O B olz a H F Baker and J I Hutchinson I t has been known for som e tim e that F r esn el s wave surface is a case of Kummer s S ixteen nodal quartic surface ; al so it is known that the surface of a dynamical m e diu m possessing certain general properties is a typ e of Ku mmer s surface which can he derived from F r esn el s surface by m eans of a ho m ogeneous strain Ku mm er s quartic surface as a wave surface is treated by H B atem an The general Ku mm er s surface appears to be the wave surface for a medium of a purely i deal character F R Sharpe an d C F Craig of Cornell University have studied birational transform ations which leave the Kummer and Weddle urfaces invariant by the application of a theory due to F Severi . . , . . . . . , . . , . , . . . , . . . . . . , , . , . , . . . , . , . . , . ’ ’ ' ’ ’ ’ . . ’ . . . . . s . , Q uintic surfaces have been investigated at intervals since , 1 86 2 , principally by L Crem ona H A Schwarz A C l eb sch M N oe ther R Sturm J G D arb ou x E Caporali A D el Re E P ascal John E Hill and A B Basset No serious attempt has been m ade to en u mer ate the different form s of these surfaces Ruled surfaces with isotropic generators have been considered by G M onge J A Serret S Lie and others L P Eisenhart of P rinceton d etermines such a surface by the curve i n which it is c ut by a plane a n d th e directions of the projections on t h e plane of the generators . . , . . . , . . , . . . , . , , , . . , . . . . , . , . . . . Camb 69 Du bl i n M a th J our , V ol 5 , 1 8 50 , p 6 9 ’ 2 C o n su l t R W H T H u d so n ( 1 8 7 6 K u mmer s br i dg e , 1 90 5 1 “ . . . . . . . . . . . Qu arti c S u rf ace, C am . A HI STORY OF M ATHE M ATIC S 3 20 of the surface In th is way a ruled surface of this type is determ ined by a set of lineal elem ents in a plane d ependin g on one param eter While the classification of cubic curves was given by I Newton and their general theory was well under way two centuries ago the theory of quartic curves was not pursued vigorously until the ti me of J Steiner and L O Hesse Neglecting the class i fication of quartic curv es due to L Euler G Cram er and E Waring n ew classifications 0 2 1 have been made either according to their genus ( Geschlecht) 3 or according to topologic considerations studied by A Cayley in H G Zeuthen Christian Crone ( 1 8 7 7)and others 1 86 5 J Steiner in 1 8 5 5 and L O Hesse began researches o n the 2 8 double tangents of a general quartic ; 2 4 inflect ions were found of which G Salm on conjectured and H G Zeuthen proved that at m ost 8 are real An enu m eration (containing nearly 2 0 0 graphs ) of the fun da “ m ental for m s of quartic curves whe n proj ected so as to cut the line i nfinity the least possible nu m ber of times was given in 1 8 96 by Ruth Gentry ( 1 8 6 2 then of B ryn M awr College Curves of the fourth order hav e receiv ed attention for many years M ore recently a good deal has been written on special cu rves of the fif th order by Fran k M orley Alfred B Basset Virgil Snyder P eter Field and others Gino Loria of the University of Genoa who has written extensively on the history of geom etry and the history of curves in particular has adv anced a theory of pa n al g eb r ai c curv es wh i ch are in general transcen d ental curves By definition a pan al g eb rai c curve m ust satisfy a certain differential equation A book of reference on curves was published by Gomes Tei xei r a i n 1 90 5 at M adrid under the title . , , . . , . . . . . . , . , , , , , , . , . . . . . . , . . . . ” . . . , , , , . , , , , , . . Tr a tado de l as cu rvas es eci a l es n ota bl es p . The i nfinitesim al calculus was first applied to the determination of the m easure of curvature of surfaces by J Lagrange L Euler and — Jean Baptiste M arie M eu sn i er ( 1 7 54 1 7 93 ) of P ar i s noted for hi s m ilitary as well as scientific career M e u sn i e r s theorem relating to curv es drawn on an arbitrary surface was extende d by S Lie a n d i n 1 90 8 by E K as n er The researches of G M onge and E P C Dupi n were eclipsed by the work of K F Gauss who di sposed of this difli c u l t subj ect in a way that opened new vistas to geom etricians His treat m ent is embo died in the Di squ i si ti on es g en er al es ci r ca su perfi ci es cu r vas and Un tersu chu n gen uber Gegen stan de der hoher en Geodas i e of ( 1 8 2 7) 1 8 43 and 1 8 46 In 1 8 2 7 he established the idea of curvature as it is understood to day B oth before and after the tim e of Gauss various d efin i t i ons of curvature of a surface had been advanced by L Euler M eu sn i er M onge an d D upin but these di d not m eet with general a doption From Gauss measure of curvatu re flows the theorem of J oha n n A u gu st Gru n er t ( 1 7 9 7 professor in Greifswald and foun der in 1 8 4 1 of the A r chi v der M a themati k u nd P hysi k that the arithmetical m ean of the radii of curvature of all norm al sections , . , . , ’ , . . , . . . . . . . . , . . - . , . , , , ’ . , , A HI STORY OF M ATHE M ATIC S 32 2 The m etric part of differential geom etry occupied the attention of m athe maticians S ince the tim e of G M onge and K F Gauss and has reached a high degree of perfection Less attention has been giv en until recently to projectiv e diff erential geom etry particularly to the diff erential geom etry of surfaces G H Halphen started with the equation y=f (x) of a curve and determ ined functions of y dy/dx 2 2 d y/dx etc which are left invariant when x and y are subj ected to a general proj ective transformation His early formulation of the problem is unsymm etrical and unhom ogeneou s Using a certa in system of partial diff erential equations and the geom etrical theory of sem i covariants E J Wilcz ynski obtained hom ogeneous form s 1 such form s being deduced later also by Halphen Wilc z ynski treats of the proj ective diff erential geo m etry of curves and ruled surfaces these surfaces being prerequisite for his theory of S pace curves Wil c zyn s k i treated ruled surfaces by a system of two l i near ho m ogeneous d iff erential equations of the second order The m etho d was extended to fi v e d imens i onal space by E B Stou ffer of the University of Kan ? sas D evelopable surfaces were stu died by W W D enton of the Univ ersity of Illinois B elonging to projective differential geom etry are J G D arb ou x s conj ugate triple system s which are generaliz ed notions of the orthogonal triple system s The proj ective diff erential geometry of triple system s of surfaces of one param eter families of S pace curves and conj ugate nets on a curved surface and allie d topics were studied by G ab ri el M ar c u s G r e e n ( 1 891 of Harvard University D iff erential projective geom etry of hyperspace was greatly advanced by C Guichard who intro d uced two elem ents dependi ng on two va r iabl es ; they are the r es eau and the con gru en ce D iff erential geometry of hyperspace was greatly enriched since 1 90 6 by Corrado Segre of Turin and by other geom eters of I taly particularly Gino Fano of 3 Turin an d Federigo Enriques of B ologna ; also by A Ranum of Cornell C H Sisam then of Illinois and C L E M oore of the M assa c h u se tt s Institute of Technolo g y The use of vector analysis in difl er en t ial geom etry goes back to H G Grassm ann and W R Ham ilton to their successors P G Tait C M axwell C B urali Forti R Rothe and others These m en have “ “ introduced the term s grad div rot A geom etri c study of trajectories with the aid of analytic a n d chiefly contact transform a tions was m ade by Edward K asn er of Columb i a Univ ersity in his “ geom etric P rinceton Colloquiu m lectures of 1 90 9 on the differential — aspects of dynamics . . . , . , . . . , , . , , . . - . . , , . , . . - . . . . . ’ . . . - , , , . . . , , . . . , . . . . . . . . - . , . , ” ” ” . , . . , . “ . , , ” . S ee E J Wil c yn sk i i n N ew Ha ven C oll oq u i u m, 1 906 N ew H a ve n , 1 9 1 0 , p 1 5 6 ; al s o hi s P r oj ecti ve D i_ [j er en ti a l Geometr y of C u r ves a n d R u l ed S u rf aces , L e ip ig , 1 90 6 2 B u ll A m M a th S oc , V o l 1 8 , p 444 3 S e e En r i co B o mpi a n i i n P r oceed 5 th I n ter n C on gr ess , C a mbr idg e, C a mb r i dg e , 1 9 1 3 , V ol II , p 2 2 z 1 . . . ' . . . . . . . . . . . . z . . ANAL Y GEO M ETRY TI C 2 3 3 A n al ysi s S i tus ” Various researches have been brought under the head of analysis S itus The subj ect was first inv estigated by G W Leibni z and was later treated by L Euler who was interested in the problem to cross all of the seven bridges over the P regel river at Konigsberg without passing 7 twice over any one then by K F Gauss D § whose theory of knots ( Vers chl i ngu ngen ) Q has been e mployed more recently by Jo hann B enedict Listing ( 1 80 8—1 88 2 )of Gottingen Oskar Si mony of Vi enna F D i ng el dey of D ar mstadt and others in their topologic studies P G Tait was led to the study of knots by Sir Wi l lia m Thomson s theory of vorte x ato ms Through Rev T P Kirkm an who had stu died the properties of polyhedra Tait was led to study knots also by the polyhedral m ethod ; he gave the n u mber of form s of knots of the fi rst ten orders of knottiness Higher orders were 1 treated by Kirk man and C N Little Th o ma s P e n yn gt on K i rk man — 1 8 0 was born at Bolton near M anchester D uring boyhood 6 1 8 95 ) ( he was forced to follow his father s business as dealer in cotton and cotton waste Later he tore away entered the University of D ublin then beca me v icar of a parish in Lancashire A S a mathe matician he was al most entirely self taught He wrote on pl u q u at er n i on s I n vol v ing more i mag i nar i es than i j k on group theory on m athe “ the most m a t i c al mne m on i cs producing what D e M organ called “ curious crocket I ever saw on the proble m of the fifteen school girls who walk out three abreast for seven days where it is requi red to arran g e them daily so that no two shall walk abreast more than once This proble m was stud i ed also by A Cayley and Sylvester and is related to researches of J S teiner Another unique proble m was the one on the coloring of maps first mentioned by A F M ob i u s in 1 840 and first seriously considered by Francis Guthrie and A D e M organ How many colors are necessary to draw any m ap so that no two countries hav ing a line of boundary in common S hall appear in the sam e color ? Four di ff erent colors are found e xperimentally to be necessary and suffi cient but the proof is diffi cult A Cayley in 1 8 7 8 declared that he had not succeeded in obtaining a general proof Nor have the later demonstrations by A B Kempe P G Tait P J Heawood of the University of D urham W E S tory of Clark University and J P eterson of Copenhagen 2 re moved the difli c u l ty Tait s proof leads to the interesting con c l u s i o n that four colors may not be suffi cient for a m ap drawn on a Further m ult i ply connected surface like that of an anchor r i ng studies of maps on such surfaces and of the problem in general are . . . , . . , ” , , . , . . , . . ’ . . . . , . . . . . , ’ . , , . - . ” ” , , , , , , . . . , . , . . . . , . . . , . . . . , . , . . , . . ’ . - . , , A M ac fa rl an e , Ten B r i ti s h 2 W A hren s , Un ter hal tu n g en 1 . . M o thema ti ci an s a nd S pi el e, , 1 90 1 , 1916 ; p p 3 40 . . . 1 2 2. A HI STORY OF M ATHE M ATIC S 3 24 due to O Veblen ( 1 9 1 2 ) and G D B irkhoff On a surface of “ genus z ero i t is not known whether or not only four colors always s ufli c e A S imi lar question considers the m axim u m possible number of countries when e v ery co untry touches every other along a line Lothar H eff t er wrote on t hi s conundr um in 1 8 9 1 and again in la t er articles as did also A B Kempe and others In the han d s of Rie mann the analysis S itus had for its obj ect the determi nation of what remains unchanged under transformations brought about by a co mbination of infinitesim al di stortions In continuation of his work Walter Dyck of M unich wrote on the analysis S itus of three di m ensional S paces Researches of this sort have i mportant bearings in m odern mathe m aties particularly in connection with correspondences and di ff er 1 e n ti al equations . . ” . . , . , . , . . . . , - . , . —di I ntri ns i c C o or nates a reaction against the use of the arbitrary Cartesian and polar c o or di nates there ca m e the suggestion fro m the philosophers K C F Krause ( 1 7 8 1 A P eters ( 1 8 0 3— 1 8 76) that m agnitudes inherent to a cur ve be used such as s the length of arc m easured from a fixed point a n d (0 the angle which the tangent at the end of s m akes with a fixed tangent Wi l l i am Whew el l ( 1 7 94 1 86 6 ) of Cambridge the author of the H i s tory of the I ndu cti ve S ci en ces 1 8 3 7 —1 8 3 8 introduced in “ intrinsic equation and pointed out its use in study 1 8 49 the na m e ing successive evolutes and involutes The m ethod was used by Wil — 1 1 liam Walton ( 8 3 1 90 1 ) of Cambridge J J Sylvester in 1 8 68 J Casey in 1 8 6 6 and others Instead of using s and 50 oth er writers have introduced the radius of curvature p and ha v e used either s were e mployed by and p or go and p The c o ordinates ( (p p ) L Euler and sev eral nineteenth century m athe maticians but alto gether the c o— or dinates (s p) hav e been used m ost The latter wer e used by L Euler in 1 74 1 by Sylvestre Fran cois Lacroix ( 1 7 6 5 by Thom as Hill ( 1 8 1 8—1 8 91 who was at one tim e presiden t of Harvard College)and in recent years especially by Ernesto Cesaro of the University of Naples who published i n 1 8 96 his Geometr i a i n tri ns eca whi ch was translated into Germ an in 1 90 1 by G Kowalewski un der ? the title Vorl es u ngen uber n atitr l i che Geometr i e Researches along of P aris the 1 90 6 ) this line are due also to Amed ee M annh ei m ( 1 83 1 — designer of a well known S lide rule The application of intrinsic or natural co ordinates to surfaces is 3 less co mm on Edward K asn er said in 1 90 4 that in the theory of surfaces natural c o— ordinates may be introduced so as to fit into the AS - . . . . , , , , - . ” , , , . , . . , . , . , , - . , , , . , . , . , , . , , - . - “ . , S ee J H adamard , F ou r L ectu res on M a thema ti cs del i ver ed a t C ol u mbi a U n i ver s i tv i n 1 9 1 1 , N ew Y or k , 1 9 1 5 , L ec t u re III ’ 2 N a t u rl i c h e K oo r 0 m i n form a t io n i s d raw n f ro m E Wo l ffin g s a r t i c l e o n d i n a te n i n B i bl i otheca ma thema ti ca , 3 S , V o l I , 1 9 00 , p p 1 4 2 1 5 9 3 B u l l A m M a th S oc , V o l 1 1 , 1 90 5 , p 3 0 3 1 . ” . . . — . . . . . . . . . . . A HI STORY OF M ATHE M ATIC S 3 26 see m desirable to depart from our e mpirical notions so far as to allow the ter m curve to be applied to a region more restricted definitions of i t beco m e necessary C Jordan de manded that a curve S hould have no double points i n the interval a S t S b Schon fl i es regards a cur v e as the frontier of a region 0 Veblen defines it in terms of order and linear contin ui ty W H Young and Grace C Young in their Theory of S ets of P oi n ts define a curve as a plane set of points dense nowhere in the plane and bearing other restrictions yet such that it m ay consist of a net work of arcs of Jordan curves O ther curves of previously unheard of properties were created as the resul t of the generaliz ation of the function concept The con , . . . . . . . . . , , - . ” n( 2 b )where = oo n curve represented by t in uou s y = . n a x c os , a is an even integer 1 b a real positive nu mber 1 was shown by We i erstrass to possess no tangents at any of its points when the product ab e xceeds 1 , , a certain l imit ; that is we have here the startling phenomenon of a continuous function which has no derivative As Christian Wiener explained in 1 88 1 this curve has countless oscillations withi n e v ery finite interval An intuitively si mpler curve was inv ented by Helge v Koch of the U niversity of S tockholm in 1 90 4 (A cta ma th Vol 30 p 1 4 5) which is constructe d by ele m entary geom etry is con 1 90 6 ti n u ou s yet has no tangent at any of its points ; the arc between any two of its points is infinite in length Wh i le this cur v e has been r epr e sented analytically no such representation has yet been found for the so called H curve of Ludwig B oltzmann of Vienna in M ath A n n al en Vol 50 1 8 98 which is continuous yet t an g e n tl ess The a djoining figure shows its construction B oltzmann used it to visualiz e theorem s in the theory of gases , . , . . , . . , , , , . , - - , , . . , , , . . . Fu nda mental P os tu l ates The foundations of mathe matics and of geom etry in particular received m arked attention in Italy In 1 8 8 9 G P eano took the nov el , , . . 1 P d u B o i s R eym o n d r ee l l e r A rg u me n t e , - . t io n e n ” G V e rsu c h e i n e r K l a ss i fi ca t io n d e r rel l e , Vo l 7 4 , . 1 8 74, p . 29 . w i llk u rl i c h e n F u n k AN A LYTI C GEO M ETRY 327 iew tha t geome tric elements are mer e thi ngs and laid down the principle that there S hould be as few undefined symbols as po s sible — of Catania used o n ly two In 1 8 97 9 his pupil M ari o P i eri ( 1 86 0— 1 90 4 ) undefined symbols for proj ective geometry and but two for metric geometry In 1 894 P eano considered the independence of axioms B y 1 897 the Italian m athematicians had gone so far as to make it a postulate that points are classes These fundamental features elab orated by the Itali an school were embodied by D avid Hilbert of G ottingen along with important novel considerations of his own in his famous Gr u ndl agen der Geometri e 1 8 99 _ A fourth enlarged e di tion of thi s appeared in 1 91 3 E B Wilson says i n praise of Hilbert : The a rc hi medean a xio m the theore m s of B P ascal and G D esargues the analysis of segm ents and areas and a host of things are treated either for the first time or in a new way and with consum mate ski ll We should say that i t was in the technique rather than in the p hilosophy 1 In H i lbert s S pace of of geometry that Hilbert created an epoch 1 8 99 are not all the points which are in our S pace but only those that starting from two given points can be constructed with rul er and compasses In his space remarks P oincaré there is no angle of So in the second e di tion of the Gr u ndl agen Hil bert introduced the assum ption of completeness which renders hi s space and ours the same Interesting is Hilbert s treatment of non Arc hi m edean geom e try where all hi s assumptions re main true save that of Archi m edes and for which he created a system of non Archim edean numbers This non Archim edean geom etry was first conceived by Gi u s eppe Ver on es e ( 1 8 54 professor of geometry at the University of P adua Our common space is only a part of non Archi m edean S pace Non— Archim edean theories of proportion were given in 1 90 2 by A Kneser of B reslau and in 1 90 4 by P J M ollerup of Copenh agen Hilbert dev oted in his Gru ndl agen a chapter to D esargues theorem In 1 90 2 F R M oulton of C hi cago outlined a simple non D esarg u esi an plane geometry In th e United States George B ruce Halsted based his Ra ti on al G eometry 1 90 4 upon Hilbert s foundations A second revised edition appeare d in 1 90 7 One of Hilbert s pupils M ax W D ehn showed that the om ission of the axiom of Archim e des ( Eudoxus ) gives rise to a sem i Euclidean geom etry in which S im ilar triangles exist and their s u m is two right angles yet an infinity of parallels to any straight l ine may be drawn through any given point Systems of axiom s upon which to build proj ective geom etry were first stu d ied more particularl y by the Ital i an school—G P eano M P ieri Gino Fano of Turin This subj ect received the attention also of Theodor Vahle n of Vienna and Friedrich Schur of Strassburg Ax ioms of descriptive geometry have been considered mainly by v , . . . . , , . , . . . . , . , , ” , . ’ . , , , . , , , , ’ - . , - . - - . . . . . . ’ . - . . . , ’ , , . , ’ . , . , - , . . , , . . . 1 B u ll A m M a th S oc , V ol 1 1 , ’ d raw n from Wil son s ar t i c l e . a re . . . . . 1 904 , p 77 . . O ur re m a rk s o n t h e I t al i a n S c h ool A 328 H I STORY or M ATHE M ATI C S I talian and American m athematicians and by D Hilbert The introduction of order was achieved by G P eano by taking the cl ass of points whi ch lie between any t w o points as the fundamental idea by G V ail ati and later by B Russell on the fundam ental conception of a class of rel ati ons or class of points on a straight line by O Veblen on the study of the properties of one sin gle three term relatio n ( 1 904) “ 1 of order A N Whitehead refers to O Veblen s m ethod : This me thod of conceiving the subject results in a notable simplification and combines advantages from the two previous m ethods While D Hil bert has six undefined term s (point straight line plane between paral lel congruent) and tw enty one assu mptions Veblen gives only two undefined term s (point between ) and only twelve assu mptions However the derivation of fundamental theorems is so m ewhat harder by Veblen s axioms R L M oore showed that any plane — m satisfying Veblen s axio s I V III X I is a number plane and con ta ins a system of continuous curves such that with reference to these curves regarded as straight lines the plane is an ordinary Euclidean plane In 1 90 7 Oswald Veblen and J W Young gav e a completely i n dependent set of assumptions for proj ective geom etry i n which points and undefined classes of points called lines have been taken as the undefined elements Eight of these assu mptions characteriz e general projective S paces ; the addition of a ninth assum ption yields properly ? projective S paces Axiom s for line geometry based upon the line as an undefined “ element and intersection as an undefined relation between u n ordered pairs oi ele m ents were giv en in 1 90 1 by M P i eri of Catania and in S im pler form in 1 91 4 by E R Hedrick and L Ingold of the University of M issouri Text books built upon som e such system of axio ms and possessing great generality and scientific interest have been written by F ede rig o Enriques of the University of B ologna in 1 8 98 and by O Veble n and J W Young in 1 9 1 0 . , . . , . . , . , - ’ . . . . , . , . , , , - , , . , , ’ . . . ’ - , , , . . , . , . ” . , , . , . . . - . , . . . Geometri c M odel s Geom etrical m odels for advanced students began to be manu fac t u r ed about 1 8 7 9 by the fi rm of L B rill in D ar m stadt M any o f the early m odels such as Ku mm er s surface twisted cubics the t ractrix of revolution were made under the direction of F Klei n and Alexander von B rill Since about 1 8 90 this fi rm developed into that of M artin Schilling ( 1 8 6 6 —1 90 8 ) of Leipz ig The catalogue of the S i nce 1 90 5 the fi rm of fi rm for 1 9 1 1 described som e 40 0 m odels B G Teubn er in Leipz ig has off ered m odels designed by He rmann . . ’ , , , , . . . . . . The A xi oms of Descr i pti ve Geometr y, C amb ri dg e , 2 B ul l A m M a th S oc , V o l 1 4 , 1 90 8 , p 2 5 1 1 . . . . . . . 1 90 7 , p . 2 . 33 0 A HI STORY OF . afl =a x ‘ (D ) (C) y M ATHE M ATIC S (E ) apply to the general exponent a and finds that (A )( B ) and (E ) are i n com “ many m any more pl e t e equations since the left m em bers have v alues t han the right m em bers although the right hand values ( i nfi nite “ in number) are all found am ong the i nfi nite times in finite values on the left ; that ( C ) and (D ) are complete equations for the general case A failure to recog niz e that equation E is incomplete led Thomas of Altona to a paradox (Grel l e s Jou rn al Vol 2 Clausen ( 1 80 1 —1 88 5) 1 8 2 7 p 2 86) which was stated by E Catalan in 1 8 6 9 in m ore con i where m and n are distinct integers i =e den sed fo rm thus : e Raising bo th sides to the power 5 there results the absurdi ty — W m = m e e O hm introduced a notation to designate som e particular value of a but he did not introduce especially the particular value which is now calle d the principal value O therwi se his treatm ent of the general power is m a i nly that of the present t ime except of course in the explanation of the irrational From the general power Ohm proceeds to the general logarith m having a complex num ber as i ts base I t is seen that the Eulerian logari thm s served as a step la dder lea ding to the theory of the general power ; the theory of th e general power i n turn led to a m ore general theory of logari thm s having a com plex base The P hi l os ophi cal Tr an s acti on s (London 1 8 2 9) contain two articles on general powers and logarithm s—one by John Graves the other by John Warren of Ca mbridge Graves then a young man of 2 3 was a class fellow of William Rowan Hamilton in D ublin Grav es becam e a noted jurist Ham ilton states that reflecting on G rav es s ideas on im aginaries led him to the i nvention of quaternions Graves obtains log Thus Grav es claimed t hat gen eral logarithm s involv e two arbitrary integers m and m instead of simply one as given by Euler Lack of explicitness inv olved Grav es In a discussion with A D e M organ and G P eacock the out come of which was that Graves wi thdrew th e statem ent contained in the title of his paper and i mplying an error in the Eulerian theory whi le D e M organ a dm itted that if Graves desired to extend the idea of a logari thm so as to use the base e + m i there was no error i n volv ed In the process Sim ilar researches were carried on by A J H Vincent at Li l le D F Gregory D e M organ W R Hamilton and G M P agani ( 1 796—1 8 5 5)but their general logarithmic system s in v olv ing complex numbers as bases fa i led of recognition as useful 1 m athe m atical inventions We pause to S ketch the l ife of D e M organ was born at M adura (M adras ) Au gu s tu s D e M org an ( 1 8 0 6—1 8 7 1 ) and educated at Tr i nity College Cam bridge For th e determ i nation of the year of his birth (assum ed to be In the nineteenth century) he 2 proposed the conun dru m I was x years of age in the year x His , ” x , , , , ” - , . ’ . . , , . , 2 n 7r 2 n 7f . , , , , r . ” t , “ . , , . , , . , , . , , . , , - . ’ . . ’ , , . , . . , , I 2 7r , . , . . . . , , . . , . . . , . . , . , “ . , 1 For 19 1 3, —8 r efe r e n ces a n d pp . 1 75 1 2. fu ll e r de t a il s se e F . C aj or i i n A m . M ath M on thl y, V ol . . 20, ALGEBRA 3: scruples about the doctrines of the established church prevente d him from procee ding to the M A degree an d from sitting for a fellowship “ I t is said of him he ne v er voted at an election and he never visited the House of Commons or the Tower or Westm inster Abbey In 1 8 2 8 he beca m e professor at the newly es tablished University of London and taught there until 1 86 7 except for five years from 1 83 1 1 835 He was the first president of the Londo n M athematical Society whi ch was founded in 1 8 6 6 D e M organ was a unique m anly char acter and pre— em inent as a teacher The value of his original work lies not so much in increasing our stock of mathem atical knowledge as in putting it all upon a m or e logical basis He felt keenly the lack of clos e “ reasoning in m athe matics as he received it He said once : We know that m athem aticians care no m ore for logic than logicians for m athe m at i c s The two eyes of exact science are mathe m atics and logic : the m athem atical sect puts out the logical eye the logical sect puts out the m athe matical eye ; each believing that it can see better with one eye than with two D e M organ analyz ed logic mathe matically a n d stu d ied the logical analysis of the laws sym bols and operations of mathe m atics ; he wrote a Formal L ogi c as well as a D ou bl e A l gebr a and corresponde d both with Sir William Ham ilton the m etaphysician and Sir William Rowan Ham ilton the mathematician Few con temporaries were as profoundly read in the history of m athem atics as was D e M organ N 0 subj ect was too insignificant to receive his “ attention The authorship of Cocker s Arithm etic and the work of circle squarers was investigated as m inutely as was the history of the calculus Nu merous articles of his lie scattered i n the volu mes of “ the P enn y an d E n gl i sh C ycl opwdi as I n the article In d uction (M athe first printe d in 1 8 38 occurs apparently for the first tim e “ the n ame m athem atical in d uction ; it was ad opte d and populariz ed “ by I Todhunter in his A l gebr a The term i n d uctio n h ad been used by John Wallis in 1 6 56 in his A ri thmeti ca i nfi n i tor u m; he use d the i nduction known to natural science In 1 6 8 6 Jacob B ernoulli critici sed him for using a process which was not binding logi cally and then advanced in place of it the proof from n to n + 1 This is one of the sev eral origins of the pr ocess of m athem atical induction From Wall i s “ to D e M organ the term induction was used occasionally in m athe m a t i cs a n d in a double sense ( I ) to indicate inco mplete inductions of the kind known in n atural science ( 2 ) for the proof from n to n + 1 D e “ M organ s m athem atical induction assigns a distinct nam e for the “ latter process The Germ ans employ m ore com m only the nam e voll s t an di g e Induktion which becam e current am ong them after the use of it by R D e d ekind in his Wa s si nd u nd w as s ol l en di e Z ahl en 1 8 8 7 D e M organ s Difi eren ti al C al cu l u s 1 84 2 is st i ll a standard work and contains m uch that is or i ginal with the author For the En cycl opa di a M etr opol i tan a he wrote on the Calculus of Functions ( giving principles of symbolic reason i ng) and on the theory of probab i lity In the Cal . , . ” , , , , . , , . , . . , . , . . . , ” . , , , , , , . , ” . ’ . - . . , . ” , ” , , ” . “ , . . ” . , , , . , ’ ” . , . . , ’ , , , e . . HI STORY A 33 2 O F M ATHE M ATIC S “ of Functions he proposes the use of the slant line or solidus for printing fractions in the text ; this proposal w as adopted by G G “ Stokes in Cayley wrote Stockes I think the solidus looks very well indeed it woul d gi v e you a strong clai m to be P reside n t 2 of a Society for the prevention of Cruelty to P rinters Celebrated is D e M organ s B u dget of P a radoxes London 1 8 7 2 a second edition of which was edited by D avid E u gene S m ith i n 1 9 1 5 D e M organ published mem oirs O n the Foun dation of Algebra in the Tr an s of the C a mbri dge P hi l S oc 1 84 1 1 84 2 1 8 44 a n d 1 84 7 The ideas of George P eacock and D e M organ recogni ze the possi Such al gebras bili ty of algebras which diff er fro m ordinary a l gebra were indee d not slow in forthcoming but like non Euclidean geo metry som e of the m were slo w in fi n di n g rec ognitio n Th i s is true of H G G ras sman n s G B el l a vi t i s s and B P eirce s d iscoveries but W R Hamilton s quaternions m e t with i mmediate appreciatio n i n England These algebras off er a geom etrical interpretation of im agi n aries — was born of Scotch parent s Wil l i am R o w an H a mi l to n ( 1 80 5 1 8 6 5) His early education carried on at ho m e was m ainly i n i n D ublin languages At the age of thirteen he is said to hav e been fam iliar with as many languages as he had lived years About this ti me he cam e across a copy of I Newton s Un i ver sal A r i thmeti c After rea ding that he took up successively analytical geom etry the calculus Ne w ton s P r i n ci pi a Laplace s M écan i q u e C el es te At the age of eighteen he pub li sh ed a paper correcting a m istake in Laplace s work I n 1 8 2 4 he entered Trinity College D ublin and in 1 8 2 7 while he was still an undergraduate he was appointed to the chair of astrono m y C G J J acobi m et Ha m ilto n at the m eeting of the B ritish Association at M anchester in 1 84 2 and a ddressing Sectio n A called Ha m ilton l e Lagrange de votre pays Ha milton s early papers were on optics In 1 83 2 he predicted conical refraction a d iscovery by aid of m athe m at ics which ranks with the disco v ery of Neptune by U J J Le Verrier and J C Adams Then followed papers on the P r i n ci pl e of and a general m etho d of dy n a mics ( 1 8 34 Varyi n g A cti on ( 1 8 2 7 ) He wrote also on the solution of equations of the fifth degree t he hodograph fluctuating functions the num erical solution of diff erential equations The capital discovery of Ha m ilto n is his quaternions in which hi s s tudy of algebra cul m inated In 1 83 5 he publ i shed in the Tran sacti ons He re of the Royal I r i sh A cademy his Theory of Algebraic Couples “ garded algebra as being no m ere art nor language nor primarily c ul u s . ‘ , ’ ” . ’ , , , ” . , . . . , , , . . - , , , . ’ ’ , . . ’ . . , . . , ’ . . . , , . . ’ . . , ’ , , ’ . , ’ . , , , , . . . . , ’ . . , . . . . . . , , , . , . . , , G G S t ok es , M a th a n d P hys P a per s V ol I C amb ri dg e , 1 880 , p V I I ; see al so J L arm or, M emoi r a nd S ci e C orr of G G S tok es , V ol I , 1 90 7 , p 39 7 2 A n e arl i er u se o f t he so l id us i n d es ig n a t i ng f rac t io n s oc c u rs i n o n e o f t he ve ry fi rs t t ext b oo k s p u bl i s he d i n C a l i fo rn i a , v i z , t he D efi n i c i on de l a s pr i n c i pal es opera ci on es de a r i s méti ca b y H e n r i C a mb u s t o n , 2 6 p ag es p r i n t e d a t M o n t e re y i n 1 84 3 The s o li du s app e ar s S l ig h t ly c u r ved 1 . . . . . . . , . . . . . . . . . . . M ATHE M ATIC S A HI STORY OF 3 34 e xtended as was predicted The change in notation made in France by Jules Hoii el and by C A L a is a n t has been considered in England as a wrong step but the true cause for the lack of progress is perhaps There is indeed great doub t as to whether the more deep seated quaternionic product can clai m a necessary and funda mental place in a syste m of vector analysis P hysicists clai m that there is a loss of naturalness in taking the square of a vector to be negative Widely different opinions have been expressed on the value of quaternions While P G Tait was an enthusiastic champion of this science his great friend William Thomson (Lord Kelvin )declared that they though beautifully ingenious have been an unmixed e v il to those who have touched the m in any way including Clerk “ 1 A Cayley writing to Tait in 1 8 74 said I ad mire the M axwell equation d 0 = u qdpq extre mely—i t is a grand exa mple of the pocket Cayley ad mitted the conciseness of quaternion formulas b u t m ap they had to be unfolded into Cartesian form before they could be “ m ade use of or e v en understood Cayley wrote a paper On C o or d i n a t es versus Q uaternions in the P r oceedi n gs of the Royal Society “ of Edinburgh Vol 2 0 to which Tait replied On the Intrinsic Nature of the Q uaternion M ethod In order to m eet m ore adequately the wants of physicists J W G i bbs and A M a cf a rl a n e have each suggested an algebra of vectors with a new notation Each gi v es a definition of his own for the product of two vectors but in such a way that the square of a vector is positive A third syste m of vector analysis has been used by Ol i ver H eavi s i de in his electrical researches What constitutes the m ost desirable notation in vector analysis is still a m atter of dispute Chief a mong the various suggestions are those of the A merican school started by J W Gibbs and those of the Ger man Italian school The cleavage is not altogether along lines “ of nationality L P ran dl of Hanover said in 1 90 4 : After long del i b cration I have adopted the notation of Gibbs writing a b for the inner ( scalar )and a ><b for the outer ( vector) product If one ob serves the rule that in a multiple product the outer product must be taken before the inner the inner product before the scalar then one can write with Gibbs a b><c and a b c without giving rise to doub t 2 as to the m eaning In the following we give German Italian notations fi rst the equiv second Inner product a Ib a b ; al en t A merican n otation ( Gibbs ) ab Ic d , v ector product ab a > <c ; ab c <h ; also ab c a b > 2 ab c d R M ehmke ab “ said in 1 90 4 : The nota t ion of the German Italian school is far pref e r a b l e to that of Gibbs not only in logical and m etho di cal but als o in practical respects . . . , - . . . ‘ . . . , , , , , ” ” , ‘ . . , “ ' , , I . , ” . , - . , . . , . . . , . . . , , . , . - . . . , . , “ ” , , . . - , ’ , . - , , , . , , . - , . 1 S P Tho mp so n L if e of L or d K el vi n , 1 9 1 0 , p J a hr es b d (1 M a th V er ei n i g , V o l 1 3 , p 39 . 2 . , . . . . . . . . . 1 138. . ALGEB RA 33 5 In 1 8 95 P M olenbroek of The Hague and S Ki mura then at Yale University took the first steps in the organiz ation of an Internationa l Association for P ro mo t ing the S tudy of Q uaternions and Allied S yste ms of M athe matics P G Tait was elected the first presi dent but could not accept on account of failing health Al e xan d e r M ac f ar l an e ( 1 8 5 1 —1 9 1 3) of the University of Edinburgh later of the University of Texas and of Lehigh University served as secretary of the Association and was its president a t t he tim e of his death At the international congress held in Rome in 1 90 8 a committee was appointed on the unification of vectorial notations but at the time of the congress held in Cambridge in 1 91 2 no defini te conclusions had been reached Vectorial notations were subjects of ex tended discussion in L E n — — s ei gn emen t mathema ti qu e Vols 1 1 14 1 90 9 1 9 1 2 between C B urali Forti of Turin R M arc ol o ng o of Naples G C o mb eri ac of Bourges H C F Timerdin g of Strassburg F Klein of Gottingen E B Wilson of Boston G P eano of Turin C G Knott of Edinburgh Alexander M acfarlane of Chatham in Canada E Ca r allo of P aris and E Jahnke of B erlin In America the relative values of notations were di scussed in 1 91 6 by E B Wilson and V C P oor We m ention two topics outside of ordinary physics in which vector analysis has figured The generalization of A Einstein known as the principle of relativi ty and its inte rpretation by H M inkowski hav e opened new points of Vi ew So m e of the queer consequences of this theory disappear when kine matics is regar ded as identical with the geo metry of four di mensional S pace H M i nk owski and following hi m M ax Abraha m used vector analysis in a li mited degree M i n k ow s k i usually preferring the m atri x calculus of A Cayley A m ore exten ded use of vector analysis was made by Gilbert N Lewis of the Uni v ersity of California who introduced in his ex tension to four di me n si on s some of the original features of H G Gr assman n s syste m “ A dyn am e is accor ding to J P lucker ( and others ) a sys t em of forces applied to a rigid body The English and French call i t a t or sor In 1 899 this subject was treated by the Russian A P K o tj el n ik o ff under the nam e of proj ective theo r y of vectors In 1 90 3 E Study of Greifswald brought out his book Geometr i e der Dyn amen in which a line geo metry and kine matics are elaborated partly by the use of group theory which are carried over to non Euclidean spaces ; S tu dy clai ms for hi s system somewhat greater generality than is found in Hamilton s quaterni ons and W K Clifford s bi . . , , . . . , . , , . . ’ 2 ’ . , . , . . . , . , . , . , . , , , . , . . . , v . , . , . . . . . . ‘ . . , . , , . - . , . , , , . . . ” ’ . . . . , . “ . . . . . , , - , - , ’ ’ . i ns u a r t er n o q . H e rmann G u n th er G ras s man n ( 1 80 9— 1 8 7 7) was born at S tettin attended a gym nasium at hi s native plac e (where his father was teacher of m athe matics and physics )and studied theology in Berlin for three years His intellectual interests were v ery broa d He started as a theologian wrote on physics co mposed texts for the stu dy of . , , . . , , O F M ATHE M ATIC S HISTORY A 33 6 German Latin and mathematics e dited a political paper and a mi s si o n ary paper in v esti gated phonetic laws wrote a di ctionary to the Rig Veda translated the Rig Veda in verse harmoni z ed fol k songs in three voices carried on successfully the regul ar work of a teacher and brought up nine of his eleven chi ldr en—all this in addi tion to the great m athem atical creations whi ch we are about to describe In 1 834 he succeeded J S teiner as teacher of m athematics in an industrial school in B erlin but returned to Stettin in 1 836 to assume the duti es of teacher of m athem atics the sciences and of religion in a school 1 there Up to thi s tim e his knowledge of m athem atics was pretty much confined to what he had learned fro m hi s father who had “ “ written two books on Raum lehre and G rOssenl ehre B ut now he m ade his acquaintance with the works of S F Lacroi x J L La grange and P S Laplace He noticed that Laplace s resul ts coul d be reached in a S horter way by som e new ideas advanced in his father s books and he proceeded to elaborate this abridged m ethod and to apply it in the study of tides He was thus led to a new geom etric analysis In 1 840 he had m ade considerable progress in its develop m ent but a new book of Schleier m acher drew hi m again to theology In 1 84 2 he resum ed m athem atical research and becom ing thoroughl y convi nced of the i mportance of hi s new analysis decided to devote himself to it It now becam e his ambition to secure a mathematical chair at a university but in thi s he never succeeded In 1 844 ap p ear ed his great classical work the L i n ea l e A u s dehn u ngsl ehr e w hi ch was full of new and strange m atter and so general abstract and out of fashion in its m ode of exposition that i t could hardl y have had less influence on European m athe matics during its first twenty years had it been published in China K F Gauss J A Grunert and A F M ob i u s glanced over it praised it but co mplained of the strange “ terminolog y and its philosophi sche Allgemei nh eit Eight years afterwards C A B re t schn ei der of Gotha was said to b e the only An article in Gr ell e s Jou r nal in man who had read it through whi ch Grassm ann eclipsed the geometers of that time by constructi ng with aid of hi s m ethod geo metrically any algebraic curve remained again unnoticed Need we m arvel if Grassmann turned his attention to other subjects —to Schleierm acher s philosophy to politics to p hi lolog y ? S till articles by him continued to appear in Gr ell e s J ou rn al and in 1 86 2 ca m e out the second part of his A usdehn u ngsl ehr e It was intended to show better than the first part the broad scope of the Aus dehnungslehre by c onsidering not only geometric applica tions but by treating also of al gebraic functions infinite series and the di fferential and integral calculus B ut the second part was no more appreciated than the first At the age of fi fty three thi s won der ful m an with heavy heart gave up mathe matics and directed hi s energies to the study of Sanskrit ach i eving in philology results which V i c tor S hl g l H m Gr m L ei p z i g 8 78 , , , , , - - , , , . . , , , , . ” ” , . . . . . , ’ . , . . ’ , , . . . , , , . . , , , , , , , , . . . , . ” . , , . , . . . , . ’ . , , , , . ’ , , , ’ , . , , , , , . - . , , , , , 1 c e e , er a nn ass an n , , 1 . A HI STORY OF M ATHE M ATIC S 338 woode spoke of i t in D ublin as som ethi ng above and beyond 4 nions I have not seen i t but Sir W Hamilton of E dinburgh used to say that the greater the extension the sm aller the intention M ultiple algebra was powerfully adv anced by B P eirce whose theory is not g eom etrical as are those of W R Hamilton and H G Grassmann B e n j a mi n P e i r c e ( 1 80 9—1 880 ) was born at Salem M as s and gra duated at Harvard College having as undergraduate carried the study of mathem atics far beyond the li m its of the college course When N B owditch was preparing his translation and comm entary of the M éca n i qu e C el este young P eirce helped in reading the proof He was m ade professor at Harvard in 1 8 33 a position whi ch S heets he retained until hi s d eath For som e years he was in charge of the N au ti cal A l ma n ac an d super i ntendent of the United S tates Coast Surv ey He published a series of college tex t books on mathematics an A n al yti cal M echa n i cs 1 8 55 and calculated together wi th Sears C Walker of Washington the orbi t of Neptune P rofound are his researches on L i n ear A ss oc i a ti ve A l gebr a The first of several papers thereon was read at the first m eeting of the Am erican Association for the Adva nce ment of Science in 1 864 Lithographed copies of a m e moir were d istributed a m ong friends in 1 8 70 but so s mall seemed to be the interest taken in t hi s subj ect that the m emoir was n ot printed until 1 88 1 (A m Jou r M ath Vol IV No P eirce works out the m ul tiplication tables first of s i ngl e algebras then of dou bl e algebras and so on up to sextuple m aking in all 1 6 2 algebras whi ch he S hows to be possi ble on the consideration of sym bols A B etc which are linear functions of a determinate nu mber of letters or units i j k l etc with coefficients which are ordinary analytical m agni tudes real or i maginary —the letters i j etc being such that e v ery 2 binary combinat ion i ij j i etc is equal to a linear function of the 1 letters but under the restriction of satisfying the associative law C harl es S P ei r ce a son of B enj am in P eirce and one of the foremost writers on m athem ati cal logic S howed that these algebras were all defecti v e forms of qua drate a l gebras w hich he had previously dis covered by logical analysis a n d for which he had devised a si mple notation Of these quadrate algebras quaternions is a simple example ; n o n i on s is another C S P eirce showed that of all linear associative algebras there are only three in which d ivision is unambiguous These are ordinary S ingle algebra or di nary double algebra and quaternions from whi ch the i maginary scalar is excluded He S howed that hi s father s algebras are operational and m atricular Lectures on m ultiple algebra w ere deli v ere d by J J Syl v ester at the Johns Hopk ins Uni versity and published in various journals They treat largely of the algebra of m atrices Wh i le B enjam in P eirce s co mparativ e anatomy of linear algebras was favorably receiv e d i n Englan d i t was cr i ti ci sed i n Germ any as . . , . . . , , . . . . , , , . . , . , . - . , , , . , . , . . , . . . . , . , , , , , , , , , , . , , . , , , , , , , . , . , , , , . . , , , , . . . . . , , , . ’ . . . . , . ’ , 1 A C ayl ey , A dd r es s be fore B r i t i s h A s so c i a t i on , . 1 88 3 . ALGEBRA 33 9 . being vague and based on arbitrary principles of classification Ger m an writers along this line are Eduard Study and Georg W S c heffe r s An estimate of B P eirce s linear associative algebra was giv en in 1 who e xtends P eirce s method and shows its 1 90 2 by H E Hawkes full power I n 1 8 98 Elie Cartan of the University of Lyon used the characteristic equat i o n to dev elop several general theore m s ; he ex h i bi t s the s emi si mpl e or D edekind and the ps eudo n u l or nilpotent Su b algebras ; he shows that the structure of every algebra may be represented by the use of d ouble units the first factor being quad rate the second non— quadrate Extensions of B P eirce s results were m ade also by Henry Taber Olive C Haz lett gave a classification of nilpotent al egb ras As S hown abov e C S P eirce advanced this algebra by using the m atrix theory P apers along thi s line are due to F G Frobenius and “ J B Shaw The latter shows that the equation of an algebra de termines its quadrate units and certain of the di rect units ; that the other units form a nilpotent system which with the quadrates may be reduced to certain canonical form s The algebra is thus made a sub algebra under the algebra of the associ ati ve u n i ts used in these canonical form s Frobenius proves that every algebra has a D ede k ind sub a l gebra whose equation contains all factors in the equation of the algebra This is the sem i simple algebra of Cartan He also S howed that the re m aining units fo rm a nilpotent algebra whose units m ay be r egu l ar i zed (J B Shaw ) M ore recently J B Shaw has extended the general theorem s of linear associative algebras to such algebras as have an i nfinite number of units B esides the m atrix theory the theory of continuous g rOu ps has been used in the study of linear associative algebra This iso morphis m was first pointed out by H P oi n c are the m ethod was followed by Georg W S cheff er s who classifi ed algebras as quaternionic and non quaternionic and worked out co mplete lists of all algebras to order five Theodor M ol ien in 1 8 93 then I n D orpat de monstrated “ that quaternionic algebras conta i n independent quadrates and that q uaternionic algebras can be classified according to non quaternionic types (J B Shaw)An ele mentary exposition of the relation between 2 l inear al gebras and continuous groups was given by L E D ickson of “ Chicago This relation enables us to translate the concepts and theorem s of the one subj ect into the language of the other subj ect It not onl y doubles our total knowle dge but gives us a better insight into either subj ect by exhibiting it fro m a new point of view The theory of matrices was developed as early as 1 8 58 by A Cayley in an i mportant me moir which i n the opinion of J J Sylvester ushered in . . . ’ . ’ . . , . - - , , , , , ’ . , . . . . . . , . . . . . . , . - . - , - . ” , . . , . . . . , . . . - . , , , ” , - . . . . . . ” , . . . . , . , H E H aw k e s i n A m J ou r M ath , V ol 2 4 1 90 2 , p 8 7 We are J B S haw s S ynops i s of L i near A ssoci a ti ve A l gebr a , Washi n g ton , D u si n g a l so 1 . . . , . . . . ’ . . S haw g i v e s b i b lio g raphy I n t ro d u c t i o n 2 B u ll A m M ath S oc , V o l 2 2 , 1 9 1 5 , p 5 3 . . . . . . . . . . C . , 1 90 7 , A HI STORY OF M ATHE M ATIC S 3 40 the reign of Algebra the Second W K Cliff ord Sylvester H Taber C H Chap man carried the inv estigations m uch further The origi nator of matrices is really W R Hamilton but his theory published in his L ectu r es on Qu ater n i ons is less general than that of Cayley The latter m akes no reference to Ham ilton 1 The theory of determ inants was studied by H oen é Wr onski ( 1 7 7 8 1 85 a poor P olish enthusiast liv ing m ost the tim e in France whose egotism and wearisom e style tended to attract few followers but who m ade som e incisiv e criticis m s bearing on the philosophy of m athe ? m a ti c s He s tudied four S pecial form s of determinants which were — of B re m en and extended by H ei n ri ch Ferdi n a n d S cher k ( 1 7 98 1 88 5) Fer di n a nd S chw ei n s ( 1 7 8 0 —1 8 5 6 ) of Heidelberg In 1 83 8 Liouville de monstrated a property of the special forms which were called wronskians by Tho mas M uir in 1 88 1 D eterm inants receiv ed the attention of Jacqu es P M B i n et ( 1 7 8 6—1 8 56 ) of P aris but the great m aster of this subject was A L Cauchy I n a paper (J ou r de l ecol e P ol yt IX Cauchy developed several general theorem s He in 1 6) t r o du c e d the nam e deter mi n a n t a ter m used by K F Gauss in 1 8 0 1 i n the functions considered by him In 1 8 2 6 C G J Jacobi began using this calculus and he gave brilliant proof of its power In 1 84 1 he wrote extended m e moirs on determ inants in Gr el l e s J ou r n al which rendere d the theory easily accessible In England the study of l inear transform ations of quantics gave a powerful impulse A Cayley de v el op ed skew deter m inants a n d P faffi a n s and introduced the use of determ inant brackets or the fa m iliar pair of upright lines The m ore general consideration of determ inants whose elem ents are form ed from the ele m ents of giv en d eterm inants was taken up by J J Syl v ester and especially by L Kronecker who gave an elegant theore m (1851) 3 known by his nam e Orthogonal determinants received the atten 2 tio n of A Cayley in 1 8 4 6 in the study of n elem ents related to each other by equations also of L Kronecker F B rioschi and others M axim al values of determ inants received the attention of and especially of J Hadamard ( 1 8 93) who J J Sylvester proved that the square of a determ inant is never greater than the norm product of the lines — Anton P u c h ta ( 1 8 5 1 1 90 3 ) of C z ernowitz in 1 8 7 8 and M Noether in 1 88 0 showed that a sym m etric d eterm inant m ay be expressed as the product of a certain nu m ber of factors linear in the elem ents D eterm inants which are form ed from the m inors of a determinant were investigated by J J Sylvester in 1 8 5 1 to whom we owe the ‘ . . . . . , , . , . , . . , , . , . , , , , . ” ' . . . , ’ . . , . . . . . , , . . . . . . . , ’ , . . . - , . , . . . . . , . , , . . . . . - . . . , . . , Th o mas M u i r , The Theor y of D eter mi n a n ts i n the H i s tor i cal Or der of Devel op men t [ V 0 ] I ] , 2 n d E d , L on don , 1 90 6 ; V ol I I , P e ri od 1 84 1 t o 1 8 6 0 , L on don , 1 9 1 1 M u i r w as S u p e r i n ten de n t G e n eral o f Ed u c a ti on i n C ape C ol ony 2 O n Wr on sk i , see J B er t ran d i n J ou rn a l des S a va n ts , 1 8 9 7 a n d i n R evu e des ’ D eu x M ond es , F e b , 1 89 7 S ee a l so L I n ter medi a i r e des M a thema ti ci ens V o l 2 3 , 1 . . . . - . . . ‘ - —1 6 7 . 19 16 , 3 1 13 , 1 64 . 18 1 —1 8 3 , , pp E P a s ca l , D i e D eter mi n an ten , t r a n sl by H L e i tz m a nn , . . . . . 1 90 0 , p . 10 7 . . A HI STORY OF M ATHE M ATIC S 34 2 The symbol E to express identity was first used by G F B 1 Riem ann M odern higher algebra is especially occupied with the theory of l inear transform ations Its develop m ent is mainly the work of A Cayley an d J J Sylv ester Arth u r C ayl e y ( 1 8 2 1 born at Richmond i n Surrey was educated at Trinity College Ca mbridge He ca m e out Senior Wrang ler in 1 84 2 He then devoted som e years to the study and practice of law While a student at the bar he went to D ublin and alongside of G Sal mon heard W R Ham ilton s lectures on quaternions On the foundation of the S adl e ri an professorship at Cambridge he ac c ep t ed the o ff er of that chair thus giv ing up a profession pro m ising wealth for a very m o dest provision but which would enable hi m to give all his tim e to m athe matics Cayley began his m athem atical publica tions in the C ambri dge M a themati cal Jou rn al while he was still an un dergra d uate Som e of his m ost brilliant discoveries were made during the time of his legal practice There is hardly any subj ect in pure m athem atics which the genius of Cayley has not enriched but m ost im portant is his creation of a new branch of analysis by his theory of inv ariants Ge rms of the principle of invariants are found in the writings of J L Lagrange K F Gauss and particularl y of G B o ol e w h o showed in 1 8 4 1 that invariance is a property of dis c r im i n a n t s generally and who applied it to the theory of orthogonal substitution Cayley set him self the problem to determ ine a pri ori what functions of the c oefli ci en ts of a giv en equation possess this prop and found to begin with in 1 84 5 th at the so e r ty of invariance called hyper determinants possessed it G B oole m ade a number of ad ditional d iscoveries Then J J Sylvester began his papers in the C ambri dge and Du bl i n l ll a themati cal Jou rn al on the Calculus of Form s After this d iscoveries followed in rapid succession At that t ime Cay ley and Sylvester were both residents of London and they sti mulated each other by frequent oral comm unications I t has often been dif fi c u l t to d eterm ine how m uch really belongs to each In 1 88 2 when Syl v ester was professor at the Johns Hopkins University Cayley lecture d there on Abelian and theta functions Of interest is Cayley s m ethod of work A R F orsyth describes it “ thus : When Cayley had reached his most advanced generali zations he proceeded to establish them di rectly by som e m ethod or other though he seldo m gave the clue by which they had first been obtained a procee ding whi ch does not tend to make hi s papers easy reading His literary style is direct si mple and clear His legal training had an influence not m erely upon his m ode of ar rangement but also upon his expression ; the result is that his papers are severe and present a curious contrast to the luxuriant enthusiasm which pervades so many 1 80 8 . . . . . . . . . . , , . , . . , ’ . . , . . , , , . . . , . . . . , . , ' . , , , , . ” , , - , . . . . . , . . , , . , . , . ’ . . . , . . , , 1 L K r o n e ck e r , Vor l esu n g en uber Z ahl en theor i e, ’ . 1 90 1 , p 86 . . ALGEB RA ” papers Curiously 343 1 of Sylvester s Cayley took little interest in quaternions — m J a e s J o s e ph S yl ve s ter ( 1 8 1 4 1 897) was born in London His father s name was Abraham Joseph ; hi s eldest brother assum ed in America the name of Sylvester and he adopted this nam e too About the age of 1 6 he was awarded a pri ze of $500 for solving a question ? in arrangem ents for contractors of lotteries in the United S tates In 1 83 1 he entered S t John s College Cambridge and cam e out Second Wrangler in 1 83 7 George Green being fourth Sylvester s J ewish origin incapacitated hi m from taking a degree Fro m 1 83 8 to 1 8 40 he was professor of natural philosophy at what is now University College London ; in 1 84 1 he becam e professor of mathematics at the Uni versi ty of Virginia In a quarrel with two of his students he slightly wounded one of the m with a m etal pointed cane whereupon b e re turned hurriedly to England In 1 844 he se rved as an actuary ; in 1 84 6 he became a student at the Inner Te mple and was called to the bar in 1 8 50 In 1 84 6 he beca me associated with A Cayley ; often they walked round the Courts of Lincoln s Inn perhaps di scussing “ the theory of invariants and Cayley ( says S ylvester ) habitually d i scoursing pearls and rubies Sylvester resumed mathematical research He Cayley and Wil l iam Rowan Ham ilton entered upon discoveries in pure mathematics that are unequalled in Great Britain S ince the ti m e of I Newton Sylvester made the friendship of G Sal m on whose books contributed greatly to bring the results of Cayley and Sylv ester withi n easier reach O f the m athematical public From 1 8 5 5 to 1 8 7 0 Sylvester was professor at the Royal M ilita ry Acade my at Woolwich but showed no great e fficiency as an elem entary teacher There are stories of hi s housekeeper pursuing hi m from hom e carrying his collar and necktie Fro m 1 8 76 to 1 8 83 he was professor at the Johns Hopkins University where he was happy in being free to teach whatever he w ished in the way he thought best He beca m e the first editor of the A mer i ca n Jou r n al of M a thema ti cs in 1 8 7 8 In 1 884 he was elected to su cc eed H J S S mith in the chair of S avi l i a n professor of geometry at Oxford a chair once occupied by Henry Briggs John Wallis and Edmund Halley Sylvester someti mes amused himself writing poetry His L aws of Ver s e is a curious booklet At the reading at the P eabo d y Institute in B altimore of hi s Rosalind poem consisting of about 400 lines all “ rhyming with Rosalind he first read all his explanatory footnotes so as not to interrupt the poem ; these took one hour and a half Then he read the poem itself to the remnant of hi s au di ence ’ . , . . ’ . , ’ . , , ’ . , . , . , , . . . ’ , , . . , . . . . , . . , , . . . . . , , . . . ” , , , , , - . . 1 P r oceed L ondon Royal S oci ety, V ol 5 8 , 1 89 5 , pp 2 3 , 2 4 ’ 2 H F B ak e r s B i og raphi c al N o t i ce i n The C oll ec ted M ath P a pers of J J S yl ves ter , V ol I V , C amb r i dg e , 1 9 1 2 We h av e u sed al so P A M ac M ah’ on s n o t i c e i n P r oceed Roya l S oc of L ondon , V o l 6 3 , 1 8 9 8 , p i x For S yl v es t e r s ac t i v i ti es i n B al timore , see F ab i an F r an k li n i n J ohn s H opki n s U n i v Ci r cu l ars , Ju n e , 1 89 7 ; F ‘ - . . . . . . . . ’ . . . . . . . . . . . A HI STORY OF M ATHE M ATIC S 344 Sylvester s first papers were on F r esn el s optic theory 1 83 7 Two years later he wrote on C S turm s m em orable theorem S turm once told him that the theore m originated in the theory of the c om pound pendulum S ti m ulated by A Cayley he made important i n v es t i g a t i o n s on m odern algebra He wrote on elimination on trans form ation and canonical form s in whi ch the expression of a cubic surface by fi v e cubes is given on the relation between the mi nor de t er mi n a n t s of linearly equi valent quadratic functions in w hi ch the notion of invariant factors is i mplicit whi le in 1 8 5 2 appeared the first of hi s papers on the principles of the calc ul us of forms In a reply that he m ade in 1 86 9 to Huxley who had claim ed that mathe ma t i c s was a science that knows not hi ng of observation induction in v ention and e xperi m ental verification Sylvester narrated his per “ sonal e xperie nce : I discovered and developed the whole theory of canonical binary form s for odd degrees and as far as yet m ade out for ev en degrees too at one eveni ng S itting with a decanter of port wine to sustain nature s flagging energies in a back o ffi ce in Lincoln s Inn Fields The work was done and well done but at the usual cost of racking thought—a brain on fire and feet feeling or feelingless as if plunged in an ice pai l Tha t n i ght w e sl ept n o mor e His reply to Hux ley is interesting reading and bears strongly on the qualities of m ental activi t y involved in m athe mati cal re search I n 1 8 59 he gave lectures on partitions not published until 1 8 97 He wrote on partitions again in Baltimore In 1 8 6 4 followed his famous proof of Newton s rule A certain fundam ental theorem in invariants which had form ed the basis of an i mportant section of A Cayley s work but had resi sted proof for a quarter of a century was demon Noteworthy are hi s m emoirs on s t ra t e d by Sylvester i n B alt i m ore C h eb i ch e v s m ethod concerning the total i ty of pri m e nu m bers wi thi n certain li mits and h i s latent roots of matrices His researches on in v ariants theory of equations m ultiple algebra theory of numbers linkages probability constitute i mportant contributions to m athe m a ti c s His final stu di es entered upon after his return to Oxford were on reciprocants or functions of d iff erential coeffi ci ents whose for m is unaltered by certain linear transformations of the variables and a generali z ation of the theory of concom itants In 1 9 1 1 G 1 Gree nh ill told reminiscently how Sylvester got everybody interested “ in rec iprocants now clean forgotten ; One day after Sylvester was noti ced walking alone a ddressing the sky aski ng i t : Ar e R ec ipr o cants Bosh ? B erry of K i ng s says the Reciprocant is all Bosh ! There was no reply and Sylvester hi m self was t iring of the subj ect and so B erry escape d a castigation B ut recently I had occasi on from the Aeronautical point of view to work out the theory of a Vortex ’ ’ . , ’ . . . . , . , , , , . , , , , , , , , ’ ’ , . , , , ” , , - . . . , . , . ’ . ’ . , . ’ . , , , , , , , . , , , . ” “ , . , , ‘ , , ’ ’ , , . C aj ori , Tea chi n g pp . 1 2 6 1- 2 7 2 a nd H i s tor y of M a thema ti cs i n the U n i ted S ta tes , . M al hemati cal G a zette V o l , . 6, 19 1 2, p . 108 . Washi n g ton , 1 8 90 , A 34 6 O F M ATHE M ATIC S HI STORY — 1 8 74 ) analysis Wi th Abb é he founded in ( A mong his pupils 1 8 5 8 the A n n al i di ma tema ti ca pu r a ed appl i ca ta 1 at P avi a were L Crem ona and E B eltrami V Volterra narrates how F B rioschi in 1 8 5 8 with two other young Ita l ians E n r i co B etti later professor at the University of P isa and F el i ce ( 1 8 23 later professor at the University of P avia C as or a ti ( 1 8 3 5 started on a j ourney to enter into relations w ith the forem ost m athe The scientific existence of Italy ma ti c i an s of France and Ger many as a nation dates from this j ourney It is to the teaching labors and dev otion of these three to their influence in the organi z ation of to the friendly scientific relations that they insti a d v anced stu dies t u t e d between I taly and foreign countries that the existence of a school of analysts in Italy is due In Germ any the early theory of invariants as developed by Cayley Syl v ester and Sal mon In England Hermite In France and F B rioschi in Italy did not draw attention until 1 8 58 when S i e g f ri e d H e inr i ch — l 1 of the technical high school in B erlin pointed Ar on h o d ( 1 8 9 1 884 ) out that Hesse s theory of ternary cubic form s of 1 844 involved i n variants by which that theory could be roun d ed out F G Eisenstei n and J Steiner had also given early publication to isolated develop m ents invol v ing the i n v a r i an tal i dea In 1 8 6 3 A ronh ol d gave a system atic and general expos i tion of invariant theory He a n d C l eb sc h use d a notation of their own the symbolical notation d i ff erent fro m Cayley s which was use d in the further dev elop m ents of the theory in Germ any Great d ev elop m ents were started about 1 86 8 when R F A C l eb sc h and P Gordan wrote on t ypes of binary form s L Kronecker and E B Christo ff el on bilinear form s F Klein and S Lie on the invariant theory connecte d with any group of li near was born at Erlangen and substitutions P a ul G ord an ( 1 8 3 7 1 9 1 2 ) becam e professor there He produced papers on finite groups par t ic u l a rl y on the sim ple group of ord er 1 6 8 and its associated cu r ve 3 3 3 = v e m ent is the proof of the x 0 His best known achie x z z + + y y existence of a complete system of concom itants for any giv en binary 2 form While C l eb sc h aim ed In his researches to devise m ethods by which he could stu dy the relationships bet w een i nvarian tal form s ( F or m en v er w an dt schaf t)the chief ai m of A ron h ol d was to examine 3 the equivalence or the linear transform ation of one form into another In v estigations along this line are due to E B Christoff el who showed that the nu mber of arbitrary param eters containe d in the substitution coefficients equals that of the absolute invariants of the form K Weierstrass who gave a general treatm ent of the equivalence of two l i ni Tor to B ar n a ba . 1 80 8 . . . . . , . , , , “ . . , , , , ” , . , , . , , , ’ . . . . . , , ’ , . . , . . . . , . . , . . - . . , . . , . . . , , . B u l l A m M ath S oc , Vol 7 , 1 900 , p 6 0 2 N a tu r e, V o l 90 , 1 9 1 3 , p 5 9 7 3 We a r e u si n g F ran M eyer , B eri cht u be r den g eg en w a rt ig en S t an d de r I n v a r i an t en the o r i e i n t he J a hr es b d d M ath Ver ei n i g u n g , V o l I , 1 8 90 9 1 , S ee p 99 pp 7 9 2 9 2 1 . . . . ” . . z . . . — “ . . . . . . . . . . ALGEB RA 34 7 linear system s of bilinear and quadratic form s L Kronecker who ex ten ded the researches O i Weierstrass and had a controv ersy with C i n 1 8 74 gave Jordan on certain d iscordant results J G D ar b oux w ho~ a general and elegant derivation of theore ms due to K Weierstrass and L Kronecker G F r oben iu s who applied the transform ation of “ bilinear form s to P faff s problem : To determ ine when two give n linear di fferential expressions of n term s can be converted one into the other by subj ecting the variables to general point transfor mations The study of invariance of quadratic and bilinea r form s from the stand point of group theory was pursued by H Werner S and W Killing Finite binary groups were exa m Lie ( 1 88 5) i n ed by H A Schwarz and Felix Klein Schwarz is led to the “ problem to find all spherical triangles whose symm etric repetitions on the surface of a S phere give rise to a finite number of spherical triangles d iffering i n position and deduces the form s belonging thereto With out a knowledge of what Schwarz and W R Ha m ilton had d one Klein was l ed to a deter m inatio n of the finite binary linear groups and their form s Representing transformations as m otions and adopting Riem an n s interpretation of a com plex variable on a S pherical surface F Klein sets up the groups of those rotations which bring the five regular solids into coincidence with them selves and the accompanying form s The tetrahedron octahedron and icosahedron lead respectiv ely to 1 2 2 4 and 6 0 rotations ; the groups in question were stud ied by Klein The icosahedral group led to an icosahedral equation which stan ds in intim ate relation with the general equation of the fifth degree Klein m a d e the icosahedron the centre of his theory of the quintic as given in his Vorl esu n gen uber das I k osaeder u nd di e A uflbsu n g der Gl ei chu ngen f u nf ten Gr ades Leip z ig 1 88 4 Finite substitution groups and their form s as related to linear d i ff erential equations were invest i gated by R Fuchs (Cr el l e 6 6 6 8 ) in 1 86 6 and later If the equation has on l y algebraic integrals then the group is finite and con v ersely F u c hs s researches on this topic were continued by C Jordan F Klein and F B rioschi Finite ternary and higher groups have been studied in connection with invariants by F Klein who in 1 8 8 7 m ad e two such groups the basis for the solution of general equations of the six th and seventh degrees In 1 88 6 F N Cole under the guidance of Kle i n had treated the sextic equation in the A m Jou r of M ath Vol 8 The second group use d by Klein was stu died with reference to the 1 40 lines in space to which it lea d s by H M aschke in 1 8 90 The relationship of i nv arian tal form s the study of which was initiated by A Cayley and J J Sylvester receiv ed S ince 1 8 6 8 em phasis in the writin gs of R F A C l eb sch a n d P Gordan Gordan proved in C r el l e Vol 6 9 the finiteness of the system for a S ingle “ binary form This is known as Gord an s theorem Even in the later si mplified fo rm s the proof of it is inv olv ed but the theorem . , . . , ” . , . . ’ . . - . . . . . . , ” , . . . , . ’ . , , . , , . . ' ‘ . , , , . , , , . , ’ . , . . , . , . . . , . , . . . . , . , . , . , . . , . , . . . . . ” , ’ . . , . . 348 . H I STORY A O F M ATHE M ATI C S yields practical m ethods to determ ine the existing system s G P eano in 1 8 8 1 generaliz ed the theorem and applied it to the cor respondences represented by certain double binary form s In 1 890 D Hilbert by using only rational processes dem onstrated the fi n i t e ness of the syste m of invariants arising from a given series of any form s in n variables A m odification of this proof which has so m e advantages was given by W E Story of Clarke University Hilbert s research bears on the nu mber of relations called syzygies a subj ect treated b e fore this tim e by A Cayley C Herm ite F Brioschi C Stephanos of Athens J Hamm ond E Stroh and P A M ac M ahon The symbolic notatio n i n the theory of invariants introduced by S H A ron h ol d and R F A C l eb sc h was developed further by P Gor d a n E Stroh and E S tu dy i n Germ any English wr i ters endeavored to m ake the expressions in the theory of form s intuitively evi dent by graphic representat i on as when Sylvester in 1 8 7 8 uses the atomic theory a n idea appl i ed further by W K Cli ffor d The sym bolic m ethod in the theory of inv ariants has been used by P A M ac M ah on in the arti cle Algebra in the ele v enth e d ition of the E n cycl opaedi a B r i tan n i ca and by J H Grace and A Young in their A l gebr a of I n var i a n ts Ca mbridge 1 90 3 Using a method in C Jordan s great m e m oirs on invariants these authors are led to novel results notably “ to an exact for m ula for the m axim um order of an irreducible c o variant of a syste m of binary form s A co mplete syz ygetic theo ry of the absolute orthogonal conco mitants of binary quantics was c on structed by E dwin B Elliott of Oxford by a m ethod that is not sym bolie while P A M ac M ah on i n 1 90 5 employs a symbolic calculus i n volving im aginary u mbr ae for simi lar purposes While the theory of invar i ants has played an important r ole in m odern algebra and analytic proj ective geom etry attention has been directed also to its e mploym ent in the theory of nu mbers Along this line are the r e searches o i L E D ickson in the M adi s on C ol l oqu i u m of 1 9 1 3 The establis hm ent of criteria by m eans of which the irreducibility of expressions in a given dom ain m ay be ascertained has been i nv es t ig a t e d by F T v Schubert K F Gauss L Kronecker F W P S chOn eman n F G M Eisenstein R D e dekind G Floquet L K o nig sb e rg e r E Netto O P erron M B auer W D u m as and H Blumberg The theore m of S chOn eman n and Eisenstein declares that — with integral coefficients is c if the polynom ial x + c 1 x + f— 2 such that a prim e p divides every coeffi cient c l but p does c not go into c then the polynomial is irred u cible in the domain of rational num bers This theorem may be regarded as the nucleus of the work of the later authors Floquet and K On ig sb erg er do not l i mit the m selves to polynom ials but consider also linear ho m ogeneous d ifferential expr e ssions Blum berg gi v es a general theore m which 1 practically includes all earlier results as special cases — F o b i bli og p hy ee T A m M th S o V ol 6 7 9 pp 5 7 544 . . ” - . . , , . ’ . . . , , . , . , . . . , . . , . , . , . . . , . . , . , . . . , ” , . , . . . . . . . ’ , , . . , , ” . . . , . . , . . . . . . . . , . . . , . . , . . ” " n . . , . , , . . , . , , . , 1 ” , , n, . . , . . r ra s r a ns . . a . c . , . 1 , 1 1 . . n 1 . , . 1 . in HI STORY A 3 50 O F M ATHE M ATIC S in his book Refl ess i on i i n tor n o all a s ol u zi on e del l equazi oni al gebr ai che was substantially the sam e as that gi v en later by P i err e 1 but only the second par t of Wan tz el s L au r en t Wa n tzel (18 14 simplified proof rese mbles R u fli n i s ; the first part is m odelled after Abel s Wan t z el by the way deserves credi t for having given the first rigorous proofs (L i ou vi l l e Vol 2 1 83 7 p of the im possibility of the trisection of any gi v en angle by m eans of ruler and co mpasses and of avoiding the irr educible case in the algebraic solution of irreducible cubic equations Wan t z el was r épétiteur at the P olytechnic School in P aris As a student he excelled both in “ mathe matics and languages Saint Venant said of him : Ordinarily he worked evenings not lying down until late ; then he read and took only a few hours of troubled sleep making alternately wrong use of coffee and opium and taking his m eals at irregular hours until he was m arried He put u nlimited tr ust in hi s constitution very strong by nature which he taunted at pleasure by all sorts of abuse He brought sadness to those who mourn his prem ature death R u ffi ni s researches on equations are remarkable as containing “ ? anticipations of the algebraic theory of groups per R u fli n i s “ m utation corresponds to our ter m group He di vided groups into “ “ S i mple and comple x and the latter into intransitive transitive i mprimitive and transitiv e primitive groups He established the “ i mportant theorem for which the nam e R u flfini s theorem has 3 been suggested that a group does not necessarily have a subgroup whose order is an arbitrary divisor of the order of the group The collected works of R u ffi ni are p ublished under the auspices of the Circolo M atematico di P alermo ; the first vol u m e appeared in 1 9 1 5 with notes by Ettore B or tol ot t i of B ologna A transcendental solu tion of the quintic invol v ing elliptic integrals was given by Ch Her m ite (C ompt R end 1 8 58 1 86 5 After Hermite s first publica tion L Kronecker in 1 8 58 in a letter to Hermite gave a second solution in whi ch was ob tained a simple resolvent of the S ixth degree Abel s proof that higher equations cannot al w ays be solved alge b r a i c all y led to the i nquiry as to what equations of a given degree can be solved by ra dicals S uch equations are the ones discussed by K F Gauss in considering the division of the circle Abel advanced one step further by proving that an irreducible equation can always be solved in ra di cals if of two of its roots the one can be expressed rationally in ter m s O f the other provided that the degr ee of the equa tion is prime ; if it is not prime then the solution depends upon that of equations of lower degree Through geometrical considerati ons ’ 1 813 , ’ ’ ’ . , , . , , , . ” , . . - . , , , , . ” , , . . ’ ” ” ” ” ’ . , , , ” . ’ , . . . ’ . . , . , , , , , , . ’ . . . . , , , , , . , E B or t ol ot t i , I nfl u en za , e t c , 1 9 0 2 , p 2 6 Wan tzel s p roo f i s g i v e n in N ou vell es A n n al es M a thémati q u es , V o l 4 , 1 8 4 5 , p p 5 7 6 5 S ee a l so V o l 2 , pp 1 1 7— 1 27 Th e ’ s eco n d p a r t o f Wa n t ze l s p ro o f, i n v o l v i ng s u b s t i t u t i on t he o r y , i s re p rod u ced i n J A ’ S e rre t s A l gebr e s u pér i eur e 2 H B u rk h ard t , i n Z ei tschr f M a themati k u P hys i k , S u p pl , 1 8 9 2 3 G A M i l l e r , I n B i bl i otheca mathema ti ca , 3 F V o l 1 0 , 1 90 9 1 9 1 0 , p 3 1 8 1 . . . ’ — . . . . . . . - . . . . . . . . . . . . — . . . . ALGEBRA 35 1 L O Hesse cam e upon algebraically solvable equations of the ninth degree not included in the previous groups The subject was power fully advanced i n P aris by the youthful Evar i s te Gal oi s ( 1 8 1 1 1 8 3 He was born at B ourg l afl f eifi e near P aris He b egan to exhi bit m ost ex traor di nary m athematical geni us after his fifteenth year His was a short sad and pestered life He was twice refused a d m i t t an c e to the Ecole P olytechnique on account of inability to m eet the ( to hi m) trivial demands of e xam iners who failed to recog ni z e his geni us He entered the Ecole Nor male in 1 8 2 9 then an inferior school P roud and arrogant and unable to see the need of the cus t o mary detailed e xplanations hi s career in that school was not s mooth Drawn into the turm oil of the revolution of 1 830 he was forced to leave the Ecole Normale After se v era l m onths spent in prison he was killed I n a duel over a love aff air Ordinary tex t books he di s posed of as rapidly as one would a novel He read J L Lagrange s m emoirs on equations also writings of A M Legendre C G J Jacobi and N H Abel As early as the seventeenth year he reached resul ts of the highest i mportance Two m emoirs presented to the Acade my of Sciences were lost A brief paper on equations in the B ul l eti n de Feru ssa c 1 8 30 Vol XIII p 4 2 8 gives results which seem to be applications of a general theory The night before the duel he wrote his scientific testament in the for m of a letter to Auguste Cheva lier containing a statement of the mathem atical results he had reached and ask ing that the letter b e published that Jacobi or Gauss pass j udg ment not on their correctness but on their importance Two m emoirs found a mong his papers were published by J Liou v ille in 1 84 6 Further m anuscrip ts were published by J Tannery at P aris in 1 90 8 As a rule Galois did not fully prove his theore ms It was only with difficulty that Liouv ille was able to penetrate into Galois ideas Several comm entators worked on the task of filling out the lac u n ae in Galois e xposition Galois was the first to use the word “ group in a techni cal sense in 1 830 He div ided groups into simple and compound and observed that there is no si mple group of any “ composite order less than 6 0 The word group was used by A Cayley i n 1 8 54 by T F Kirk man and J J Sylvester in Galois proved the i mportan t theore m that every inv ariant subgroup gives rise to a quotient group which exhibits many funda mental properties of the group He showed that to each algebraic equation corresponds a group of substitutions which reflects the essential character of the equation In a paper published in 1 84 6 he established the beautiful theorem : In order that an irreducible equation of prim e degree be solvable b y r adicals it is necessary and suff i cient that all its roots be . . . , - ‘ - . , . . , . , . , . , , . , - . ’ . . , . , . . . . . , . . . . . ’ , , . , , . , ” , , . , . . . . . ’ . ” ’ . . , ” , . . , . . . . . . , A nn a l es de l ecol e n or mal e s u pér i eu r e, 3 S , V ol X II I , ’ 1 896 S ee al so E P i c a rd , O eu vr es ma th d Eva r i s te Gal oi s , P a ri s , 1 8 9 7 ; J P i e rp o n t , B u ll eti n A m M a th S oc , 2 S , V o l I V , 1 8 9 8 , pp 3 3 2 — 3 40 2 G A M ill er in A m M a th M on thl y, V o l 18 , 191 3, p 1 See l i fe by P aul D u pu y ’ In . . . . . . . . . . . . . . . . . . . XX . . . A 3 52 O F M ATHE M ATIC S HI STORY rational in any two of them Galois use of substitution groups to determine the algebraic solvability of e quations and N H Abel s so m ewhat earl i er use of these groups to prove that gen er al equations of degrees higher than the fourth cannot be solved by radicals fur ni shed strong incentives to the vigorous cultivation of group theory It was A L Cauchy who entered this field next To Galois are due also so m e valuable results in relation to another set of equations presenting them selves in the theory of elliptic functions vi z the m odular equations To Cauchy has been given the credit of being 1 the founder of the theory of groups of fini te order even though funda m ental results had been prev iously reached by J L Lagrange P ietro Abbati ( 1 7 86 P R u ffi n i N H Abel and Galois Cauchy s first publication was in 1 8 1 5 when he proved the theorem that the number of distinct values of a non sym m etric function of degree n cannot b e less than the largest prim e that divides n without b ecom ing equal to 2 Cauchy s great researches on groups appeared in hi s Exer c i s es d a n a l ys e et de phys i q u e ma théma ti qu e 1 8 44 and in articles — in the P aris C omptes Ren du s 1 84 5 1 84 6 He did not use the term group but he uses (x y z u v w ) and other devices to denote sub “ s t i t u t i on s uses the ter m s cyclic substitution order of a su b s ti tu “ “ “ tion identical substitution transposition transitive in transit ive In 1 844 he prov ed the fundam ental theore m ( stated but not pro v ed by E Galo i s ) whic h is known as Cauchy s theore m : E v ery group whose order is divisible by a given prim e nu mber p m ust contain at least one subgroup of order p This theore m was later extended by L Sylow A L Cauchy was the first to enu merate the o i d er s of the possible groups w hose degrees do not e xceed si x but thi s enum eration was inco mplete At ti mes he fixed attention on prop er t i e s of groups without i mm ediate concern as regards applications a n d thereby took the first steps towar d the consideration of abstract groups In 1 84 6 J Liouville m ade E Galois researches bett er known by publication of two m anuscripts At least as early as 1 848 J A Serret taught group theory in P aris In 1 8 5 2 Enrico B etti of the Uni v ers i ty of P isa published in the A n n al i of B Tor tol i ni the first rigorous exposition of Galois theory of equations that m ade the theo ry intelligible to the g eneral public The first account of it gi v en in a text book on algebra is in the third edition of J A S erret s A l ge ’ . ’ . , . , . . . . , . , , . , . . , ’ . . , . . , , - , " ’ . ’ , ” ” “ . , ” , , ” ” , , ” , “ ” , , , ” . ’ . . . . . . , . , ’ . . . . . . . , . ’ . ’ - . br e , 1 86 6 . . In England the earliest studies in group theory are due to Arthur Cayley and William R Ham ilton In 1 8 54 A Cayley published a paper in the P hi l os ophi cal M agazi ne which is usually accepted as foun ding the theory of abstract groups although the idea of abstract groups occurs earl ier in the papers of A L Cauchy and Cayley s . . . , ’ . . , O u r accou n t of C a u c h y s res earc h es o n g rou p s i s dr aw n fro m th e ar ti c l e o f G A — — M il l e r i n Bi bl i otheca W l a thern a ti ca , V o l 1 9 0 9 1 9 1 0 , pp 1 3 7 3 2 9 , a n d t ha t o f 1 9 1 3 , pp 1 4 1 1 48 , Jo sephi n e E B u rn s i n A m M ath M onthl y, V ol ’ 1 . . . . X . . . XX — . . . . O F M ATHE M ATIC S HI STORY A 3 54 substitutions of n letters which are co mmutative wi th every sub s ti tu tion of a regular group G on the sam e n letters constitute a group which is S im ilar to G To Jordan is due the funda mental concept of class of a substitution group and he prov ed the constancy of the factors of composition He also proved that there is a finite nu mber of primitiv e groups whose class is a given nu mber greater than 3 an d that the necessa ry and s uff i cient condition that a group be solvable 1 is that its factors of co mposition are pri me numbers P ro minent a mong C Jordan s pupils is Edmon t M oi l l et ( 1 8 6 5 editor of L I n ter medi ai r e des mathémati ci en s who has m ade ex tensive c on tri b u tions In Germ any L Kronecker and R D edekind were the earliest to becom e acquainted with the Galois theory Kronecker refers to it in an article publ i shed in 1 8 53 i n the B eri chte O f the B erlin Acade my D edekind lectured on it in G Ot ti n g en in 1 8 58 In 1 8 79—1 8 80 E Netto gave lectures in Strassburg His S u bs ti tu ti on s theori e 1 88 2 was trans — e by i u s e B a t t a i n i 1 2 lated into Italian in 1 8 8 5 G of the ( 8 6 1 8 94) pp gl Un iv ersity of Rom e and into Engl ish in 1 8 9 2 by F N C ol e then at Ann Arbor The book placed the subj ect within easier reach of the m athem atical public In 1 8 6 2 —1 8 63 Lu dw i g S ylo w ( 1 83 2 —1 9 1 8) gave lectures on sub s ti tu tion groups in Christiania Norway which were attended by S oph u s Lie Extending a theorem given nearly thirty years earlier by A L “ Cauch y Sylo w obtained th e theorem known as Sylow s theorem m“ m Every group whose order is d ivisible by p but not by p p being a prim e nu mber contains 1 + hp subgroups of order pm About twenty years later this theore m was e xten ded still further by Georg Fr oben i u s — of the Univ ersity of B erlin to the e ff ect that the number ( 1 8 4 9 1 91 7 ) of subgroups is k p+ 1 k being an integer even when the order of the group is d ivisible by a higher po w er of p than pm Sophu s Lie took a very im portant step by the explicit application of the group concept to new dom ains and the creatio n of the theory of continuous groups 2 — M a ri u s S Oph u s L i e ( 1 84 2 1 8 99)was born in N or dfj or dei de i n Nor way In 1 8 59 he entered the Univer sity of Christiania but not until 1 8 6 8 di d this slowly developing youth d isplay m arked interest i n m athe m atics The writings of J V P oncelet and J P l ucker awakened — 8 his genius In the winter of 1 6 9 18 7 0 he m et Felix Klein in B erli n and they published so m e papers of j oint authorship The sum mer of 1 8 70 they were together i n P aris where they were in close touch w i th C Jordan and J G D arb o ux I t was then that Lie discovered his contact transform ation which changes the straight li nes of ordinary space over into spheres This l ed h i m to a general theory of trans form ation At the outbreak oi the Franco P russian war F Klei n — l t m t i S V X 99 9 p 3 3 i B i bli th m h G A M il l 3 — 6 t l I 6 F E g l i B i bl i th t h m i S V m 4 ; M N o th er 9 pp 3 — l i M th A V l 5 3 pp 4 . . , . ’ . ’ , . . . . . . . . , , . , , . . . , , . . ’ , , , . , , , , . . , . . . . . . . . . . . - . - 1 . 2 . n a er . n . e . , . n n n n a en , eca o o o ec a . e a , e a . a 1 a ca , 1. ca , . . . , . o o , . , . 1 , 00, 1 0 . 1 1 10 , 20 . 2 . . ALGEBRA 3 55 left P aris ; S Lie started to travel afoot through France into Italy but was arrested as a spy and imprisoned for a month until D arb oux was able to secure his release In 1 8 7 2 he was elected professor at the Univ ersity of Christiania with all his time a v ailable for research In — 1 8 7 1 1 8 7 2 he entered upon the study of partial di fferential equations of the first order and in 1 8 7 3 he arrived at the theory of transforma tion groups according to which finite continuous groups are applied to infinitesim al transform ations He considered a very general and important kind of transform ations called contact transfor mations and their application in the theory of partial di ffere n tial equations of the first and second orders As his group theory a n d theories of integration m e t with no appreciation he ret urne d in 1 8 7 6 to the study of geo metry—minim al surfaces the class ification of surfaces according to the transformation group of their geodetic lines The starting of a n ew journal the A rchi v f or M athemati k og N a tu rvi den s k ab in 1 8 7 6 enabled h im to publish his results promptly G H H al ph e n s pub l ic a t i on s of 1 8 8 2 on di ff erential in v ariants induced Lie to direct a t tention to his own earlier researches and their greater generality In 1 88 4 Friedrich Engel was induced by F Klein and A M ayer to go to Christiania to assist Lie in the preparation of a t r ea ti se the Theor i e der Tr an sf or ma ti on s gr u ppen 1 8 8 8 — 1 8 93 Lie accep ted in 1 8 8 6 a professorship at the University of Leip zig In 1 88 9—1 8 90 over work led to insomnia and depression of spirits While he soon recovered his power for work he ever afterwards was over sensitiv e and mis trustful o f his best friends With the aid of Engel he published in 1 8 9 1 a m em oir on the theory O f i n finite continuous transfor m ation groups In 1 8 98 he returned to No rway where he died the following year Lie s lectures on Difler en ti al gl ei chu n gen given in Leip z ig were brought out in book form by his pupil Georg S cheffer s in 1 8 9 1 In 1 8 95 F Klei n declared that Lie and H P oincar é were the two most activ e m athe matical inv estigators of the day The following quota tion from an article written by Lie in 1 8 95 indicates h ow his whole “ 1 soul was perm eated by the group concept : In this century the concepts kno w n as substitution and substitution group transforma tion and transform ation group operation and operation group inv ariant differential invariant and differential para meter appear continually m ore clearly as the most important concepts of m athe m atic s Wh ile the curve as the representation of a function of a single variable has been the m ost important object of m athe matical inv estigation for nearly two centuries fro m D escartes while on the other hand the concept of transform ation first appeared in this century as an e xpedient i n the study of curves and surfaces there has gradually d eveloped i n the last deca des a general theory of trans formations whose elem ents are represented by the transform ation , . . , . , , . - , . , , . , , , ’ . . . ‘ . . . 3 , . , - . . - , . . ’ . , , , . , . . . , , , , , , . , , , B eri chte d K oen i gl S aechs Gesel l schaf t, M ath M on thl y, V ol I I I , 1 89 6 , p 2 96 1 . . . . . . . 1 89 5 ; t ran sl a t e d b y G A . . M ill er i n A m O F M ATHE M ATIC S HI STORY A 3 56 ” its elf while the series of transformations in particular the transforma tion groups constitute the obj ect In close association with S Lie in the advancement of group theory and its applications was F elix K l ein ( 1 849 He was born at D usseldo r f in P russia and secured hi s doctorate at B onn in 1 868 After studying in P aris he becam e privat— docent a t G ottingen in 1 8 7 1 professor at Erlangen in 1 8 7 2 at the Technical High School in M u nich in 1 8 7 5 at Leip z ig in 1 88 0 and at G ottingen in 1 8 8 6 He has been active not only in the advance men t of various branches of ma them a t ics but also in work of organi z ation Fa mous for laying out lines of research is hi s Erlangen paper of 1 8 7 2 Vergl ei chende B etr achtu ngen uber n eu er e g eometr i s che For s chu n gen He beca me member of the com mission on the publication of the E n cykl opci di e der mathemati s chen Wi ss en s chaf ten and editor of the fourth vol um e on m echani cs also editor of M a thema ti sche A n n al en 1 8 7 7 and in 1 90 8 president of the International Co mmission on the Teachi ng of M athe matics A S an inspiring lecturer on m athe matics he has wielded a wide influence upon German and American students About 1 91 2 he was forced by ill health to discontinue his lectures at G Ot ti ng en but in 1 9 1 4 the ex c i t em e n t of the war roused h i m to acti v ity m uch as J La g range was aroused at the outbreak of the French Revolution and Klein res um ed lecturing He has constantly e mphasi z ed the importance of both schools of m athe m atical thought nam ely the intuitional school and the sc hool that rests everythi ng on abstract logic In his opinion “ the intuitive g rasp and the logical treatment should not exclude but should supplem ent each other S Lie s m ethod of treating differential invariants was further i n — v e s t i g a t ed by K Z oraw ski in A cta M a th Vol XVI 1 8 9 2 1 8 93 In 1 90 2 C N Haskins deter m ine d the nu mber of functionally i n dep e n d ent in v ariants of any order while A R Forsyth obtained the invariants for ordinary Eucli dean S pace Diff erential param eters have been 1 inv estigated by J Ed mund Wright of Bryn M awr College Lie s theory of inv ariants of finite continuous groups was attacked on logi cal grounds by E S tudy of Bonn in 1 90 8 The vali di ty of this e riti c i sm was partly ad mitted by F Engel Another m ethod of treating di ff erential invariants originally due t o E B C hr i s tofl el has been called by G Ricci and T Levi — Civita of P adua covariant derivation (M athema ti sche A n n al en Vol 54 2 A thi rd method was intro d uce d by H M aschke who used a s ymbolis m S i mi lar to that for algebraic invariants — Henry W S tager published i n 1 9 1 6 A S yl ow Factor Tabl e f or the fi rst Tw el ve Thou s a n d N u mbers : For every nu mber up to 1 200 the d ivisors of the for m p(kp+ 1 ) are given where p is a pri me greater than 2 and , . , . ” . , , , . , . , , . ' , , , . . - , . , , . , , , . ” , , . ’ . . . . . , . , . . , . . ’ . . . . , . . , . . . , . “ , , . , . . . , 1 We a re u s i n g J E Wrig ht ’ . . s ' f Quadr ati c Difier en ti al I n var i an ts o 5 8 pp - 2 Tra n s A m M ath S oc . . . . , Vo l . 1, 1 90 0 , pp . 197 —4 20 . For ms , 1 90 8 , O F M ATHE M ATI C S HI STORY A 3 58 L E Dickson said in 1 900 : When a problem has been exhibited in g roup phraseology the possibility of a solution of a certain char acter or the e xact nature O f its inherent di fli c u l ti es is deter mined by a study of the g roup of the proble m As the che mist analyz es a compound to d etermine the ulti mate elements composing it so the group theorist deco mposes the group of a given problem into a chain of si mple groups M uch labor has been e xpended in the de termination oi simple groups For continuous groups of a fini t e number of para meters the problem has been completely solved by W Killing and E J Cartan with the result that all such simple groups aside fro m five isolated ones belong to the systems investi gated by S ophu s Lie vi z the general proj ective group the p ro j e c ti v e g roup of a linear co mplex and the projective group leaving invariant a non degenerate surface of the second order The cor responding proble m for infinite continuous groups re mains to be sol v ed With regard to finite si mple groups the problem has been 2 3 attacked I n two directions O H older F N C ol e W B urn side G H Ling and G A M iller have shown that the only S i mple groups of co mposite orders less than 2 000 are the previously known S imple groups of orders 6 0 On the other hand 50 4 var i ous infinite syste ms of finite si mple groups have been determ ined The cyclic groups of pri me orders and the al ternating group of n letters (n > 4 ) ha v e long been recogni z ed as S im ple groups The other known syste ms of fi nite S i mple groups have been discovered in the study of linear groups Four syste m s were found by C Jordan in his study of the general linear the abelian ( Tr a i té des s u bsti tu ti on s ) and the two hypoab el i a n groups the field of reference being the set of resi dues of integers with respect to a prim e m odulus p Generaliz a " i t ons m ay be made by e mploying the Galois field of order p (desig n a t e d GF co mposed of the p Galois co mplexes formed wi th a root of a congruence of degree n irreducible m odulo p Groups of linear substitutions in a Galois field were studied by E B etti E M ath i eu and C Jordan ; but the structure of such groups has been determined only in the past decade The si mplicity of the group of unary linear fractional substitutions in a Galois field was first proved by E H M oore (B ul l eti n A m M a th S oc D ec 1 8 93) and shortly afte r w ard by W B urnside The co mplete generaliz ation of C Jor dan s four syste m s of S i mple groups and the determination of three new triply i nfi n i t e syste ms have been made by the writer (i e by 1 . . , . , - . . , . . . , , . , , , , - . . , . . . , . . , , “ . . . , . , , , . . . . , , , , . ” . . , , . . . . . . . . , . , . . ” ’ - 1 . S ee L E D i ck s on i n C ompte . pp 1 90 2 , . . 2 25 , 2 26 du I I vendu . Con gr i n ter n . , P ar i s , 1 900 . . . P a ri s , . O H ol de r p ro v e d i n M a th A n n al en , 1 89 2 , t h a t th e r e a re o n l y t w o S i mp l e g ro u p s o f c o mpos i t e o r d e r l ess t h an 200 , v iz , t hose o f o r de r 6 0 a n d 1 6 8 3 F N C o l e In A m J ou r M a th , 1 8 9 3 fo u n d t ha t t h e i c co u l d b e o n l y t hre e su c h 660 g ro u ps b e t w ee n o rd e rs 2 00 a n d 6 6 1 , v iz , o f o rd e rs 4 W B u rn side s ho w ed t ha t t here w as on l y on e Si mp l e g rou p of co mposi te orde r b e t w een 6 6 1 an d 1 09 2 2 . . . . . . . . . . . AL GEBRA 3 59 L E Dickson in Aside fro m the cyclic and alternating groups the known syste ms of finite si mple groups have been derived as quo tient groups in the series of co mposition of certain linear groups M iss I M S c ho t t en fe l s of C hicago showed that it is possible to con struct two si mple groups of the sam e order The determination of the s m allest degree ( the class of any of the non identical substitutions of pri mitive groups whi ch do not include the alternating group was taken up by C Jordan and has been called “ Jordan s problem It was continued by Alfred B ocher t of B reslau and E M aillet B oc her t proved in 1 8 92 : If a substitution group of deg ree n does not include the alternating group and is more than S i mply transitive its C l ass e x ceeds i n — r if i t is m ore than d oubly transitive its class e xceeds 3n 1 and if i t is more than triply transi — n ti v e its class is not less than % 1 E M aillet showed that when the degree of a primitive group is less than 2 0 2 its class cannot be ob t ai n ed by di mi n i shing the degree by unity u nl ess the degree is a power of a prime n umber In 1 900 W B urnside proved that eve ry transitive per muta tion group in p symbols p being prime is either solvable or doubly tra nsiti ve As regards linear groups G A M iller wrote in 1 8 99 as follows The linear groups are of e xtreme i m portance on account of their numerous direct applications Eve r y group of a finite order can clearly be represented in many ways as a linear substitution group since the ordinary substitution (perm utation )groups are merely very special cases of the linear groups The general question of rep resenting such a group with the least nu mber of variables seems to be far from a co mplete solution I t is closely related to that of de t ermi n i ng all th e linear groups of a finite order that can be represented w i th a small number of variables Klein was the first to determ ine all the finite binary groups (in 1 8 7 5) while the ternary ones were con s i der e d independently by C Jordan ( 1 880 ) and H V a l en ti n er The latter discovered the i mportant group of order 3 60 which was o mitted by Jordan and has recently been proved (by A Wi man of S i mply iso m orphic to the alter n ating group of degree 6 Lund ) H M aschk e has considered m any quaternary groups and established in particular a complete for m syste m of the quaternary group of — r 1 8 0 linear substitutions i n i h a s H e c M c h k e 1 8 was born ( 53 1 90 8 ) 5 4 in Breslau studied in B erlin under K Weierstrass E E Kumm er and L Kronecker later in G ottingen under H A Schwarz J B L i sting and F Klein He entered upon the study of group theory un der Klein In 1 8 9 1 he came to the United States worked a year with the Weston Electric C o then a cc ep t ed a place at the University of Chicago Linear groups of fin i te order first treated by Feli x Klein were later used by h i m i n the extens i on of the Galo i s theory of algebraic equat i ons as seen in his I k os aeder A S state d above Klein s de . . , - . . . . - ” ’ . . . . ’ , , , . . . . , , . . , . . . . . . . . . . . , , . . , . , . , . , . . . , . , . . , . , . , , ’ , . , . A HI STORY OF MATHE M ATIC S 36 0 termination of the linear groups in two variables was followed by groups in three variables developed by C Jordan and H V al en tin er and by groups of any num ber of variables treated by C Jordan Sp ecial linear gr oups in four variables were di scussed by E and G Bagnera of P alermo The complete G ou r sa t ( 1 88 9) determination of the groups in four variables aside from intransi ti v and m onomial types was carried t hrough by H F B l i chfel dt of L e 1 land S tanford University Says B l i chfel dt : There are in the main four distinct principles employed in the determination of the groups the original geo metrical process of Klein in 2 3 or 4 variables :( a ) the processes lea di ng to a diophantine equation which may be (b ) approached analytically ( C Jordan or geom etrically (H Valen tiner G B agnera H H M itchell ) a process involving the relativ e ; (c ) geo metrical properties of transform ati ons whi ch represent hom ologies and like forms (H V al en ti n er G B agnera H H M itchell (d) a process developed from the properties of the m ultipliers of the trans form ations which are roots of unity (H F B li chfel dt ) A new prin c i pl e has been added recently by L Bieberbach though i t had already been use d by H V al en ti n er in a certain form Independent of these principles stands the theory of group characteristics of whi ch G F rob en i u s is the discoverer There is a m arked diff erence between finite groups of even and of ? o dd order A S W B urn side points out the latter admit no self in v erse irreducible representation except the identical one ; all irre G A du c i bl e groups of o dd or d er in 3 5 or 7 sym bols are soluble M iller pro v ed in 1 90 1 that no group of odd order with a conj ugate set of operations containing fewer than 50 m e mbers could be simple W B urnside prov ed In 1 90 1 that transitive groups of odd order whose degree I S less than 1 00 are soluble H L Rietz I n 1 90 4 extended thi s last result to groups whose degrees are less than 2 43 W B urnside has shown that the num ber of prime factors in the order of a simple is a lower group of odd order cannot be less than 7 and that li mit for the order of a group of odd degree if S im ple These results suggest that perhaps simple groups of odd order do not exist Recent researches on groups m ainly abstract groups are due to L E Dickson Le Vavasseur M P o tr on L I Neikirk G Frobenius H Hilton 3 A Wiman J A de Ség u i er H W Kuhn A Loew y H F B l i chfel dt W A M anning and m any others E x tensive researches on abstract groups have been carried on by G A M iller of the University of Illinois In 1 9 1 4 he showed for instance that a n on abelian group can have an abelian group of iso morphism s by proving the exi stence . , . . , ' . . . , . , . . , , . , , . . , . , . . . . . , . , . , . . . , . . . ” , . . . , , . , . . . . . . . . . , , . , , . , . . . , , . . . , . , . . . . . , , . , . , . , . , . , . , . . - . 1 We , — 74 1 7 7 pp 2 W B u rn si d e 1 H u si n g a re . F . B l i ch fel d t , ’ s Fi n i te C oll i n eati on Gr ou ps , C hi cag o, 1 9 1 7, . Theor y of Gr ou ps of Fi n i te Or der , 2 Ed C a m b r i dg e , 1 9 1 1 , p 5 0 3 ’ 3 C o n s u l t G A M i l l e r s Thi rd R e po r t o n R e c e n t P ro g ress i n t h e T heo ry of G r o u p s o f F i n i t e O r de r i n B u l l A m M a th S oc , V ol 1 4 , 1 90 7 , p 1 24 . . , . ” . . . . . . . , . . . . A HI STORY OF M ATHE M ATIC S 36 2 then the exact number of positive roots is ascertainable fro m the v ariations of S ign in the series M ichel Fekete and Georg P OIya ? — both of B udapest use x) for the sam e purpose The theo ry of equations commanded the attention of L e opol d He was born in Liegnitz near Breslau Kr on e ck e r ( 1 8 2 3 studi ed at the gymnasi u m of his native town under Kummer later in B erlin under C G J Jacobi J Steiner and P Dirichl et then in B reslau again under E E Ku mm er Though for elev en years after 1 8 44 engaged in business and th e care of his estates he did not neglect In 1 8 55 he went to B erlin m athematics and his fam e grew apace where he began to lecture at the Univers ity in 1 8 6 1 He was a very stim ulating and interesting lecturer K umrn er K Weiers trass and L Kronecker constitute the triumv i rate of the second mathematical school in B erlin This school e mphasi z ed severe rigor in dem onstra tions L Kronecker dwelt intensely upon arithm etization which repressed as far as possible all space representations and rested solely upon the concept of nu mber particularly the positive integer He displayed m anysided talen t and extraor di nary ability to penetrate 2 “ new fields of thought B ut says G Frobenius conspicuous as his achiev ements are in the different fields of num ber research he does not quite reach up to A L Cauchy and C G J Jacobi in an al y SiS nor to B Riemann and Weierstrass in function theo ry nor to Dirichl et and Kumm er in nu mber theory Kronecker s papers on algebra the theory of equations and elliptic functions proved to be diffi cult reading A m ore co mplete and simplified exp osition of hi s results was giv en by R D edekind and H Weber A mong the finest 3 “ of Kronecker s achieve ments says Fine were the connections whi ch he established among the various di sciplines in which he worked : notably that between the theory of quadratic form s of negative deter minant and elliptic functions through the S ingu lar m oduli which give rise to the complex m ultiplication of the elliptic functions and that between the theory of n u mbers and algebra by hi s arithm etical theory of the algebraic equation He held to the view that the theory of fractional and irrational numbers could be built upon the integral “ numbers alone Die gan z e z ahl said he schuf der liebe Gott alles U eb rig e ist M enschenwerk Later he even denied the existence of irrational numbers He once paradoxically remarked to Linde “ m ann : Of what use is your beautiful research on the num ber i r ? Why cogitate over such problem s when really there are no irrational nu mbers whatever ? In 1 8 90—1 8 9 1 L Kronecker developed a theory of the algebraic equa tion with num erical coeffi cients whi ch he di d not live to publish From notes of Kronecker s lectures H B Fine of P rinceton prepared . , n , , , . . . . , . . , , . . , . , . ' . . , , . . . . , ” “ . . . , , , . ” . , . . . - . - , ’ . , . ” . ’ . . , , , . , ” ” ” , , , . , . . ” , . . , ’ , . . B u l l A m M ath S oc , V o l 2 0 , 1 9 1 3 , p 2 0 2 G F ro b e n i u s Ged ii chtn i ssrede a uf L eopol d K r on eck er , B e rli n , 3 B ul l A m M a th S oc , V ol I , 1 89 2 , p 1 7 5 1 . . . . . . . . , . . . . . . . 1 893 , p . 1. AL GEB RA 3 63 ” ? an address in 1 91 3 giving Kronecker s unpublished results All “ who have read Kronecker s later writings says Fine are familiar with his contention that the theory of the algebraic equation in its final for m m ust be based solely on the rational integer algebraic nu mbers being excluded and only such relations and operations being admi tted as can be expressed in finite ter ms by means of rational numbers and therefore ulti mately by means of integers These lec tures of 1 890 — 9 1 are chi efly concern ed with the develop ment of such a theory and in partic u lar with the proof of two theore ms which therein take the place of the fundam ental theorem of algebra as commonly stated ’ ’ , “ , , . , . S ol u ti on f o N u meri cal E qu ati on s a native of Geneva Switz erland and the successor of P oisson in the chair of mechanics at the Sorbonne published in 1 8 2 9 hi s celebrated theorem determining the nu mber and situation of real roots of an equation co mprise d between given limits D e M organ has said that this theore m i s the co mplete theor eti cal solution of a di fficul ty upon whi ch energies of e v ery order have been employed since the ti m e of Descartes S turm e xplains in that article that he enjoyed the privi lege of readi ng Four i er s researches whi le they were still in m anuscript and that his own discov ery was the result of the close study of the princi ples set forth by Fo urier In 1 8 2 9 S turm published no proof P roofs were given — in 1 830 by Andreas von E ttinghausen ( 1 7 96 1 8 7 8 )of Vienna in 1 8 3 2 by Charles C ho q u e t e t M athi as M ayer in their Alg ebre and in According to J M C D uham el S turm s 1 8 3 5 by S tur m h i m self discovery was not the result of observation but of a well ord ered l i ne of thought as to the kind of function that woul d m eet the r e “ According to J J Syl v ester the theore m stared him q u ir em en t s in the face in the midst of som e mechanical investigati ons ( Sturm) connected with the motion of compound pendulum s D uh amel an d Syl v ester both state that they received their informat i on from S turm di rectly Yet their statements do not agree P erhaps both statem ents are correct but represent diff erent stages in the evolution of the di s ? c ov e ry in Stur m s m ind By the theorem of S turm one can ascertain the nu mber of comple x roots but not their location That limitation was re moved in a bril liant research by another great French man A L Cauc hy He di s covered in 1 8 3 1 a general theorem whi ch reveals the number of roots whether real or co mplex which lie withi n a given contour This theorem makes heavier demands upon the m athem atical attainm ents J acqu es Char l es Fr an coi s S tu r m ( 1 80 3 , , , “ . ” . ’ . . , , ’ . . . . , - , . . . , ” . . . , ’ , . , , . . . , . , B u ll A m M ath S oc , V ol 2 0 , 1 9 1 4 , p 339 “ 2 C o n su l t a l so M B och e r , T he p u b l i s h e d S t u rm o n a l g eb ra i c an d di f e ren ti al Eq u at ion s 1 9 1 2 , pp 1 1 8 1 . . . . — . . . . . ” i . an d n u n p u b l i sh e d B u ll . Wo rk of A m M ath S oc . . . , C h a rl es V ol 1 8 , . A 3 64 O F M ATHE M ATIC S HI STORY of the reader and for that reason has not the celebrity of Sturm s theore m B ut it enlisted the lively interest of men like S turm J Liou v ille and F M oigno A remarkable article was published in 1 8 2 6 by Germi n al Dandel i n — in the m em oirs of the Academy of Sciences of Brussels ( 1 7 94 1 84 7 ) He gave the conditions under which the Newton Raphson m ethod of approxim ation can be used with security In this part of his research he was anticipated by both M ou rrail l e and J Fourier In another part of his paper ( the second supplem ent ) he is more fortunate ; there he describes a new and m asterly device for approximating to the roots O f an equation which constitutes an anticipatio n of the fa mous m ethod of C H Gr affe We m ust add here that the fundamental i d ea of G raff e s m ethod is found even earlier in the M i scel l anea a n al yti ca 1 76 2 of Edward Waring If a root lies between a and b —b < 1 and a is on the convex side of the curve then D an del in a puts x = a + y an d transform s the equation into one whose root y is small He then m ultiplies f (y) by f ( y) and O b tains upon writing 2= z an equation of the sam e degree as the original one but whose y =0 roots are the squares of the roots of the equation f (y) He remarks that this transform ation m ay be repeated so as to get the fourth eighth an d higher powers whereby the m oduli of the powers of the roots div erge suffi ciently to m ake the transform ed equation separable into as m any polygons as there are roots of distinct m oduli He ex plains how the real and i maginary roots can be obtained D an del in s research h ad the misfortune of being buried in the ponderous tom es of a royal acade my Only accidentally d id we co m e upon this antici pa t i o n of the m ethod of C H Gr affe Later the Acade m y of Sciences of B erli n off ered a priz e for the inventio n of a practical m etho d of computing im aginary roots The priz e was awarded to C a r l H e i nri ch G r afi e ( 1 7 99 professor of m athematics in Zurich for his paper published i n 1 83 7 i n Zurich entitled D i e A ufl osu n g der hoher en n u mer i s chen Gl ei chu n gen This contains the fa mous Gr affe m ethod to which reference has been m ade Gr affe proceeds from the sam e principle as did M or i tz A br aham S ter n of G ottingen in the m ethod of recurrent series and as did D an del in By the process of involution to higher and higher powers the s maller roots are caused to vanish i n comparison to the larger The law by which the n ew equations are constructed is excee dingly S imple If for example the coeffi cient of the fourth term of the given equation is a 3 then the corresponding coefli c i en t of the first transform ed equation is — — 2as In the com putation of the new coeff icients a 2 2 a 2a 4+ 2 a 1a Graff e uses logarithm s By this re markable m ethod all the roots both real an d i maginary are found S im ultaneously without the necessity of determ ining beforehand the nu mber of real roots and the locat i on of each root The d iscussion of the case of equal i maginary roots o mitte d by Graffe was taken up by the astrono mer J F Encke ’ , . . , . , . . - . . . , . . . ’ , , . , , , , - . , , , . , , , , . ’ . . ' . . . . ” , , ’ , ‘ , , . . ' . , , . . , , , 5 , . , . , , . , , . . A HI STORY OF M ATHE M ATIC S 3 66 Italian mathem aticians have placed the determination of real a n d I m aginary roots of nu merical equations by the m ethod of infinite series w i thin reach of the practical co mputer The methods them sel v es indicate the num ber of real and i maginary roots so that one can dispense with the application of Stu rm s theorem here just as easily as one can in the D a n del i n Gra ffe m ethod Considerable at tention has been given to the solution of special types—trinom ial equations— b y G D an del i n K F Gauss ( 1 840 J Lord John M L a ren The last three used B e l l a v i ti s logarithm s of su m s and diff erences which were first suggested by “ G Z Leonelli in 1 8 0 2 and are often called Gaussian logarithm s The extension of the Gaussian m ethod to q uadrino mials w as under taken by S G u n delfi n g e r i n 1 884 and 1 88 5 Carl F aerb er in 1 889 and Alfre d Wiener in 1 8 8 6 The extension of the Gaussian method to any equation was taken up by R M eh mke professor in D arm stadt who published in 1 8 89 a logarith mic graphic m ethod of solving nu m erical equations an d in 1 8 9 1 a m ore nearly arith metical method of solution by logarith m s The m ethod is essentially a mixture of the Newton R aphs on m etho d a n d the regula falsi as regards its the oretical basis Well known is R M ehm k e s article on m ethods of co mputation in the En cykl opadi e der mathemati schen Wi ss enschaf ten Vol 1 p 938 an d . , ’ - . . . . , . ’ , . . . , . , . . , , - , . - , ’ . . . , M agi c S qu ar es an d , . . C ombi n a tory A n al ysi s The latter part of the nineteenth century witnesses a revival of interest in m ethods of constructing m agic squares Chief among the writers on this subj ect are J Horner S M D rach Th H armu th W W R B all E M aillet E M E M c C lin toc k M agic L a q u i er e ( 1 88 0 )E Lucas squares of the diabolic typ e as Lucas calls the m are designated by M c C l in tock These and S imilar form s are called p an di ag o n a l Nasik squares by A H Frost An interesting book M agi c S qu ar es Chicago 1 90 8 was prepared by the A merican electrical a n d C u bes engineer W S Andrews S till m ore recen t is the C ombi n atory A n al ys i s Vol I Ca mbridge 1 9 1 5 Vol II 1 9 1 6 by P A M a c M ahon “ which touches the subj ect of magic squares Says M a cM ahon : In fact the whole subj ect of M agic Squares and connected arrange ments of nu mbers appears at fir st S ight to occupy a position w hi ch is completely isolated fro m other departm ents of pure mathe matics The Object of Chapters II and III is to establish connecting lin ks where none previously existed This is accomplished by selecting a certain diff erential operation and a certain algebraical fun ction I p VIII “ The P robl em e des Rencontres can be discussed in the sa me The reader will be familiar with the old question of the m anner . . . . ” “ . . . . . ” . . . . , , . . , . . , . . , . , , , , . , . , , . , . , . , . . , , . . ’ ‘ — . 1 En cycl opedi c des s ci ences mathém F I , Vol . . . 2 , 1 90 6 , pp 6 7 7 5 . . ANALYSIS 36 7 letters and en v elopes A given nu mber of letters are written to di f f eren t persons and the envelopes correctly addressed but the letters are placed at rando m in the envelopes The question is to find the probability that not one letter is put into the right envelope The enu meration connected with this probability question is the first step that must be taken in the solution of the famous problem of the Latin Square I p IX The proble m of the L atin Square : The q uestion is to place n dif 2 feren t letters a b c in each row of a square of n co mpartmen ts in such wise that one letter being in each compart ment each colu mn involves the whole of the letters The num ber of arrangemen ts is required The question is famous because from the tim e of Euler to that of Cayley inclusive its solution was regarded as being beyond the powers of mathematical analysis It is solved without difficul ty by the method of diff erential O perators of whi ch we are speaking In fact it is one of the simplest exa mples of the method whi ch is S hewn to b e c apabl e of solvin g questions of a much m ore recondi te charac l ter The ex tension of the prin ciple of magic squares of the plane to thr ee dimensional S pace has commanded the attention of many M ost successful in t hi s field were the Austrian Jesui t Adam A daman du s K oc han sk y the French man Josef Sauveur the Germans Th Hugel ( 1 8 59) and Hermann Scheffl er In Vol II M ajor M ac M ahon gives a re markable group of identi ties discovered by S Ra manujan of Cambridge which have applications in the partitions of numbers but have not yet been established by rigorous demonstration . . . ” , . , , , . , , , . . , , . . ” . . . , . , . , . A n al ysi s Under this head we find i t convenien t to consider the subj ects of the diff erential and integral calculus the calculus of variations i n finite series probability di fferential equations and integral equations An early representative of the critical and philosophical school of mathematicians of the nineteenth centu r y was B e rna r d B ol zan o professor of the philosophy of religion at P rague In ( 1 78 1 1 8 1 6 he gave a proof of the bino mial for m ula and e xhibited clear notions on the convergence of series He held advanced views on variables continui ty and li mits He was a forerun ner of G Cantor Noteworthy is his posthumous tract P ar adoxi en des Un endl i chen e di ted by his pupil Fr P i ihon sk y B ol zano s writings ( P reface were overlooked by mathematicians until H Hankel called attention “ “ to them H e has everything says Hankel that can place hi m in thi s respect [notions on infinite series] on the same level with Cauchy only not the art pecul iar to the French of re fi ning their ideas and communicating them in the most appropriate and taking manner , , , . , . . , . . . , ’ ' , , ” . . . . , , , . 1 P A . . M acM aho n , Combi natory A n al ys i s , Vol I , C ambri dg e , . 1 9 15 , p ix . . A HI STORY OF M ATHE M ATI C S 368 ” So it ca me about that B ol z ano re mained unknown and was soon for gotten H A Schwarz in 1 8 7 2 looked upon B ol zano as the inventor of a line of reasoning further dev eloped by K Weierstrass In 1 8 8 1 O Stol z d eclared that all of B ol z ano s writings are remarkable inasm uch as they start with an unbiassed and acute criticism of the 1 contributions of the older literature A reformer of our science who was e minently successful in reachi ng the ear of his contemporaries was Cauchy 2 Au gu s ti n Lo u i s C au chy ( 1 7 8 9— 1 8 5 7) was born in P aris a nd r e c ei v e d his early education fro m his father J Lagrange and P S Laplace with whom the father cam e in frequent contact foretold the future greatness of the young boy At the Ecole Centrale du P a n theon he excelled In ancient classical studies In 1 80 5 he entered the Ecole P olytechnique and two years later the Ecole des P onts et C h au S S ées Cauchy left for Cherbourg in 1 8 1 0 in the capacity of engineer Laplace s M ecan i qu e C el este and Lagrange s F on cti on s A n al yti q u es were a mong hi s book co mpani ons there Considerations of health induced hi m to return to P aris after three years Yielding to the persuasions of Lagrange and Laplace he renounced engineerin g in favor of pure science We find him next holding a professorship at the Ecole P olytechnique On the exp ul sion of Charles X and the accession to the throne of Louis P hilippe in 1 8 30 Cauchy being exceedingly conscientious found hi mself unable to take the oath de man ded of hi m B eing in consequence depri v ed of his positions he went into voluntary exile At F ri b ou rg in Switzerland Cauchy r e sum ed his stu dies and in 1 83 1 was induced by the king of P iedm ont to accept the chair of mathe m atical physics especially created for hi m at the Un iversity of Turin In 1 8 33 he obeyed the call of hi s exiled king Charles X to undertake the education of a grandson the D uk e of Bordeaux This gav e Cauchy an opportunity to visit various parts of Europe and to learn how e x tensively his works were being read Charles X bestowed upon hi m the title of B aron On his return to P aris in 1 8 3 8 a chair in the Coll ege de France was o ffered to hi m but the oath dem anded of hi m prevented his acceptance He was nominated m e mber of the B ureau of Longitude but declared ineligible by the ruling power D uring the political events of 1 848 the oath was suspended and Cauchy at last became professor at the P olytechnic School On the establishment of the second e mpire the oath was r e instated but Cauchy and D F J Arago were exempt from it Cauchy was a man of great piety and in two of his publications staunchly de fended the Jesuits Cauchy was a prolific and profound mathem atician By a prompt publication of his results and the preparation of standard text books he exercised a m ore imm ediate an d benefic i al influence upon the great C s l t H B e g ma D P hil d B lz H ll e 9 9 phi h W k B . . . . . ’ ” . “ . . - , . . . , . , . . , . , ’ ’ ’ ’ . . . , . , . , , , . , , , . , , , . , , , . . , . , , . ‘ , . , . , . , . . . , . . - , , 1 2 on u . r n, as oso sc e or er n ar o C A Va l son , L a Vi e cl l es trava ux du B ar on C a uchy, P ari s, . . a nos , 1 86 8 . a , 1 0 . O F M ATHE M ATIC S HI STORY A 3 76 wi th the indefinite equations in order to determ ine co mpletely the m axi m a and m inima of m u l tiple integrals was awarded a priz e by the French Acade my in 1 84 5 honorable m ention being made of a paper by C E D elaunay P F S arr u s s m ethod was S implified by — 2 of P avia at A L Cauchy In 1 8 5 Gaspare M ainardi ( 1 800 1 8 7 9) tempted to exhibit a new method of discri minating ma xim a and minim a and ex tended C G J Jacobi s theorem to double integrals M ainardi and F B rioschi showed the value of determ ina n ts i n ex h i b i ti n g the terms of the second variation In 1 86 1 I s a ac Todhu n ter — 1 8 2 0 1 8 84 ) of St J ohn s College Cambridge published his valuable ( work on the H i s tory of the P r ogr ess of the C al cu l u s of Vari ati on s which contains researches of his own I n 1 8 66 he published a m ost important research develop ing the theory of discontinuous solutions (discussed in particular cases by A M Legendre ) and doing for this subj ect what P F Sarrus had done for m ultiple integrals The following are the more important older authors of systematic treatises on the calculus of variations and the dates of publication : Robert Woodhouse Fellow of Caius College Ca mbridge 1 8 1 0 ; Richard Abba t t in London 1 83 7 ; J ohn Hewitt Jell e tt ( 1 8 1 7 once P rovost of Trinity College D ublin 1 8 50 ; Georg Wilhehn S trauch of Aargau in Switz erland 1 849 ; F r an goi s M oigno ( 1 8 0 4 (181 1 — of the z 1 8 2 of P aris and Lorent Leonard Lindel of ( 7 1 90 8) 1 884 ) University of Helsingfors in 1 8 6 1 ; Lewis B uff ett Carll in 1 8 8 1 Carll ( 1 8 44 was a blind m athe matician graduated at C 0 lumbia College in 1 8 70 and i n 1 8 9 1 — 1 8 92 was assistant in m athe m atics there That of all plane curves of given length the circle includes a maxi m u m area a n d of all closed surfaces of given area the sphere encloses a maxim u m volum e are theore m s considered by Archimedes and Z en odoru s but not prove d r i gorously for two thousand years until K Weierstrass and H A Schwarz Jakob Steiner thought he had proved the theore m for the circle On a closed plane curve different from a circle four non cyclic points can be selected The quadrilateral ob tained by successively joining the S ides has its area increased when it is so deform ed ( the lunes being kept rigid ) that its vertices are cyclic Hence the total area is increased and the circle has the m a xi m um area Oskar P erron of Tubingen pointed out in 1 91 3 by an ex “ a mple the fallacy of this proof :Let us prove that 1 is the largest of all positive integers N 0 such integer larger than 1 can be the m axi mum for the reason that its square is larger than itself Hence I “ m ust be the m axi m u m S teiner s proof does not prove that am ong all closed plane curves of given length there exists one whose area is a 1 K Weierstrass gav e a simple general existence theorem maxim u m applicable to the extrem es of c ontinuous ( stetige ) functions The max imal property of the S phere was first prov ed r igorousl y I n 1 884 by bin ed , , ’ . . . . . . . . ’ . , . . . . . ’ . , , , . , . . , . . . , , , , , , , , , . , , . , , , , , , . . . . . - . , . ” . - . ” , ’ . , . . . . 1 S ee W . B l asc hk e In J a hr es b d deutsch M ath Ver ei n i g . . . . . V ol . 2 4, 1 9 1 5, p . 1 95 . ANALYSIS 37 1 H A Schwarz by the aid of results reached by K Weierstrass in the calculus of v ariations Another proof based on geo m etrical theorems was giv en i n 1 90 1 by Hermann M inkow ski The subj ect of m inimal surfaces which had received theattention of J Lagrange A M Legendre K F Gauss and G M onge in later ti me co mmanded the special attention of H A Schwarz The blind physicist of the University of Gand Joseph P l ateau ( 1 8 0 1 in 1 8 7 3 described a way of presenting these surfaces to the eye by means of soap bubbles m ade of glycerine water Soap bubbles tend to be co me as thick as possible at eve ry point of their surface hence to make their surfaces as sm all as possible M ore recent papers on m inim al surfaces are by H a r ri s H ancock of the University of Cincinnati Ernst P ascal of the University of P avia expressed him self In 1 8 97 1 “ on the calculus of variations as fOl l ow s : It m ay be said that this de v e l opm en t [ the finding of the di ff erential e u a t i o S which the u n known q functions in a problem must satisfy] closes with J Lagrange for the later an alysts turned their attention chiefly to the other m ore dif fi c u l t proble m s of this calculus The proble m is finally disposed of if one considers the S i mplicity of the form ulas which arise ; wholly dif f e ren t is this m atter if one considers the subj ect fro m the standpoint of rigor of deriv ation of the formulas and the ex tension of the dom ain of the problem s to which these form ulas are applicable This last is what has been do ne for some years I t has been found necessary to prov e c ertain theorem s which underlie those formulas and which the first workers looked upon as axioms which they are not This n ew fiel d was first entered by I Todhunter M Ostrogradski C G J Jacobi J B ertrand P du B ois Reymond G Erd mann R F A C l eb sc h but the I ncisive researches which m ark a turn i ng point in the history O f the subj ect are due to K Weierstrass As an illustration of Weierstrass s m ethod of c ommu n i c a ti ing m any of his m athem atical 2 “ results to others we quote the following fro m O Bolz a : U n for tu n a t el y they [ results on the calculus of variations ] were given by Weier strass only in his lectures [ since and thus became know n only very slowly to the general m athem atical public Weierstrass s results and m ethods may at present be considered as generally known partly through dissertations and other publications of his pupils partly through A K n eser s L ehrbu ch der Vari ati on s r echn u n g (B raun schweig partly through sets of notes of which a great number are in circulation and copies of which are ac cessible to every one in the library of the M athematische Verein at B erlin and i n the M athe matische Lesez imm er at G ottingen Under these circu mstances I have not hesitated to mak e use of Wei er strass s lectures j ust as if they had been published i n print Weier strass applied modern require ments of rigor to the calculus of varia l Di V i ti A S h pp L i pz ig h 899 p 5 E P g ub e s C hi g O B l z a L ct res on the C a l cul 9 4 pp ix xi f V i ti . . . , . , . , . . , . . , . . . , . . , . , . . . , ’ , . , , . . ” . , . . , , . , . . , . , . . , . . . - , . . ’ , . ’ . , , ’ . , , . ” ’ . 1 . 2 . asc a o , e , e u ar a on s r ec n un , us o r . ar a v . on s , . c e , ca o , 1 e 0 1 , , . . , , . O F M ATHE M ATIC S HI STORY A 372 tions in the study of the first and second v ariation Not only did he giv e rigorous proofs for the first three necessary conditions and for the sufficiency of these con d itions for the s o called weak extremum but he also extended the theory of the first and second variation to th e case where the cu rves under consideration are given in para m eter representation He discov ered the fourth necessary con dition and a s uffi ciency proof for a so called strong extremu m which gave for the first tim e a co mplete solution by m eans of a new m ethod based 0 11 1 the so called Weierstras s s construction Under the stimu lus of Weierstrass new dev elop ments were m ade by A Kneser then of D orpat whose theory is based on the extension of certain theore ms on geodesics to extrem als in general and b y D avid Hilbert of Gif t tingen who gave an a pri or i existence proof for an extre m um of a — definite integral a d iscovery of far reaching i mportance not only for the Calculus of Variations but also for the theory of differential equations and the theory of functions (O B olz a) In 190 9 Bol z a published an enlarged German edition of his calculus of variations including the results of Gustav v Escherich of Vienna the Hilbert m ethod of proving Lagrange s rule of m ultipliers (m ultiplikator regel ) and the J W Lindeberg of Helsingfors treatm ent of the isoperim etric proble m About the sam e tim e appeared J Hadamard s C al cu l des va r i a ti on s r ecu el l i es par M J a cqu es H adama rd Fr echet P aris 1 9 1 0 was born at Versailles is editor of the A n n al es sci en tifi qu es ( 1 86 5 de l ecol e n or mal e su pér i eu r e In 1 9 1 2 he was appointed professor of mathe matical analysis at the Ecol e P olytechnique of P aris as successor to Cam ille Jordan In the above m entioned book he regards the cal “ c u l u s of variations as a part of a new and broader functional calculus along the lines followed also by V Volterra in his functions of lines This functional calculus was initiated by M aurice Fr echet of the Uni versity of P oitiers in France The authors include also researches by W F Osgood Other prominent researches on the calculus of varia tions are due to J G D arb oux E G ou rsa t E Zerm elo H A Schwarz H Hahn and to the Am ericans H Hancock G A Bliss E R Hedrick A L U nderhill M ax M ason Bliss and M ason systematically ex tended the Weierstrassian theory of the calculus of variations to problems in S pace In 1 8 58 D avi d B i er ens de H aan ( 1 8 2 2—1 8 95) of Leiden published his A rev ision an d the consid eration of the Ta bl es d I n tegral es D efi n i es underlying theory appeared in 1 8 6 2 It contained 8 339 form u las A critical examination of the latter m ade by E W Sheldon in 1 91 2 “ showed that it was re markably free fro m error when one i mposes proper li mitations upon constants and functions not stated by Haan The lectures on definite integrals delivered by P G L Dirichlet in 1 8 58 were elaborated into a standard work in 1 8 7 1 by Gustav Ferdi nand M eyer of M u nich . ” “ - , ” . - , ” ’ - , . , , . , , , “ , - , , . . , . , ’ - , . . ’ . . . , . , , ’ ’ . . , . . . . . . . . . . , . , , . . , . , . , . . . . , , . , . . ’ ’ ’ . . . . . , , . , . , . . , . 1 Thi s su mmary i s t ak e n fro m O B olz a, . p o . ci t . , P r efac e . A 3 74 O F M ATHE M ATIC S HI STORY Abel His letter to his friend B M H ol mb oe ( 1 8 2 6 ) contains severe criticisms It is very in ter es t ing reading even to m odern students In his de monstration of the binomial t heorem he established the theore m that if two series and their product series are all convergent then the product series will converge towards the product of the sum s of the two given series Thi s remarkable resul t would dispose of the whole problem of m ultiplication of series if we had a universal practical criterion of convergency for se mi convergent series Since we do not possess such a criterion theorems have been recently e s t abli shed by A P r in g sh ei m of M unich and A V O S S now of M un ich which remove in certain cases the necessity of applying tests of con vergency to the product series by the application of tests to easier related expressions A P ri n g shei m reaches the following interesting conclusions : The product of two conditiona l ly convergent series can never converge absolutely but a conditionally convergent series or even a divergent series mu ltiplied by an absolutely convergent series may yield an absolutely convergent product The researches of N H Abel and A L Cauchy caused a considerable stir We are told that after a scientific m eeting in which Cauchy had presented hi s first researches on series P S Laplace hastened hom e and re mained there in seclusion un til he had exam ined the series in hi s M ecan i qu e C el es te Luckily every one was found to be convergen t ! We m ust not conclude however that the new ideas at once displaced the old On the contrary the new views were generally accepted only after a long struggle A S late as 1 844 A D e “ M organ began a paper on divergent series i n t hi s style : I believe it w ill be generally admitted that the headi ng of this paper describes the only subj ect yet remaining of an elem entary character on whi ch a serious schi sm exists a mong m athematicians as to the absolute correctness or incorrectness of results First in ti me in the evolution of m ore delicate criteria of convergenc e and div ergence co m e the researches of Josef Ludwig Raabe ( 1 80 1 of Zurich in Cr el l e Vol IX ; then follow those of A D e M organ 1 8 59) as given in his calculus A D e M organ established the logarithm ic criteria whi ch were di scovered in part independently by J B ertrand The form s of these criteria as given by J B ertrand and by Ossian B onnet are m ore convenien t than D e M organ s It appears from N H Abel s posthum ous papers that he had anticipated the above nam ed w riters in establishing logarithmi c criteria It was the O pin ion of B onnet that the logarithmic criteria never fail ; but P D u Bois— Reymond and A P rin g shei m have each discovered series dem on s t r ab l y convergent in whi ch these criteria fail to deter mi ne the con vergence The criteria thus far alluded to have been called by P ring s h ei m s peci al criteria because they all depend upon a co mparison of " n t h the term of the series with special functions a n n (log etc A mong the first to suggest gen er a l criteria and to consider the subject . . . . . , , . - . , . . . . , , , , . . . . . . . , . ’ . , , , . , ” . . “ ’ ” , , . , . . , . . . . . , ’ , . ’ . . . . . . , , , . AN ALYSIS 375 fro m a still wider poin t of view cul mi nating in a reg ul ar mathematical theory was E E Kummer He established a theorem yiel di ng a test consisting of two parts the first part of whi ch was afterwards found to be superfluous The study of general criteria was con tinued by — of P isa P D u B ois Reymond G Kohn of Ulisse D ini ( 1 84 5 1 91 8) Vienna and A P r in g sheim D u B ois Reymond di v ides criteria into two classes : criteria of the fir st ki nd and criteria of the s econd ki nd ac th term and cordi ng as the general n th term or the ratio of the (n + 1 ) the n th term is m ade the basis of research E E Kummer s is a criterion of the second kind A criterion of the first ki nd analogous to this was invent ed by A P r in g sheim From the general criteria established by D u B ois Reym ond and P r in g sheim respectivel y all the S pecial criteria can be derived The theo ry of P rin g sh eim is very complete and o ff ers in addi tion to the criteria of the fir st ki nd and second kind entirely new criteria of a thi r d ki nd and also generaliz ed cri teria of the second kind w hi ch apply however only to series with never increasing term s Those of the thi rd ki nd rest m ain ly on the consideration of the lim it of the diff erence either of consecutive terms or of their reciprocals In the generali z ed criteria of the second ki nd he does not consider the ratio of two consecutive ter ms but the ratio of any two terms however far apart and deduces among others two criteria previously given by Gustav Kohn and W Ermak off re spec , . , . . , . - . , . , - . . , , , ’ . , . . . , . , . - , . , , , , , , , . . , , , , . t iv el y . It is a strange vicissitude that divergent series which early in the nineteenth century were supposed to have been banished once for all from rigorous m athem atics S hould at its close be invited to return In 1 88 6 T J Stieltjes and H P oincar é S howed the im portance to analysis of the asym ptotic series at that tim e employed in astronom y alone In other fields of research G H Hal phen E N Laguerre and T J S ti el tj es have encountered particular examples in which a whole series being divergent the corresponding continued fraction was conv ergent In 1 8 94 H P ad e now of B ordeaux established the possi b ili ty of defining in certain cases a function by an entire divergent series This subj ect was taken up also by J Hadam ard in 1 892 C E Fabry in 1 896 and M Servant in 1 8 99 Researches on div ergent s eries have been carried on also by H P o i ncar é E B orel T J S t i el tj es E Ces aro W B Ford of M ichigan and R D Carm ichael of Illi — e e nois Thomas J ean S ti l tj s ( 1 8 56 1 8 94)was born in Zwolle in Holl a nd cam e in 1 88 2 under the influence of Ch He rm ite beca m e a French citiz en and later received a professorship at the University of Toulouse Stieltj es was interested not only in divergent and con di t i on all y convergent series but also in G F B Rie m ann s C function and the theory of num bers 1 Difficult questions arose in the study of Fourier s series A L , . , . . . , . . . . . , , . . , , . , . , , . . . . . . . . . , , . , . . , . , . . - . , . , , . ’ , . . . . ’ . . A rn o l d S a ch se , Vers u ch ei n er Ges chi chte der Dar s tel l un g wi ll k i trl i cher Fn u k ti on en ei ner var i a bl en d urch tr i g on ometr i sche Rei hen , G ot t i n g en , 1 8 79 1 ‘ . . A 376 HI STORY - or M ATHE M ATIC S Cauchy was the first who felt the necessity of inquiring into its con vergence B ut his m ode of proceeding was found by P G L D irichl et to be unsatisfactory Dirichlet m ade the first thorough researches on this subj ect (Gr el l e Vol IV) They culm inate in the result that whenever the function does not becom e infinite does not hav e an infi nite nu mber of discontinuities and does not possess an infinite nu mber of m axi ma and m inim a the n F ou ri er s series converges toward the value of that function at all places except points of discontinuity an d there it converges toward the m ean of the two boundary values L S chl afli of Bern and P D u B oiS Rey mond expressed d oubts as to the correctness of the m ean value which were however not well founded D i ri chl e t s conditions are sufli c i en t but not necessary Ru dolf L i ps chi tz ( 1 8 3 2 of B onn proved that F ou r i er s series still represents the functio n when the nu mber of discontinuities is infi n ite a n d established a condition on which it represents a function ha v ing an infinite nu mber of m axi ma and m i n ima D i ri chl e t s belief that all continuous functions c an be represented by Fourier s series at all po i nts was S hared by G F B R i emann and H Hankel but was prove d to be false by D u Bois Reymond and H A Schwarz A Hurwitz S howed how to express the product of t w o Ordi n ary Fourier series i n the form of another Fourier series W W K ii s t ermann solved the analogous proble m for double Fourier series i n which a relation i n v ol v ing Fourier constants figures vitally For functions of a single var iable an analogous relation is due to M A P arseval and was proved by h im under certain restrictions on the rfat u re of convergence of the Fourier series involved In 1 8 93 de la Vall ée P oussin gave a proof requiri n g m erely that t h e functio n a n d its square be integrable A Hurwitz in 1 90 3 gave further develop m ents M ore recently the subj ect has com man d ed general interest through the r e ? searches of Frigyes R i esz and Ernst Fischer (R ie sz Fischer theore m) R i emann inquired what properties a function m ust have so that there may be a trigonom etric series which whene v er it is convergent converges toward the value of the fu n ction He found necessary and s u ffi cient con ditions for this They do not decide however whether such a series actually represents the fu n ction or not Rie m ann rejecte d Cauchy s definition of a definite integral on account of its arbitrar i ness gave a n ew definition a n d then inquired when a function has an integral His researches brought to light the fact that continuous functions need not always have a d iff erential co effi cient B ut this property which was shown by K Weierstrass to b e long to large classes of functions was not found necessarily to exclude them from being represented by Fourier s series D oubts on so m e of the conclusions about F ou r i er 1s ser i es were thrown by the observation m ade by Weierstrass that the integral of a n infinite series can be shown to be equal to the s u m of the integrals of the separate term s . . . . . . , . , , ’ , , , . - . . , , ’ , ‘ . , . ’ , , ’ . ’ . . . . , - . . . . . . . . . . . . . . - , , , . . , , . ’ , , . . . , , ’ . , , 1 S u mm a r y t ak e n fro m B u ll A m M ath S oc . . . . , V ol . 2 2 , 1 91 5, p 6 . . A HI STORY OF M ATHE M ATIC S 3 78 1 through the use of illustrations with urns that were exactl y alike and contained black and white balls in different n umbers and different ratios the observed event being the drawin g of a white ball fro m any one of the urns For the sam e purpose Johannes von Kr ies in his P ri nzi pi en der Wahrs chei nl i chk ei tsr echnu ng Freiburg i B 1 886 used as an illustration six equal t u b es of which one had the S ign on one S ide another had it on two S ides a third on three S ides and finally the six th on all six sides All other sides were marked w ith a 0 Nevertheless obj ections to certain applications by B ayes Theore m hav e been raised by the D anish actuary J B in g in the Tidsskrif t f or M atemati k 1 8 79 by Joseph B ertrand in his C al cu l des probabi li tes P aris 1 8 8 9 by Thorwald Nicolai Thiele ( 1 8 3 8— 1 91 0) of the observa tory at Cope nhagen in a work published at Copen hagen in 1 88 9 ( an English edition of which appeared under the title Theory of Observa ti on s London 1 90 3) by George Chrystal ( 1 8 5 1 —1 9 1 1 ) of the Univer ? A S recently as 1 90 8 the Danish and others s i ty of E d inburgh philosophic writer Kro m an has com e out in defence of B ayes Thus it appears that as yet no unanim ity of j udgm ent has been reached in this m atter In determ ining the probability of alternative c auses deduced from observed events there is often need of evidence other than that which is afforded by the observed ev ent By in v erse prob ability som e logicians ha v e explained induction For example if a m an who has never heard of the tides were to go to the shore of the Atlantic Ocean and witness on m successiv e days the rise of the sea t hen says A dol phe Qu etel et of the observatory at B russels he would i ti es , , . , , . . , , , , , . . ’ , . ’ , , , , , , , , . , , ’ . . . , , , , , , be entitled to conclude that there was a p robability equal to m+ 1 m+ 2 that the sea would rise next day P utting m = o it is seen that this view rests upon the unwarrantable assu mption that the probability of a tota lly unknow n ev ent is 3 or that of all theories proposed for investigation one half are true Willia m Stanley Jevons ( 1 83 5—1 88 2 ) in his P ri n ci pl es of S ci en ce founds induction upo n the theory of inverse probability and F Y Edgeworth also accepts it in his M athemati cal “ D aniel B ernoulli s moral expectation which was elab P s ychi cs orated also by Laplace has received little attention from more recent French writers B ertrand e mphasiz es its im practicabil ity ; P oincar é 3 in hi s C al cu l des probabi l i tes P aris 1 8 96 disposes of it in a few words The only noteworthy recent addi tion to probability is the subject of local probability developed by several Engli sh and a few Amer ican and French m athem aticians G L L B uff on s needl e problem is the earliest i mportant problem on local probability ; it received the . , , - . . , ” . ’ . , , . , ’ ” , , , . , ’ . . . . Encycl ope di a M otr e p I I , 1 84 5 ’ 2 We ar e u s i n g Em an u el C z u b er s E ntwi ckel u n g der Wahrschei n l i chkei tstheori e in t he J a hr es b d deu ts ch M a thema ti k er Ver ei n i g u n g 1 8 99 , p p 9 3 — 1 0 5 ; a l so A rne F i she r , The M a thema ti ca l Theor y of P r oba bi l i ti es , N e w Y o rk , 1 9 1 5 , pp 5 4 5 6 3 E C z u b er , op c i t , p 1 2 1 1 . . — - . . . , . . . . . . . . ANAL YSIS 3 79 consideration of P S Laplace of E mile B arbier in the years 1 8 6 0 — of the m il i tary school and 1 8 8 2 of M organ W Crofton ( 1 8 2 6 1 9 1 5) at Woolwi ch who in 1 86 8 contributed a paper to the London P hi l “ P rob os ophi cal Tr a ns acti on s Vol 1 5 8 and in 1 8 8 5 wrote the article ability i n the En cycl opedi a B r i ttan n i ca ninth edition The name “ local probability is due to Crofton Through considerations of local probability he was led to the evaluation of certain defi nite in . . , ‘ . , , ” . , ” , , . . t eg ral s . Noteworthy is J J Sylvester s four point problem : To find the probability that four points taken at random within a given boun dary shall form a re entrant quadrilateral Local probability was studied in England also by A R Clarke H M c C oll S Watson J Wol s t en hol me W S Woolhouse ; in France also by C Jordan and E Le moine ; in A merica by E B Seitz Ric h collections of problem s on local prob ability have been published by E manuel C zu b er of Vienna in his Geometr i sche Wa hr s chei n l i chk ei ten u n d M i ttel w erte Leip z ig 1 8 84 and by G B M Zerr in the E du cati on al Ti mes Vol 55 1 8 91 pp 1 3 7 The fundamen t al concepts of local probability have recei ved the 1 92 ? — special attention of Ernesto Ces aro ( 1 8 59 1 90 6 ) of Naples Criticism s occasionall y passed upon the prin ciples of probability and lack of confidence in theoretical results have induced several scientists to take up the e xpe r imental side which had been e mphasi z ed by G L L B u ffon Trials of this sort were m ade by A D e M organ W S J evons L A J Quetelet E C zu b e r R Wolf and S howed a remarkably close agreemen t with theory In B u ffon s needle prob l em the theoretical probability involves This and S i milar e xpres 2 sions have been used for the empirical determination of Attempts to place the theory of probabil i ty on a purely empirical basis were m ade by John S tuart M il l John Venn ( 1 8 34 and G Chrystal M ill s induction m etho d was put on a sounder basis by A A C hu pr off in a brochure D i e S ta ti s ti k al s Wi s s en s chaft Em p i r i c al m etho d s have co mmanded the attention of another Russian v B or tk i evi cz In 1 83 5 and 1 83 6 the P aris Academ y was led by S D P oisson s researches to discuss the topic whether questions of m orality coul d be treated by the theory of probability M H Navier argued on the affi rmative while L P oi n sot and Ch D upin denied the applicability “ as une sorte d ab erra t i on de l espr i t ; they declared the theo ry applicable only to cases where a separation and counting of the cases or events was possible John Stuart M ill opposed it ; Joseph L F B ertrand ( 1 8 2 2 p rofessor at the Coll ege de France in P aris ? and J v Kries are a mong more recent writers on thi s topic ’ . . , - . . . . , . , . , . . . . . . , . . . , . , . , , , . , . _ , . . . . . . . , , . . . . , . , , ’ . , ’ . . . . . , , . . ’ . . , . , . . ’ ’ . . ” . . . . S e e Encycl opédi e des sci en ces ma th I , 2 0 p 23 2 E C zu b e r , op ci t , p p 88— 91 3 C o n s u l t E C z u b e r , op c i t , p 1 4 1 ; J S M i ll , S ys tem Ed , 1 884 , C h ap 1 8 , pp 3 7 9— 3 8 7 ; J v K r i e s , o p c i t , pp 1 . . . . . . . . . . . . . . . . . . . . . . f o L og i c , N e w Y o r k , 8 t h 2 53 —2 59 . A H I STORY O F M ATH E M ATIC S 3 80 Among the various applications of probability the one relating to v erdicts of j uries decisions of courts a n d results of elections is specially interesting This subj ect was studied by M arqui s de Condorcet P S Laplace and S D P oisson To e xhi bit Laplace s m ethod of determ in i ng the worth of candidates by co mbining the votes M W Crofton e mploys the fortuitous division of a straight line Thi s in volves however an a pr i or i distribution Of values covering evenly the whole range fro m 0 to 1 00 E xperience S hows that the normal law of error exhibits a m ore correct distribution On this point Karl ? P earson produced a m ost i mportan t research He took a random sample of n individuals from a population of N me mbers and derived an e xpression for the average d i fference in character between the pth and the (p+ 1 ) th indi v idual when the sa mple is arranged in order of H L M oore of Columbia University mag nitude of the character h as atte mpted to trace P earson s theory in the statistics relating to the e ffi ciency of wages (Econ omi c J ou r n al D ec Early statistical stu dy was carried on under the nam e of political arithmetic by such writers as Captain John Graunt of London ( 1 6 6 2 ) Application of the and J P S ussmil ch a P russian clergyman theo ry of probability to statistics was made by Edmund Halley Jakob B ernoulli A D e M oivre L Euler P S Laplace and S D The establishm en t of offi cial statistical societies and statis P oisson tical off ices was largely due to the influence o f the B elgian astronomer and statistician A d olph e Q u e te l e t ( 1 7 96 —1 8 74) of the observatory “ “ at B russels the foun d er of m odern statistics Q u et el et s average i n who m all processes correspond to the average results man “ obtained for society who could be considered as a type of the beautiful has given rise to m uch critical discussion by Harold “ A de Foville in his homo Westergaard J B ertillon of 1 90 7 Joseph Jacob s in his the M iddle Am erican m e dius 2 and the M ean Engl i shm an Qu e t el e t s visit in England led to the organi z at i on in 1 8 3 3 of the statistical section of the B ritish Association for the Advance m en t of Science and in 1 83 5 of the S tatis tical Society of London Soon after in 1 8 3 9 was formed the A mer ican Stat i st i cal Society Qu e t el e t s best researches on the application of probability to the physical and social sciences are given in a series of letters to the duk e of Saxe Coburg and Gotha L ettr es su r l a theor i e “ He laid e mphasis on the law of des pr oba bi l i tés B russels 1 84 6 large numbers whi ch was advanced also by the Frenchm an S D the Scandi P oisson and d iscussed by the Germ an W Lexis n avi an s H Westergaard and Carl Charlier and the Russian P a n u ti f — h e bi h i i h C c e v 1 8 2 of the University of P etrograd To L w ow c 1 1 8 94 ) ( C h eb i c hev we owe also an interesting proble m :A proper fraction being , . , ’ . . . . , . . , . . , , . . . . . ’ ” , . , ' . . , , . , . , . . , . , . . , ” ’ . , “ . , ” , ” . . ” , “ ’ . , , , . , , ’ . - , , . . , . . . , . 1 “ 2 N o te on S ee F ran 19 13; P 3 74 z A Z Iz ek ’ s — B i ometr i ca , V ol I , pp 3 90 399 S ta ti s ti cal A vera ges , t ra n sl b y W M P e rson s , N ew Y or k , Fra n c i S C al to n ’ s P ro bl e m , . . . . . . A HI STORY OF M ATHE M ATIC S 382 ” general and adequate m athematical m ethods for the analysis of “ biological statist i cs To hi m are due the term s mode standard “ dev iat i on and coe fficient of variation B efore hi m the normal curve of errors had been used exclusi v ely to d escribe the distribution of chance events This curve is symm etrical but natural phenomena som eti m es indicate an asymm etrical di stribution Accordin gly P earson in his C on tr i bu ti on s to the Theory of E vol u ti on 1 8 99 de v el op e d skew frequency curves About 1 8 90 the Georg M endel law of inheritance beca m e generally known and caused some m odification in the application of statistics to heredity Such a readj ustm ent was ? eff ected by the D an ish botanist W Johannsen The first study of the most advantageo u s combinations of data of observation is due to Roger Cotes in the appendix to hi s H armoni a men s u r ar u m 1 7 2 2 where he assi g ns weights to the observations The use of the arithmetic mean was advocated by Thom as Simpson “ in a paper An atte mpt to S how the advantage arising by taking the 2 m ean of a nu mber of obser v ations in practical astrono my also by J Lagrange in 1 7 73 and by D aniel B ernoulli i n 1 778 The first printed statement of the principle of least squares was made in 1 80 6 by A M Legendre without dem onstration K F Gauss had used it still earlier but d id not publish it until 1 80 9 The first deduction of the law of probability of error that appeared in prin t was given in 1 8 0 8 by Robert A dra i n in the A n al ys t a journal published by him self in P hiladelphi a Of the earlier proofs given of this law perhaps the m ost satisfactory is that of P S Laplace K F Gauss gave two proofs The first rests upon the assumption that the arithm etic m ean of the observations is the most probable value Atte mpts to prove this assu mption have been m ade by Laplace J F Encke A D e M organ G V Schiaparelli E J S tone and A Ferrero Valid criticis m s upon so m e of these investigations were 3 passed by J W L Glaisher The foundi ng of the Gaussian proba bil i ty law upon the nature of the ob served errors was atte mpted by F W B essel G H L Hagen P G J F Encke Tait and M W Crofton That the arithm etic mean taken as the m ost probable value is not under all circumstances co mpatible with the Gaussian probabilty law has been S how n by Joseph B ertrand I n his C al cu l des pr obabi l i tés and by others The developm ent of the theory of least squares along practical lines is due m ainly to K F Gauss J F Encke P A Hansen Th Gallo 5 Simon way J B ienayme J B ertrand A Ferrero P P i zzetti ” ” ” . “ “ , . . , . , , , . . . , , . , ” , , . . . . . , . , . . , . , . . . . . . . . , . . . . . . . . . , . . . . . . . . . . . . . , , . . . , . , . . . , . , , . . , . . , . P u b A m S tat A ss n , N S , Vo l X I V , r 9 1 4 , p 4 5 2 M i s cell a n eou s Tr acts , Lo n don , 1 7 5 7 3 L and A s tr S oc M em 3 9 , 1 8 7 2 , p 7 5 ; for f u r t her re fe ren ces , see Cykl opadi e d M ath Wi ss , I D 2 , p 7 7 2 1 C o n s u l t E L D o dd , P ro b a bi l i ty o f t he A ri t h me t i c M ean , e t c , A n n a l s of M athema ti cs , 2 S , V o l 1 4 , 1 9 1 3 , p 1 8 6 5 E C z u b er , op ci t , p 1 79 1 ’ Qu ar t . . . . . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . ANALYSIS 83 ” generali z ed theory of the Newco mb of Washington ad v anced a 1 co mbination of observations so as to obtain the best resul t , when large errors arise more frequently than is allowed by the Gaussi an probability law The sa m e subj ect was treated by R Lehmann Filhes in A str on omi sche N achr i chten , 1 88 7 . . . A criterion for the r ejection of doub tful observations was given by B enjamin P eirce of Harvard It was accepted by the Am erican astrono mers B A Gould ( 1 8 2 4 W Chauvenet ( 1 8 2 0 and J Winlock ( 1 8 2 6 but was criticised by the English as t r o n omer G B Airy The prev ailing feeling has been that there e xists no theoretical basis upon which such criterion ca n be rightly established The application of probability to epidemi olog y was first consider ed by Daniel B ernoulli and has more recently comm anded the atten tion of the English statisticians William Farr ( 1 80 7 John B rownlee Karl P earson and Sir Ronald Ross P earson studied norm al and abnorm al frequency curves Such cur ves have been fitted to epide mics by J B rown lee in 1 90 6 S M Greenwood in 1 9 1 1 and 1 91 3 a n d Sir Ronald Ross in So me interest attaches to the d iscussion of whist from the stand point of the theory of probability as is con tained in William P ole s P hil osophy of Whi s t New York and London 1 88 3 The problem is a genera liz ation of the game of trei z e or recontre treated by P ierre R de M ontmort in 1 7 0 8 2 . . . . . . . . . , . , . . , . . , ’ ” , , ” . , , . . Difier en ti al E qu ati on s Difler en ce Equ ati on s - . ’ Criteria for distingui shing between singular solutions and particular solutions of diff erential equations of the first order were ad v anced by A M Legen d re S D P o i sson S F Lacroix A L Cauchy and G Boole After J Lagrange the c d i scrim inant relation commanded the attention of J ea n M ar i e C on s tan t D u hamel ( 1 7 97—1 8 7 2 ) of P aris C L M H Navier and others B ut the entire theory of S ingular solutions was r e investigated about 1 8 70 along new paths by J G D arb ou x A Cayl ey E C Catalan F C a sora t i and others The geometric side of the subj ect was considered more m inutely and the cases were e xplained in which Lagrange s m ethod does not yield S ingular solutions E v en these researches were not altogether satis factory as they did not furnish necessary and suffi cient conditions for singular solutions which depend on the d iff erential equation alone and not in anyw ay upon the general solution Return ing to m ore purely analytical considerat i ons and building on w ork of Ch Briot and J C Bouquet of 1 8 56 Carl Sch m idt of Giessen in 1 8 84 H B of Fine of P rinceton in 1 890 and M eyer Hamburger ( 1 8 38—1 90 3) . . . , . . . , . , . , - . . . , , . . . . . , - . . , . , . , . . . , ’ . . ' . ‘ . . , , , A m J ou r M a th , V ol 8 , 1 886 , p 3 43 2 Gou l d A s tr J ou r , I I 1 8 5 2 3 N atur e, V o l 9 7 , 1 9 1 6 , p 2 43 1 . . . . . . . . , . . . . . A HI STORY OF M ATHE M ATIC S 3 84 Berlin brought the problem to fi n al solutions Acti v e in this line ? were also John M uller Hill and A R F or syth The first scientific tr eatm ent of partial diff erential equations was gi v en by J Lagrange and P S Laplace These equations were i n v es ti g a t d i n m ore recent ti m e by G M onge P f f F fa C G J J e Jacobi E m ile B our ( 1 83 1 —1 8 66 ) of P aris A Weiler R F A C l eb sch A N K ork i n e of S t P etersburg G B oole A M eyer A L Cauchy J A Serret S ophu s Lie and others In 1 8 73 their r e seaches on partial diff erential equations of the fi rst order were presented i n text book form by P aul M ansion of the University of Gand P ro c eedi n g to the consi d eration of som e detail we re m ark that the keen researches of Jo h ann Fri e dri c h Pf aff ( 1 7 6 5 1 8 2 5) m arked a decided ad v ance He was an intim ate friend of K F Gauss at G ottingen Afterwards he was with the astronom er J E B ode Later he beca m e professor at Hel mst adt then at Halle B y a peculiar m ethod P faff found the general integration of partial d iff erential equations of the first order for any number of variables Starting from the theory of ordina ry diff erential equations of the first order in n variables he gives first their general integration and then consid ers the integra tion of the partial di fferential equations as a particular case of the form er assu ming howe v er as known the general integration of differential equations of any order between two variables His r e “ searches led C G J Jacobi to introduce the n a m e P fafli an prob l em From the connection observ ed by W R Hamilton between a syste m of or dinary d ifferential equations ( in analytical m echanics) and a partial differential equation C G J Jacobi drew the conclu sion that of the series of syste m s whose successive integration P faff s m ethod de m an d ed all but the first syste m were entirely superfluous R F A C l eb s ch cons idered P fa ff s proble m fro m a n ew point of vie w and reduced it to syste m s of si multaneous linear partial di ff erential equations which can be estab l ished in dependently of each other with out any integration Jacobi m aterially ad v ance d the theory of dif The problem to determ ine u n f er e n t i al equations of the first order known funct i ons i n such a way that an i n tegral containing these func tions and their d iff erential coefficients in a prescribed m anner S hall reach a m axim u m or m ini mu m value dem an ds in the first place the van i shing of the first variation of the integral This conditio n l eads to differential equations the integration of which determ ines th e functions To ascertain whether the value is a m axim u m or a mini m u m the second variation m ust be e xa mi ne d This leads to new and difli c u l t d i fferential equations the integration of which for the simpler cases was ingeniously deduced by C G J Jacobi from the integra tion of the d ifferent ial equations of the first variation Jacobi s soluti on was perfected by L O Hesse while R F A C l eb sch extended . . . . . . . . , , . . . , . . , , . . , . . . , , . , . . . . , . . , . , . , , - . , , - ' . . . . . . . . , , . , , , , , , . ” . . . . . , , . . , . . ’ , . , ’ . . , . , . ' . , , , , , . , . . , , , . , . . ’ . . 1 We A bit . 2 . h av e u sed S R o t h en b e r g , Gesek d M a th Wi ss en s ch . . . . . , . G eschi ch t e der ( M C an tor , H ef t . ) . . s i n g u l are n XX , z L os u n g e n 3 L e ip i g , . 1 90 8 . in A HI STORY OF M ATHE M ATIC S 38 6 prim itiv e is obtained by the use of processes that so met imes are frag m entary in theory usual ly are tentative i n practice an d nearly always are indirect in the sense that they are compounded of a nu mber of formal operations ha v ing no organic relation with the primitive In such circu mstances is the prim itive co mpletely compr eh en sive of all the integrals belonging to the equation ? A M Amp ere i n 1 8 1 5 propounded a broad definition of a general integral — one i n which the only relations which subsist a mong the variables and the derivatives of the dependent variable and which are free from the arbitrary elem ents in the integral are constituted by the diff erential equation itsel f and by equations deduced from it by di fferentiation This definition is inco mplete on various grounds E G ou r sa t gave i n 1 8 98 a S im ple instance to sho w that an integral satisfying all of A m p ere s requirem ents was not general A second definition of a general integral was given in 1 88 9 by J G B arboux based on A L Cauchy s existence theore m : An integral is general whe n the arbitrary ele m ents which it contains can be S peciali z ed in such a way as to provide the integral established in that theorem This definition according to A R F or syth calls for a m ore caref u l discussio n of obvious and latent singularities There are three principal m ethods of procee ding to the c on s t ru c tion of an integral of partial differe n tial equations of the second order which lead to success i n special cases One m ethod given by P S Laplace in 1 77 7 applies to linear equations with two in dependent variables I t can be used for equations of order higher than the second I t has been developed by J G D a rb ou x and V G I msh e ne t ski 1 8 7 2 A second method or iginated by A M Amp ere while general in S pirit and in form depends upon in dividual skill unassisted by critical tests Later researches along th i s line are due to E B orel and E T Whittaker A third method is due to J G ( 1 8 95) D a rb ou x and includes according to A R Forsyth s classificatio n the earlier work of M onge and G B oole A S first given by J G Dar boux in 1 8 70 it applied only to the case of t w o in dependent variables but it has been extended to equations of m ore t ha n t w o independent variables and orders higher than the second ; it is not universally “ “ e ffective Such then says Forsyth are the principal m ethods hitherto devised for the formal integration of partial equations of the second order They have been discussed by m any m athe maticians and they have been subj ected to frequent mo d i fi cations in details : but th e substance of the processes remains unaltered Instances are known in ordinary linear equations when the primitive s can be expressed by definite integrals or by m eans of asym ptotic e xpansions the theory of which owes m uch to H P oincar é Such instances within the region of partial equations are due to E Borel G F B Riem ann had re m arked i n 1 8 57 that functions expressed by K F Gauss hypergeometric series F ( a 8 y x)which satisfy , , . ” . . , , . . . ’ . ’ . , . . . - . . , , . . , . . . . . . , . . . , . . , . , . . . . . . ’ . , . . , . . . , , ” . , , . ” . . , . . . . . ’ . . , , , , , . ANALYSIS 38 7 a homogeneous linear diff erential equation of the second order with rational coeffi cients m ight be utilized in the solution of any lin ear dif ? fere n ti al equation Another mode of solving such equations was due to Cauchy and was e x tended by C A A B riot and J C B ouquet) and consisted in the development into power series The fertility of the conceptions of G F B Riemann and A L Cauchy with regard to diff erential equations is attested by the researches to which they have given rise on the part of L azaru s Fu ch s ( 1 833— 1 90 2 ) of B erlin Fuchs was born in M oschin near P osen and became professor at the Uni versity of B erlin in 1 884 In 1 8 6 5 L Fuchs co mbined the two m ethods in the study of linear differential equations : One method using power series as elaborated by A L Cauchy C A A B riot and J C Bou quet ; the other m ethod using the hypergeometric series as had been done b y_G F B Riemann B y this union Fuchs initiated a new ? theory of linear di ff erential equations Cauchy s develop m ent into power series together with the calcul des limites aff orded e xistence theore ms which are essentially the same in nature as those relating to diff erential equations in general The S ingular points of the linear diff erential equation received attention also from G F rob en i u s in B ocher in 1 90 1 A second approach to 1 8 74 G P eano in 1 8 8 9 M existence theore m s was by successive appro xi m ation first used in 1 86 4 b y J Caqu é then by L Fuchs in 1 8 7 0 and later by H P oin care and G P eano A third line by interpolation is originally due to A L Cauchy and received special attention from V Volterra in 1 8 8 7 The general theory of linear diff erential equations received the atten tion of L Fuchs and of a large number of workers including C Jordan V Volterra and L S chl e sin g er Singular places where the solutions are not indeterm inate were investigated by J Tanne ry L Schlesinger G J Wallenberg and m any others Ludwig Wilhel m Thome ( 1 84 1 of the University of Greifswald discovered in 1 8 7 7 what he 1 91 0 ) called normal integrals Divergent series which formally satisfy dif fer en t i al equations first noticed by C A A Briot and J C B ouquet in 1 8 56 were first seriously considered by H P oincaré in 1 88 5 who pointed out that such series may represent certain solutions a symp Asymptotic representations have been examined by A t o t i c al l y and A Hamburger Kneser E P icard J Horn “ A special type of linear diff erential equation the F u ch si an type with coe ffi cients that are single valued (eindeutig)and the solutions of which hav e no points of in determinateness was investi gated by Fuchs and i t was found that the coe ffi cients of such an equa tion are rational functions of x S tudies based on analogies of linear differential equations with algebraic equati ons first undertaken by , . . . . . . . . . . . . , , . . . . , . . . . , . . , . . . ’ - , . . , . , . . , - . . , . . , . , , . . . . . , . , , ' . , . . . . . , . , . , , . . , . . . . . , . . . . . , - , , , , . , We l L S ch e si n g e r , En twi ck el u n g d Theor i e d l i n ear en Di ffer en ti al g l e i chu n g en s ei t 1 8 6 5 , L e i p i g a n d B e r l i n , 1 90 9 2 We a re u si n g h e r e a re po r t b y L S chl esi n g e r i n J ahr es b d d M ath Ver ei n i g u n g , — l 1 o 1 1 0 8 , 9 9, pp V 33 2 6 0 1 are u si n g . z . . . . . . . . . . . A HI STORY OF M ATHE M ATIC S 388 N H Abel J Liouville and C G J Jacobi were pursued later by P Appell by E P icard w ho worked under the influence of S Lie s theory of transform ation groups and by an army of workers in France England Germ any and the United S tates The consideration of differential invariants enters here Lamé s differential equation considered by hi m in 1 8 5 7 was taken up by Ch Herm ite in 1 8 77 and soon after in stil l m ore generali z ed form by L Fuchs F Brioschi E P icard G M M ittag L effi er and F Klein The anal ogies of linear di ff eren tial equations wi th algebraic f unc tions problem s of inversion and uniformi z ation as well as questions in v olving group theory received the attention of the analysts of the second half of the century The theory of invariants associated with linear di ff erential equations as developed by Halphen and by A R Forsyth is closely connected with the theory of functions and of groups Endeavors have thus been made to deter mine the nature of the fun ction defined by a di f f er en t i al equation fro m the d iff erential equation itself and not from any analytical expression of the fun ction O btained first by sol v in g Instead of studying the properties of the t h e di ff erential equation integrals of a di fferential equation for all the values of the variable investigators at first contented the m selves with the study of the prop The nature of the i ntegrals e r t i e s in the v i cinity of a gi v en point at S ingular points and at ordinary points is entirely di ff erent Char l es A u gu ste A l ber t B r i ot ( 1 8 1 7— 1 88 2 ) and J ean Cl aude B ou qu et ( 1 8 1 9—1 88 5) both of P aris stu di ed the case when near a singular poin t the di f . . . , . . . . , . . ’ , , , . , ’ . , . , ‘ . . , , - , . . . . . , , . . . . , , . , . . ‘ , fe r en t i al , , Q equations take the form (x —x o) dx L Fuchs gave . the develop ment in series of the integrals for the particular case of linear equati ons H P oincar é di d the sam e for the case when the equations are not linear as also for partial d ifferential equati ons of the first order The develop m ents for or di na ry points were giv en M adam e by A L Cauchy and S ophi e K oval evs k i ( 1 8 50 K ov al ev ski was born at M oscow was a pupil of K Weierstrass and beca me professor of Analysis at Stockhol m — H e nri P o in c ar é ( 1 8 54 1 91 2 ) w a s born at Nancy and co mm enced hi s stu dies at the Lyc ée there While taking high rank as a student he di d not di splay exeep ti on al precocity He atten d ed the Ecole P olytec hnique and the Ecole Nationale Sup érieure des M ines in P aris receiv ing his doctorate from the University of P aris in 1 8 7 9 He b e cam e instructor in m athem atical analysis at the Univ ersity of Caen In 1 8 8 1 he occupied the chair of physical and experim ental m echanics at the Sorbonne later the chair of mathem atical physics and after the death of F Tisseran d the chair of m athem atical astronomy and celestial mechanics Al though he di d not reach old age he published numerous books and more than 1 500 m em oirs P robably neither . . , . . . . , . . , . , . . , , . , . , . HI STORY OF M ATHE M ATIC S A 0 39 ' Every day I seated myself at my work table and S pent an hour or two there trying a great m any co mbinations but I arrived at no result One night when contrary to my custom I had taken black coff ee and I could not S leep ideas surged up in crowds I felt them as they struck against one another until two of the m stuck together so to S peak to form a stable combination B y morning I h ad established the existence of a class of fuchsian functions those whi ch are derive d from the hyp ergeo metric series I had m erely to put the res ults in 1 S hape which only took a few hours P oincaré enriched the theory of integrals The attempt to express i ntegrals by develop m ents that are always convergent and not li mi ted to particular points in a plane necessitates the introduction of new transcendents for the old functions per mit the integration of only a s mall nu mber of differential equations H P oincaré t ried this plan with linear equations which were then the best kn own having been studied in the vicinity of gi v en points by L Fuchs L W Tho me G Frobenius H A Schwar z F Klein and G H Halphen C on fi n ing hi mself to those with rational algebraical c o efli ci en t s H P oincaré was able to integrate the m by the use of functions na m ed by h im Fu ch “ ? s i an s He divided these equations into families If the integral of such an equation be subj ected to a certain transformation the resul t will be the integral of an equation belonging to the sa me fam ily The new transcendents have a great analogy to elliptic functions ; while the region of the latter may be divided into parallelogra ms each representing a grou p the form er m ay be divi d ed into c urvi linear polygons so that the knowledge of the function inside of one polygo n carries with it the knowledge of i t inside the others Thus H P oin car e arrives at what he calls Fu chs i a n gr ou ps He found m oreover that F u chsi an functions can be expressed as the ratio of two trans in the sa m e way that elliptic functi ons can c e n den t s ( theta fuchsians ) be If instead of linear substitutions with real coe ffi c i ents as e m ployed in the above groups i m aginary coeffi cients be used then d is continuous groups are ob tained which he called K l ei n i a ns The ex tension to non linear equations of the m ethod thus applied to linear equations was begun by L Fuchs and H P oincar é M uch interest attaches to the deter mination of those linear d i ffer e n t ial equations which c a n be integrated by si mpler functions such as algebraic ell iptic or Abelian This has been studied by C Jordan P Appell of P aris and H P o i n car e P a u l Appe l l ( 1 8 5 5 was born in Strassburg After the an n e xa t i o n of Alsace to Ger m any in 1 8 7 1 he e mi grate d to Nancy to escape Germ an citiz enship Later he stu died in P aris and in 1 88 6 n o r an t . , , , . , , . , . , ” . , . , . , . . , , . . , . . , . , . , . , . . . . , ” . , . , , . , . . . , , - . , , , , , . - . . . , , , . , . . . , . . , . H P o in c aré , The Fou n dati ons of S ci en ce , t ran sl by G B H al s t ed , The S c i e n ce P ress N ew Yo rk a n d G a rr i so n , N Y , 1 9 1 3 , p 3 8 7 2 H en r i P o i n c a ré, N oti ce s u r l es Tr a va u x S ci en tifi q u es de H en r i P oi ncare, P a ri s , 1 . . . , 1 886 , p 9 . . . . . . . ANALYSIS 39 1 becam e professor of mechanics there His researches are in analysis function theory infinitesimal geo metry and rational m echanics Whe ther an ordinary diff ere n tial equation has one or more solutions which satisfy certain terminal or boundary conditio n s and if so what the character of these solutions is has received rene w ed attention th e last quarter century by the consideration of finer and m ore re m ote ? questions E xistence theore ms oscillation properties asymptotic expressions develop m ent theore ms have been studied by D avid Hil bert of G ottingen M axim e B ocher of Harvard M ax M ason of the University of Wisconsin M auro P icone of Turin R M E M ises of Strassburg H Weyl of G ottingen and especially by George D B irk hoff of Harvard Integral equations have bee n used to so me extent “ in boundary proble ms of one dim e n sion ; this m ethod would see m however to be chiefly valuable in the cases of two or m ore dim ensions where many of the S implest questions are still to be treated A standard text book on Differ en ti al Equ ati on s inclu d ing original matter on integrating factors S ingular solutions and especially on symbolical m ethods was prepared i n 1 8 59 by G B oole A Tr eati se on L i n ear Difi er en ti al Equ ati on s ( 1 889) was brought out by Thomas Craig of the Johns Hopkins University He chose the algebraic m ethod of presentatio n followed by Ch Herm ite and H P oincar é instead of the geom etric method preferred by F Klein and H A Schwarz A notable work the Tr ai te d A n al yse 1 8 9 1 —1 896 was published by Emile P icard of P aris the interest of which was made to centre in the subj ect of di fferential equations A second editio n has appeared Simple d iff erence equations or finite diff erences were studied by eighteenth century mathem aticians When in 1 8 8 2 H P oincar é de v el oped the novel notion of asy m ptotic representation he applied it to linear diff erence equations In recent years a n ew type of proble m has arise n in connection with the m I t looks n ow as if the continuity of nature which has been for so long assu med to exist were a fictio n “ and as if discontinuities represented the realities I t see ms al most certain that electricity is done up i n pellets to which we have give n the name of electrons That heat co mes i n quanta also see ms prob 2 able M uch of theory based on the assu mption of continuity may be found to be m ere approximation Hom ogeneous linear diff erence equations not intimately bound up with continuity were take n up i n depen dently by invest i gators widely apart In 1 90 9 Niels Eri k N or lund of the University of Lund I n S w eden Henri G al b ru n of l Ecole Norm ale I n P aris and i n 1 9 1 1 R D Carm ichael of the University of Illinois entered this field of research Carm ichael used a m ethod of successive approxi m atio n and an extension of a contour integral due to . , . , , , , , , , , , , , . , . . . . , . , ” , . - , , , . , . . . . . , ’ . . , . , , , . . . . , . . , , . , ” . . . , , . ’ , , . . , . See hi st or i cal s u mmary b y M axi me B ech e r i n P r oceed gr es s, C ambr i dge, 1 9 1 2 , V o l I , C a mb r idg e , 1 9 1 3 , p 1 6 3 2 R D C ar mi c h ae l I n S ci ence , N S V ol 4 5 , 1 9 1 7 p 4 7 2 1 a . . . . . . . . . . . f o the 5 th i n ter n . Cou HI STORY A 39 2 O F M ATHE M ATIC S C Guichard G D B irkho ff of Harvard m ade important c on t rib u tions showing the existence of certain intermediate solutions and of the principal solutions The asymptotic form of these so l utions is de t erm i n ed by hi m throughout the co mplex plane The extension to non homogeneous equations of results reached for ho mogeneous ones ? has been made by K P Williams of th e U niversity of Indiana . . . . - . . - . . I n tegral Equ ati on s , I n teg r o difi er en ti al Equ a ti on s , Gen er al A n al ysi s , Fu n c ti on al C al cu l u s - The mathem atical perplexities which led to the invention of integral 2 equation s were stated by J Hadamard in 1 9 1 1 as follows : Those problem s ( such as D i ri chl e t s) exercised the sagacity of geom etricians and were the obj ect of a great deal of i mportant and well know n work through the whole of the nineteenth cen tury The very variety of ” ingenious m ethods applied S howed that the question did not cease to preserve its rather m ysterious character Only in the last years of the century were we ab l e to treat it with som e clearness and under stand its true nature Let us therefore inquire by what d evice this new vie w of D i ri c hl e t s problem was ob tqi n ed I ts peculiar and most re markable feature consists in the fact that the partial differential equation is put aside and replaced by a new sort of equation namely the integral equation This new m ethod makes the m atter as clear as it was form erly obscure In many circu mstances i n m odern analysis contrary to the usual point of view the operation of integration proves a m uch simpler one than the operation of derivation An exa mple of thi s is given by integral equations where the unknown function is written under such signs of integration and not of d iff erentiation The typ e of equation which is thus obtained is m uch easier to treat than the partial differential equation The type of integral equations correspon ding to the plane D irichlet problem is “ . ’ - . . . ’ . , , . . , , . . . d>(x) K (W ) dy Mr ) where (b is the unk now n function of x in the interval (A B ) f and K are known functions and A is a known param eter The equations of the elliptic type in m any d im en S Ion al space give sim ilar integral equations containing however m ultiple inte5rals and several in de pendent variables B efore the introduction of e q uations of the abo v e type each step in the stu dy of elliptic par t ial diff e ren t ial equations seemed to bring wi th it new diflficu l ti es [ B ut] an equation such as ( I ) gives al l the required results at once and for all the pos sible types of such problems P reviously in the calculation of , , . , - , . , . , . Tr an s A m M a th S oc , V ol 1 4 , 1 9 1 3 , p 2 0 9 2 J H adama rd , Four L ectu r es on M a l hemati cs del i ver ed 1 9 1 1 , N ew Y o r k , 1 9 1 5 , pp 1 2 1 5 1 . . . . . . — . . . . at Col u mbi a Un i vers i ty i n A HI STORY OF M ATHE M ATIC S 3 94 was born in B oston and graduated 1 91 8 M ax i me B é ch er ( 1 8 6 7— ) at Harvard in 1 888 Af ter three years of study at Gottingen he r e turned to Harvard where he was successively instructor assistant professor and professor of m athem atics He was president of the Am erican M athem atical Society in 1 90 9—1 9 1 0 Among his works are Rei hen en twi ck el u n gen der P oten ti al theor i e 1 8 9 1 enlarged in 1 894 and L egon s su r l es M ethodes de S tu rm contai n ing the author s lectures de liv ered at the Sorbonne in 1 9 1 3—1 9 1 4 1 A Voss in 1 91 3 stresses the value of integral equations thus : In the last ten years the theory of integral equations has attained extraordinary importance because through them problem s in the theory of diff erential equations m ay be solved whi ch previously coul d be disposed of only in S pecial cases We abstain from sketchi ng their theory which m akes use of infini te determinants that belong to linear equations with an infinite num ber of unkn owns of quadratic forms with infinitely many variables and which has succeeded in throwing new l ight upon the great problems of p ure and applied m athe matics especially of m athe m atical physics I mportant advances along the line of a general analysis and its application to a generali z ation of the theory of linear integral equa tions hav e been m ade since 1 90 6 by E H M oore of the University ? of Chica go Fro m the e xisten ce of analogies in different theories he infers the existence of a general theory co mprising the analogous “ theories as special cases He proceeds to a unification resul ting first fro m the recent generaliz ation of the concept of independent v ariable effected by passing fro m the consideration of variables defin ed for all points in a giv en interval to that of variables defined for all points in any giv en set of points lying in the range of the variable secon dl y fro m the consideration of functions of an infin ite as well as a fin ite n umber of variables and thirdly from a still fui ther gen “ e ral i zat i on which leads hi m to fun ctions of a general variable E H M oore s general theo ry includes as special cases the theories of E I Fredh ol m D Hilbert and E Schmi dt G D B irkhoff in 1 9 1 1 3 presented the following birds eye View of recent m ovem ents : Since the researches of G W Hill V Volterra and E I F r edh ol m in the di rection of extended linear system s of equations m athematics has been in the way of great develop ment That attitude of mind which conceives of the function as a generali z ed point of the method of successive approxi mation as a Taylor s expansion in a function va r i abl e of the calc ul us of variations as a li miting form of the ordinary a lgebraic proble m of m axi ma and m ini ma is now c rystalli z ing into a new branch of mathematics under the leadership of S P incherle J . , . . - , , , ’ ’ , . . , . , , , . , . . ” . , , , , , , ” , , “ . ’ . . . . . , . , ’ . . , . . . - . , . . , . , ’ , . A Vo ss , U eber das Wesen d M ath , 1 9 1 3 , p 6 3 2 S ee P roceed 5 th I n ter n C on gr ess of M a thema ti ci a n s , C amb ridg e , . , 1 . . . p . 2 30 3 . . . B u ll A m . . M ath S oc , V o l . . . 1 7, 1 91 1 , p 415 . . . 19 13 , V ol I , . AN ALY SI S 395 H adamard D Hilbert E H M oore and others For thi s field defined as P rofessor M oore proposes the term General Analysis the theory of syste ms of classes of functions functional O perations etc i nvolving at least one general variable on a general range He has fixed attention on the most abstract aspect of this field by con The nearest s ideri n g functions of an absolutely general variable approach to a si milar investigation is due to M Fr éch e t (P aris thesis who res tricts hi mself to variables for which the notion of a limiting value is valid Researches along the li ne of E H M oore s General Analysis are due to A D P itcher of Adelbert College and E W C hi ttenden of the University of Illinois In his General Analysis M oore d efines co mplete independence of postulates whi ch has received the further attention of E V Huntin gton R D B eetle L L D ines and M G Gaba V Volterra di scusses integro — differential equations which involve not only the unknown functions under signs of integration but also the unknown functions themselves and their derivatives and shows their use in m athematical physics G C E v ans of the Rice Institute e xtended A L Cauchy s existence theore m for partial differential equations to integro differential equations of the static type in which the variables of differentiation are different from those of i n t eg r a ti on M ixed linear integral equations have been discussed by W A Hurwitz of Cornell University The S tu dy of integral equations and the theory of point sets has led to the developm ent of a body of theory called functional calculus One part of this is the theory of the functions of a line As early as 1 88 7 Vito Volterra of the University of Ro m e developed the funda mental theory of what he called functions depen ding on other func tions and functions of curves Any quantity which depends for its value on the arc of a curve as a whole is called a func tion of the line The relationships o f functions depending on other functions are called fon c t i on el l es by J Hadamard in his L egons su r l e cal cu l des 1 91 0 var i a ti on s and f unctionals by English writers Functional equations and syste m s of functional equations have received the atten tion of Griffi th C Evans of the Rice Institute Luigi Sinigallia of P avia Giovanni L T C Giorgi of Ro me A R Schweit z er of Chicago Eric H Neville of Cambridge and others Neville solves the race course pu zzle o i cov ering a circle by a set of five circular discs Says 1 G B M athews : We must express our regret that English math e ma t i c s is so predo m inantly analytical Cannot som e one for in stance give u S a truly geometrical theory of J V P oncelet s poristic polygons or of von S t au dt s thread constructions for c on i coi ds ? In “ the theory of functional equations a single equation or a syste m of equations expressing som e property is taken as the definition of a class of fun ctions whose characterist i cs particular as well as collective . , . , . , . ‘ ’ , ‘ , , ’ . . , . ” ” . , ’ . “ ” . . . . . . , ” . “ . . . , . . “ . , . . . “ . , . . . ” ’ . . “ - . . . . . . . . ” “ . “ , , . . , . . , . . , . . , . , . “ . . . , ’ , . . ’ - ” , , , , 1 Nature, V ol 9 7 , . 1916, p 39 8 . . A HISTORY OF M ATHE M ATICS 396 are to be developed as an outco m e of the equations (E B Van V leck ) An i mportant generali z at i on of Fourier series has been made and we have a great class of expansions in the so— called orthogonal and b ior thog on al functions arising in the study of diff erential and integral equations In the field of diff erential equations the most irnpor tan t class of these functions was first defined in a general and explicit m anner (i n 1 90 7) by G D B irkhoff of Har vard Univer si ty ; and their leading fun da mental properties were developed by 1 In boun dary value problems of diff erential equations which hi m are not self adjoi n t b i or thog on al system s of functions play the sam e Anna J r Ol e as the orthogonal syste m s do in the self adjoint case P ell established theorem s for b i o r th og on al syste m s analogous to those of F Ri esz and E Fischer for or thogonal systems . . . _ , . , ” . . . - , - . . . Theori es . . I r r ati on al s and Theory f f The new non m etrical theories of the irrational were called forth “ by th e demands for greater rigor The use of the word quantity as a geo metrical m agnitude without reference to number and also as a nu mber w hi ch m easu res som e magnitude was disconcerting e s p ec i al l y as there existed no safe ground for the assu mption that the same rul es of operation applied to both The metrical view of n umber in volved the entire theory of measurem ent whi ch assu med greater In a t di fli cul t i es w i th the advent of the non Euclidean geo metries tempts to construct arithm etical theories of number irrational n um bers were a sour ce of trouble It was not satisfactory to operate with i r rational numbe r s as if they were rational What are irrational numbers ? Considerable atten tion was paid to the definition of them as limits of certain sequences of rational nu mbers A L Cauchy in “ an irrational number is the hi s C ou r s d An al ys e 1 8 2 1 p 4 says l imit of div erse fractions w hich furnish m ore and m ore approxim ate P robably Cauchy was satisfied of the e xistence of values of it irrationals on geometric gr ounds If not his exposition was a rea soning in a circle To make this plain suppose we have a develop m ent of rational n umbers and we desire to define l i mi t and also i rr a “ With Cauchy we may say that when the successive ti on al n u mber val ues attributed to a variable a pproach a fi xed value indefinitely so as to end by di ff ering from it as l ittle as is wished this fix ed value is called the limi t of all the others Since we are still confined to the field of rational numbers this limit if not rational is non existent and fictitious If now we endeavor to define irrational number as a limit we encoun ter a break down in our logical develo pment It becam e desirable to define irrational number arithmetically w i thout reference to limits This was achieved independently and at al mos t o o A ggr ega tes - . , . ‘ - . , . . . . . ’ ” , . , , . . , , . . ” , . - , , , . - , . . 1 R D C armi ch ael i n S ci en ce, N S . . . . , V ol 4 5 , . 1 9 1 7, p 471 . . O F M ATHE M ATIC S HI STORY A 3 98 has been placed upon a basis en tirely independent of measu r able m agnitude and pure analysis is regarded as a schem e whi ch deals with number only and has per s e no conce rn with m easurable quan tity Analysis thus placed upon an arithmetical basis is characteri z ed by the rej ection of all appeals to our S pecial intuitions of S pace tim e and m otion in support of the possibil i ty of its operations ( E W Hobson )The arithm eti zation of m athem atics whi ch was in progress during the en tire nineteenth century but m ainly durin g the ti me of Ch M eray L Kronecker and K Weierstrass , was characteriz ed by 1 “ E W Hobson in 1 90 2 in the following terms : In some of the text books in common use in this co u ntry the symbol 0 is still used as if it denoted a n u mber and one in all respects on a par with the fin ite numbers The foun dations of the integral calculus are treated as if Riemann had never lived and worked The order in which doubl e li mits are taken is treated as imm aterial and in m any other respects the critical results of the last century are ignored ” The theory of exact m easurement in the domain of the ideal ob j ec t S of abstract geometry is not i mmedi ately derivable from intui tion but is now usually regarded as requi ring for its develop m ent a previ ous independent investigation of the nature and relations of number The relations of n umber having been developed on an independent basis the scheme is applied by the help of the principle of congruency or other equivalent principle to the representation of extensive or intensive m agnitude This complete separation of the notion of number especially fractional number from that of m agnitude involves no doub t a reversal of the hi stori cal and psychological or ders The ex treme arithm etiz ing school of which perhaps L Kronecker was the founder ascribes reality whatever that may m ean to integral nu mbers onl y and regards fractional numbers as possessing only a derivative character and as being introduced only for convenience of notation The ideal of this school is that every theorem of analysis S hould be interpretable as giving a rela tion b e tween integral numbers only ” “ The true ground of the difli cu lti es of the older analysis as regards the existence of limits and In relation to the application to measu r able quantity lies in its inadequate concept i on of the domain of number i n accordance with whi ch the only num bers really defin ed were rational numbers This inadequacy has now been removed by means of a purely arithm etical definition of irrational n umbers by means of which the continuum of real numbers has been set up as the domain of the independent variable in ordinary analysis Thi s — definition has been given in the main in three form s one by E Heine and G Cantor the second by R D edekind and the third by K Weier strass Of these the first two are the simplest for working pu rposes an d are essentially equivalent to one another ; the diff erence between ti on al , , , , , . ” , . , . . , , . . . , . , . 0 , , . . , “ , . , , , . , , , , , . , . , , , , , , , . , , , . , . . . . , . , , . 1 P r oceed L ondon . M ath S oc , V ol 3 5 , 1 90 2 , pp . . . . 1 1 7 - 1 39 ; se e p . 1 1 8. ANALYSIS 399 them is that while D edekind defines an irrational number by means of a section of all the rational numbers in the Heine Canto r form of definition a selected convergent aggregate of such num bers is em ployed The essential change introduced by thi s definition of irra t i on al numbers is that for the sche me of rational n u mbers a new scheme of numbers is substituted in which each num ber rational or irrational is defined and can be exhibited in an indefinitely great number of ways by means of a convergent aggregate of rational n u mbers By thi s conception of the do main of n u mber the root d iffi culty of the older analysis as to the e xistence of a lim it is turned each number of the continuum being really defi ned in such a way that it itself exhibits the li mit of certain classes of convergent sequences It S ho ul d be observed that the criterion for the convergence of an aggregate is of such a character that no use is made in it of i nfi n i t esi mals definite fin ite numbers alone being used in the tests The old attempts to prove the e xistence of limits of convergent aggregates were in default of a previ ous arithmetical definition of irrational num ber doom ed to inevitable failure In such applications of analysis—as for example the rectification of a cu rv c the length of the curve is defined by the aggr egate formed by the lengths of a proper sequence of inscribed polygons In case the aggregate is not convergent the curve is regarded as not r ec t ifi abl e “ It has in fact been shown that many of the properties of functions such as continuity diff erentiability are capable of precise definition when the domain of the variable is not a continuum prov ided how ever that domain is perfect ; this has appeared clearly in the course of recent investigations of the properties of non dense perfect agg r e gates and of fun ctions of a variable whose domain is such an agg re gate In 1 91 2 P hilip E B Jourdain of Fleet near London characteriz ed 1 “ Dedekind s theories of the irrational substantially as follows : theory had not for its obj ect to prove the existence of irrationals : it S howed the necessity as D edekind thought for the mathematician to create them In the idea of the creation of numbers Dedekind was followed by O S tol z ; but H Weber and M P asch showed how the supposition of this creation could be avoided : H Weber defined real numbers as sections (S chni tte) in the series of rationals ; M P asch as the segments which generate these sections In (like B Russell ) K Weierstrass theory irrationals were defined as classes of rationals Hence B Russell s obj ections ( stated in his P r i nc i pl es of M athemati cs Cambridge 1 90 3 p 2 8 2 ) do not hold against it nor does Russell se em to credi t Weierstrass and Cantor with the avoidance of quite the contradiction that they did av oid The real objection to Weier theory and one of the objections to G Cantor s theory is s trass , - , . , , , , , , . , . , . , , . ; , , . . , , , , , , , - ” , . . . , , ’ , , . , . . . . . . . ’ . , . ’ . , , , . , . ’ ’ , P E B Jou rda i n , I ntern ati on al C ongress 1 . . . . , O n I soid R el a t ion s an d The ori e s o f I rra t i o n al N u m b e r o M athemati ci a n s , C am b r id e , 1 1 2 f g 9 . in M ATHE M ATIC S A HI STORY OF 400 that equality has to be r e— defi n e d In the v arious arithm etical theories of irrational num bers there are three tendencies : ( a ) the n umber is de fined as a logical entity—a class or an operation as w ith K Weierstrass H Weber M P asch B Russell M P ieri ; (b ) it is created or more frankly postulated as with R D edekind O Stol z G P eano and Ch M eray ; ( c ) it is defi ned as a S ig n ( for what is left indeterm inate )as with E Heine G Cantor H Thomae A In the geom etrical theories as with P aul du Bois P r in g sh e im Reymond a real nu mber is a sign for a length In B Russell s theory it appears to be equally legitimate to define a real number in various way s The theory of aggregates (M engenlehre th éorie des ense mbles theory of sets) owes its d e v elop m ent to the en d eavor to clarify the concepts of in depen dent var iable and of funct i on Form erly th e notion of an independent variable reste d on the nai ve concept of the geom etric continuu m N o w the in dependent variable is restricted to som e aggregate of values or points selected out of the continu um The term function was destined to receive various definitions J Fourier advanced the theorem that an arbitrary functio n can be represented by a trigono metric series P G L D irichlet looked upon the general functio n al concept as equivalent to any arbitrary table of values When G F B Riem ann gav e an exa mple of a function ex pressed analytically which was d i scontinuous a t each rational point the nee d of a m ore comprehensive theory becam e evident The first atte mpts to m eet the n ew needs were m ade by Herm ann Hankel and l P aul d u B ois Re ym ond The Al l gemei n e Fu n k ti on en theor i e of du Bois— Reym on d brilliantly sets forth the proble ms in philosophical form but it remained for Georg Cantor to advance and develop the necessary ideas invol v ing a treat m ent of infinite aggregates E v en though th e infinite h ad been the subj ect of philosophic conte mplation for m ore than two thousan d years G Cantor hesitated for ten years before placing his i deas before the m athematical public The theory of aggregates sprang into being as a science when G Cantor intro ? G Cantor began his du c e d the notion of enu m erable aggregates publications in 1 8 70 ; i n 1 8 8 3 he publi shed his Gru ndl agen ei n er al l I n 1 8 95 and 1 8 97 appeared in gemei n en M a n n i chfal ti gk ei ts l ehr e M athemati s che A n n al en his B ei tr age zu r B egr undu ng der tran sfi n i ten 2 These researches have played a m ost conspicuous r Ol e M en gen l ehr e not only I n the march of m athematics toward logical exactitude but also in the real m of philosophy G Cantor s theory of the continuu m was used by P Tannery in 1 8 8 5 in the search for a profounder vie w of Zeno s argum ents against . . ” . , “ , , . , . , , , . , . , . , . , . , , . , . . , . , . , ’ . ” , . . , , . . . . . . . . . . . . . , . - . , . , . , , ” . . , . , . ’ . . ’ A S ch oen fli es , En twi ck el u n g der M en genl ehr e u n d i hr er A n w end un g en , gemei n s a m n zi t H a n s H a hn her a u s g eg eben , L e i p ig u B e r l i n , 1 9 1 3 p 2 2 T ran s l a t ed i n t o En g li sh b y P hi l ip E B Jo u r d ai n an d p u bl i s hed b y t he O p e n C o u r t P u b l C o , C hi c ag o , 1 9 1 5 1 . z . , . . . . . . . A 2 46 OF M ATHE M ATIC S H I STORY in 1 90 6 relates to the aggregate of decim al fractions between 0 and 1 which can be defined by a finite num ber of words ; a new dec imal frac tion can be defined which is not included in the previous ones B ertrand Russell discovered another paradox given in his P ri n ci pl es of M a thema ti cs 1 90 3 pp 3 6 4— which is stated by 368 10 1 P hilip E B Jourdain thus : If w is the class of all those term s x such that x is not a m em ber of x then if w is a m ember of w it is plain that w is n o t a m ember of w ; while if w is not a m e mber of w it is equally 1 p l ain that w is a member of w These paradoxes are closely allied to th e Epi m enides pu zzle : Epim eni des was a Cretan who said that all Cretans were liars Hence if his statem ent was true he was a li ar H P oin care and B Russell attribute the paradoxes to the open and “ clan destine use of the word all The difli cul ty lies in the definition “ of the word M enge Noteworthy among the attempts to place the theory of aggregates u pon a foundation t hat w i ll exclude the para doxes and antino m ies that had arisen was the formulation in 1 90 7 of seven restricting axioms by E Zerm elo in M a th A n n al en 6 5 p 2 6 1 Ju l i u s K an i g ( 1 8 4 9 the Hungarian mathe m atician in bi N eu e Gru n dl agen der L ogi k A r i thmeti k u nd M en gen l ehr e 1 9 1 4 speaks of E Z erm el o s axiom of selection (Auswahlaxiom) as being reall y a l ogical assu mption not an axiom in the old sense whose freedom from contradiction m ust be dem onstrated along with the other axiom s He ta kes pains to steer clear of the antinom ies of B Russell and C B urali Forti For a discussion of the logical and philosophical questions invol v ed i n the theory of aggregates consult the second edition of E B orel s L econs su r l a théori e des f on cti ons P aris 1 9 1 4 note IV wh i ch giv es letters written by J Hadamard E Borel H Lebesgue R B a i re touching the val idity of Z e rm el o s d em onstration that the l inear continuu m is well ord ered A set of axiom s of ordinal m a g nitu d e was given by A B F ri zell in 1 9 1 2 at the Ca mbridge Congress In the treatm ent of the infinite there are two schools Georg Cantor prov ed that the con t inuum is not denum erable ; J A Richard con tending that no m a thematical entity e xists that is not defin able in a finite num ber of w ords argued that the continuum is denum erable H P oincar é claim ed that this contradiction is not real since J A ? 3 Richard e mploys a non predicative definition H Poincaré in di scussing the logic of the infinite states that according to the first school the pragm atists the infinite flows out of the fi nite ; there is an infinite because there is an infinity of possible finite things Accord ing to the second school the Cantorians the infinite precedes the finite ; the finite is obtained by cutting off a small piece of the infinite , . , , , . , , . . , , , ” ” , . . . . , ” . ” . . , . . , , . . , , , , ’ . , , . . - . . , ’ . . , , , , . , , . ’ . , , - . . . . . . . , . , . . , . - . , , , , , . , , , . P E B Jo u rdai n , C on tr i bu ti on s , C hi cag o , 1 9 1 5 , p 2 B u l l A m M a th S oc , V o l 1 7 , 1 9 1 1 , p 1 93 3 11 S c i en ti a , V o l 1 2 , 1 9 1 2 , p p 1 — 1 . . . . . . . . . . . . . . 206 . ANALYSIS 40 3 For pragmatists a theore m has no meaning unless it can be verified ; they reject indirect proofs of e xistence ; hence they reply to E Zermelo who proves that S pace can be converted into a well ordered aggregate : Fine convert it ! We cannot carry out this (wohl geordnete M enge) transformation because the number of operators is infinite For Cantorians m athematical thi ngs exist independently of man who may think about them ; for them cardinal number is no myste ry On the other hand pragma t ists are not sure that any aggregate has a cardinal number and when t hey say that the M ach tig k ei t of the continuum i s not that of the whole nu mbers they mean simply that it is i m possible to set up a correspondence between these two aggregates which co u ld not be destroyed by the creation of new points in S pace If mathe maticians are ordinaril y agreed a mong themselves it is because of confirm ations which pass fi nal j udgment In the logic of infinity there are no confirmations E J Brouwer of the University of Amsterdam expressing views of G M an n ou ry said in 1 91 2 that to the psychologist belongs the “ task of e xplaining why we are averse to the S O called contradictory systems in whi ch the negative as well as the positive of certain propo s i t i on s are valid that the i ntuitionist recogni zes only the ex i stence “ of denum erable sets and can never feel assured of the exactness of mathematical theory by such guarantees as the proof of its being non contradictory the possibility of defining its concepts by a finite number of words or the practical certa i nty that it will never lead to 1 misun derstandi ng in hu m an relations A B Fri z ell showed in 1 9 1 4 that the field of denu m erably infinite processes is not a closed — domain a concept which the i ntuitionist refuses to recogni z e but “ which need not disturb an intuitionist who cuts loose from the prin M ore recent ten dencies of research In this c ipi um c on t r adi c t i on i s 2 “ field are described by E H M oore : From the linear continuum with its infinite var i ety of functions and corresponding singularities G Cantor developed his theory of cl ass es of poi n ts (P u n ktmengen l ehr e) with the notions : li mit point derived class closed class perfect class with etc and hi s theory of cl asses i n gen eral (allgem eine M engenl ehre ) These th e n o t i on s :cardinal n u mber ordi nal number order type etc theories of G Cantor are perm eating M odern M athematics Thus there is a theory of functions on point sets in particular on perfect point sets and on more general order types while the arithm etic of cardinal numbers and the algebra and function theory of ordinal numbers are under development “ Less techni cal generaliz ations or analogues of fun ctions of the continuous real variable occur throu ghou t t h e various doctrines and applications of analysis A function of several variables is a function of a S ingle m ultipartite variable ; a distribution of potential or a field . - , . . , , , , . , . . . . , . , - ” ” , - ” , , . . . , . . . . - , . , , , , ‘ - , , . , . . - , - , - , , . ‘ . 1 L E . 2 N ew . J B rou w er i n B u ll A m M a th S oc V ol 2 0 Haven Col l oq ui u m, 1 906 , N ew H a v en 1 9 1 0 , . . . . . . , , , 19 13, p . 2- pp 4 . . A HI STORY OF M ATHE M ATIC S 40 4 of force is a function of position on a cuve or surface or region ; the value of the definite integral of the Calculus of Variations is a func tion of the variable function entering the definite integral ; a curvilinear integral is a function of the path of integration ; a functional operation is a fun ction of the argum ent f u nction or functions ; etc etc A mul tipartite variable itself is a fu nction of the variable index of the part Thus a finite sequence : x 1 ; x of real numbers is a =1 i function x of the inde x i V i z n ) S i mi larly ( ; an i n finite sequence :x l ; of real num bers is a functi on x =1 of the ind ex n v i z u Accordingly n fold ( ; 2; algebra and the theory of sequences and of series are embraced in the theory of functions “ A S apart fro m the determ ination and e x tension of notions and theories in analogy with simpler notions and theories there is the e xtension by direct generaliz ation The Cantor m ove ment is in this direction Finite generali zation from the case u = 1 to the case n = u occurs throughout Analysis as for instance in the theory of func tions of several independent variables The theory of functions of a 1 denu merable in fi nity of variables is another step in thi s directi on We notice a more general theory dating fro m the year 1 90 6 Recog n i z i ng the funda m ental r ole played by the notion l i mi t el emen t (n u m ber point fun ction curve etc ) in the various S pecial doctrines M F réch e t has given with e xtensive applications an abstract generaliza ti on of a considerable part of Cantor s theory of classes of points and of the theory of continuous functions on classes of points F réchet considers a general C l a S S P of elements p with the notion l i mi t defined for sequences of ele ments The nature of the elem ents p is not S peci fi ed ; the notion l i mi t is not expli citly defined ; it is postulated as de fined subj ect to specified conditions For particular applications explicit d efinitions satisfying the conditions are given The fun ctions considered are either functions u of variables p of Specified character or functions p on ranges P with postulated features : e g l i mi t; di stan ce; el emen t of con den sa ti on ; conn ecti on of specified char acter E H M oore s own form of general analysis of 1 90 6 considers f u n cti on s p of a g en er al vari abl e p on a gen er al r ange P where this g en er al e mbraces every well defi n ed particul ar case of variable and range Early in the develop ment of the theory of point sets it was pro posed to associate with them nu mbers that are analogous to those ? representing lengths areas volumes On account of the great arbi t r ar i n ess of thi s procedure several di fferent definitions of such n u m bers have been given The earliest were given in 1 8 8 2 by H Hankel and A Harnack Another definition due to G Cantor ( 1 8 84) was generali z ed by H M inkowski in 1 900 M ore precise measures were . “ . , n, . . , , - . , , , . , . . , , , , , . . . - , , , . , . , , , ’ . ’ . . . , , . . , ’ . . . , , - . , , , . . . . . . . D H i l be r t , 1 90 6 , 1 909 2 En cycl opédi e des sci ences m a théma ti q u es , To me I I , Vol 1 . . . I , 1 91 2, p . 1 50 . . HI STORY A 46 6 O F M ATHE M ATI C S admits a finite number of discontinuities but ( Riemann s integral ) ’ an infinite nu mber only under certain narrow restrictions A totally discontinuous function—for exa mple one equal to z ero in the rational points whi ch are everyw here dense in the interval of integration and equal to 1 in the rational points which are likewise everyw here dens e—is not integrable a la Riemann The restriction became a very hampering one when mathe maticians began to reali z e that the analytic world in whi ch theorem s are deducible does not consist m erely of hi ghl y ci v ili z ed and continuous functions In 1 90 2 Lebesg ue with great penetration fram ed a new integral which is identical with the integral of Riemann when the latter is applicable but is immeasur ably more comprehensive It will for instance include the totally discontinuous function above mentioned This new integral of Lebesgue is proving itself a wonderful tool I might co mpare it with a m odern Krupp g un so easily does it penetrate barriers which before were i mpregnable Instructive is also the description of this m o v e 1 “ Volterra has pointed out in the m ent as given by G A Bliss : introductory chapter of his L egons s u r l es f on cti ons des l ign es the rapid develop m en t which is taking place in our notions of infinite processes e xamples of which are the definite integral limit the solu tion of integral equations and the transition fro m functions of a finite num ber of variables to functions of lines In the field of i n t eg ra ti on the classical integral of Rie mann perfected by D arb oux was such a convenien t and perfect instrum ent that it impressed itself for a long time upon the m athematical public as being somethi ng unique and final The advent of the integrals of T J S tieltj es and H Lebesgue has shaken the co mplacency of m athe maticians in thi s respect and with the theory of linear integral equations has given the S ignal for a r e examination and extension of many of the types of processes which Volterra calls passing from the finite to the infinite It shoul d be noted that the Lebesgue integral is only one of the evi den c e s of this restlessness in the particular do main of the integration theory Other new defin itions of an integral have been dev ised by S tieltjes W H Young J P ierpont E Hellinger J Radon M F réch e t E H M oore and others The definitions of Lebesgue Young an d P ierpont and those of S tieltjes and Hellinger form two rather well defined and distinct types while that of Radon is a gen eral i z a t i on of the integrals of both Lebesgue and S tieltjes Th e e fforts of Frechet and M oore have been directed toward definitions valid on m ore general ranges than sets of points of a line or higher spaces and whi ch include the others for S pecial cases of these ra nges Lebesgue and H Hahn with the help of somewhat complicated transformations have shown that the integrals of S tieltj es and Hel . , , . . . , , . . ” , . . , . , , , , . , , . . . . , , , - . . , . . , . , . . . , . , . , , . , , , , , . . , . , , G A B l i ss , I n t e g ral s o f L eb e sg u e B u ll A m M ath S oc , V ol 2 4 , 1 9 1 7 , pp 1 S ee al so T H H i l debran d t , l oc c i t , V ol 2 4 , pp 1 1 3 1 44 , w ho g i ves b i bli og ra 47 phy 1 . . . . . . . . . . . . . — . . . ANALYSIS 40 7 linger are expressible as Lebesgue integrals Van Vleck has remarked that a Lebesgue integral is expressible as one of S tieltjes by a transfor mation much S i mpler than that used by Lebesgue for the opposite purpose and the S tieltj es integral so obtained is readily expressible in terms of a Riemann integral Further more the S tieltj es integral see ms distinctly better suited than that of Lebesgue to certain types of questions as is we