G E O ME T RY D E SC RI P T I V E FO R STUD E NTS O F E NGI NEE RI NG BY J A ME S A MB RO SE M O YE R, S B . . E B . , . , AM . f M ec h a n i c a l E ngi n eer i ng i n C h ar ge of th e Il l ech a ni c a l L a bo r a to r i es i n th e Un i ver s i ty of IlI w h i ga n; f o r mer l y I n str u c tor i n D es cr i p ti ve G eo m etry i n Ha r var d U n i vers i ty : E n gi n eer w i th th e G en er a l E lectr i c Co mp a n y a n d wi th W es ti ngh o u s e C h u r ch K er r a n d Co mp a n y M em ber of th e A mer i c a n So ci ety of M echan i c a l E n gi n eer s ; Jl I i tgl i ed d es V er ei n es d eu ts ch er I n gen i eu r e; M em ber of F r a n k l i n I n s ti tu te; B o s to n A ss oc i a ti o n f o r th e A d van c e men t of Sci enc e; A mer i ca n S o c i ety of C i vi l E n gi n eer s ; S o ci ety f o r th e P r omo ti o n of E n gi ne er i n g E d u c a ti o n etc A ss i s ta n t P r of ess o r o , , . , T H I RD E D I TI ON T H I RD T H O U S A N D NE W YO RK J O HN LO ND O N : W I LE Y H A P MA N C 1 9 09 SO NS H ALL L M T D , I I E copy ri gh t, 1 904 and 1905 BY E J AM B OSE MO YER S AM R P RE FA CE . TH I S b ook i s the result Of teachi n g desc ri ptive geometry to stude n ts o f e n gi n eeri n g My aim is to presen t the su bj ect SO as to make it most easily applicab le to the requireme n ts of rece n t e n gi n ee ri n g practice The methods Of prese n tatio n i n thi s b ook therefore are no t tra di tio n al E xperie n ce has shown that most stude n ts i n o u r b est tech ni cal schools have difficulty i n applyi n g their k n owledge o f thi s subj ect to subs eque n t work i n structural Two thi n gs have bee n attempted i n thi s an d machi n e desig n b ook to overcome thi s failure Of o u r stude n ts : ( 1 ) The n otatio n is essen tially the same as that used i n mechani cal drawi ng Fo r a lo n g time practical drafti n g and desc ri ptive geometry have had 2 to o little i n commo n ( ) The exercises have b ee n carefull y graded to e n courage a studen t to do thi nk i ng fo r hims elf ; an d to stimulate h i s i n terest man y co n crete exercises showi ng usually practical applicatio ns have b ee n i ns erted S uch exercises I thi nk should be i n troduced from the b egi n ni ng so that the studen t may see the practical applicatio n o f his pro blems as he goes alo ng The data for the exercises are stated by the system Of coor Reaso n s for choosin g this di n ates used i n a n alytic geometry system are O b vious Fo r a class b egi nn i n g thi s subj ect there is a great adva n tage i n statin g the exercises wi th ab solute defi ni te If a defi ni te pro blem i s n o t gi ven man y studen ts i n order n ess to Show a sat i sfactory solutio n will waste much time selecti n g data ; an d others will presen t drawi ngs that fo r their complicatio n are mostly u ni n telligi b le . . , . , . . , . , , , , . , , , . . . _ , , . , . “ 2 36 38 4 , Illustratio n s are of more u se than much wordy desc riptio n Fo r this reaso n an u n usually large n umb er of perspective an d orthographic drawi n gs have b ee n i n serted The il lustratio n s i n perspective are very helpful Whe n ever it is possi ble however stude n ts should b e en couraged to make models o f bardbo ard an d “ pe n cils that they may b uild W hat they are drawi n g This b ook is n o t i n te n ded for self ins tructio n Like lan guages this su b j ect can be learn ed successfully o n ly from a teacher an d " The stude n t must take the n o t alo n e from b ooks an d lectures time to work out ma n y exercises S pace h as b ee n left o n the right han d pages for lecture n otes an d Sketches The studen t may well put the solutio n s for man y of the exercises o n these pages A good deal O f space is take n to explai n P ro b lems 6 7 an d 8 These are co n sidered fun dame ntal ; an d the teacher Shoul d be sure they are mastered before the studen t goes further With these pro blems well i n mi n d there should be no difficulty w ith those that follow It has b ee n my O bj ect to make the explan atio n s Of the pro blems throughout the b ook co n siste n tly b riefer as the su bj ect matter i s developed I am u n der great O bligatio n to P rofessor Ira N Hollis an d P rofessor Le w is J J oh n so n fo r much assistan ce an d e n couragemen t i n prepa ri n g this b ook I o w e S pecial ack n owledgme n t however to P rofessor He n ry S J aco by who led i n teachi n g thi s subj ect with its practical app l icatio ns He has carefully read much Of this book an d I have received man y suggestio n s from him Fo r assista n ce i n ma n y ways I wish to tha nk my b rother Mr J Clare n ce Moyer M E O f P hi l adelphi a Mr C B Lewis o f C i n ci n n ati an d Mr B rya n t White O f C ambridge J A MO Y E R mb CA M R D G D 1 503 . . . , , . - , . , . . . . . , , " . , ‘ . - . . . . , . , , . , . . , . , . . , , . , . . . . B I E , ece . er, . . . SE CO ND T HE P RE FA CE T O E D I TI O N . gratifyi ng results with the first editio n showed that the methods O f this b ook were appreciated b eyo n d my expectatio n s I n the seco n d editio n I have added a n um b er O f n e w exercises Man y O f these appear throughout the text I n prepa ri n g the seco n d editio n the help O f Mr A E N orto n Fo r valua ble suggestio n s an d P h B has b ee n i n valuab le to me criticisms I am much i n deb ted to C omma n der B arto n U S N aval A cademy ; P rof A dams Mas s I n st of Tech n ology ; P rof Ke n n edy H arvard Un iv P rof O gde n C orn ell Univ P rof Ra n dall B rown U n iv P rof S pan gler U n iv O f P en n sylva n ia ; P rof Tilde n U n iv Of Michigan ; P rof Tracy Y ale Un iv ; an d Mr W V Moses of the Ge n eral E lectric C ompan y The A merican B ridge C ompan y an d the B osto n B ridge “o rk s have ki n dly supplied drawi n gs from whi ch the data for some O f the exercises have b ee n take n I am much gratified that i n P rof Ferri s s b ook o n descriptive geometry which h as just b ee n pu blished an e ff ort is sho w n to meet i n a d egree pra c tical requiremen ts S i n ce the first edi tio n Of this b ook appeared I have received man y letters regard i ng the relative importa n ce to b e given this sub j ect from a practical View poi n t i n a course i n e n gi n eeri n g These i n qui ri es i n terest me much an d i n replyi n g I have gladly give n the results Of my expe ri e n ce J A MO Y E R J CA M R D y 1 9 05 T HE , . . . . . . . , . , , . . . . . , . , , . , . . . , . . . . , . . . , . . . . l . ’ . , . , . , , . . , . . B I GE , an u ar , . . . P RE FA CE T O T H E T H I RD E D ITI O N . IN D U STRI AL educ atio n is bec omi ng every day more important The te n de n cy i n educ atio n is toward i n all systems O f teachi ng the ec o n omic applic atio n s The advan tages o f teachi ng with the help o f practic al pro blems an d exercises is more appreciated tha n ever with c orrespo n di ngly more satisfactory results These n ew requireme n ts are measured i n a degree by the success Of this b ook I n this editio n s me cha nges mostl y suggested by teache rs o have bee n made i n the text and an i n dex h as bee n added to make the b oo k more c o n ve n ie n t f o r refere n ce Fo r very valuable cri ti c i sm s I am especially i n de b ted to P rof Dr Li nse l O f B erli n Ge r ma n y and P rof J aco by Of Ithac a Much Of the work o f revisio n h as falle n to my c olleague Mr A E N orto n of C am b ridge whose services I c ann o t to o highly appreciate J A MO Y E R LY NN De cem be 1 906 , , . . . , , , . , , , . . , . . , . . . . , . . , r, . . . CO NT E NT S I NT R O D U CT I O N 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C E 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 HA PT E R I L E M E N TARY PRI N C L E S AND IP Pl an es o f P o j ecti o n P ro j ecti o n s o f Po i n ts an d L i n The 0 NOTA T I O N r es . H A PT E R II PRO MS R A T N G TO H PO N T L N P bl m ti l E x m pl d P C B LE ro e s an EL r ac T I a ca E Co n v o l u te S u rfaces , I E , AND PL AN PL AN S TANG E N T To E To S OL I D S . Su rfaces H A P T E R IV I N T RS E T O N S AND D LO M N T C E I n terse cti o ns o f Su De C r f ac e s v l p m ent o f S e o u rf a c e s E VE P PT E R V I w i th E HA P T E R III PRO B LE M S R LAT I NG of I es C Class i fi cati o n E P l an E S OF S OL I D S es . I ntersecti o ns o f Su rf aces CHA MI SCE LLAN E O U S PRA CT I CA L E xE R CI SE s . C SH HA PTE R AD S AND E VI SH AD O W S HA P T E R VII C VVA R P E D SU R F C HA PT E R P RS E ipl s f P sp P p tiv D i t ti n P p tiv Sk t h f P acti al E xe ci s Th e P ri n c er o e e rs ec e s or e rs ec e e c r c r se o es . v e c ti e PE C T V A S CE III I VE D r aw i n g . ro m W ki or ng D raw i n gs D E SC RI P T I V E G E O ME T RY I N TRO D U CTI ON treats of th e m eth o ds of maki n g draw ings to represen t o b j ects w ith mathematical accuracy There are two commo n methods for such represe n tatio n B y o n e method all ed perspective d rawi n g the chief purpose is to produce a picture which will b e plai n to a perso n u n familiar wi th the methods used for tech n ical drawi ngs B y the other method however the chief aim i s to Show an O b j ect with the true dime n sio n s that are n eeded The drawi ngs are i n the co n structio n O f b uildi n gs an d machi n es the n made b y a method which does n o t give a pictorial effect ; m f b O ther ha d shows views the O j ect fro which by n O n t h e o t bu very S imple processes true dime n sio n s Of all parts can b e quickl y O b tai n ed This latter method is called o rth ograph i c proj e ctio n I t i s the method with w hich the stude n t must b ecome most familiar an d with which this treatise must most c o n c ern hi m for some time Pers pective drawi n g will b e discussed later The method Of orth ographic proj ectio n represe n ts the outli n es Of the O b j ect as they might b e traced o n trans pare n t plan es placed arou n d the Ob j ect as shown i n Figs 1 ( fro n tispiece ) an d 2 a where three views o f a hexago n al pyramid are S hown pictorially o n horizo n tal D raw i n gs represe n ti n g these vi ews b y the an d vertical plan es orthographic method are made i n the same way as i n mechani cal drawi n g The O b j ect i s thus represe n ted as though the eye were infi nitely distan t ; that is the vani shi ng Of the l i nes Of the O bj ec t i n the dista n ce is n o t represe n ted I D escri ptiv e G eometry . ‘ . . , , , , . . , , , , , . . ~ ‘ , . . , . . . , . C HA PT E R I E L E ME NT A R Y P R I NCI P L E S A ND N O T AT I O N The ho ri zo n tal and two vertical plan es upo n which the three vrew s Of the pyramid are show n i n Fi g 2 a are called the n s f r e n n l e oj ctio These pla es are always take at right a o n p p a ngles to each other an d are desig n ated accordi ng to their positio n The li nes Of i n ter as h ori zo n t al fro n t verti c al an d si de v e rtic al sectio n o i the horizo n tal w i th the fro nt vertical and side vertical plan es are called respectively the X an d Y axes The i n tersectio n Of the fro n t vertical and side vertical plan es is called the Z axis These axes are show n plai nl y i n the figure an d the poi n t where they i n tersect is called the o ri gi n and is usually marked O 2 . . . , , . . . , , . r n the pla es Of proj ectio n are shown i n a pic torial 3 drawi ng where they are placed arou n d a pyramid which is the O bj ect to b e represen ted The pla n es are arranged as we must imagi n e them placed to Sh ow the top fro n t an d side views Of the pyramid accordi ng to th e co n ve n tio n al methods used i n prac tical drafti ng I n this figure the views Of the p y ra mi d Shown o n the pla n es Of proj ectio n are its outli n es made b y rays O f li ght reflected from poi n ts o n the pyrami d perpe n dicular to a pla n e Of proj ectio n The poi n ts where the rays pierce these pla n es are called the proj ectio n s of poi n ts o n the surface Of the pyra mid Thus i n the figure two corn ers O f the pyramid are marked a an d b From these poi n ts dotted li n es are draw n represe n tin g rays of ligh t reflected from them perp en dic u l ar to th e pl an es The i ntersectio ns Of these dotted li nes from o f pro j ectio n h at an d a a an d b with the pla n es are marked respectively a h f O f th ese th e first three are called the pro j ec an d b n b b a d tio n s o f th e poi n t a ; an d the last three the pro j ectio n s o f th e n ts are fou n d i n the same f oi t The proj e tio s other poi n o n c b p . I n Fi g 2 a . , . , , e , . , . . , , . . ‘ s , ' 8 , , . , , . , that the complete proj ectio n s O f the outli n es o f the pyra mid can be made o n each Of the plan es Of proj ectio n The co m l n f e t e o n proj ectio s the outli es Of an o bj ect are called its h o ri p z o n tal fro n t v e rti c al an d si de v e rti c al proj ec tio n s Fo r o b j ects with a ngular outlin es o nl y the proj ectio ns o f the corn ers are us ually n eeded The views Of the o bj ect are the n o f course drawn b y j oi ni n g the proj ectio ns Of the corn ers The dotted li n es i n the fi gure represe n ti ng the rays from the poi n ts o n the pyramid to the proj ectio ns are called proj ectin g l in es I n Fi g 2 a we see the plan es O f proj ectio n the hexago n al pyra mi d an d the proj ectio ns o f the outli n es Of the pyramid o n the pla nes as i n a picture A l l is shown as o ne complete view such as we see whe n several sides O f an O b j ect we are looki n g at are see n from a si ngle viewpoi n t If however the eye is moved SO that we see o nly o ne proj ectio n at a time a set o f three difi eren t views would b e Ob tai n ed called o rth o gr aph i c proj ectio n s B y the methods o f orthographic proj ectio n these views wo u ld be arrang ed I n this latter fi gure a horizo n tal li n e is first drawn as i n Fig 2 b to represe n t the X axis usually n ear the middle O f the space to The n at right angles to this li n e the be take n for the drawi ng To represe n t b y t hi s method Y an d Z axes are drawn as show n the views shown pictorially i n Fig 2 a the hori z o n tal proj ectio n is drawn behi nd the X axis an d o n the left han d Side Of the vertical The fro n t vertical proj ectio n is drawn b elow the X axis Y axi s The side ver an d vertically b elow the horizo n tal proj ectio n tical proj ectio n is also draw n b elow the X axis b u t o n the other side Of the Z axis As the views are thus show n the hori z o n tal proj ectio n shows the outli n es O f the pyramid when the eye is i m mediately over the horizo n tal plan e The fro n t an d side vertical proj ectio ns represe n t the outli n es as they appear whe n the eye is moved i n fro n t Of the fro n t an d side vertical plan es This is a very co n ve nie n t way to arran ge the proj ectio ns O f an Ob j ect an d it h as the advan tage that it is more easily u n ders tood by mecha nics Of ordin ary ab ility than some other arra ngeme n ts o f the same proj ectio ns that will b e discussed later I n Fi g 3a the same pyramid that is Show n i n Fi g 2 a is rep w ay , SO . , , . , . , , . , . , , . , . , , . , , ' , . , , , . . , . . . , - . . . . . , , . . . rese n ted in a differe n t positio n with respect to the plan es of pro i n n i 2 e c o I F a the pyramid is placed b e l o w h l t e h r i z n o t o a t g j plan e an d b ehi n d the fro n t plan e ; i n Fi g 3a it is placed above the horizo n tal plan e an d b ehi n d the fro n t plan e Fo r this arra n ge me n t the drawi n g made by orthographic proj ectio n is show n i n This method however is scarcely ever used as it crowds Fi g 3b the proj ectio n s too much for ordi n ary purposes O b serve that i n the orthographic proj ectio n the fro n t vertical proj ectio n is ab ove the X ax is an d th e h o ri z o n tal proj ectio n is b ehi n d as b efore It thus happe ns that for this method Of arra n gemen t Of views b oth the hori z o n tal an d the vertical proj ectio n s are shown i n ortho graphic proj ectio n O n the same side O f the X axis I n Fi g 4 a however a little b etter arra ngeme n t of views is S hown H ere the pyramid is a bo ve the hori z o n tal plan e an d i n fro n t o f the fro n t plan e I n orthographic proj ectio n the same views are show n i n This arran geme n t o f the proj ectio n s was o n ce much used Fi g 4 b It does n o t crowd the views as i n Fi g 3b i n practical drafti ng I n Fi g 5 a the pyram id is bel o w the horizo n tal pla n e an d i n f ro n t O rthographic proj ectio n s O f these Views are O f the fro n t plan e shown i n Fi g 5 b This last arra n geme n t O f the proj ectio n s i s also likely to produce crowdi ng and h as n o Sig n ifica n ce i n practical drafti n g It should b e me ntion ed here that the arra ngemen t o f Views Shown by orthographic projectio n i n Fi g 2 b is adopted almost exclusively f o r e ngi n eeri ng drawi ngs i n the U n ited S tates This arra ngeme n t is almost universally applied i n modern machi n e d rawi n g B this method the views are placed i n the most n atural positio n s to S uggest a me n tal picture Of the Ob ject represe n ted b y the drawi ngs ; the to p proj ectio n is at the top Of the drawi n g an d the fro n t View j ust i n fro n t of the top view The right han d side view is at the right han d side of the Sheet The views are thus arran ged where they can b est suggest a me n tal picture to a workma n ‘ . . , . . , . , , . , . ’ , . , . , . , . . . . . . . . . . . , . . . y . , , - . . . n g a drawi n g like Fi g 2 b b y The actual method of maki 4 orthographic proj ectio n will n o w b e take n up It can be most easi l y explai n ed b y S howi n g how the pri n cipal poi n ts i n the drawi n g . . , . w ere lai d o ut A corn er o f the pyramid marked a has b ee n referred h af were poi n ted o u t to b efore ; an d i ts proj ectio ns a an d a They are als o marked in the orthograph ic proj ectio ns i n Fi g 2 b These proj ectio ns are located by their distan ces fro m the X Y h Thus the dista n ce from the hori z o n tal proj ectio n a an d Z axes to the vertical Y axis measured ho ri z o n tally sho ws the dista n ce i n Space from the poin t a to the Side pla n e The distan ce from h a to the X axis meas u red verti call y shows the dista n ce Of the p oin t a b ehi n d the fro n t vertical pla n e The fro n t ver tical projec tio n af is b elow the X axis an d the dista n ce measured vertically from this proj ectio n to the axis shows the distan ce that the poi n t a is b elow the horizo n tal plan e The Side vertical proj ectio n a is fou nd by layi ng o ff a di stan ce measured hori z o n tally equal to the dista n ce that the poin t a is b eh in d the fro n t vertical pla n e O f course the tw o pro j ectio n s a f an d a are at equal distan c es b elow the X axi s . s , . , . . w . , , , , , , , , . , , , . , , , , , , , s . , , , , . 8 , . r t r d s e r t i f e c a c c a l e m o e The methods i iv o tr y are useful o p p 5 g to e ngi n eers and a rchitects i n ma n y structural an d mechanical Operatio ns I n desig ni ng and co n structi n g b u ildin gs and machi n es it is Ofte n n ecessary to fi n d the true size an d Shape Of parts Shown Wh e n the n ecessary dimensio n li n es are no t shown o n drawi n gs and whe n some Of the actual le ngths are fo resh o rten ed i n di rect geometric al methods Of measureme n t must be used The study Of this su b j ect is useful however fo r more than its i n dustrial utility The stude n t b ecomes accustomed to co n sideri n g very complicated geometri cal comb i n atio ns an d to follow accu ratel y t h e correspo nd “ e n ce b etwee n the drawin gs an d the O b j ects represe n ted De “ scriptive Geometry a well k n own e n gi n eer h as said trai ns o n e ” I ndeed it exercises i n the most precise to see arou n d corn ers mann e r the power to vi sualize which is represe n tin g to ourselves clearl y an d easily ideal Ob j ects as if they were really b efore us The importan ce o f this sub j ect i n trai n in g stude n ts fo r work i n des i gn i ng b ridges b uil di ngs an d machi n ery can hardly b e over u b t u f hi s s e h t c d e s n t timated N everthel ss s d y o j o t t e if o e es l i s m s s e a d h t e n k hi o i t t t n o e t u d s teach th e g . , . , . , _ . , , . ' , . - , , . , , . , , , . , , . The methods Of d escri p tive geome try are a bsolu tely gen eral i n their app licatio n so tha t i n the w or k that follows if the solutio n o f a p ro b lem is give n for an y o n e o f the arra ngeme n ts o f views that have b ee n explai n ed it is applica ble as well for all the others T h e pl an es o f proj ectio n also ar e i n de fi n it e i n ext en t ; that is they ex tend withou t limit i n every directio n P roj e ctio n s o f l i n es m ay be p r o d u c e d as f ar as the y are n e eded wh en th e solutio n o f a p ro bl em r e q uir es it , , , . , , , . , . other than the plan es Of proj ec tio n must be O fte n repres en ted A ny plan e that can b e Show n withi n the limi ts o f the drawing wi ll i n tersect o n e o r more o f the plan es Of proj ectio n These li n es o f i n tersectio n called the tra ce s o f i n s traight l i n es the plane are made use Of to represe n t plan es i n orthographic pro n n n rsectin g the three pla n es A b draw gs O lique pla e i te i n i n ec t o j n tersectio n o f the pla n e The i o f proj ect i o n i s sho n i n Fi g 6a w with th e horizo n tal pla n e Of proj ectio n i s called its h orizo n tal I ts i ntersectio ns with the fro n t an d side vertical pla n es trace are called respectivel y i ts f ron t vertic al an d si de vertic a l tr a c e s The same pla n e is Shown i n Fig 6b by its traces as it is represe n ted Fo r b revity however b y the me thod O f orthographic proj ectio n these traces will be called simply h o ri z o n tal fro n t an d si de tr a ce s The Simpler n ame for the last two traces can lead to n o co n fusio n Fo r an d short n ames are prefera ble to a bb reviatio n s o r s y m bols th e same reas o n the pla n es Of proj ectio n wil l b e called hereaf ter simply h o rizo n tal fro n t and si de pl an e s ; and w e shall use the correspo n di ng simpler n ames fo r the proj ectio n s o f poi n ts and li nes 6 P l an es . . , . , , . . . . . . , . , , , , . . , , , , , . N O TA T I ON . n t t n i n s a n The roj io Of oi Space are desig ated a small e c b p y p 7 letter w i th h f o r s placed above it to i n dicate w hich proj ectio n is meant ; thus the h ori z o n t al fro n t and si de proj ectio n s o f apo i n t h f a a are mark d respectively an d a I n th e drawi ng these e a proj ec tio ns are located by the di stan ces o f the poi n t a from the plan es o f proj ectio n measured parallel to t h e X Y an d Z ax es ; . , , , , s , , , . , , , the geometry o f space the di stances alo ng these axes are represented respecti vely by the co Ordi nateS as y and z D i st an ces al o n g th e X axi s ( represen ted by th e a: co o rdi n ates) Lo n g are m e asu red to th e l ef t o r ri gh t f r om th e si de pl an e u sage h as e stabli sh ed th at th ese di stan ce s sh al l b e c o n si dered n egativ e w h en m e asu r e d to th e l e f t o f th e si d e pl an e an d po si tiv e w h en m easu red to th e rig h t D i stan ces al o n g th e Y axi s ( represen t ed by th e y co o rdi n at es) T h ese are are m e asu red b ehi n d o r i n f ro n t o f th e f r o n t pl an e n egati ve w h en b e hi n d an d po sitiv e w h en i n fro n t o f th e f r o n t and in , , . , . . . l a n e p D i stan ces . lo n g th e Z axi s ( represen te d by th e z c oordi n ates) are m easu re d b el ow o r ab ov e th e h ori z o n t al pl an e ; n eg ativ e w h en bel o w po sitiv e w h en ab ov e — — a 2 If a poin t is represe n ted as: 3 we mean that the = — 3 an d z = — 4 — that poi n t a h as fo r its c rdi n ates a: y ; the poin t a is 2 u ni ts Of le ngth to the left o f the side plan e 3 u nits b ehin d the fro n t pla n e an d 4 u nits b elow the horiz o n tal plane a . , , , , , , . The proj ection s o f a l i n e are den o ted by the pro j ectio ns O f tw o o r more po i n ts i n the li n e ; thus a li n e co n tai ni ng the tw o poi n ts a and b i s called the li n e a b and is represen ted by the co br di n ates o f these tw o po i n ts The poin t where a l i ne i n tersects the horizo n tal plan e Of pro b s h i is marked the letter the i tersectio s a o n a n n ec t i d n f o y ; j lin e with the fro n t and side pl an es by i i and s i T O locate thes e poin ts more plai nl y draw a small circl e arou n d th eir pro j ectio ns a s show n i n Fi gs 8 and 9 o n pag es 2 1 an d 2 9 8 . . . . , . f s t r a e The c O 9 pl an es are repres e n ted i n a w ay sugges ted by the method Of co Ordi nates fo r poi nts A plan e is shown in Fi gs T h e horizo n tal and fro n t traces i n tersect o n the X 6a an d 6b axi s to the left o f the origin and make with thi s axis the a ngles mark ed a and fi B y symb ols such a pla n e P is represen ted as T his n otatio n fo r planes is rememb ered b es t by a o b servi n g that the fi rst numb er ( the x co Ordi n ate) represe n ts the . . . . . ° , , , i n tersectio n o f the traces o n the X axis ; and that the seco n d an d thi rd refer to the n umb er o f degrees the horizo ntal an d fro nt traces make with the X axis These a ngles are measured i n anti cl ockwise direc tio n as i n trigo n ometry I n Fig 6b the a n gles a I n such a n otatio n an d fl are respectivel y ab out 2 0 an d for the traces it is n o t n ecessary to desig n ate the side trace as an y two traces deter mi n e the pla n e an d data co n cer n i n g a third is usually superfluous I n the drawin gs the traces of a plan e are marked with the same letter used i n nami ng the plan e with H Fo r example i n Fi g 6b the hori F o r S w ri tte n b efore i t z o n tal fro n t an d side traces of the pla n e P are marked respectively H P F P a nd S P I n all drawin gs the horizo n tal an d fro n t traces must in tersect o n the X ax i s an d testi n g f or this i n tersectio n is a check o n the accuracy O f the co n structio n s 10 Li n es an d traces O f pla n es give n or required are r epr e sen ted i n orthographic proj ectio n s b y full li n es whe n visible by dotted lin es whe n in v isible P roj ecti n g lin es are i n dicated by short dashes Traces O f auxiliary pla n es are usuall y represen ted by o n e lo n g an d two S hor t dashes . . . ° , , , . , , , . , , , . , , , , , . , , . . , , , . . . C HA PT E R II P R O B L E MS R E LA T I N G T O T HE P O I NT LI NE , , A ND P LAN E The relatio n b etween the actual positio n of a li n e i n spac e an d its pro j ectio n s o n a d rawi n g is easily co n ceived for a li n e tha t is parallel to a pla n e O f proj ectio n D i fficulty is ho w ever usually experien ced i n co n c eivi n g this relatio n for a li n e that is O b lique to all th e pla n es Of proj ectio n A pictorial drawi n g of such a lin e is Shown i n Fi g 7 a The proj ectio ns Of the li n e are drawn by j oi n i n g Fo r the li n e show n th e proj ectio n s O f an y tw o poi n ts i n the lin e i n the figure the poi n ts most easily determi n ed i n the drawi n g are These i n ter i ts i n tersectio n s with the horizo n tal and fro n t plan es h h i sec tio n s are marked a and b The former a has its horizo n tal proj ec tio n coi n cide n t w ith the poi n t itself and i ts fro n t proj ectio n is of cour e i n the X axis at a f S imilarly the la tter i n tersec tio n h bf has its horizo n tal an d fro n t proj ectio n s at b ( i n the X axis ) The horizo n tal and fro n t proj ectio ns Of the li n e are an d at bf " ” the n draw n by j oi n i n g a with b an d a f w ith bf I I . , b , , . ‘ . . . . , . . , , , s , . , , , . . reversin g the process the i n tersectio ns o f the li n e w ith the pla n es o f proj ectio n can be fOu n d whe n the proj ectio n s O f the li n e are give n ; thus i n Fi g 7b the i n tersec tio n Of the li n e a b with th e horizo n tal pla n e is the poi n t a Show n by its horizo n tal pro h n of the fro n t proj ectio n Of the n ehi d the i tersectio n n t i a b ec o ( j li n e with the X axi s ) an d its fro n t pro j ectio n a f (i n the X axis ) The in tersectio n Of the same lin e with the fro n t pla n e is the poi n t " f n n s I a b d show Similarly its proj ectio by n b Wh e n o n l y tw o pl an e s o f proj e ction ar e m en tio n ed ( as i s the case for mo st pr o bl em s) it i s assu me d th e si de pl an e i s n o t 12 By . . , , , , , , . , ) , . , n ee de d 1 3 . . P ROBLE M the i n ter secti o n s o To draw the pr o j ecti ons o f a li n e havi ng gi ven the l i ne wi th the ho r i zo ntal and fron t planes 1 f . . Method Draw th e horizo n tal pro j ectio n Of the li n e by j oi ni ng the horizo n tal proj ectio ns Of the two in tersectio ns Draw the fro n t proj ectio n Of the li n e by j oini n g the fro n t proj ectio ns o f the tw o in tersectio ns . . . E XE Fo r n expressed 1 otatio n see A rts i n i n ch es . R CIS E S — 7 9 . —Th e c oor di n ates poi n ts of are . n n n n li e i t e rsects the horizo tal pla e at the poi n t a ( ) — 3 — 2 0 an d the fro n t pla n e at the poi n t b — 1 0 ) Draw the proj ectio n s Of the li n e — — n n e li e passes t rough the poi t b A h 2 2 n a d ) ( i n tersects the horizo n tal an d fro n t plan es at o (0 0 Locate the proj ectio ns Of the lin e a . A , , , , . , , , , . ; Gi ven the proj ecti o n s of a l i ne to find the poi nt 4 wher e the l i ne i n tersects (a) the hori z on tal pl an e ( b) the fro n t pl an e Method Fo r (a) produce if n ecessary the fro n t proj ectio n o f I . PROBLE M 2 . , , . . the li n e to the X axis This is the front proj ectio n o f the required poi n t Of i n tersectio n TO fi nd the hori z ontal pro j ectio n draw a pe rpen di cular to the X axi s through the fro n t proj ecti o n j us t fou nd to meet the hori zo n tal pro j ectio n Of the give n li n e ; Fo r ( b) pro duce the horizo n tal pro j ectio n o f the li n e to the X axis This is the hOri z onta l proj ectio n o f the requi red poi nt o f i n tersectio n Th e front pro j ectio n o f the poi n t is the n e asily fou n d . “ . . , , ‘ . . . E XE 2 . R CI SE S Give n a li n e p assi ng through the po rn ts c 3 — 2 Fi n d the poi n ts where this li n e 1 an d d i n tersects ( 1 ) the horizo n tal plan e (2 ) the fro n t plan e n 3 the side pla e ( ) w n t n n s o o Draw the proj ectio Of li es a e parallel to th e ( ) horizo n tal plan e an d O blique to the fro n t pla n e the other parallel to the fro n t plan e and O bl ique to the hori zo n tal , , , , , . 3 . —1 — 2 , ) , , n b F i d ) ( the in tersectio ns o f each li n e wi th the horizo n tal an d fro n t pla n es o f proj ectio n O n the li n e give n i n E x 2 locate a poi n t k 1 i n ch b elow the horizo n tal pla n e an d a n other poi n t l i i i n ches b ehi n d the fro n t pla n e S ho w three proj ectio n s of each poi n t located Give n the li n e through the poi n ts e — 3 — 1 4 2 ) an d f — 1 — 2 Locate its proj ectio n o n the side pla n e A ssume any l i rie i n space an d draw its proj ectio n s Fi n d the n ew proj ectio ns o f this li n e ( a) when the X axis is perpe n dicular to its former positio n ( coi n cidi ng with the vertical Y axi s ) ( b) whe n the X axis is revolved 30 n a ( ti clockwise ) from its first positio n S uggesti o n The exercise i s easily solved b y fi n di n g h i Whe n the plan es of proj ectio n are an d f i o f the li n e revolved the positio n s of these poi n ts with respect to the axes will n dt b e cha n ged . . , , , , , . . 5 . , , , , 6 . . , . ° , - . . . , . li n e lyi ng i n a give n pla n e i n te rsects the horizo n tal plan e o f proj ectio n at a poi n t i n the hori z o n tal trace ; that is i n the lin e showi ng the i n tersectio n of the give n pla n e with the horizo n tal plan e The same li n e i n tersects also the fro n t pla n e at a poin t i n the fron t trace o f the given plan e This is illus trated b y a pictorial d rawi n g i n Fi g 8 a where a li n e a b lyi ng i n a plan e P is shown The li ne is here produced upward u n til i t i n tersects the hori z o n tal plan e at h i and down ward to i n tersect the fro n t plan e at f i The pro blem n o w takes this form (see Fi g 8b) z G ive n o nly the fro n t proj ectio n af bf of the li n e a b determi n e the h o rizo n t al h h ne P h n a i n n roj e tio that li e b shall lie the pla a so t e b c p h h I nstead of fi ndi ng at o n ce the poi n ts a b it is first n ecessary to loc ate b oth proj ectio n s of th e poin ts h i an d i i where the give n li n e a b i n tersects the hori z o ntal and fro n t planes respect The n the hori z o n tal projectio ns of the poi n ts hi an d i i i vel y provide wh e n j o i ne d th e required horizo n tal projectio n of the li n e O bvi l y th h i tal p j ti f th p i t h i i i n th h i t l m h i i i h h t p j i p t d t t P t f f f th l t t p f fi e p ti v l y S i m i l l y t h f t d h i t l p j ti X xi 1 5 A . , . . . , , . , , . . , , , , . , , , . , ous e r ac e o a s . . , , e an e ar or z o n , e an ro n on o ro e c e an ro n e ro ec or z on a o n on o ro e c e s e sa ons o e o n a re r s or zo n a s ec n e e i n th e f r o n t trace hi to o an d i of i i n th e X . m any l e tte r s P an d i n th e X axi s . m ar k ed to axi s a r e n o t j I n th e fi gu r es th e pro ec ti o n s o f a o i d co n f u si n g th e dra w i n gs w i th v . the horizon tal projectio n of th e li n e b etwee n h i an d f i h h thus fou nd the required projectio ns a an d b are loc ated b y p ro f an d bf i n s n X li perpe dicular to the ax through i n e a s ec t j g 1 6 P R O BLE M 3 Gi ven o ne proj ecti o n o f a l i n e o r a po i n t i n a On , , ' . . . , e r o ec n d o t h er t o n i a o t h e n l n e t v i , p j g fi p Metho d (a) Give n so n e proj ectio n , . a li n e Determi n e the po sitio ns o f the in tersectio ns o f the li n e i n the give n pla n e w ith th e horizo n tal an d fro n t pla n es and draw the re q ui red proj ectio n M ethod ( b) Given o ne pro j ectio n o f a poi n t Draw a pro nd n oi t i i n f an y li n e through the give n proj ectio n o f the F o c t o e j p the other proj ectio n o f this li n e as descri b ed ab ove A t the i n ter sectio n o f the proj ectio n that has b ee n fou n d with a proj ecti n g li n e from the given proj ectio n o f the poi n t is the required pro of . . . , . . . . , , j ecti o n . E 7 . X E R CI SE S —2 —1 i s in a an d b The lin e through a plan e P (0 Draw the fro n t an d side pro o n s o f the li n e i ec t j G iven o n e proj ectio n o f a li n e which is o b lique to the X axis i n a plan e Q with traces parallel to th is axis Fin d an other proj ectio n o f the lin e Locate a poin t m i n the pla n e P give n i n E x 7 that shall b e i n ch b ehin d the fro n t plan e I n the same plan e locate also a po i n t n 1 1 in ches b elow the hori z o n tal pla n e Draw the three projectio n s o f a poin t 0 i n a plan e R which is perpen dic ul ar to tw o plan es o f pro j ection Draw the three proj ectio n s o f a po i n t at in a plan e S which is parallel to the horizo n tal plan e The s10 pe o f a roof o n a b uildin g is represen ted by i ts hori maki ng an gles respectivel y of z o n tal an d fro n t traces There is a hole i n th e 1 50 an d 2 2 5 with the X axi s roof for a chimn ey of which the horizo n tal projectio n is shown i n th e drawin gs as a regular hexago n ( length o f , , , . 8 . . , , . 9 . , , , . , . » , , , . , , , , . , , . , 0 ° . " , ides is i n ch ) The horizo n tal pro j ectio n o f the cen ter o f the hole is located 1 ? i n ches to the left o f the in ter sectio n o f the traces and i n ch b ehin d the X axis Draw th e fro n t proj ectio n of the hole The required r o c e ( p j tio n is fou n d readily by drawin g the proj ectio n s of the diago n als of the hexago n ) S tate the usual n otatio n fo r the plan e of the roof (A rt A circular wat r pipe o f which the diameter is 1 i n ch e passes through an i n clin ed floor represen ted o n a draw i n g b y h orizo n tal an d fro n t traces makin g a n gles respect i vel y of 1 5 0 an d 2 1 0 with the X axis T h e ce n ter lin e o f the pipe is parallel to the horizo n tal pla n e The fro n t proj ectio n of the pipe is therefore a circle an d its cen ter is shown 3 i n ches to the left o f the i n tersectio n of the traces an d 5 i n ch b elow the X axis C omplete the draw in g b y fi n di n g the horizo n tal proj ec tio n of the hole through which the pipe passes ( D raw a n umb er of diameters of the circle, produci n g them whe n n ecessary The an d fi n d the horizo n tal proj ectio n s of these li n es poi n ts i n the outli n e of the hori z o n tal proj ectio n of the hole will b e vertically over the correspo n din g poi n ts i n the g i ven fro n t proj ectio n ) The hori z o n tal trace of a plan e i n tersects the X axis at — = A poi n t 1 % an d makes with it an a n gle of x — — — 4 ) lies i n the pla n e D etermin e the fro n t 1 1 0 trace o f the plan e ( D raw through 0 an y lin e that will have its hori z o n tal i n tersectio n (h i ) i n the horizo n tal trace The i i of this li n e determin es the fro n t trace ) s . . . . . 13 . , ° , ° . . , ? . . , . . 14 . 5 , . . . . 1 to a 7 . P R O B LE M 4 T o draw thro ugh . a e i v g n poi n t a li ne para llel e a n e n l i v p g . Method Draw o n e proj ectio n of an y l i n e an d b y the method prob lem determi n e its oth er pro j ectio n so that the o f the last lin e will lie i n th e given plan e Through the two proj ectio n s of th e gi ven poi n t draw the proj ectio n s of the required li n e parallel i n n the correspo di g proj ectio s of the l e which has b ee n drawn n n to , . , . , ' the plan e The li n e through the poin t and the lin e in the plane shown t hus by parallel proj ectio n s are parallel to each other ; and the lin e passi n g through the poin t b ei ng parallel to a lin e lyi ng i n the pla n e is parallel to the pla n e P h v p ll l p j t i n ll l l i n ny p l in . , , , . , a ra n es e a a ra e e ro e c E XE 15 —3 o an e . a s o R CISE S Through a poin t a draw a li n e parallel to — the pla n e R 3 Draw through the poi n t of i n tersectio n o f th e li n e b — 3 — l% c 0 { ) with the horizo n tal pla n e a lin e parallel to the pla n e T (0 Fin d the i n tersectio n with the side pla n e 8 i of a lin e with b oth proj ectio n s paralle l to the X axis — 3 Fin d the i n tersectio n o f the li n e d e Through thi s poin t draw 1 3) wi th the side pla n e 1 the side proj ectio n of a lin e wh ich is to b e parallel to the pla n e U o f which the hor i zo n tal and fro n t traces are li nes parallel to the X axis The former trace is 1 5 i n c h es behi n d an d th e latter is 2 i n ches b elow the X axis . — 1 , , , 16 . , - s , , , , 17 , . , . 18 , . 7 , . . . that the lin e a b i n Figs 8a and 8b which are agai n shown o n the Opposite page is in the pla n e P O bse rve also that the i n tersectio n s h i an d i i o f th i s li n e are respectivel y No w if the pro i n the horizo n tal an d fro n t traces of the pla n e its i ter o n s O f a seco n d li n e i n the same pla n e were give n i n c t e j sectio ns h i an d i i wo uld b e poi n ts also i n the traces of th e pl an e The n suppose the co n di tio n s of the pro blem are reversed and the i n a pla n e P are gi v e n an d we are to co n two li n es s f o o n e c t i o r p j struct the traces H P an d F P The horizo n tal an d fro n t i n ter sectio n s h i an d f i o f each lin e are usually very easily fou n d T he tw o horizo n tal i n tersectio n s will determi n e th e horizo n tal trac e ; and the tw o fro n t i n tersectio n s will determin e the fro n t trace Le t us n o w appl y this method to a co n cre te pro blem I n Fi g 9 the horizo n tal an d fro n t projectio n s o f a tria n gu lar p yramid are shown and w e w i sh to sh o w th e pl an e o f a si de a b c by i ts traces 18 Rememb er . , , . , . , , , , . , ‘ , , . , , , ' . , , , . . . , . . The proj ectio n s o f two li n es a b an d a c in this side are marked The horizo n tal an d fro n t i n tersectio n s of each lin e i n the figure with the pla n es of proj ectio n are marked respectively h i an d f i The horizo n tal trace O f the plan e is O b ta in ed by j oin i n g the two horizo n tal i n tersectio n s an d the fro n t trace by joi n in g the two If we call the side a b c the plan e P the fro nt i n tersec ti o ns horizo n tal trace should b e marked H P an d the fro n t trace F P The accuracy o f the drawin g should b e checked b y O b servin g whether these trace s i n tersect o n the X axis I n the example j ust explai n ed the li n es determin in g the pla n e i n te r se ct ed each other ; b u t the solutio n is the same for paral l el r li n e s A pla n e is determi n ed also b y an y three poin t s n o t i n the same straight lin e o r b y a poi n t an d a l i n e The first case that of the three poi n ts is most easily solved by j oi n i ng them by straight ” “ I n th e seco n d case that of the poin t an d li n es two an d two li n e solve by drawin g through the poi n t an y lin e i n tersecti ng the given lin e B oth bases are thpn resolved in to that of drawi n g a pla n e through tw o i n te r se cti n g l i n es . . , ' , . . . , ’ . . , , , . , , . . r n h r h n w n t n e e l The pro lems of d i l oug li ar ll a a a e a e o b p g p 9 to an oth e r o r th r ou gh a giv en poin t p a rall e l to tw o gi v en lin e s are scarcely more tha n variatio n s of this same pro blem I n the firs t case o n e lin e i n the required pla n e is give n b y its proj ectio ns Through an y poin t i n the first li n e an d the directio n Of a n other draw a li n e parallel to the seco n d an d the problem is easily solved I n the last case the directio n s of two li n es are given an d the pla n e is determin ed b y drawi ng two li n es parallel to them through the give n poi n t B oth cases are resolved agai n i n to passi ng a pla n e through two i n tersecti n g li n es 1 . , , . , . . , , . - . . p I f tw o l i n es i n te rse c t, th e h o riz o n tal , I n tersecti ng l i nes m e et i n a o i n t r o ec ti o n s o f th e fr o n t , an d si d e r o e cti o n s i n te r se c t i n th e c o rres on d i n g p j p o int p . v s ha l i n e l l e l r a P a T th a t i s , i f tw o l i n e s tw o . si de p j e are ro e c ti o n s are th e i r h o ri z o n tal , f ro n t , p p p j r o ec ti o n s th e tw o h o ri z o n tal , th e tw o fro n t , a r al l el ar al l el an d si d e p j . p a ral l el an d ; th e 20 PR OBLE M . r a l l el a p l i n es 5 T o pass . a l a n e h o r t u gh tw o i n ter secti n p g or . Method Fi n d the poi n ts of in tersectio n of the given li n es with the hori z o n tal an d fro n t pla n es The lin e j oin i n g the i n tersectio n s The i n the hori z o n tal pla n e i s the hori z o n tal trace of the pla n e lin e j oi n i n g the i n tersectio n s i n the fro n t plan e is the fro n t trace The side trace is located by the horizo n tal an d fro n t t races . . . . . E X E R CIS E S the f o llowin g exerci ses m ark the hori zon tal fro n t an d si de trace s o f a pl an e n o t other w ise desi gn ate d by the l etters H P P P an d S P — — n 1 a d b 2 1 9 The li n e through a i 2 0) an d d m ter sec ts the li n e thro u gh c — — Pass a pla n e through 1 l% at e these two li n es s e e n t r c t i n n i f n a raw the proj ectio s O two li es n D 20 g at the y — Determi n e the pla n e i n which 1 poi n t m these two lin es lie n e a r a l l l n f raw the traces a pla e through the li es o D 21 p — — — — — l I m i a 2 b 1 i i a d g t) ; 2 ) i In , , , . , , “ , , . - , , , . . , . . _ - , —1 22 ) , d - , P ass a plan e through the three poi n ts : . — 1, b 23 — 1 i — 1 — 0 n d a t) , , — t t w , , — i‘ r a —2 — , i , ) —1 . , , , , , n d n i d the pla e passi g through the li e n n F — 1 2 n o i t the n d a § e f p h n Through the li e a g ( ) pass a plan e parallel to the li n e i — , 1 - — —1 h g ( O bserve . that the traces O f the two plan es are parallel ) — n pass a pla e parallel 1 n 0 Through the poi t — — n d a 2 1 l 4 i to the li n es It ) g . 25 . , — i) i i ( l n Through pass a pla e para lel to i b j ( ) ~ , , , m — 1 , n , —2 — 2 , , , Pass a plan e whi ch is parallel to the X axi s through the — — Draw the trace of the plan e 1 2 poi n t p o n the side pla n e The corn ers A skew b ridge is shown i n the figure below of the portal Of the b ri dge are give n by the poi n ts a ‘ , , . . —4 - , 2i b . —2 i —2 . s a ) , , a ( c s , w it the figure The po rtal is the plan e The li n es a b b ou n ded b y the li n es a b c d an d b d an d c d are called the en d po st s an d b d is the po rtal stru t D etermi n e the pla n e o f the portal d (0, as in . . , , . . The n n o b posts the portal Of a skew ridge are show of en d — — 2 r i n e gi eer s drawi gs b the l es n i n n an y — — — 1 u a — d t n } a s i ll i s H > i ; a The horizo n tal proj ectio n shows the plan an d the n es n o D ro t proj ectio the elevatio raw the three pla n n f n Of proj ection the traces o f the plan e i n which the li n es n n b a n i lie Measure degrees the gle etwee r s an d t u n n r i z n d a pla e Of the posts the ho o tal pla e en d n th e — c 2 b Th e poi n ts a — deter i e a surface n m 1 an d d n ? n you a pla e which will i clude these poi ts n fin d Can ? Is it then a plan e surface — 2 a n pyramid is give the poi ts b n y A tria n gu lar — f o r n at the co ers — 2 c n d a b( 2) its b ase and its vertex d which i s 1 % i n ches ab ove the n d the traces F n 0 d ase equidista t from b a i a n an d b ’ , , - v , , , , , , . . . , . , . 1 7 u , , , , . plan es respectively Of th e of a db an d bd c, mark i ng them P an d Q . practice the prob l ems o f des c ri pti ve geome try are mai nl y those o f fi n di n g the i n tersectio ns o f plan es with other plan es ( P ro blem the in ters ectio ns o f l i n es with planes ( P rob lem o r the true le n gt h s o f lin es ( P ro b lem These may be spoken o f as the fun dame n tal prob lems o f descriptive geometry E very stude n t mus t n o w learn these solutio ns so that he can use them immediately u n der any co n ditions I n Fi g 1 0a two pla n es P an d Q are shown by their tra ces A The plane tria n gular pyramid i s also shown by its proj ectio n s o f its side a b d is the pla n e marked P ; an d a n other side b d o O b viously the i n tersecti o n o f these tw o sides i s the plan e Q f n d b a n i pla n es is the edge o the pyram d d co struct o o n n i is ; ) ( n ecessary whe n the poi n ts b an d d are give n b y their proj ecti o ns The first o f the fun damen tal problems me n tio n ed ab ove arises however when the poin ts b and d are n o t k n own the traces an d the li n e in which the pla nes in o f the plan es are give n The pro blem to be solved is shown tersect must b e foun d more simply in Fi g l ob where the traces H P F P H Q an d F Q shown without the pyrami d Explan atio n is u nn ecessary are to show that if a li n e i n the pla n e P i n tersects a li n e i n th e plan e Q a po in t i n th e lin e o f i n terse ctio n o f th e tw o pl an es The hori z o n tal trace H P is a l i n e i n the plan e i s determ i n ed P ; an d the hori z o n tal trace H Q is a lin e in the plane Q Where H P and H Q i n tersect is a poin t then i n the requi red lin e o f i n ter sectio n Of the two pla n es The horizo n tal proj ectio n o i this poi n t " f n n n the fro t pro j ectio is eviden tly in the X axis S im n d is n a f n F a d F n where the fro t traces P n i tersect is o r l th e il a y Q fro n t proj ectio n of an other poi n t i n the li n e o f i n tersectio n The k hori z o n tal proj ectio n o f this poi n t is o i n the X axis The hori z o n tal an d fro n t proj ectio n s Of the li n e o f i n te rsectio n are fou n d h h the n by drawi n g n o an d rd o f If these proj ectio n s are dra wn also i n Fi g l 0a we can check the accuracy o f o u r work by O bserv i n g whether n o coi n cid es with d b as i t sh o ril d 2 1 . In , . , . . . . . , , . ' , , , , . . , , , , . , . , , . , , . , , , , , . , , . . . . , . some pro blems where the li n e o f i n tersectio n Of tw o plan es is to b e fou n d the traces o f the plan es do n o t in tersect S uch a case is shown o n the sheet o n which the drawi n g is made i n Fi g 1 1 where the fro n t traces do n o t i n tersect i n the limi ts of the dra w i n g Fo r the solutio n o f this pro blem an auxiliary plane A parallel to the fro n t plan e o f proj ectio n is draw n to i n tersect the pla n es P an d Q The hori z o n tal trace of this plan e is shown b y H A Thi s auxiliary pla n e cuts auxiliary li n es from the plan es P an d Q The horizo n tal proj ectio n s o f these li n es are Of course coin ciden t with the trace H A an d the fro n t proj ectio n s are parallel to the fro n t traces The i n tersectio n o f o f the fro n t proj ectio n s Of these auxilia ry li n es determi n es o n e poi n t i n the li n e Of i n tersec h tio n an d th e h o ri z o n tal proj ectio n o is vertically over o f i n the ho ri zo n tal pro j e cti o ns o f b oth lin es A s explai n ed in the pre cedi n g paragraph the poi n t n is also a poi n t i n the lin e o f i n ter h h sectio n o f the plan es P an d Q B y drawi n g the n n o an d n f o f we O b tai n the tw o proj ectio n s of the required li n e o f i n tersectio n I f i n this pro blem the hori z o n tal traces did n o t i n tersect o n the paper an auxi liary plan e would b e n eeded parallel to the hori z o n tal pla n e 2 2 . In , . . , . , , . . . , , , . , , ‘ , , , . , . . , . a case where b oth plan es are parallel to the X axis their li n e o f i n tersectio n is likewi se parallel to the axis ; an d the req u rred li n e is determi n ed by the i n tersectio n o f the side traces o f the give n pla n es I n Fig 1 2 the pla n es P an d Q are repre se nted by their horizo n tal an d fro n t traces parallel to the X axi s The side traces o f the plan es are shown at the right o n the draw ” The ho ri z o n tal an d fro n t pro i ng i n tersecti n g at the poi n t as " " n f n n x x b the required li n e i tersectio are show ec o n f o i s t o y j 2 3 . In . . . . , " 7 n x at a d 2 4 . . P R OBLE M 6 . To nd fi th e li ne o f i ntersecti on o f two pl an es . M etho d The poin t where the ho ri z o n tal traces i ntersect i s th e poi n t o f i n tersectio n o f the required li n e with the ho ri z o n tal plan e The poin t where the fro n t traces i n tersect is the poi n t o f i ntersec tio n Of the required lin e with the fro n t plan e A fter locatin g the . . . proj ectio n s o f each o f these poin ts j oin the like pro j ecti o ns O b tai n the li n e o f i n tersectio n tw o to , . E 31 i d the li e Fn . ° an d 32 . in tersectio of n N X E R CIS E S — n —3 plan es M o f tw o , 1, Draw the horizo n tal and fro n t proj ectio ns o f the li n e o f i n tersectio n o f the plan e of the end posts i n E xercise 2 8 with ario th er plan e parallel to the X axis making an an gle o f 30 with the ho ri zo n tal pla n e an d pas si n g through a poi n t 1 i n ch b ehi nd the fro n t plan e an d l i n ch b elo w the horiz on tal plan e ( Use the side plan e ) Fin d the proj ectio n s o f the i n tersectio n o f the plan e M — 1 i n E xercise 3 1 with the pla n e P b O ( serve that the li n e o f i n tersectio n is parallel to the fro nt plan e an d that the fro n t proj ecti on i s parallel to th e fro n t traces ) Fi n d the lin e O f in tersectio n O f the pla n e Q ( 0 with a vertical plan e paral lel to the fro n t plan e and 1 i n ch b ehin d i t (The fro n t proj ectio n of the lin e o f i n tersectio n is parallel to the fro n t trace of Q T he h o ri o z ntal projectio n is parallel to the X axis ) Fin d the l i n e O f i n tersectio n o f the pla n e M i n E xercise 3 1 with the plan e Q in E xercise 34 ( Draw an auxili ary plan e parallel to the fro n t plan e cutti ng the planes M It will cut from each of these pla n es a lin e an d Q parallel to the fro n t plan e The in tersectio n of the two l i n es thus o b tai n ed is one poi n t in the required li n e o f in tersectio n ) — — 2 1 b as t he li n e o f Take the lin e a in tersectio n o f tw o plan es R and S I n an y direc tio n through the fro n t proj ectio n of a draw the fro n t traces Determin e the horizo n tal traces o f the two pla n es an d elevatio n s o f the roofs of a stab le I n Fi g 1 3 the pla n , , ° . 33 . . , , , . 34 . , . . . 35 . , . , , , , . . . 36 . , , . , , . . . P la n i s th e f ro n t an o th er o r si d e n am e pro j ecti ons . f o r th e h o ri z o n tal pr oj ecti o n , an d elevati on fo r adjoin i n g shed are shown C omplete the draw i ngs by showin g the proj ectio n s of the li n e where the two roofs i n tersect The dime n sio n s an d slopes n eces sary for drawi n g the traces of the roof plan es are give n Mark the stab le an d shed roofs respectively R an d S Take scale an d an . . . . th r o u gh th e . T h e f r o n t t r a ce s . ti o n c o i n c i de n t ti o n s w i th th e l i n e s of ro . m i n e s th e th e i n te rse c ti o n s sh o w T h e l in e ’ mpe i n th e d ra 5 . X of th e HS xi a th e pl ro o f th e , s, an es , r o o f sl o an d r o o fs p O P — th e F S, are , i n th e fr o n t pro j e c th ro u gh th e i n te rsec a ral l el to th e l in e s i n th e pl w i th th e h o ri z o n tal sh o w i n g l ine an d pe s d raw n ar e FR pl an es , R an d S , th e i n te rse c ti o n s an e o f d e te r of th e . e ec d raw i n g 4 1 F i ) is ( g . add e d k m erel y to m a e th e o th e r a n er s 2 an e rs e k j i n te rse cti o n Of th e se tw o Of O f th e l i n e pl p tiv Th p w in g p l i r o o fs an d th e f ro n t trac e s w i th th e pl an w h i ch p j ecti o n Of sho w i n g Th e h o ri z o n tal tr ace s , H R . p , i n th e d raw i n g th e n , p —I n th e fi u re th e h o ri z o n tal l an e o f pro e cti o n i s ta en g b o tto m o f th e sh ed r o o f thu s l aci n g th e X axi s as i t i s sh o w n Su ggesti on . O f the fun dame n tal prob lems the fir st that of fi n din g the , , in tersectio n of a pla n e with a n other pla n e should b e no w well i n We shall n o w take up the seco n d of these most importa n t min d prob lems that of fi ndi ng the i n tersec tio n of a give n lin e with a — h r a n e a n e give n pla n e It should b e plai n that if ot called pl usuall y an auxiliary plan e —i s passed th rou gh th e gi v en lin e th e o iv l i t n rs ec t s th e giv en pl an e i s i n th e l in e i n e h n e e h r t e e e i n t w g p l an e with th e giv en pl an e To o f i n te r sectio n o f th e a uxi li a ry p illustrate take two sheets of card board and a pe n cil Place o n e sheet o n a tab le an d hold the pe n cil i n an y way to in tersect this sheet N ow hold the other sheet soli th at o n e of its edges touches the first sheet while at the same time the pe n cil lies i n its pla n e O b serve that th e pen c il n o w to u ch es th e sh ee t o n th e t abl e i n th e This same prin ciple is li n e o f i n ters ecti oir o f th e tw o sh ee t s show n also in the pictorial drawi n g i n Fi g 1 5 H ere we wa n t to show the in tersectio n of the li n e 0 d with the plan e Q The lin e h h f n o is shown b y its projectio n s c d a d df an d the plan e by its traces H Q an d F Q The auxiliary plan e A marked by its traces H A an d F A is passed through the lin e c d The plan es , . , ‘ , . , , . . , ' ~ . . , ' . . . . , . , , , , , , . Q and A in tersect i n ml 111 an d the li n e represen ted the pro j ectio ns by Rem ember th at th e po i ri t w h ere th e li n e . in h n i n ter cd This re q uir ed poin t is also o f course i n the lin e 0 d We k now then that the poi n t we are seekin g is in both O f the lines m n and c d and therefore at the poin t i where they in tersect The same pro blem is shown in orthographic proj ectio n in Fi g The lin e 0 d i s shown by its proj ectio n s an d the plan e Q by 16 ts traces The a u xil iary pla n e A is passed through the li n e 0 d The solutio n is ge neral so tha t any other plan e in cludin g the l i n e Fewer lin es are n eeded 0 d could be take n for the auxili ary pla n e for the drawing ho wever if the auxiliary plan e is drawn perpen I n Fig 1 5 it is per di cul ar to o n e o f the pla n es o f proj ectio n n t plan e l to the fro so that the horizo n tal trace H A a r n di c u e p is perpe n dicular to the X axis The plan es Q and A in tersec t i n the li n e m n ; an d the poin t where the lin e c d in tersects the — n n a n is at the i n t ersectio of m d at the poin t i shown d c pla n e Q h I n this partie b y its horizo n tal an d fro n t proj ec tio ns i and 17 h the projectio n i is determi ned by the in tersectio n o f ul ar case the horizo n tal proj ectio n s o f m n and e d The fro n t proj ectio n h 17 is fou n d b y drawi n g a proj ecting lin e thr o ugh i to i n tersec t the fro n t proj ectio ns o f m n and c d which are coin cident th e pl an e sects m u st be i n th e l in e , " Q , , mn . . , , , , . , . . , , . . , . , , . . , , , . , , , , _ . , . , , , 2 6 . PR OB L E M 7 e n l a n v e i g p Method Pass sects a . To nd fi . the poi nt i n whi ch a v e i g n li ne i nter . plan e through the given li n e tusrfii l ly a plan e perpe n dicular to the fro n t plan e) The l in e o f in tersecti o n o f this auxiliary pla n e with the give n plan e i n tersec ts the g i ven l i n e at the poin t that is requi red . ' an y . , . E XE R CIS E S — — n i d the poi t where the li e n Fn k 15 j 1 — 1 in tersects the pla n e U 0 ) ( Determi ne where the lin e j lc give n i n the precedi ng exer c ise in tersects the pla n e W ( 0 , , , , Draw the plan e P — a Fi n d i) , where the lin e i n tersects it — 2, b ( 0, . —1 § Locate — —1 the poin t where the lin e c d i —1 passes through the plan e Q o f which b oth the horizo n tal an d fro n t traces are parallel to the X axis an d are respectively 5 5 in ch b ehi n d an d i i i n ches b elow this axis The top of th e desk shown i n the accompa n yi n g figur e is — — 12 10 b located by the poin ts a 8 — — 2 4 c (0 an d d 6 A light placed — 4 1 1 0 + 2 ) h as its rays reflected so that the at l most i n te n se light is i n cli n ed 60 from the verti cal S how the curve O f i n tersectio n o f the rays o f maximum i n ten si ty with the pla n e Of the desk , , , . . 42 . , , , " - , , , , - , , ° . , ‘ . 43 . The plan e M the poin t where a ray represe n ts a mirror Fi nd light passi ng through the poin ts . of r - —1 2, ) an d — s 5) is reflected from the surface of the mirror A steam pipe i n a b uilding passes through a slopin g floor The axis of the p i pe i s located b y the poi n ts v — w 1} The plan e of the floor ma y an d Fin d b e represe n ted b y the plan e F the in tersectio n o f the axis o f the pipe with the floor . 44 - . . 1 . h r e r r u i n t t n e a l i l n a a e e e h t 7 p pp g I n Fi g 1 7 the horizo n tal and i n th eir proj ectio n s o n th at pl an e fro n t proj ectio n s o f a hip roof are shown Lin es that are parallel either to the horizo n tal plan e o r to the fro n t plan e such as the lin es o d or c e i n the figure are here drawn i n their true len gth A lin e that is o blique however to b oth pla n es of proj ectio n as fo r example the lin e b i i s n o t sho wn in its true le n gth i n the drawin g ; b u t i n this case a thi rd view may b e made to show its true dime n sio n s This is illustrated i n the right han d drawi ng i n the fi gure The roof is here proj ected o n a vertical plan e V drawn through the lin e b f an d the n this vertical plan e is revolved i n to the plan e of the drawin g This proj ectio n is co n structed b y draw A t g o n the proj ectin g i ng the b ase li n e V V parallel to V V h lin e b b produced the li n e g b is laid o ff perpe n dicular to V V Its le ngth is equal to the altitude Of the poin t b o r to the dista n ce bf gf i n the fro n t view The li n e b f shows the n the true le n gth O f b f The completed drawin g shows also the true le ngth of the lin e a c as it is parallel to the vertical plan e V 2 . Lin e s th at ar e paral l el to a . . . , . , , , , , - . , . , , . ’ ’ ’ , , . ’ ’ ’ ’ ’ . , , ’ ’ . . , . , practice these co n structio n s are simplified by passi ng the h h auxiliary vertical plan e throu gh b i The lin e V V is the trace of this plan e i n the plan e of the b ase Of the roof If this plan e i s rev olved together with the lin e b i about V V to coi n cide with the plan e o f the b ase the lin e b f wil l then lie i n a pla n e where true dimen sio n s can b e measured The revolutio n o f o n e lin e about an other lin e as an axis is ao complish ed usually by the revolutio n of two poi n ts i n th e lin e A poin t revolved thus ab out a lin e as an axi s describ es a circle with 2 8 . In . . , , , . . radius equal to the actual perpe n dicular distan ce from the poin t to the axis I n this case the po i n ts b an d f must b e revolved ab out the axis V V The axis is here i n the pla n e o f the b ase so that the perpen dicular dista n ces o f the poin ts from it can b e measured in Fo r the poi n t b this dis ta n ce is gf bf which is laid th e fro n t view h perpe n dicul ar to V V The revolved O ff o n the lin e through b ” positio n of b is at b The poin t f i s i n the axis so that i n r evo l u ” h tio n it is statio n ary The lin e b f i s then the positio n Of b f when revolved i n to a plan e of the drawin g an d shows its true le ngth a . , . , . . , . , . . If it is required to l ay off a gi ven di stan ce o n a lin e n o t shown i n its true le ngth i n a drawi n g we must first revolve the li n e ab out an axis to b ri n g it i n to a pla n e where its true le n gth i s shown an d the n measure the dista n ce Fo r example if we wish to measure a dista n ce b 33 alo n g the li n e b i ( Fig 1 7 ) from the poin t b we lay ” h locating the o ff the give n le n gth o n the revolved positio n b f poi n t x an d then reversi ng the preceding process we revolve at h h b ack i n to the li n e b i The horizo n tal proj ectio n o f b x i s the n b sc 3 0 Usually whe n the true le n gths of lin es are to b e fou n d i t is most co nve n ie n t to revolve them i n to either the horizo n tal or fro n t pla n es rather tha n in to an auxiliary pla n e which is parallel to o n e Of the plan es o f proj ectio n O f course an y lin e which lies i n o n e of the pla n es o f proj ectio n i s sho w n there i n its true le ngth This method o f solutio n is illustrated i n Fig 1 8a where a li n e m n is show n as i t is located in space an d also by its proj ectio n s " h in n an d mi ni The poi n t i n in this lin e lies i n the horizo n tal h pla n e so that this poi n t is marked o nl y by its proj ectio n m Th i s figure shows the lin e m n also whe n it is revolved in to the plan es Of proj ectio n Let us co n sider first how i t is revolved in to the hori z o n tal pla n e The poin t 777 b ei ng already i n this plan e i n r evo l u ti o n remai n s statio n ary O nly th e poi n t n therefore must b e revolved to s h ow the revolved positio n o f the lin e This poi n t h moves i n the arc of a circle ab ou t its horizo n tal proj ectio n m as a ce n ter an d with a radius equal to the distan ce the poin t n is b elow the horizo n tal plan e Its revolved positio n is at n In a h drawi ng however this revolutio n is shown by constructing at n 2 9 . , . , , , . , , , . . , , . ' . . , , , . , . . . . , . ' . , ’ . , , " n an d layi g n l i ne perpen dic ul ar to th e axi s m o ff o n the per cul ar the dis ta n ce the poi n t n is b elow the horizo n tal pla n e e n di p B y the d i mensio n lin es in the figure this dista n ce is marked s h The lin e m n is thus ob tai n ed It i s a lin e i n the horizo n tal plan e and is therefore shown i n its true length I n the same way the true length Of the lin e w as foun d b y revolving i nto the fro n t plan e The po i n ts m an d n revolve n o w respectively to Dimen sio n lin es t an d u show the m an d n i n the fro n t plan e distan ces that i n this case are e qual The true length is shown If the lin e m n is revolved in to the side plan e the same by m n r esult is ob tai n ed Figure 1 8a shows all th i s very pla i nl y as i n a picture This method however is the same fo r prob lems in orthographic pro i c n I n n n i s n n i b this way the same li e m represe ted 1 e t o i F 8 g j b y its horizo n tal an d fro n t proj ectio ns an d its true le n gth is shown h The studen t shoul d meas n o w very accura tely by m n an d m n u re these le n gths to satisfy himself that they are equ al A case occurs sometimes where the horizo n tal an d fro n t plan es have n o t b ee n advan tageously located so that lin es pass through The n the pro jec an d co n tin ue b eyo n d the pla n es of proj ectio n tio n s o f parts o f the li n e fall o n Opposite sides of the X axis Whe n such a l i n e is revolved i n to the pla n e which i t p asses through distan c es must b e laid o ff o n opposite sides o f the axis o f rev o h a , , . . , ' . , , . . ’ ’ . , ’ . , ’ . , . . , , . . , , ’ ’ ’ . . , . . , l u ti o n . a lin e a c is shown i n tersecti ng and p assin g thr ough If this lin e is revolved in to the horizo n tal th e horizo n tal pla n e at b h h plan e ab out a c as an axis the poi n t b remai ns station ary an d The distan ce that ai is b elow a an d c revolve i n o ppo si te di r ecti o n s h h the X axis is me asured o n o ne side o f a c an d the dista n ce that The n a c is the true a is ab ove is measur ed o n the other side le ngth o f the lin e If however the same li n e is revolved in to the " fro nt plan e this diffi culty is n o t met as a c shows n o w the true le ngth I n Fig 1 9 . . , , . , ' ‘ ’ . . , , ’ , , . 31 . PRO B LE M ro ecti on s; or p j to 8 . To nd the fi nd fi the tr ue l ength o f a l i ne gi ven by i ts di stance betw een tw o poi nts . Method P ass an auxiliary plan e through the li n e perpendi cu lar to a plan e i n which lin es are shown i n their true le ngths o n the drawin g ( usually a pla n e o f proj ectio n ) With the lin e of i n ter section of the two plan es as an axis revolve the lin e i n to the seco n d plan e where it is shown in its true length . . , . , E Fi n d b Fi n d X E R CIS E S the distan ce b etwee n the poin ts —l - , a —5 an d , 3, the t rue dista n ce b etwee n the poi n ts an d l , —6 — 1 —2 ) , , 0 — 2 , d Locate , i n a pla n e parallel to the fro n t pla n e two poi n ts that are two i n ches apart an d are n o t equal dista n ces b elow the horizo n tal pla n e — 5 0 an d f ( l A li n e passes through the poi n ts e D raw the side proj ectio n of this li n e Fi n d the len gth o f this li n e i n cluded b etwee n its i n tersectio ns with the horizo n tal an d fro n t plan es ; an d w ith the fro n t an d side pla n es Two statio n s 3 1 an d 3 2 are to b e co nn ected by a telegraph — 3 3 an d 3 2 li n e The locatio n s are 1 Fi n d the le n gth O f the shortest li n e that will co n n ect the two statio n s Fi n d the le n gth Of the shortest b elt to co n n ect two pulleys B oth are two i n ches i n diameter an d are i n the same — 1 plan e Their ce n ters are at b an d , . , , , . . , . . 50 . . , . c — i , i n ches lo n g The proj ectio n s of i ts en ds are lin e is — — n a 5 1 a d 1 n b located b y the poi ts 3 Determi n e the pro jectio n that is n o t give n 3 O n e proj ectio n A li n e lies i n the pla n e M — n 1% an d o f the l rn e i s give n b y the poi ts g — O n this li n e lay O ff 1 } i n ches from its 1 h i n tersectio n with the fro n t pla n e A 1 43 . - - , , , . - , 7 , . , plan es P an d H are shown in Fig 2 0 A lin e a c is perpe ndicular to the plan e P h From the poin t a the pro j ecti ng li n e a a is draw n perpe n dicular h to the pla ne H The plan e determin ed by the lines a c an d a a is perpen dicular to the plan es P an d H It is therefore perpen di cu l ar to the trace H P which is the i n tersectio n o f the plan es h " Then a c which is a lin e lyin g i n th is plan e is perpe n dicular to H P C o ns ider n o w the plan e H as a plan e of proj ection ; the n h h is the proj ec tio n O f the li n e a c while H P is the trace o f the a c plan e P We have show n then that when a li n e a c i s perpen dic ular to a plan e P its horizo n tal proj ectio n is perpe n dicular to the hori The same relatio n holds o f course fo r the other z o n tal trace proj ecti o ns o f the li n e an d the correspondin g traces o f the plan e I f th en a straigh t li n e i s to be dr aw n perpen di cu l ar to a r aw i ts proj e ctio n s pe rpen di cu l ar t d r i o n l y n ece ss y o i a s t l e a n p An d to dr aw a pl an e to th e co rrespo n din g tr aces o f th e pl an e raw th e t race s perpen di cul ar to th e e d l l i n n u a r t o a r e d i c e p p ro j e ctio n s o f th e l in e p 32 . Li n es P erpen di cul ar to a P l an e Tw o . . . . . . , , . , , . , , , . , , . , . , , , . , . 33 . PR OBLE M e a n l n v e i p g Method 9 . To nd fi the di stan ce from a t o v e n n to i i g p a . through th eg ve n poi n t a l i n e perpendi cu lar to the plan e Fin d the poin t where this lin e i n tersects the give n plan e “ The required distan ce is the true length o f the l i n e j oin in g t hi s last poin t with the give n poi n t . D raw . . . E —2 X E R CISE S is perpendicular to a l i n e drawn plan e Q through the poin t j 2 Draw the proj ectio ns Of the lin e ; an d fi n d the distan ce from j to Q I n E x 4 2 fi n d the dista n ce from th e poi n t t to the pla n e Of the top O f the desk Fi n d the dista n ce from the poin t w in the axis of the steam pipe give n i n E x 4 4 to the pla n e O f the floor A A hillside is represe n ted by the pla n e S (0 A , , . 54 . . . . . , ole is pla The n ted o n it perpe n dicular to its plan e p — n t li t b ottom of the pole passes through the poi —1 1i ) Measuring by the same scale as for th e c o ordin ates of t locate a poi n t that is 1 i n ch ab ove th e grou n d What is the length O f the part o f the pole i n the groun d ? A poin t i is ab ove the roof represen ted A shaft for tra n smitti n g by the plan e R ( 0 “ power to an other b uildi ng passes through this poin t perpe ndicular to the roof Locate poin ts o n the shaft 1 i n ch ab ove the roof an d 2 i n ches b elow Draw the proj ectio n s Of a cub e an d fi n d the distan ce from The any cor n er to an o b lique pla n e passin g through it plan e should n o t b e parallel to an edge Fi n d the dista n ce b etwee n two parallel pla n es o f which all the traces are Ob lique to the X axis . , - . , , . , . . . . , . PROBLE M 1 0 To proj ect a gi ven li ne u pon a gi ven plan e Method S elect any tw o poi n ts i n the li n e an d through each draw the proj ectio n s of a lin e perpen dicular to the pla n e T h e li n e j oin ing the poin ts where these perpe n dicular lin es in tersect the given plan e is the pro j ectio n o f the lin e upon tha t plane 34 . . . , . . . E —1 ) upon 1 1 n the li n e m — 1 the plan e P The maj or an d min or axes of an elliptical cam wheel are determi n ed respectively b y the lin es d 14 60 P roj ect . X E R CISE S - - , , - , e — 1 t, ( — 1 t, —l i — , i , Draw the proj ectio this cam wheel o n the pla n e — 5 by proj ecting a n umb er O f diameters T o f the ellipse The vertices Of a triangle shown i n the figure are at th e po in ts : a b ( 1F c li i n of - ’ , . _ _ _ ’ 1 r ' ) Proj ec t this triangle upon 0 ( , th e pl ane R n n i s b n n If n li e give its proj ectio s a d a pl e is e a n o to be y 35 draw n perpe n dicular to it it follows from the explan atio n i n A rt 32 that the traces o f the required pla n e must b e draw n perpen di cu lar to the c orrespon di ng proj ectio n s O f the give n li n e I n Figs 2 1 a an d 2 1 b a lin e a b is shown by its tw o proj ectio n s an d it is re quired to draw through a give n poi n t 0 a plan e perpe n dicular Through the poin t 0 draw a lin e m 0 parallel to to the lin e a b A th e horizo n tal pla n e which shall lie i n the required pla n e l in e which is parallel to th e horizo n tal pla n e is commo n ly called “horizo n tal ” an d is a lin e with its fro n t proj ectio n parallel a “ A n d if this horizo n tal shall lie i n the required to the X axis z o n tal proj ectio n must b e parallel to the horizo n tal la e its hori n p I n other words i n this case the trace O f the pla n e to b e draw n co nditio n s to b e satisfied are : ( 1 ) that the fro n t proj ectio n W o f ” horizo n tal must b e drawn parallel to the X axis ; an d (2 ) o f the h h that the horizo n tal projectio n m o must b e drawn perpe n dicul ar , . , . . . , . . , . , . , , — b the horizo n tal proj ectio n o f the g i ve n lin e a the same as sayin g i t mus t b e parallel to the horizo n tal trace Of the required pl an e H avi n g thus determin ed a lin e m o lyi n g in the required pla n e the fro n t trace F P is drawn through the in tersectio n ( f i ) o f the lin e m o with the fro n t plan e an d perpe n dicular to a) bf The horizo n tal trace H P is drawn through the in tersectio n of F P h h with the X axi s an d perpe n dicular to a b A pla n e P perpen di c u l ar to the lin e a b an d passi n g through a give n poin t 0 is thus determi n ed A lin e parallel to the fro n t p an e an d i n tersec ti ng the horizon ta l l pl an e (d e termi n i ng the horizo n tal trace first) might O f c ourse b e “ ” used i n the place o f the hori z on tal to Ob tai n the same result to . , , , , . , , . , , , ‘ i . , , . , 36 . PR OBLE M di cu l ar to a 11 T o pass . e n v e n l i i g a h t l a n e r ou gh p agi ven poi nt perpen . Method D raw through the give n poin t a lin e which will lie “ ” horizo ntal lin e is usually most e asil y i n the requ i red plan e ( a used ) Through the i n tersectio n Of this li n e with o n e of the plan es o f pro j ectio n draw o n e trace Of the required pla n e perpe n dicular to the correspo n di n g proj ectio n o f the give n li n e The other trace is drawn perpe n dicular to the correspo ndi ng proj ectio n o f the li n e an d through the i n tersectio n o f the first trace with the X axis . . . , . E X ER CIS E S Draw throu gh the poi n t e — 1 — 1 which shall be perpe ndicular to the li n e , —1 ) h ( , “ Z — i a plan e , g —3 , U, —l , } , , The poi ts b 0 5 are i n the eaves of a roof The poi n t g is i n the ridge D raw through the poi n t w (0 the s r o e c t o n f n i a arrow that will show the directio O n of j p a force due to win d pressure o n the roof Make the tip o f the arrow tough the surface Of the roof P ressures ( o f fluids are perpe n dicular to the pla n es o n which they are exerted ) D raw a pla n e parallel to the pla n e P ( 0 at a distan ce of two in ches from it o n th e right han d side n , an d 0 — , . . , . . . , - . a complicated drawing it is ofte n n ecessary to fin d the true size o f the a n gle b etwee n li n es i n a pla n e surface which is n o t parallel to any pla n e showing true dimen sio n s The usual process is to imagi n e the plan e Of the surface exte n ded to i n tersect the plan es thus determini n g the horizo n tal an d fro n t traces o f projectio n A b ou t o n e o f these traces o f the pla n e i n which the surface lies as an axis the pla n e is the n revolved till it coin c ides with the hori z o n tal o r fro n t plan es The simplest case of fi n din g the true size o f a plan e surface is illustrated at the left han d side of the roof shown i n Fig 2 2 The side a b c is n o t shown i n its true size n either are its angles If however the side is revolved ab out its in tersectio n with the plan e h h o f the b ase of the roof b c i n to the plan e of the b ase its true size will b e see n The n the lin es a b an d a c will be see n i n their true le ngths and with th e tru e si z e o f th e an gl e betw een th e m I n this h h revolutio n ab out the axis a b the path traced by the poi n t a is show n i n its fron t proj ectio n by the dotted li n es of the arc o f a with its ce n ter at bf d The poi n t a shows its c ircle through of h h revolved positio n i n the pla n e o f the b ase an d a b c shows true dime n sio n s for any part Of the outlin e of the surface 37 In . . , . , . - . . , . , , , , , . . , , ' . , ’ , . I n the preceding case the problem was simplified b ecaus e the surface to b e determ i n ed was perpe n dicular to the fro n t plan e o f proj ectio n so that the radius for the revolutio n of the cor n er a A t the right w as show n i n its true le n gth i n its fro n t proj ectio n ha n d side o f Fi g 2 2 where the side o f the roof d e f is represen ted H ere whe n the revolutio n a more diffi cult pro b lem is prese n ted h h is made ab out the lin e e f ( the in tersectio n o f the side wi th the plan e o f the b as e) as an axis the poi n t d will move i n the arc Of a c ircle wi th a radius equal to the perpe n dicular dis tan ce from d to the axis O bviously the lin e d g is this radius The p erspe ctive vie w in Fi g 2 3 shows this radius and b y the arrow o n d d the * n t e direc tio n of revolutio n The r u l e gth is fou nd e asily from its d b y th e h y p th n f th e i gh t t i n gl e T h e t e l n gth i m I n th i t i n gl d dh i l ai d o ff eq u al to d dh gh i n th e h o i o nt l p o j ti o n 38 ' . , , . . , , . , . . ’ , . . ru e r z easu r e s a r ec o . s r a th e d i stan ce f ro m df to th e l in e o f th e b ase o f th e u se O e e ro o f r r a s bf of cf f f . two pro j ectio n s The true len gth d gle o f th i s radius whe n laid o ff o n h h d g produced shows the revolved positio n Of the cor n er d at d The true size O f the gi v eri surface is show n by the tria ngle d eh f" fro m which true an gles can b e measur ed The perspe cti ve v i ew o f this roof represen ted in Fig 2 3 shows h h more plai n ly the right tria n gle called d d g i n th e precedin g co n structi o n togethe rwith the ar e describ ed by the poi nt d i n rev o lv h h i n g to d a b out e f as an axis f - . , , ’ , , , . ’ , . / . , ’ . tri an gl e d dh g ( Fi g 2 3) sh o w s al sO th e tr u e an gl e th e si d e d w i th th e l an e o f th e b ase T h i s angl e 1s m ar ed a i n th e fi gu re The mak es r i gh t . p k . e f . Fig: 2 4 sh o w s th e sirnpl est sta temen t o f the problem to fin d N on e th e tru e an gl e betw een tw o in t erse cti n g l in e s m n an d o p Of the angles b etwee n the proj ectio n s Of these lin es show the true a ngle b etwee n the lin es ; an d they must b e revolved i n to a plan e where true dime n sio n s are shown B efore however the lin es c an b e revolved in to o n e o f the pla n es of proj ectio n the traces o f the pla n e i n which they lie must b e determi ned The i n tersectio ns o f the li n es with the horizo n tal an d fro n t pla n es are marked respect The lin es j oi n i ng these po in ts that are correspo n d i vel y h i an d f i The li n es mus t the n b e i ng are the traces o f the required pla n e revolved ab out o n e o f the traces in to the correspo nding plan e o f proj ectio n ; that is we must revolve ab ou t the horizo n tal trac e i n t o the hori z o n tal plan e ab out the fro n t trace i n to the fro n t p l an e etc I n the figure the li n es are show n revolved i n to the hori z o n tal plan e ab out the horizo n tal trace H P as an axis The true le ngth o f the two o f the radius for revolvi n g the poi n t of i n tersectio n i lin es is fou n d by co n structin g the right tria ngle shown at the righ t The hypothe nuse of this triangle is equal to the O f the drawin g true distan ce from i to H P The revolved positio n of i is shown at i by layi n g o ff a d i stan ce equal to th e le ngth of the hypothe n us e at right a ngles to H P The e nds of the li n es m n an d o p are 39 5 . . , . , , . . . , , , . . , , , , . . ’ ( . In th at the p r a c ti ce , u su a l l o nl y o n e ri gh t v hy p , thi s r i gh t tr i a n gl e l e g m u s t b e t ra n s f e r r e d tri an gl e w i th d i i d e rs y on as s h o w n th e o th en u se c o ul X xi a , . Fo r th e d i s ta n c e s , a t ri h t g d b e m ea su red i n e x a be p p pl a ced o n m l e i n s tea d m a rk e d an gl es one o c an tO th e e rati o n . so o f c o n s tr u c ti n g v m i gh t h a e b ee n l a i d O ff d i stan c e m ark e d b an d th e a ‘ , t h e d ra w i n g H P; and i n revolving the lin es these poin ts remain s tationary The lin es show n by heavy dashes i n the figure represe n t the lin es m n and o p whe n they are revolved i nto the horizo ntal plane The angle [9 is the true size o f the acute a ngle b etween the tw o lin es O b serve that for the co nstructio n o nl y o ne trace is n eeded the o ther might be omitted in , . . . , . 40 . PR OBLE M i ntersecti ng li nes 12 To . nd fi the tru e si z e o f the angle between two . Method Determi n e o n e o f the traces o f the plan e i n which With this trace as an axis revolve the tw o th e give n li n es lie li n es in to the plan e o f pro j ectio n i n which the axis lies The angle b e twee n the li n es i n their revolved positio n is the tru e siz e o f the re q u i red angle . . , . . E XE 66 . De termin e the plan e co brd i n ates : c —l i — , 1 of —2 a R CISE S the lines a b and b0 gi ve n b , by the an d With the horizo n tal trace O f this axis revolve these lin es in to the horizo ntal , plan e as an plan e — — 2 b 1 The li n e a 1) i ntersect s — — 2 d the li n e 0 l % ) at 6 1 Fin d the true size o f the ob tus e a ngle betwee n these two lin es A b oat is towed alo n g a ca n al by tw o mul es o ne walki n g o n each b ank I n proj ec tio n drawi ng the b oat is shown at The to w paths are n o t at the same b —2 level an d the po si ti o n s o f the mules are sho wn at m 1 —1 —1 — — Fi n d th e true i ) and m2 1 size of the angle b etwee n the to w ropes If i n the precedi ng exercise the forces exerted by the tw o mules are the same show the course the boat will take S uggesti o n If the forces in the tw o to w ropes are equal the c ourse of the b oat is shown by the bis ec to r Of the a ngle b etwee n them , . - , , , , . 68 . , , . - , , c , , , - . , . - . , . The vertices of —2 a triangle are at the poin ts —1 i —3 a , Draw the projectio n s o f the b isector o f the a ngle b etween the sides a b and b c o n the horizo n tal fro n t an d side pla n es Th e mast o f a derrick i s shown b y the li n e c — 2 —2 2 d Gu y ropes attached to the to p ) g i) o f the mast at c are faste n ed to the grou n d at a b , an d c , , , . , - - , , . —2 — 2 ) and b — 4 — i ( a) Fin d th e a n gle b etween the guy ropes a c and b c F n b i d the a n gle etwee n the n m b c a d the mast b ) ( m , , , - i c d . . C heck this las t res ul t plan e revolvi ng b 0 i n to the fro n t . Su ggesti o n drawi ng th e by . Ob serve th at the h i fo r c is d at c h h d in . The a ngle which a line m ak es wi th i ts pro j ection o n an y ngle b etw ee n the li n e an d the plan e t la e measures the rue a n p e from a poi n t i n the B y drawi ng a lin e perpe n dicular to the plan — give n li n e a right a ngled triangle is formed i n which the perpen di c u lar is o ne leg the proj ectio n of the li n e is an other leg an d the li n e itself is the hypothen use The required a ngle is that b etwee n the hypothe n use and the leg lyi n g i n the plan e ; b u t the other acute a ngle o f this triangle the compleme n t Of the angle b etwee n the lin e an d the pla n e is more easily fou n d b y the method of Ar t 4 0 41 . . , , , . , . , 42 . P R OBLE M e l a n e v n i p g Metho d 13 . To fi nd the angle betw een a . e v e i n l i n g and a . poi n t i n the give n lin e draw a lin e perpen The Fi n d the angle b etwee n these tw o li n es di cul ar to the pla n e complemen t o f this angle is th e required a ngle b etwee n the lin e an d the plan e . From any . . . E 72 . Fin d X E R CIS E S the angl e the li e makes with the plan e P n a — 1 —l , — 1 - 1, ) b , —5 —2 — n i n c i d the a gle the l e d n F 4 1 makes with the plan e M — 3 ( O b serve that the an gle most con ve n ie n tly foun d i n this case is the supplemen t o f the an gle b etwee n the perpe n dic ular an d the give n li n e as show n i n the right tria n gle men —1 , — , , , , ti o n ed i n Ar t . The slope Of the b ank o f a can al makes an angle of 30 with the water level so that the plan e o f the b ank is as shown i n the figure A r eprese n t ed b y P ( 0 mule o n the b ank draws a b oa t i n the can al The traces o n the mule are attached to a rope at a po i n t m —3 The other en d Of the rope is faste n ed to a — 4 l As sumi n g there is n o s ag b oat at b t the poi n ts m an d b i n the figure are i n a i n the rope ( th a straight li n e ) fi n d the true an gle b etwee n the rope an d the b ank o f the ca n al ° - , , . . ° , - , , , . 75 I n . co n structi ng shadows o n we take rays o f light that are reflected down ward from the left han d side an d are show n b y lin es whose hori z o n tal an d fro n t proj ectio n s - , make respectively angles o f 4 5 an d 3 1 5 with the X axis ( a) Fi n d the a ngle b etwee n these rays an d a roof R ° ° . (0 , Fi n d the an gle b etween these rays and the hori z o n tal an d fro n t pla n es of proj ectio n — 1 A ray of light passes through the poin t p ) an d is reflected from a poin t r i n a pla n e mirror repres e n ted b y M (0 Fin d the a n gle * Of refl ec ti o n an d the distan ce o f the poin t p from the mirror Fi n d the an gle b etwee n a li n e with b oth proj ectio n s parallel to the X axis an d the pla n e Q (0 S u ggesti on S i n ce the pla n e Of the give n lin e an d th e perpe n dicular must i n clude a lin e parallel to the X axis its traces are parallel to the axis ( b) . , , . , . ‘ , . n L M a n L two pla es N d N 0 are shown i n 43 a pictorial drawi n g an d we wish to determi n e the a n gle b etwee n them If from an y poin t p we draw the lin es p g an d p r perpen d i c u l ar respectively to the pla n es L M N an d L N 0 these perpen d i c u l ar li nes will determin e a plan e whi ch is perpe n dicular to b oth The o f the give n pla n es an d i n tersects them i n the lin es g e an d e r a ngle q e r is therefore the a n gle b etwee n the two give n plan es This angle is n o t usually determin ed directly The method o r di n ar il y used is to fi n d the true an gle g p r b etwee n the i n tersec t This angle is the suppleme n t o f i ng lin es p g an d p r ( A rt the an gle g e r O f course either o f the an gles g e r ( gt) o r q p r n n n 1 is the a gle b etwee the two pla es 80 ( I n Fi g 2 5 . , . , , . , , . . . . . ° . T he a th e l i n e s th e m , od is p ra c t i c al l y er v f ro m th e tw o gi e n e n d i c ul a r to th e i r l i n e cut p p T he mi rro r b o ve m eth a n gl e o f re fl e c ti o n b efo re refl ec ti o n , is w h i ch pl th e an e s Of by as an au i n te rse c ti o n equa l is sam e to th e c all ed th e fi n d i n g th xi l i a ry pl a n gl e e an e p a ssed be tw ee n th ro u gh . a n gl e b etw ee n an gl e o f th e i n ci d en ce . ray an d th e ' 44 . PROBLE M 14 To . the fi nd an gl e o bl i qu e between two s l a n e p . Method From any poin t in space draw a lin e perpe n dicular to The true a ngle b etwee n these tw o li n es each o f the give n pla n es is th e angl e b e twee n the plan es . . . E XE Fin d the angle b etwee n the pla es n T S —3 by the poi ts an d , (0 , The corn ers _ R CIS E S i a hip roof are give n Of - b ' : ( " F _ r i ’ 1) y _ i C — n i an d 21 _ ' a i —2 —2 § d The ridge is the li n e e —1 n n 1 F i d the a gle b etwee the sid n es ( ) g Of the roof c d e g an d a b g e ( Use the side traces o f the pla n es ) ( 2 ) Fi n d the an gle betwee n the sides o f the roof a b g e and g b c — n Fi n d the angl e b etwee n th e pla e R 1 an d a plan e parallel to the X axis with its horizo n tal an d fro nt traces respectively 1 i n ch b ehin d an d 1 } in ches b elow the X axis The i n tersectio n o f o ne o f th e perpen Su ggesti on di cu l ars with either th e horizo n tal o r the fro n t plan e is foun d easil y by usin g the side pro j ectio n s Make a drawi ng similar to the figure o n p 7 6 taki ng th e " h followi ng data : Draw i n n with a slope o f 30 to the X axis Take fi = 60 a = 4 b = 2 c = 1 % d = 2 e = l i 2 h n 1 C omplete the dr w i g determ i g a b i n 1 n 5 y f 1 g a ccurately the l i n es o t an d 0 q n n o b n t d the a gle etwee the roof pla e the i n a n F d 1 o n e ) p ( i n which the li n e r s lies s n i The li n e r represe ts a rafter n the ro f i d o F n 2 t h e ) ( an gle o f the b evels to b e cut at its e n ds so that it may b e j oi n ed to the ridge at r an d to th e valley rafter o g at s The corn ers an d ridge of the i rregular hip roof shown In th e fi gure at the top o f p 78 are loc ated by the follow in g —2 , , , . . 80 . , 1 . . . , . ° ° , . , , , , , , . . . , , . - . , poin ts : d ( 0, - a b 0 0 , , ( 0, — l 4, % 0 e , - 5, — 3 , min e the poin t e by fi n ding the lin e Of in tersectio n sides meeti ng in the ridge (g e) D eter of th e . n b n the a gle etwee the sides of the roof meet i ng ( ) i n the ridge n b t i n d the a gle of evel for the o side Of the hip F b ) p ( rafter e c ; tha t is fi nd the an gle b etween the plan es o f the sides d e c an d b c e g n m n n i n The li e represe ts a rafter the side c b0 eg ) ( Fi n d the a n gle of b evel for its en d at m to j oi n the hip rafter e c The fro n t proj ection of m n must be supplied a Fi n d . , . . . . shows a square b utt j oin ted h O pper The edges o f the outside to p an d b ottom squares are re The outside mpi ng spec ti v el y -5 i n ches an d 2 in ches edge is 3 in ches long Find the a ngle o f b evel for th e j oints b etween the sides o f the hopper 83 Th e fi gure b elow - . . . . gen eral method used i n the precedin g exercises an d fi n d the an gle b etwee n the pla n e P (0 the horizon tal plan e o f proj ectio n The horizo n tal trac e o f a plan e makes an an gle of 4 5 with the X axis an d the plan e itself makes an an gle o f 60 with the fron t plan e Draw the fro n t trace of the pla n e Take the data given fo r the skew b ridge i n E x 2 7 and By th e . , . ° ° , . . . fi nd n n The a n gle etwee the pla e Of the portal b ) ( a a horizon an d tal plan e n n The a n gle etwee n the pla e of the portal a d a vertical b b ) ( plan e through o n e O f the en d posts n n d n The a gles etwee the p o rtal strut the posts 0 b b a n d d e ) ( . . a b an d c d . The a ngle b etwee n the portal strut b d an d the li n e Of i n tersectio n o f a vertical plan e through o n e of the end posts with a plan e through the portal strut perpe n dicular to the pla n e o f the portal S u ggesti on A simple way to pass a plan e through a give n lin e perpe n dicular to a give n pla n e is to draw through any poi n t in the give n l i n e a lin e that will b e per i n cu l ar to the give n pla n e The required pla e is e d n p determin ed by these tw o i n tersecti n g li n es e i n n i Measur degrees the a gle fou n d n d n the a gles a d n ) ( ( ) e marked a an d [i i n the figure B y trigo n ometry the tan ge n t O f the angle foun d i n (d) is equal to si n a tan fl With this formula check the an gle fou nd d ( ) . . . . . . . very s i mple method for fi n ding the angle b etwee n tw o It is shown there h o w sides o f an O b j ect i s explai n ed i n A r t 38 the a ngle a b etwee n the side O f the roof d c i i n Fi g 2 2 and the plan e of the b ase is fou n d immediately from the proj ectio n s The an gle b etwee n the side d e f an d the fron t plan e can n ot however The be fou n d so easily without fi n di n g th e traces o f the pla n es method to b e explain ed i n this article applies particularly to fi n di n g the an gles b etwee n a plan e give n b y its traces an d the horizo n tal an d fron t plan es O b serve that the prob lem is the same as that solved i n E x 84 The problem ho w ever appears so Ofte n for solutio n that a Special case should b e made o f it If an ob lique plan e is pepen di cu l ar to either the horizo n tal o r the fro n t pla n e Of proj ectio n o n e o f its traces w il l b e perpe n dicular to the X axis an d the other trace will show by its s 10 pe the a ngle the plan e makes with o n e of the plan es o f projection I n Fig 2 6a a plan e P is show n perpe n dicular to the horizo n tal pla n e an d 45 . A . . . . , , . . . , . , . fi , , . . ' , , , th e s 10pe horizon tal trace shows the angle b etwee n the plan e P and the fron t plan e The same plan e i s shown by orthogr aphic projection in Fig 2 6b and the an gle mark ed 0 measures accur atel y the same angle The prob lem is a little more complicated when the plan e is oblique to b oth plan es o f proj ectio n as shown in Fig 2 7a In this case o f c ourse the a ngle b etwee n o ne o f the traces and the X axis does no t show the an gle b etwee n the plan e P an d a pla n e ction If ho wever an auxi liary plan e marked by its o f proj e trac es H A and F A is placed so that it in tersects the plan e P an d is perpe n di cul ar to th e horizo n tal pla n e as shown i n Fi g 2 7 a th e a ngle 0 b etwee n the lin e of in tersection o f the plan es P an d A an d the trace H A is the angle b etwee n the plan e P an d the hori z onta l plane The method o f findin g this angle from th e The given plan e orthographi c pr o j ec ti o ns is shown in Fi g 2 7 b i s shown by its tr aces H P an d F P ; and the auxiliary plan e by its traces H A ( perpe n dicular to H P) an d F A ( perpe n dicular The lin e of in tersectio n o f these tw o plan es is to the X ax i s ) " h shown by its pro j ectio n s i j and 17 j f This l i n e whe n revolved h " n n a l n into the horizo t pla e ab out its horizo tal proj ection i j as h n n a d shows the a gle true size 0 i n i an axi s takes the positio n i t s j A di me nsio n l in e marked s is shown to make the co n struction plainer It sho ul d b e evi den t that the auxiliary plan e A can b e drawn through any poin t i n the trace o f the give n plan e S imilarl y we can fin d the angle b etween the same plan e P an d the fro n t pla n e b y drawin g the fro n t trace F B O f an au xfl i ar y plan e B perpe n dicular to the fro n t trace Of P an d makin g th e horizon tal trace H B perpe n dicular to the X axis The required angle b etwee n the plan e P an d the fro n t plan e o f proj ection is shown by the true size o f the angle b etwee n the fron t plan e and the lin e o f in tersectio n O f the auxil iary plan e B with the plan e P of th e . , . . . . , , , , . , , , , . , . . . , , . . , , ’ , . . , , , , , , , , , , . , , , , . The reverse o f this last operation is m ade use o f in draw in g th e traces o f pla n es whe n o nl y o n e o f them is give n o n the draw i n g If the horizon tal trace o f a plan e is given an d the angle the plan e makes with the horizo n tal plan e is kn own the fro n t trace c an 46 . . , constructed A ssume n o w that i n Fig 2 7b the horizon tal trace of the pla n e P an d the angle 0 the pla n e makes with the horizo n tal plan e are given Through any poin t in H P draw th e h horizon tal trace H A o f an auxiliary plan e an d the line i j makin g with H A an angle equal to the angle the plan e makes with the horizo n tal plan e This l ast li n e is the revolved positio n in the horizon tal plan e of a l i n e i j of which we k n ow the horizo n tal h h proj ectio n i an d the dista n ce ( 3 ) o f the poin t j b elow the hori The fro n t proj ection o f j is located by layin g O ff o n a z o n tal pla n e h lin e perpe n dicular to the X axis through j the distan ce marked s The lin e i j determi ned n o w by two proj ecti on s is a li n e i n th e The requir ed required pla n e an d j f is a poin t i n its fro n t trace fro n t trace is drawn the n through the proj ectio n j f and the in ter sectio n o f the give n horizo n tal trace with the X axis The meth o d is ex ac tly sim ilar when the fro n t trace and the angle the plan e makes with the fro n t plane are give n and the horizo n t al trace is to b e co nstru cted be . . , , . ’ ” , , , . ° , , . . . , . , . 47 PR OBLE M . ei ther 15 the hori z on ta l . or To nd fi the an gl e fron t pla n es of made by j on ec t ro i p a h v e n l a n e w i t i g p . Metho d To measur e the in cli n atio n to the horizo n tal plane Through any poin t i n the horizo n tal trace of the grven plan e pass auxiliary plan e perpe n dicular to this trace an ( It will b e perpe n dicular to the horizo n tal plan e ) The true angle b etwee n the horiz o n tal plan e an d th e li n e of i n tersectio n O f the auxiliary plan e with the give n plan e is the required an gle n n a n : me ure the i cli atio to the fro t pla e P ass auxil n n n a s TO n n b n pla e perpe dicular to the fro t tra e The true a gle etwee c n n i ary the fro n t plan e an d the lin e Of i n tersectio n Of the a u xiliary pla n e n n i ith the give pla e s the required a gle n w . . . . . . E 87 . X E R CISE S Fin d the a n gles b etwee the pla e P ( 0 1 2 0 horizo n tal an d fro n t plan es Of proj ectio n Take the data give n fo r the skew b ridge in n n an d ° , th e . 88 . Ex 2 7 . an d the angle b etween the plan e o f the portal horizon tal an d fron t plan es o f proj ection find an d th e . 48 PROBLE M . 16 Gi ven . one trace the an d mak es wi th the correspondi n g plan e of pr oj ecti on Method . Revers e the method E of , angl e a to find l a e n p e v i g n the o ther trace . the precedin g problem . XE R CIS E S The fro n t trace Of a plan e Q makes an an gle o f 315 with the X axi s The plan e itself makes an angle of 4 5 wi th the fro n t plan e D raw the horizo n tal trace The horizo n tal trac e o f a plan e R makes an angle of 30 with the X axis The plan e itself makes an an gle O f 4 5 with the horizo n tal plan e Draw F R — The pla n o f a dry dock is shown b y the poin ts a 4 — 2 ° , , ° . . . ° , , ° . . . - b —2 , — 4 , c ( , —1 , an d d —3 , T he , plan es o f the sides through a b an d c d slope toward the middle Of the dock an d make an gles of 4 5 with the hori z on tal D raw the traces o f the plan es of the two sides me n tion ed ° , . . n n Whe n n o e of the traces Of a pla e are give n an d we k n ow 49 onl y the angles the plan e makes with the plan es o f projection we have a more complicated problem than the last I n Fi g 2 8a a plan e P is shown i n a pictorial drawing A sphere is also repre sen ted w ith its ce n ter o n the X axis at e an d is ta n ge n t to the plan e P at i An auxiliary plan e A is represe n ted as drawn perpen di cu lar to the fron t plan e an d passin g through the po int i an d th e ce n ter o f the sphere e This auxiliary plan e cuts a great circle from the Sphere an d a li n e a b from the plan e P This last lin e is It is evide n t that the angle or b etween th e tangen t to the circle at i lin e a b and the trace F A shows the an gle between the plan e P and the fro n t plan e If the n the lin e a b is revol ved ab out the trace F A into the fron t plan e its revolved position wil l b e shown b y a b Lik ewise if the circular sectio n cut from the sphere bythe auxiliary plan e is also revolved in to the fro n t plan e it wi ll be a c i rcle . , . , , . . , , , . , , . , . . . , , ’ , . , coi n ciding however w ith the outli n e o f the sphere By this rev o l u ti o n in to the fro n t plan e the lin e a b an d the circular sectio n O f the sphere are shown in their true relative positio n and the poin t o f tange n cy i is shown at i The angle b etwee n a b an d F A marked a is the true size Of a S imilarly an auxiliary plan e B is represen ted i n the figure perpe ndicular to the horizo n tal plan e an d passing through the poin ts e an d i This plan e cuts from the give n plan e P the lin e 0 d an d a circular sectio n fr om the sphere The an gle fl b etwee n the lin e c d an d the trace H B shows the a n gle b etwee n the pla n e P an d the horizo n tal pla n e B y revolvi ng c d an d the c ircular sectio n in to the horizo n tal plan e the true size of Bcan be show n This method of a n alysis is most useful whe n the co n dition s — are reversed whe n o nl y the angles a an d fi are give n and the traces H P an d F P are to be determi n ed The actual process for the so Through a poin t e o n the l u ti o n of this case is shown i n Fi g 2 8b X axis as a ce n ter draw a circle of any co n ve n ie n t radius This represe n ts i n orthographic proj ectio n the revolved position in either the horizo n tal o r the fro n t plan es of an y sectio n s of the sphere cut b y auxiliary plan es passin g through the ce n ter I n order t o show the revo l ved po si ti on of the l i n e o f i ntersecti on with the plan e P o f an auxiliary pla n e perpe n dicular to the fro n t pla n e draw the lin e a b ta n ge n t to the circle at any co n ve n ie n t poi n t an d draw a radius e a so that the a ngle b a e is equal to the give n a ngle or b etwee n the plan e P an d the fro n t plan e The lin e e b is drawn perpen di cu lar to a e The triangle a b e that is thus formed correspo n ds to the revolved positio n O f the trian gle a b e shown very much fo resh o rt e n ed i n Fig 2 8a If n o w the le ngth e b ( Fig 2 8b) is measured an d laid O ff perpe n dicular to the X axis b ehi n d the poi n t e the h poi n t marked b is Ob tained A n d this is a poi n t i n the hori C on ti nui n g with the same ge n eral method draw z o n tal trace H P c d ta nge n t to the circle at a co n ve n ie n t poi n t an d by drawin g the radius 0 e lay o ff the angle 5 The i n tersectio n Of c d with e d perpen dicular to e c determines the poi n t d which is the revolved positio n of a poin t located o n the trace F P Layin g O ff then e d f n d equal to e d the poi t is Ob tain ed If n o w a e happen ed to , , ~ . , , ’ . , , ’ , ’ , . , , , , . , . . . , . , . . . . . , , , ’ , ’ , , ’ . ’ . ’ . . . , . . , ’ , ’ . ’ , ’ , , . ’ . " taken in such a position that it is perpen dicul ar to F P i n i ts true locatio n this trace could b e drawn immediately through d} " similarly H P c oul d be drawn through b an d 0 an d a ; an d S i n ce however a e was drawn in an y con ven ien t direction i t c ould n o t b e taken n ecessarily perpe n dicular to F P bu t O b vi o u sl y if an arc with a radius a e is draw n as shown i n the figure F P must b e draw n ta n ge n t to this are an d through the poi n t d Fo r the same reaso n H P will b e draw n ta nge n t to the arc with h a radius c e and thr ough the poi n t b be , . , , , , , , , , , ’ . 50 . PR OBLE M 17 . To nd fi the traces o f a l a e n w h h e e n t p angl es front plan es are gi ven Method Imagine a sphere placed tange n t to the plan e Of which the traces are to b e foun d an d tw o auxiliary pla n es are passed through t h e ce n ter Of the sphere an d through the poi n t where the — n o n e perpe n dicular to the fro n t pla n e sphere touches the pla e the other perpen dicu lar to the horizo n tal plan e These plan es will each cut a c i rcle from the sphere an d a tange n t li n e from the give n plan e The a ngles these tange n ts make with the fron t an d horizo n tal plan es resp ec tively are the a ngles the give n plan e make s with the fro n t an d horizo n tal plan es the pl an e ma kes w i th both the hori z on tal an d . . ‘ , , . . , , . E XE R CISE S Draw the traces o f a plan e P which makes angles o f 4 5 an d 60 respectively with the horizo n tal an d fro n t pla n es Draw the traces of a plan e which is i n clin ed 1 2 0 to the hori z o n tal plan e an d 7 5 to the fro n t plan e The side of a b ridge pier i n a river makes an angle o f 60 with the plan e o f the water an d 50 with a vertical plan e at right an gles to the course o f the river Represe n t the plan e o f the side of the pier by its traces o n ass umed plan es o f projectio n ° , , ° . ° ° . ° ° , . . 1 5 to a . PRO BLE M ne n l i v e i g Method . 18 . To nd fi the tru e di stance from a gi ven poi nt . D etermi n e the l e a n p Of the poin t an d the li n e by drawi ng through the poin t a l in e parallel to or in tersecti ng the given lin e Fi n d the i n tersectio n s of b oth lin es with either the horizo n tal or the fro n t pla n e With a trace of this plan e as an axis revolve these lin es i n to the correspon ding plan e o f proj ection and measure the dista n ce required . . , , . E XE R CIS E S the distan ce from the poi n t i — 2 — l L} ) to the — — — — — — lin e 7 2 li t i) k i t) The telepho n e wi res ru n n in g from a village to a house o n the side o f a mou n tain follow the shortest lin e b etwee n — n 2 n h A camp the poi ts v 3 0 )a d at c is to b e co nn ected to the telephon e system o f the v illage by erecti ng a li n e j oi n in g the o ne Draw the proj ectio n s of the shortest b etwee n v an d h li n e th at can b e put up ; an d find the le ngth of the lin e thus located I n the tria ngle give n i n E x 62 fi n d the dista n ce from the poin t e to the li n e a b Fo r supporti ng a cran e a cab le is to b e attached at o ne — — — 1 2 ) o n its mast an d at the 1 en d to a poi n t c other en d to a steel b eam a b — 1 o n an adj oi n i ng b uildi ng S how the pro jec ) tio ns o f the shortest cab le that c an b e u sed Fi n d - , , ° ~ , , , . , - , , . ' . . . , , , . . 2 5 n ot PROBLE M . i n the 19 me plan e sa Method To . fi nd the shortest di stance betw een two l i nes . Tw o li n es a b an d c d n o t i n the same plan e are sho wn P ass a plan e M N through a b parallel to c d ( Ar t i n Fig 2 9 Proj ect 0 d upo n this plan e A t the poi n t e where the pro n c d in tersects a b draw a li n e perpe n dicular to the pla ne i c t o e j i n tersecti ng c d at e The true leng th o f the perpen dicular e e i s th e r e q ui red distan c e . . , . . , ’ . ’ ’ . , ' . . E XE 99 . Fin d R CIS E S the shortest distan ce b etween Ex 25 . th e lin es to l m n in an d . Fi n d the distan ce b etwee n a lin e from a to b an d the m ast o f the derrick i n E x 7 1 Through each o f tw o lin es pass a pla n e parallel to the other l in e Fin d the shor test d i stan ce b etwee n these tw o planes S olve Ex 65 by the method o f this article . . . . . . o f PR O B LE M Gi ven the proj ecti on s of the cen ter of a ci rcl e draw i ts pr oj ecti o n s s o that i t sha l l l i e i n a 20 53 k n o wn di ameter , to . . l a n e v e n i p g ethod . M The cen ter o f a c ircle is shown by its proj ectio n s c The horizo n tal an d d i n Fi g 30 as lyi n g i n the give n pla n e P an d fro n t proj ectio ns o f the circle are to b e drawn so that the circle also shall lie in the plan e The ce n ter o f the circle is revolved ab out F P as an axis in to the fro n t plan e an d the true siz e o f the c ircle is draw n When th i s circle is revolved b ack i n to the plan e P b oth proj ectio n s will b e ellipses b ecause the proj ectio n s o f a circle o n la The n es of proj ectio n that are O b lique to its pla n e are ellipses p le ngth o f the maj or axis of the ellipse in the fro n t projectio n is the same as the diameter o f the circle an d is o f course parallel to F P As all le ngths which are perpe n dicular to the axis o f revolutio n ar e foreshorte n ed i n the fro n t proj ectio n the mi n or axis is the fore The fro n t proj ectio n s h o rten ed diameter perpe n dicular to F P o f the min or axis is the n o n a li n e o f i n defi n ite le n gth drawn through Mark the poin t where this proj ectio n c perpe n dicular to F P crosses the fro n t trace i f an d revolve the lin e i 0 i n to the fro n t plan e ab out i f cf as an axis The revolved positro n 1s shown by i f c F o m c lay o ff the le ngth o n which true le n gths c an b e measured r I n coun ter revolutio n c e equal to the radius ( r ) of the circle the poi n t 0 revolves b ack to c} and e to ef Then er of is the semi mi n or axis o f the ell iptical fron t proj ectio n of the give n circle The horizon tal proj ection o f the circle is the n easily foun d by h . . . . ' , . , , . , , . , . , , . , ’ . , ’ . ’ ’ - . ’ ’ . . h a s n r i g li es that lie the pla e P suc diameters through i n n ( n a w d n n o e t n d r n a c i ce ter ta ge ts to the fro t projectio n n n d c a ) n p j g th e poin ts o n them from the fro n t proj ection o f the circle The hori z o n tal proj ectio n o f the circle could b e fou n d also b y repeati n g the method used for ob tain ing the fro n t proj ectio n , , , . . n n i n n n This ro lem has n importa t applicatio determi i g a b 54 p th e plan e Of guide pulleys to direct b el ts ru nn ing b etwee n pulleys ? which are o n shafts at right angles to each other I n Fig 3 1 two pulleys are shown with ce n ters at e an d b The directio n of motio n The b elt must b e led O ff the pulley at b i n i s shown b y arrows To accomplish this i ts plan e an d led o n the pull ey at ai n i ts pla n e Usually th e guide pulley a guide pulle y is n eeded to direct the b elt may b e placed at any co n ve n ien t poin t b etween the two pulleys S elect a poin t where the directio n Of the b elt is to at a an d at b be cha n ged as the poi n t d i n the figure an d draw the l i n es f d an d d e ta nge n t to the p ulleys The plan e of the guide pulley mus t This plan e be the n in the plan e o f these tw o ta n ge n t li n es is shown by the traces H P and F P The proj ection s o f the guide pul ley are fou n d b y revolvi n g the lin es f d an d d e i n to th e horizo n tal plan e of proj ectio n ab out H P as an axis The revolved positio n o f d is show n at d The actual size O f the guide pull e i s shown tan ge n t to the revolved positio n s O f f d an d d e A fter r ev o l v i ng b ack i n to the plan e P the cen ter ( c ) O f the guide pulley is shown h f n n c c its proj ectio s a d The proj ectio n s O f the gu ide pu ll ey by are fou n d b y the method explai n ed i n the last article The shaft Of the guide pulley b ei n g perpe n dicular to its plan e is shown by proj ectio n s perpe n dicular to the co rrespo nn i ng traces I n Fi g 31 o n o n e side the b elt is led O ff the pulle y a i n l i n e with the rim o f the p ul ley b so that o n this side there is n o cha nge i n the direction o f the b elt I n practice however very often the give n pulleys are n o t placed so advan t ageousl y an d tw o guide pul leys are n eeded . . . . . . , , . . “ , , " . . . . . ’ y . ’ , . . . , , . , . . , , E 1 03 . X E R CIS E S Draw the proj ectio n s o f a circle diameter 1 5 i n ches l yi ng — i n the plan e Q 3 Two pulleys revolvi ng o n li n es of shafti ng at right angles to each other are to b e co nn ected by a b elt Determ in e the plan es of i n termediate pulleys to properly d i rec t the b elt drawi ng also the proj ectio n s of all the pulley s that are n eeded , , , 1 04 . . , . 55 a PR OBLE M . s t l a n e i b y p 21 sl o pe, Gi ven . a f su r ace to determi n e the by i ts secti o n o f co ntou r ed the l a n , p f su r a ce cu t a nd by the Method Draw the horizo n tal proj ection s o f a n umb er o f horizon tal lin es lyi n g i n the give n plan e an d havin g the same i ndices as the co n tour lin es The poin ts where these li n es mee t th e co n tour li n es with the same i n dices are poi n ts i n the required The compl ete sectio n is Ob tain ed by draw i ng a fair curve s ectio n thr ough the poin ts th u s O b tai n ed E X E R CIS E S 1 05 The figure b elow represe n ts a hill b y its co n tour li n es D raw plan es to show the emb a n kme n ts o f a rai lroad ” “ passi ng through it S how the i n tersectio n s o f cut these plan es with the surface of the hill . , . . . . . . . p j v v p Co n to u r l i n es a re u se d to o i n o i n ts a t th e sam e el e a ti o n ab o e a l an e Num b e rs o n th ese l i nes , c al l ed o f w h i c h th e el e a ti o n i s a ss u m e d to b e z ero i n dices re r ese n t th e el e ati o ns , p v . v . CHA P T E R P R O B L E MS R E LAT I N G TO E very s u rface may II I P LA NE S T ANGE NT SO LI D S TO gen erated by the motio n of a li n e an d the diff ere n t positio ns assum ed by this li n e are called the el e m en ts o f the surface A pla n e s urface o r a pl an e is ge n erated by a straight li n e movi ng alo n g a n other s traigh t lin e an d remain in g always parallel to its fi rs t * ositio n p A si n gl e curved surf ace IS ge n erated b y a straight lin e movi n g so that any tw o o f its co ns ecutive positio n s are i n the same pla n e A w arped o r tw i sted su rf ace is ge n erated b y a straight lin e movin g so tha t n o tw o o f i ts co nsecutive position s are i n the same la n e p Plan es sin gle c u rved sur faces and warped surfaces are ge n erated by the motio n of a straight lin e an d therefore all have eleme n ts that are straight l ines E very warped surface however is curved an d it is therefore possib le to co n ceive i t also as b ei ng ge n erated by a curve which as i t moves c o n tin ual l y cha n ges its form accordi n g to a de fi n ite l aw A d o u bl e c urved su rf ace is ge n erated b y a curve movi n g alo n g an other curve I t has no elemen ts that are straight lin es 56 . be , . . . . , , , . , , , , , . . . n n n o e is a si gle curved surface ge erated b y a straigh t 57 lin e moving along a curve an d also passi ng through a poin t n o t i n the plan e o f the curve This poin t is the v ertex Of the con e A cy lin der is a si ngle curved surface ge n erated b y a straight li n e movi ng alon g a cur ve with all its positio n s parall el It may b e regarded as a Special case o f a co n e with th e vertex at in fi n ity . A c . . . . A kn o w l edge o f T h e m eth o ds o f di scu sse d i n th e re p p p ti ti g p l g h pt th e re sen p recedi n ro er pl a n es , a n d n c es o f a e rs . an e s p w a s assu m e d i n th e o in ts an d l i n es i n th em , b egi nn in g h ave b een . P roblems relating to cylin ders are solved therefore the same methods that are applied for similar prob lems relati n g to co n es A pla n e cuttin g all the straight li n e eleme n ts of a c on e or o f a cylin der i n tersects it i n a curve called the base If all the eleme n ts of a co n e make the same a n gle with a straight lin e passin g through the vertex it is a righ t c on e ; otherwise it is If all the eleme n ts of a cylin der are pe rpen dicular an O bli qu e c o n e to the b ase it is a righ t cyl in de r ; otherwise it i s an o bli qu e cyl i n by . , , . , , . , der , ) . o n vol u te is a Single curved surface ge n erated by a straight li n e m o vrng alo ng a curve of doub le curvature SO that it is always tange n t to the curve The co n secutive positio n s o f the straigh t li n e ge n erating the surface i n tersect two an d two n o three i n ter sec ti n g i n a commo n poi n t There are as many ki n ds o f co nvolutes as there are curves o f doub le curvature S ome are importan t for their practical appl i catio n s The methods o f co n struct in g an d represe n ti ng them will b e discussed i n Ar t 7 6 58 A . c , . , . . . . . u rf a c e o f revo l utio n is o n e that is ge n erated b y the rev o l u ti o n of a straight li n e or a pla n e curve ab out a straight li n e i n the same pla n e as an axis — There are o nly two Si ngle curved surfaces of revolutio n the right co n e an d the right cyli n der whe n they have circular b ases The prin cipal doub le curved surfaces O f revolutio n are the S phere — a n the ellipsoid the torus the parab oloid d the hyperb oloid sur faces which are explain ed later 59 . A s , . , , . , , , , . poi n t i n an y plan e or curved surface is determi n ed b y If the n a su rfa ce is give n by the proj ectio n s of tw o proj ectio n s its outlin es an d a poi n t o n the surface is give n by o nly o n e proj ectio n an other projection c an b e located after determi n ing two proj ectio n s o f an el emen t of the surface passi ng thr o u gh the po i n t I n Fi g 32 a con e is Show n b y the hori z o n tal an d fro n t proj ectio n s Of i ts outlin es A poi n t a o n the surface Of the co n e is give n b y its 60 . A . , , , , , . . ~ . horizont al pro j ection The horizo n tal proj ectio n o f an element h and the vertex o f the co n e is draw n through a As the poi n t a may be o n the top side o f the co n e n earest the horizo n tal plan e o r o n the lower side there are two eleme n ts b v and c v with hori z o n tal h proj ectio n s passi ng through a The fro n t proj ectio n s of these two eleme n ts bf vi an d cf vf are drawn through the vertex and through the fro n t proj ectio n s of the i n tersectio n s of the two ele me n ts wi th the b ase, The required fro n t proj ection s O f the poi n t a are the n o n the eleme n ts bf vi an d o f vi at a l f an d a zf Fo r the case Of the cyl i nder the same method o f solutio n is applicab le . . , , , , . , , , . . 61 . PROBLE M 22 Gi . ven on e j o e t i o r c n p o f poi nt on a the su r face o f a con e to find the o ther pr oj ecti on Method Through the give n proj ectio n O f the poin t an d th e vertex of the c o ne draw eleme n ts Of the surface Fi n d the required projectio n s o f the poin t o n the other proj ectio n s o f these eleme n ts , . . ‘ . . 62 . PR OBLE M face of a cyl i nd er , 23 Gi ven . find to the on e o ther j r o e o c t n i j p o e c o n r t i p o f o o n t n i p a the su r . Method Through the give n proj ection o f the poin t d raw eleme n ts o f the surface parallel to an y eleme n t shown A s i n th e case o f the co n e precedin g the required proj ection s o f the poin t are fou n d o n the other proj ectio n s o f these eleme n ts . . , . Whe n a po in t o n a double curved surface such as a Sphere ellipsoid torus etc is give n by o nly o ne pro j ectio n a differe nt method is used for fi n din g the other projectio n o f the poin t o n the surface tha n that employed for the co n e an d the cyli n der I n Fig 33 the horizo n tal an d fro n t proj ectio n s O f an ellipsoid are shown A poi n t a o n the surface o f the ellipsoid is give n b y its fro n t pro i n through a an d the ce n ter o f the ne i A pla P is draw n a e c t o j ellipsoid perpe n dicular to the fro n t plan e Its fro n t trace i marked F P If this plan e is the n revolved SO that it is parallel to the horizo n tal plan e the fro n t trace is shown by F P and the fron t projectio n o f a is at M The plan e F P cuts from the ell i p so i d a secti on o f which th e h o ri z o n tal proj ectio n o f the surface is an 63 . , , , . , , . . . , , , . , s . . ’ , , ’ . ~ , ’ ’ exact represen tatio n ; an d a ( the revolved positio n o f a) h as i ts h I n revolvi n g the pla n e P b ack to its horizon tal proj ectio n at a o rrgl n al positio n the poi n t a moves to a i n a circular arc l yi n g m a vertical plan e The fro n t proj ection of this ar e is M of ; an d its h h horizon tal proj ectio n is O f course a a parallel to the X axis h The required hori z o n tal proj ectio n a is then determ i n ed b y f n n a n drawi g proj ecti g li es from O b serve that the solution gives also an other projecti o n a l h s h ow n at the top o f the fi gure . , , . , , , , . , . , , . PROBLE M 2 4 Gi ven o n e proj ecti on of a poi nt o n a dou bl e cu rved su r face to find the o ther proj ecti o n Method Through the give n projectio n of the poi n t an d the cen ter o f th e double curved surface draw the trace of a pla n e perpe ndicular to the pla n e of proj ectio n i n which the proj ectio n o f the poi n t is give n Revolve this plan e SO that it b ecomes parallel to a seco n d plan e O f prO jec ti o n D etermi n e the projectio n s of B y revolvi n g b ack to the the poi n t i n its revolved positio n origi n al positio n the required proj ectio n o f the poi n t is located * 64 . . , . . . . . . , . gen eral a pla ne is tangen t to a surface at a give n poi n t when it passes through tange n ts to tw o li n es of the surface meeting i n the give n poi n t If the n through a given poin t any two i n ter se cti n g li n es of the surface are drawn an d a ta n ge n t to each l i n e is drawn at the poi n t the required pl an e is determi n ed by the ta n gen ts Fo r drawin g a pla n e ta n ge n t to a si n gle curved surface the ge n eral method is somewha t simplified I n the case of the co n e we may ob serve that if a plan e is tan ge n t to the surface at a give n poin t it is tange n t to the surface thoughou t the le ngth of an 65 In . , , , . , , , , . , . , , An o th er m e th o d i s to th e d o u b l e c u rved su f ac e r j j ec ti o n ec ti o n O f of b, h th e c, h th e of a s b ase i ts f ro n t o in t i n th e Of a h b an d , I f th e p p j p j d r aw th at i s gi p w i th and , v fi b as . p ro ec ti o n is in th e el l i p so i p an arc . p xi a s on xi th e a s of th ro u gh th e pro th e pro gi en as s i n g v . o int 1s d es p . . ro ec ti o n o f a o u tl i n e o f i ts g ri gh t c yl i n d e r T h e h o ri z o n tal h nd a r n a e a a a d O f th e oin t a , su rf a c e as a c e n te r , a n d a rad i u s th e one o f w i th i ts by p ro j ec ti o n th e b a se a e I n Fi g 34 th e o i n t a i s ra w th ro u gh (Lf th e f r o n t re D u g en re c e d i n a ri gh t c yl i n d e r gi v by en T h e f ro n t to ro ec ti o n s o f i ts h o ri z o n tal w i th th e f ro n t e q u al p j p j ro r p j ec ti o n o f ro ec ti o n th e xi a s Of p j ro ar e th en dl f an d th e " th e h o ri z o n tal d i stan ce f r o m ec ti o n s dh , as d . eh to element passing through the give n poin t and is therefore tangent T he to the co n e at the poi n t where this elemen t meets the b ase con structio n o f tange n ts at the gi ven poi n t makes it n eces sary to represe n t sectio n s o f the con e which is usually a lab orious process A tange n t to the base at its i n tersection with the eleme n t is more easil y co n structed an d is used i n stead o f the ta nge n t to a sectio n at the g ive n poin t I n Fig 35 a co n e i s Shown with a poin t a marked o n its surface The plan e ta n ge n t to the co n e at this poi n t is determi n ed by th e elemen t b v through a an d by a ta ngen t b c to the curve o f the b ase at its i n tersectio n with b v T w o i n tersectin g lin es b v and b c are thus represe n ted They determi n e the plan e P which is tan gen t to the co n e at the poi n t a As a cylin der may b e regarded as a special case o f a co n e wi th th e vertex at i n fi n ity the problems relati n g to the cyli n der will be solved b y the s ame methods as fo r similar pro blems relati ng to the c o n e , . , . , . . , . , . , . , . , . PROBLE M 66 . der thro ugh a To pass a plan e tangent to s u rface o n t o h e i n t p 25 gi ven . a con e or a cyl i n . Method Through the give n poi n t draw an eleme n t O f the surface A t the i n tersectio n Of this eleme n t with the b ase draw a line tange n t to the b ase The required plan e is determin ed b y the elemen t and this tange n t l i n e . . , . . E XE 1 06 1 07 . . R CISE S Pass a plan e tange n t to an Oblique cyli nder through a poin t b o n its surface : The b ase o f an i nverted right c i rcular c on e is i n the ho ri z o n tal pla n e an d the a ngle b etwee n the eleme n ts of the surf ac e and the axis is P ass a plan e tangen t to the co n e through a poin t c o n its s urface , . plan e may b e drawn tange n t to a co ne a l so through a poin t which is ou tside the surface B oth the vertex o f the con e an d the given poin t must b e o f course in the tangen t plan e A lin e 67 . A . . j oini ng the vertex the b ase o f ta nge n t plan e the give n poin t and another line tangent the con e an d i n tersecting the fi rst lin e determin e the to an d , , . a poin t 0 outside o f it are shown A lin e 0 v is drawn through the poin t 0 an d the vertex v Through the intersectio n o f o v with the plan e B o f the b ase the lin e i t is drawn ta nge n t t o the b ase The tangen t plan e P is determin ed by these li n es o v an d i t Whe n for the same co n dition s a cyli nder is used instead of a con e the solutio n is the same except that the lin e drawn through th e vertex for the c o n e i s replaced by o n e through the give n poin t parallel to an eleme n t I n Fig 36 . a co n e an d . . , , , . . , , . 68 . PROB L E M der throu gh a 26 T o pass . v e n n t i o i g p a o u tsid e n e e o l a t a n n t t p g the su r face a cone o r a eyli n . Method Through the give n poi n t draw the proj ection Of a lin e which i n th e case o f the c o ne passes through th e vertex an d i n the case o f the cyli n der is parallel to an eleme n t Produce this lin e to in tersect the plan e o f the b ase and draw a tange n t to the The required plan e is de b ase through the poin t o f in tersectio n term i n ed by this ta nge n t li n e and the lin e already drawn through the give n poin t . , , , , , . . . E X E R CI SE S P ass a plan e tange n t to i n the X axi s P ass a pl an e tangen t an oblique co n e and through a poin t . a cylinder which h as o n e b ase i n the horizo n tal plan e an d a n other i n the fron t plan e an d throu gh a poi n t i n the fro n t pla n e outside the b ase ' to , . 69 to a . PROB L E M v e e i n l n i g 27 . To pass a l a e n t a n e t o n t p g nd a co n e a a r a ll el p . Method Through the vertex Of th e co n e draw a lin e parallel to the given lin e A t the poin t where this lin e in tersects the plan e Of the b ase draw a lin e tangen t to the b ase These tw o lin es de termin e the required plan e . . , . . E X E RCIS E S Pass a plan e tangen t to an in verted Obli que co ne and paral lel to an Oblique li n e P ass a plan e tange n t to a right c ircular con e to a lin e i n the side plan e P ass a plan e tangen t to a right c ircul ar con e to an Ob li q ue lin e . an d parallel an d parallel . . 70. ll e l r a a p PR O B L E M to 28 T o pa ss . plane tangent to a a cyl i nder and e n v l i n e i g a . Method Through any poin t i n the give n lin e draw a li n e parallel The pla n e determ i n ed by the give n to an eleme n t o f the cyli n der line an d the l i n e j ust drawn will be paral l el to the required plan e A pla n e ta nge n t to the cyli nder is the n determi n ed b y a lin e tan e n t to the b ase an d p arallel to the pla n e already fou n d and the g eleme n t o f the c y linder which the t ange n t l i n e in tersects . . . , . E XE R CIS E S plan e tangen t to an Obli q ue c yl inder and parallel to the X axis P ass a plan e tangen t to a righ t circular c y lin der wi th i ts b ase i n an oblique plan e an d parallel to a li n e i n the same Oblique plan e P ass a . , . 1 7 . PRO B L E M l uti on thro ugh a 29 To pass . e n v o i n t i g p on a e t a e l a n n t t o n p g i ts f su r ace f f a su r a ce o revo . Metho d Draw through the given poi n t a lin e tangen t to the i ntersectio n o f the surface with a plan e passi n g through the po in t Whe n this lin e is revolved ab out the axis it ge n erates and the axis a right con e tange n t to the surface i n a circum fere n ce which c o n tain s the give n poi n t A plan e tan ge n t to the con e at the given poin t is the re quired plan e tange nt to the surfac e . . . . . R CISE S Th ro ugh any point a o n the surface o f an ellipsoid wi th a vertical axis pass a tange n t plan e A circle 1 in ch i n diame ter with its plan e perpe n dicular to the horizo n tal plan e r evo l ves a bo u t a ver ti ca l a xi s which is three in ch es from the cen ter o f the circle A surfac e o f revolutio n called a to ru s is thus ge n erated Thro ugh a poin t b o n t his surface draw a tangen t plan e E XE 1 15 . , , . , 1 16 . , . . . 2 7 PRO B LE M . thro ugh a 30 . To p ass a n l a n e t a e n t t o g p a pher e s and v l i i e n ne g . Method P ass an auxil iary plane perpendicular to the give n line through the ce n ter o f the sphere (This plan e cuts a great circle from the sphere an d wi ll cu t a li n e ta nge n t to this circle from th e requi red tan ge nt plan e ) Revolve the auxil iary plan e with i ts in tersec tio ns with the given l i n e and the sphere in to a plan e o f pro n o f the give n li n e with n n Through the poi t Of i tersectio n c i o e t j the auxiliary plan e draw a lin e ta ngen t to the circular i n tersectio n A plan e passed through o f the auxiliary pla n e with the Sphere th e ta n ge n t li n e ( whe n revolved to i ts o riginal o r true position ) and th e giv en li ne is the o n e r eq uired . . . . . . R CIS E S Draw a pl ane tange n t to a Sphere and passi ng thro ugh an y ob lique lin e P ass a plan e through a lin e parallel to the X axis an d tange n t to a sphere wi th i ts cen ter in the horizo n tal plan e E XE . . regular prism wi th sixteen sides Th e studen t must n o w f orm a me n tal pic ture o f a righ t is Shown h k r n n f b n ria gle made o thi card oard esti g o t h pro ectio e n 3 n i t j This proj ectio n shall be al so the horizon tal leg o f in the figure the trian gle The vertical leg is Shown in the fron t pro j e ction o f the prism by the distan ce from 17 to the bas e We c an imagi n e then suc h a paper triangle wrapp ed aro und th e pri sm wi th th e ver 73 . Convo l utes . I n Fig 37 . a . , . . . tical leg through i held station ary and the long leg of th e triangle always touches the b ase of the prism The fro n t proj ectio n o f the hypothe n use o f this paper tria n gle is the n a b roke n li n e co nn ectin g the front proj ectio n s Of the poin ts i h g c b a E ach portio n of this b roke n li n e i s equ al l y in cl in ed to the edges The horizo n tal proj ectio n Of the h ypothe n use is o f the prism the broke n lin e j o in ing the horizo n tal proj ectio n s of the same poi n ts The surface o f the paper trian gle i s n o w u n wrapped tak i ng it o ff A n d if i t is tur n ed o n each o n e S ide of the prism at a time edge of the prism i n successi on as o n a hinge till each un wrapped portio n co i ncides with the plan e of the n ext Side the portio n o f the hypothe n use that has b ee n released b ecomes an exte n sio n an d a tange n t Of the portio n o f the b roke n li n e o n that side of the prism Thus whe n the portio n b etwee n a and b is u nwr apped it b ecomes tange n t to the S ide in which b c lies ; an d whe n also the portio n b etwee n b an d c is u n rolled the portio n a b c o f the h ypothe n use i s tan ge n t to the side co n tain i n g 0 d Let us n o w co n sider the properties Of this b roke n li n e from The portion a b i n tersects b c b c in tersects c d etc ; tha t a to i ” “ is the y in tersec t tw o an d two ; b u t a b does n o t i n tersect c d no r does b c i n tersec t d e etc . , , , , , . . . , . , , . , , . , . , . , . , li n e o n the prism If the n umb er of S ides of the prism is in creased in defi n itely the b roken lin e o n its surface b ecomes a curve called a h eli x It is a curve ge n erated by a poin t movi n g o n the surface Of a cylin der Of revolution SO as to cut all the eleme n ts at a co n stan t a ngle The movi n g poin t has u n iform motio n ar o u n d an d at the same time n struc ti n g ll l to the axis The method for co o f the cyli n der e r a a p a helix i s Shown i n Fig 38 The axis of the hel i x is vertical SO that the horizo n tal proj ection is a circle with its cen ter at o in the axis N ow if the ge n erati n g poin t moves the d istan ce from f i to i n maki n g o n e complete revolutio n a b out th e axis v m passin g th rough the poi n ts m p s t u an d v the vertical dista nc e f is called th e i tch Of th e helix etwee n v a d W n b p 74 . C o n sider also an other property of the b roke n , . . . , . , . . , . , , , , , , , . is formed o f the tangen ts to th e broke n li n e in Fi g 37 whe n the n umb er O f S ides O f the prism has b een in creased in defi n itely an d it b ecomes a cylin der The elemen ts o f this surface are the li n es m b n c o d p e q f etc S uch elemen ts when tange n t to a cyli n de r form a co n volute su rf ace P ortion s o f such surfaces are represe n ted i n Figs 39 an d 4 0 They are surfaces ge n erated by a str aigh t lin e m ovi n g alon g a c u rve o f dou bl e cu rv atu re so th at th e li n e I n this surface agai n an y two i s alw ay s t an gen t to th e cu rv e b u t n o three c on secutive straight l i n e eleme n t lie i n the same plan e The co nvolute surface i n Fig 4 0 can b e regarded as formed by the co n secutive positio n s of the hypot he n use O f a paper tria n gle as it is u n wou n d from the surface of a cylin der o f which the b ase h h h " is the circle a d n e The poin t a at the en d of the u n wi n din g h h h h tria ngle will always lie i n the curve a c i f i n the hori z o n tal plan e This curve is the in v o lute of the circular b ase of the cyli n der ; The b u t it is also the hori z o n tal trace o f the co n volute surfac e cyli n der itself i s n o part of the s u rface O b serve the striki ng resemblan ce b etwee n the way this surface wi n ds arou n d a cyl i n der S hell an d the c o n volutio n s o f a sea — Whe n a helical co n volute is to be represe n ted o n a drawi n g the curve of the hel i x to which the surface is ta nge n t should — draw i ng first the top and fro n t views b e accurately co n structed Of the cylin der o n which it lies If the axis is vertical with the b ase i n the horizo n tal pla n e it is show n ab ove that the horizo n tal trace of the co n volute is the in volute Of the c i rcular b ase 75 A . v cu r e d su rf ace . . , , , , , , . . . . , . , , , , . . . . . . . , . , , . If a poi n t m o n the con volute surface i n Fi g 4 0 is given h o nly by the horizon tal proj ectio n m the fro n t proj ectio n can be foun d by co n structio n The horizo n tal proj ectio n o f an elemen t 76 . . , . If a v cu r on tan gen t in e c al l e d an th e th re ad i n vo l u te c i rc u l a r at a , of ro l l s u v on a o l u te O f b ase th en th e th e p c i rcl e . an d th e fix d c u ve an y p i n t fi st I n Fi g 4 0 su pp k pt e en d a t a e r r . tau t o , . as i t is w i l l d es c ri be o mi t d esc ri b es o se a u n w o un d th e c ur v a s ec o n d th re a d to b e w o u n d f ro m th e h h e a c i h e nd O f th e ed th e " al l f , c pass i ng through the poin t m can b e drawn tangen t to the c i rcul ar " " an d it will in tersect the in volute at i The front b ase at n proj ection s o f n an d i are respectively in the helix at rd an d at 17 h f B y drawin g the proj ectio n i n } i a n d a projecti n g lin e from m the fro n t proj ectio n o f m is determi n ed The solution can b e reversed : If the fron t proj ection Of a poin t o n the c o n volute surface is give n the horizo ntal proj ectio n c an b e fou n d . , . , , . , . 77 . PR OBLE M 31 . Gi ven o ne j e o t o n o r c i p f a n t a v o o lu te o n co n i p Method Draw a proj ec tio n o f an eleme n t through the give n proj ec tio n Of the poin t D etermin e the other proj ection of this eleme n t an d locate o n it the required projec tio n o f the poi n t . . . E X E R CIS E S Draw the pro j ectio n s o f ten equidis tan t elemen ts o f a helical co nvolute surface with a vertical axis The diameter an d pitch of the helix are respectively 2 i n ches an d 3 in c hes Fi n d the i n tersectio n s o f the con volute surface give n i n E x 1 1 9 with tw o plan es perpen dic ul ar to the ax is of the hel i x Ob serve the Shape o f the c urves cut by these plan es Draw the pro j ections o f six elemen ts o f a con volute sur f ace O f which the axi s is parallel to the X axis The diameter and pitch o f the helix are respectivel y2 % i n ches A ssume o n e pro j ectio n of a poi n t o n the an d 4 i n ches surface an d locate the other proj ection (Use the Side plan e ) D raw tw o helices o n e right han ded an d the other left han ded o n a cylin d er 1} in ches I n di ameter an d 2 i n ches high the former to b e Of 1 in ch pitch an d the latter 1 Of in ch pitch Represe n t a square thread ed screw Of the followin g . . . . . . . . . - , 7 , , 2 . - dimen sio n s : O u tside diameter o f the thread is 2 } in ch es Diameter at the b ottom o f the thread is 1 5 i n ches Pitch is 1 inch Thick n ess O f the thread is 4 i n ch S how two complete turn s of the thread A Spiral sprin g is O f the form of a square screw thre ad The cross sectio n is 4 i n ch square and the outside diam eter an d pitch are respectively 3 i n ches an d 2 in ches Draw two complete turn s of the sprin g ” A Spiral Sprin g is made Of rou n d wire as S hown i n the fi gure The diameter o f the wire is 5 in ch The outside b elow diameter O f the spri n g is 2 } in ches an d the pitch is 2 i n ches Draw the plan an d elevation o f tw o tur ns O f the Sprin g Su ggesti on If a Spiral Spring is made Of roun d wire w e co n ceive its surfa ce to b e ge n erated by a sphere m o v i ng alo ng a helix which is the ce n ter li n e o f the wire The proj ec tion s o f the helix are fi rst drawn and the n th e projectio n s o f the sphere i n a n um b er o f di fferent positio n s 7 . . . . . . - , . . « . . . . . , . . 8 7 . PROBLE M face through a 32 gi ven To pass a plane tangen t to su rface o i h e n t o n t p . a co nvo lu te sur . Method (The same as for the con e o r the cylin der ) Through A t the in tersectio n th e give n poi n t draw an eleme n t of the surface The requi red plane o f this eleme n t with the b ase draw a ta nge n t is determin ed b y the eleme n t an d the tan ge n t lin e . . . . . 79 and . PROBLE M 33 throu gh Metho d a e i v g n . To pa ss a pla n e tan gen t to o u tsi de the su r face t o n i p f a co n vo l u te su r ace . Through the give n poi n t pass a p lan e w hi ch is per n tersectio n of thi s pla n e The i i cu l ar to the axis of the Surface n d e p with the surface is an i n volute to which a tan ge n t is then drawn from the give n poi n t Draw an eleme n t o f the surface at the poin t . . , . ta n ge n c y T his element req uired plan e of . an d the tan gen t lin e determi n e . E XE 12 6 . Draw a plan e tange n t to the helical c onvolute c onstructed i n E x 1 1 9 at any poi n t o n the surface Draw a plan e tangen t to the con volute surfac e c onstruc ted in E x 1 2 1 and through any po in t o u tside th e surface . 127 . R CISE S . , . . C HA P T E R I N T E R SECT I O NS A ND DE IV V E L O PME NT S O F SO LI D S The i n tersectio n o f an y su r f ace with a gi v en pl an e is fou n d by passi n g a series o f au xi li ary pl an e s I n such a way that they cu t from the sur face strai gh t lin es c i rcl es o r oth er cu rv es th at can b e qu i ck l y dr awn ; an d from the give n plan e strai gh t l i n e s The in tersectio n s o f these li n es cut from the surface with the l in es cut from the plan e determin e poin ts o n the required i n tersectio n Whe n straight li n e elemen ts can b e cut from the surface the aux il i ary plan es are usually passed perpe n dicular to o n e o f the pla n es Wh en circles c an b e cut from the surface the aux o f proj ectio n i l i ary plan es should b e drawn par a llel to the plan e o f pro j ection o n which the proj ection s o f the circles w il l appear i n their true form The tan gen t to a cu rve o f i ntersectio n at a give n poin t o n a su r face lies i n the plan e which cuts from the surface this lin e o f i n tersecti o n It is als o a li n e i n the tange n t plan e to the surface at the give n poin t 80 . , , , . , , , . . , . . . The curve o f i n tersection o f an o bli qu e c on e with a plan e P The required curve o f in tersectio n is shown is Shown i n Fig 4 1 i n the figure by its elliptical proj ectio n s o n which the po m ts s an d t are marked The curve is Ob tai n ed b y drawi n g a series o f au xili ary h r n h e n h h l r u t h n n n u a r t o t t t o g v o r l f o a e s e e r t e f t e d e e di c x e o c a p p p a n e n l the horizo tal traces wi l perpe n dicular the X axis t l e o b p ( ) E ach auxiliary plan e cuts from the c on e el em en t s an d from the given plan e a strai gh t li n e I n the fi gure o ne o f these auxiliary plan es is marked b y its traces H A an d F A This auxiliary plan e cuts from the c on e the elemen ts a v an d b v an d from the plan e a straight lin e m n The in tersection s o f the proj ection s o f this last lin e with the proj ection s o f a v an d b v give respectivel y the poin ts 3 an d t o n the re q uired li n e o f i n tersec ti o n 81 . . . . . i , . , . . . The curve o f in tersection o f an obli que c ylinder with a given plan e is foun d by the same ge n eral method usin g auxiliary planes that will cut eleme n ts from the surface o f the cyli n der and straigh t lin es from the give n plan e , . A pl an e w h i ch i s tan gen t to a gi ven c o n e o r a cyli n der, If , then , the surface o f a co n e , c o n tai n s an el em en t o f i ts su rf ace 82 . . a cylin der is rolled o n a tangen t plan e u n til each o f its eleme n ts has come in to this plan e the par t Of the plan e passed over and i n c luded b etween the extreme elemen ts is a pl an e su rf ace equ al to th e gi v en su rf ace The surface thus p as sed over is called a dev elop men t I n o rder to determin e the positio n s o f the diff ere n t ele me n ts o f the surface as they come in to the plan e o f developme n t it is n ecessary to lo cat e so m e c u rv e o n th e su rf ace w h i ch wi ll dev elo p i n to a str aigh t l i n e Or a sim pl e curv e upo n which the actual distances betw een th e eleme n ts can b e laid o ff The sectio n cu t I n Fig 4 2 an Ob lique cyli n der is Shown f rom thi s c y li n der b y a hori z o n tal pla n e happe n s to b e a circle Through the poin t a a plan e is passed cutting the surface i n the straight li n e through the poi n ts a c and e The curve of in ter sectio n whe n revolved through 90 in to the plan e o f the drawi n g is shown as the circle 1 2 3 4 5 T h e ci rcumferen ce o f th i s c i rc l e i s th e a ctu al l en gth o f th e dev elo pm en t o f th e cyli n de r If we wish to develop the part Of the cylin der ab ove the i n ter sectio n we draw the b ase li n e a a making its le n gth equal to the c ircumfere n ce of the circular i n tersectio n A poi n t b o n the curve of the dev elopme n t is immediately located over the poin t a at a distan ce laid o ff o n an eleme n t equal to that from a to b i n the to p b ase O ther poin ts are take n in the same way To locate an other poi n t o n the curve of the devel o pm en t th e distan ce 1 2 is laid O ff o n the b ase li n e equal to the arc 1 2 an d the le ngth c d is the width at this poi n t o f the surface we are developi n g B y co n ti n uin g the process a series o f poin ts is Ob tai n ed an d the surface in cluded b etwee n the curve drawn through these p oin ts an d the b ase li n e is the developme n t o f the surface o f the cyli n der ab ove the in tersectio n with the plan e passed through a or , , . . , , . . . . . , . , , ° , , , . , . , , , . , ' , , . . ' , , , , . , . The method for the developmen t o f a con e b ei ng similar it ne eds n o expl an ti o n The problems relating to developme nts Of surfaces are co n O f course theoretic stan tl y appl i ed by w o rk e rs i n sh ee t m etal ally i t makes n o diff ere n ce which elemen t o f the surface is cut “ for the developmen t ; b u t practically it is eco n omical to ou t ” so as to make the shortest seam unless however there are good reaso n s for doi ng otherwise , . . , , , , , , , . 83 e l a n p . PROBLE M 34 . To nd fi ‘ the i n tersecti on o f an y cone wi th an y . Method P ass through the co ne a series o f aux i liary plan es take n either perpe n dicular to its axis or through the vertex an d perpe n dicular to o ne of the plan es o f proj e ctio n Fo r the curve o f i n tersectio n j oi n the poi n ts where the l i nes cut from the c o n e in ters ect th e l in es cu t from the plan e . , . . ’ . . E XE R CIS E S Draw the c urve o f i n tersectio n o f a right c one axis ver tical with an Ob lique plan e Draw the devel opmen t o f the portio n Of the co n e b etwee n the li n e o f i n ter sectio n an d the vertex Taking the data of E x 4 2 determin e the curve o f i n ter sectio n o f the co n e of rays of maximum in te ns ity with the plan e Of the desk Make the draw i ngs for the patterns o f the b ath tub shown i n the figure o n page 1 34 — s o e S u gg ti n Th is exercise requires merely the devel n es with vertices at n and O pm e n t of porti on s o f tw o c o As sume sui table o an d the patter n s o f pla n e surfaces dimen sio n s for those n o t give n i n this exercise and i n those that follow Draw a pattern for the sheet metal for a regularly flaring n n n n a l e o roof co ectio lik the o n i c e Shown i n the c ) ( , . , . . , . - . . , , . figure xis o f the cyli ndri cal p1pe is vert i cal and th e pla n e o f the roof is represen ted by R( 0 A con ical tower is to b e placed o n the righ t han d s i de S how the 82 o f the irr egul ar hi p roof shown i n E x true size of the hole to b e cut i n the roo f — s Fi n d the true size o f the curve o f in ter Sugge ti on sectio n b y r evo l vi ng the cu rve ab out o ne o f the traces C f A rt 5 3 o f its pla n e in to a plan e of proj ectio n Dr aw the pattern fo r a b oot to j oin two pieces o f stove pipe o n e o f which is c ircular and the other oval The circul ar pipe is 6 in ches i n diameter an d the oval pipe is represen ted by parallel sides 2 } in ches apart long wi th se micircles at the en ds o f an d 5 4 in ches I n other words the over all di men th e parallel Sides Mak e the s io ns o f the oval are 8 in ch es by 2 k in ch es “ oo ” 1 0 in ches long b t Th e . a , - . . . . . , . . . , , 1 , - , . . . . 84 any . PRO B L E M l n e a p 35 . To nd fi the i n tersecti o n o f wi th an y cyli nder . Method Pass through the cylin der a series o f auxili ary plan es taken either perpen dicul ar to its axis o r parallel to its axis and r the cu rve o f n F n f n f o erpe dicular n the pla es proj ectio o t o o e o p in tersectio n joi n the poi n ts where the l in es cut from the cyli n d er in tersec t the l i n es cut from the give n plan e , . , . . EXE R CIS E S Fin d the true size and shape o f the hole cut fo r a circular chi mn ey i n a ti n coveri n g fo r the right ha n d S ide o f the hi p roof give n i n E x 7 9 Draw the pattern for the i n cli n ed en d o f a b ath tu b with a semicircular cross —sectio n The i n cli n ed n is as d e ( sumed to be a plan e surface Fi n d the true size of the Ope n i n g to b e cut in the wal l Shown i n Fig 5 1 for a pipe 3 feet in diameter maki n g an gles o f 30 an d 2 0 respecti vel y wi th the hori z o n tal an d with the vertical pla n e Of the b ack o f the wall I n the figure a flue from a b oiler house is Shown pass in g through the roof o f a smal l Shed Fi n d the true - . . - . . . ° , ° ‘ , . - . i e o f the hole that w as cut in the roof for the flue Make a pattern to Show a Sheet o f ti n to cover this roof D evelop th e i n w ith the hole cut o u t f o r the flue cl i n ed portio n o f the flue ab ove the roof (S elect suit ab le data fo r the co Ordinates o f the poin ts that are marked in the fi gure ) s z . . . . 85 o . PRO B LE M f revo l u ti on wi th nd fi 36 To any a n l e p . the o f i nter secti on f o f an y su r a ce . M ethod Pass through the surface o f revolutio n a series o f auxil i ary plan es perpe n dicular to its axi s These plan es cut circles from . . curve of in tersectio n . E 1 38 . X E R CIS E S Fi n d the i n tersectio n o f the torus given i n E x 1 1 6 with an O b lique pla n e Draw the proj ecti o n s of the hexago n al n u t S hown i n the figure represen ti n g accurately the lin es o f in tersectio n . . 139 . , 1 40 . . “ Draw accurately the curves o f the stub end i n g rod of a co nn ec t - . 14 1 . The b lades Of a ve n tilatin g fan are plan e surfaces attached S how the in tersectio n s to a Spherical h u b . . The in tersecti o n o f any two curved su rf aces is fou nd by p as sing auxiliary plan es to cut from each surface l in es tha t can The in tersectio n s Of these li n es give be easily co n structed poin ts o n the required curve o f in tersectio n The auxil iary plan es should b e selected so that the li n es cut f rom the surfaces are straight lin es circles parallel to a plan e o f proj ectio n o r some other curve o f which the proj ectio ns can be easily drawn 86 . . . , , . shaded drawi n g of tw o i n tersecti ng co n es is shown The same co n es are shown i n orthographic pro j ectio n I n Fi g 4 3 The curves o f i n terse ctio n that are shown were o h i n Fi g 44 tai n ed b y the use o f auxiliary pla n es passed SO as to cut elemen ts from each co n e ; i n other words the auxiliary plan es were passed through the vertices Of b oth c o n es The elemen ts cut from each co n e b y an auxiliary plan e are drawn through its i n tersectio n s with the b ase an d through the vertex S in ce it is a I n Fi g 4 4 an auxilia ry plan e A i s marked plan e passin g through the vertices o f b oth c on es its horizo n tal trace H A is draw n through the i n tersection o f the lin e v w with " the p lan e of the b ases marked x O b serve that the horizo n tal rojectio n s O f the co n es are represe n ted o n the pla n e of the b ases p i i d x that the li e through d is used as the axi s S howin g n w n o an d the intersectio n Of the hori z o n tal an d fro n t plan es The auxiliary plan e cuts from the co n e with vertex v the eleme n ts c v an d d v; the eleme n ts a w an d b w an d from the co n e with vertex w The i n tersectio n s of the horizo n tal proj ection s of these elemen ts ” two an d two determin e the horizo n tal proj ectio n s Of four poin ts The curves in the fron t proj e ction o n the curves o f i n tersectio n are Ob tain ed b y drawin g the proj ection s Of the eleme n ts Of o n e con e an d proj ecti ng o n them the poin ts in the horizon tal pro n s o f two The pro j ectio i o n s o f the curves of i n tersectio n c t e j oi ts i n the curves are m arked m an d n n p 87 . A . . . . , ' . . . , , . , , , . , , , . , . , , . , . . PROBLE M 37 To find the curve of i ntersecti on o f two cones Method P ass through the con es auxiliary plan es drawn through 88 . . . line j o mmg their vertices E lemen ts cut from each con e by these pla n es determin e by their in tersection s the requir ed curv e th e . . E X E RCI SES Fi n d the curve o f in tersection of tw o right con es with axes that do n o t in tersect The axis of o n e co n e is horizo n tal the o ther verti cal Draw the developme n t of the co n e with the horizon tal axis showing the curve o f i n tersection Draw the curve o f in tersection o f two oblique con es with i n tersecting axes S how the developmen t o f o n e o f the c on es . , . ‘ , . . . the meth od most comm onl y used for fi n din g the in tersectio n of two cylin ders is shown The solutio n is a si mplified met h od o f passing plan es perpen dicular to the fro n t plane— o ne set parallel to the axis o f the smaller cylin der an d an other set parallel to the axis of the larger cyli n der The figure is lettered so that n o other explanatio n is n eeded 89 . I n Fi g 4 5 . ~ . . . 90 . P R O B LE M 38 cyl i nders . To nd fi the cu r ve o f i n ter secti o n o f two . Method P ass through the cylin ders tw o sets of auxiliary plan es o ne set parallel to each axis The eleme n ts cut from each cyli nder b y these planes determi n e by their in tersection s the re quired curve . . , . E X E RCI SES D raw accurately the li n es o f i n tersectio n appearing o n th e surfac e o f the flanged pipe fitti n g shown i n the figure o n page 1 44 The fitti ng is made u p of two cyli n ders with their axes i n tersecti n g each other symm etrically Fi n d the i n tersectio n of tw o ob lique cylin ders with their b ases i n the hori z o n tal plan e A vertical steam drum is to b e put o n a horizo n tal cyl i n , . . . - Make a pattern to show the size h ole to b e cut i n the b oiler plate (C f Fig dri cal b oiler . . 147 . . of th e . Fin d the intersection o f tw o cyli n ders forming a b ran ch “ Y fo r a b lowpipe as show n i n the figure o n page 14 6 D evelop b oth cylin ders to show the curve of in tersection . . n f n n a very simple case o the i tersectio of a co e 9 The horizo n tal proj ectio n of the c yli n der an d a cyli n der i s shown shows immediately the hori z on tal proj ectio n of the curve of in ter section an d th e front proj ection o f the curve is fou n d by proj ection 1 I n Fi g 4 6 . . . s . . Horizon t al lines drawn through the fro n t pro j ections of the po in ts a b and c to show a simple method for fi n di ng the tr ue le ngths o f elemen ts of the c on e an d the true distan ces from the vertex o f poi n ts o n an eleme n t These true le ngths are needed for a d evelopme n t o f the surface o f the co n e are , , , . . . This is a special c ase n ext pr o bl em . The ge n eral method is ed stat i n the f a cyli nder . 92 . P RO B LE M 39 and a con e . To find the cu rve o f i nter secti on o . Method P ass through the vertex o f the c o n e auxiliary p lan es parallel to the axis o f the cylin der The eleme n ts cu t from each surf ace by these plan es determin e b y their i n tersectio n s the requ i r ed curve When th e two surfaces have circular b ases i t is most ad van tageo us to use aux i liary pla n es which cut circles from each s u rface . . . , . E X E RCI SES c ircular tower has a co n ical roof through which a hori Fi n d the size of a coverin g for the z o n tal pipe passes roof an d show i n the developme n t the hole cut for the pipe Fin d the i n tersectio n o f an o b lique c o n e with a righ t cylin der The axes do n o t in tersect and o ne axis is parallel and the other perpe ndicul ar to the front plan e Make the n ecessary pa tter ns fo r an arch stone o f a coni c al arch i n a c ircular w all A . . . , . . horizo n tal steam pipe 1 1 i n ches i n diameter is in tersected b y a co n ical n o z z le an d two smaller vertical pipes as shown i n the figure The s10 pe o f the curved s u rface o f the n oz z le is 7 5 n D a f etermi e the developed t rue size o the hole c u t in ) ( the hori z o n tal pipe by the n o z zle n Develop the c o ical surface of the n ozzle b ( ) A 7 ; . 3 . . . 1 52 . Fin d the i ntersectio n of the co n e an d the cylin der formin g the steam exhaust head shown i n the figure o n page 1 5 0 - 93 . P RO B L E M 40 . To . nd fi the l i n e o f i n ter secti o n o f an y tw o o n ( spher e el li pso id to ru s e o l u t i r v f f Method If the axes of the two s u rfaces of revolution in tersec t su r a ces o , , , . . poi n t of in tersection of the axes is taken as the cen ter fo r a series o f auxiliary spheres These plan es cut c ircles from each surface The in tersection s o f these circles with each other are poin ts o n the required curve If the axes do n o t in tersect pass through the surfaces auxiliary n n i n la es perpe dicular t o the ax s of o e surface a n cut i g circles d n t p th e . . . , from that surface an d cuttin g some other curve from the The i n tersectio n s of the correspo n din g proj ectio n s o f the surface curves give the poin ts to b e foun d T he Fig 47 shows the in tersectio n o f a sphere with an ellipsoid poin t m is take n as the cen ter for the auxiliary spheres ( at the i n The arcs of the auxiliary circles shown de terse c ti o n of the axes ) B y co n ti n ui n g this termin e b y their i n ter sectio n the poi n t xf co n structio n a series o f poin ts is ob tai n ed which whe n conn ecte d f t n f a b a smooth curve gives the li e o i n tersectio n The hori by z o n tal proj ectio n is ob tai n ed easily b y proj ectio n , . . . . . . . . E 1 53 . X E R CI SES Draw the curve o f i n tersectio n o f a sphere and an ob lique co n e Draw the lin e of i n tersectio n o f the ellipsoid and th e toru s shown i n the first figure o n p age 1 52 . 1 54 . . U se th e Suggesti o n th e el li p se oh H 1 55 i n th e h E o r . i p x m p ro a fi gu re , a te meth o d mak i ng C D t o f ol rc u l ar arc s A B F ' E Oh f or Oh F co n str u cti n g an d G 0h . is shown i n the figure bel ow The cente r " line of o n e portio n is the arc o f a circle i n tersectin g the axis of the smaller portion whi ch is cylin drical Make the diameters respectively 1 } i n ches an d 1 i n ch Draw the curves o f i n tersectio n o n the outside o f the fitt i n g A pi pe fitting . . 7 . . T h e sewer show n i n the figure b elow by its sectio n is i n ter se cted by two elliptical sewers with ma j or an d m in or The dimen sion marked r axes o f 4 feet an d 2 % feet for the large sewer i s 5 feet S how i n a pl an drawi n g the li n es o f i n tersectio n to be made i n the mason ry where the sewers meet The b ottoms o f the three sewers The small s ewers are o n o p are i n the same pla n e o si te sides o f the large sewer p . . . . , . CHA PT E R V MI S CE LLANE O U S P R A C TI CAL E XE RCI S E S ' A shaft o f a min e follows approximately th e l i n e b etwee n — an d b n a 3 1 the poi ts — n A tu nn el is to be made from a poi t e 1§ o n the side of a mou n tai n to i n tersect the shaft Fin d the shortest le n gth o f the tu nn el an d the a n gle be twee n the ce n ter lin e o f the shaft and the ce n ter li n e of the tu n n el — nn n n 4 a d a I b eam are show n as the y a cha el 8 I n Fi g i n tersect i n a roof Take the followi n g co ordi n ates fo r the poi n ts mark ed i n the figure : a - , , . , . . . b e a , _ s) e , 4) (w O) h ( —l i) + 5% C — 2 e , , , 47 _ d i (w e , 4 4 , n u) , Draw the proj ections a secti o n drawi n g o f a bent pl a te con n ecti o n an d in Show the true a n gle b etwee n its sides A cylin drical pipe 2 feet i n diameter passes through the roofs shown i n Fi g 1 4 a t a poi n t i n the i n tersectio n The axis o f the pipe is perpen dicular o f the roofs to the l in e o f i n tersectio n an d is i n cl i n ed 4 5 from th e vertical Fin d the true size of the hole cut o u t o f the roofs for the pipe O b tain by developme n t the true si z e and shape o f the coverin g n eeded for a sy m metrical dome with eigh t sides I n Fi g 4 9 a portio n of a locomotive b oiler is shown Make the to p elemen t o f the slope sh eet at an in cli n a tion o f 30 to the hori z o n t al and show the true srz e o f a steel plate to b e used i n maki n g the slope sheet The san d —b o x o n a locomotive sta n ds partly o n the slope —21 5, 1 3 4 3, (9 - 7 5 - , 2, . , , . . ° . . . . . ° , . sheet and partl y o n the cyl in drical portio n Fin d the shape of the b ottom o f the sa n d b o x to fit the b oiler draw n for E x 1 61 Make the pattern for the co ni cal portio n o f the eave t ro ugh outlet shown in the figure . - . 163 . . . 164 . A b loc k wood with a s quare cross sec tion has b ee n turn ed i n a lathe to the shape shown i n the figure S how the lin es of in tersection b etween the part with the square sectio n and the c o n ical portio n of - . . Make the patterns for the — oil can an d grocer s scoop ’ shown o n page 1 60 — The stack of a b oiler is supported b y gusset plates as show n i n Fi g 50 Make the pattern s for the gusset plates Fin d the i n tersectio n o i a sphere with a cyli n der whose axis does n o t pass through the ce n ter of the sphere Fin d the in tersectio n of the cyli n drical ceilin g o f a corridor with the hemispherical ceil i n g of a vaul t . . . . . . DO ME 4 O D EVE L P ME NT O F T H E SLO P E SHE ET . FI G . 49 . A semicircul ar wire loop 1 } in ches i n diameter rotates on a vertical axis supported at the poin ts a — 1 —1 — 1f an d b }) at the en ds o f its vertical diameter A b all in ch i n diameter is attached to the en d o f a hori z o n tal supportin g arm an d revolves ab ou t the poi n t c The distan ce from th e cen ter o f the b all to the ce n ter of revolution is 1 inch Will the ball meet the wire loop ? , 7 , , ’ , . , , . A metal shade for an electric lamp is made up o f a hemi sphere and half o f a circular cylin der The axis o f the n cyli der passes through the ce n ter o f th e Sphere D raw n the i tersection of the two surfac es an d a pattern to b e s u ed i n cutti ng o u t the metal to m ake the shade Fin d the i n tersectio n of a hexago n al prism with an o b liqu e n D pla e raw the developme n t of the par t o f the prism ab ove the li ne o f in tersectio n . . . . . 1 72 . Make a pattern for o n e of the section s el b ow shown i n the figure of the stovepip e . I n Fi g; 5 1 a b uttress i n a slopi ng wall is d i me n sio n s c an d 9 are 1 0 feet an d 8 feet shown T h e respectively As sume other suitab le dime n sio n s and make all the pat tern s a sto n e cutter wil l n eed for makin g the top sto n e of the buttress Make the patter n s for the furn ace setter s o ffset b oot shown i n the figure The sectio n of the top portio n is oval an d of the lower portio n circular . . . , - . ’ - . . 1 75 . the size o f the hole tha t must be cu t i n the roof of th e shed i n E x 1 3 7 to allow a tigh t b el t to ru n betwee n the pulleys q a n d r Make the pattern s for the ash chute head show n i n F1g 52 Fi n d . . 1 76 - . . . 1 77 D evelo p a portio n of the vertical pipe i n the accompan y i n g fi gure to show the true si z e of the hole to b e cut s o that the smaller pipe i n clin ed 30 to the vertical may B oth pipes have circular sectio n s b e j oi n ed to it . ° , , . 1 78 . . Make the pattern s for the tran sitio n conn ectio n b etween a square duct an d a circular pipe . CHA PT E R VI S HAD O WS SH A D E S A ND p erson w h o un derstan ds descriptive geometry can usuall y get a correct co nception o f an ob j ect from the orthographic pro f n i n o its edges or other li es of its co n tour A proper s t o ec j c o n ceptio n o f the form an d relatio n s of the d iff ere n t parts of some however more careful study o f the proj ection s o b j ects requires Fo r this reaso n drawi ngs than is desirab le fo r practical purp oses are sometimes made to show an e ffect simil ar to that produced b y the shad ows from illumin ation This eff ect is a great assistan ce also i n makin g draw i n gs plain to person s who are un familiar with th e methods of ort hographic proj ectio n The subj ect o f sh ades an d sh adow s treats o f the application ry to produce the e ffect o f f descriptive geomet o f the methods q il lumi n atio n which gives a more real appearan ce to the proj ectio ns o f an o b j ect If an Opaque b ody is placed n ear a source of light par t of th e surface wi ll b e bright and the remain der will b e dark A portio n o f the li ght from the lumi n ous b ody wil l b e in ter cepted an d a portio n of the space b ehin d the b od y will b e i n dark n ess Thi s dark space is call ed the sh adow o f the b ody and the lin e o n its surface separatin g the b righ t side fro m the dark is the sh ade 94 . A . , , . . . , . , . . , lin e . co n e is shown near a vertical plan e P P aral lel rays of light are represe n ted pass in g through the poin ts a b c d The i n te rsectio n s o f these rays wi th the p l a ne determi n e an d v the sh ado w o f the co n e o n the plan e The sh ade lin e is foun d by j oini ng poin ts o n th e s urface where ravs are ta nge n t 95 . I n Fi g 5 3 . a . , , , , . . ‘ . U nless it i s o therwise specified the rays o f light are represe n ted by parallel lin es B y the usual co nve n tio n 6 9 be . , . to in practical drafti n g the rays are take n as comin g over the left shoulder so that the horizo n tal an d fro n t proj ectio n s o f a ray make respectively an gles o f 4 5 an d 3 1 5 with the X axis , ° ° . The method for co n structi n g the shadow of a co n e o n the hori zo n tal plan e through its b ase is shown i n Fi g 5 4 The pro f n s of a ray through the vertex v are first draw n i c o n e t d h a e t j i n tersecti o n o f this ray with the plan e of the b ase is fou n d at the 1 2 poi n t marked by the proj ectio ns v and v Li n e s are drawn i n 1 the hori z o n tal proj ectio n tan ge n t to the b ase and through v These are the limiti n g l i n es of the shadow an d determi n e at the poi n ts o f ta n ge n cy the shade li n es e v an d d v “ Fi g 55 shows the shadow of a circular cap o n a cyli n drical colum n S carcely an y expla n atio n is n eeded Rays are drawn ” through poi n ts o n the cap and their in tersectio n s with the sur face o i the colum n are easily foun d The horizo n tal projecti o n s of the rays determi n e the poi n ts of i n tersectio n The xerti c al shade li n es at ti and 37 are determi n ed by ta ngen t rays 97 . . , . , , . . . . . . . . . The shadow of an ellipsoid o n a hori z o n tal pla n e P is show n The l i n e o f shade is made use o f to determi n e the shado w i n Fi g 5 6 “ ” O bviously it is the li n e of co n tact with the ellipsoid of a cyli nder of rays ta nge n t to the surface This li n e of co n tact is of course I n the figure two proj ectio n s of an ellipso i d are shown an ellipse If a vertical auxiliary plan e A is draw n parallel to th e dire ctio n o f the rays an d through the ce n ter 0 o f th e ellipsoid i ; will c u t an elli p se from the ellipsoid an d two eleme n ts ta nge n t to the ellipse ” “ from the cyli n der of rays These poi n ts of tan ge ncy w ill b e the highest an d lowes t poi n ts in the ellipse of shade I f the pla ne 4 i s revolved ab out a vertical ax i s through 0 so that it is parallel to the fro n t pla n e the sectio n cut from the ellipsoid by the auxiliary pla n e will b e made to coin cide with the fro n t proj ectio n A ray drawn through the ce n ter 0 i n tersects the horizo n tal pla n e P at th e 2 A fter revolutio n wi th poin t marked b y the proj ectio n s o an d 0 h the auxiliary plan e th is ray is shown b y the proj ectio n s o 0 1 an d D r aw the fro n t proj ectio n s o f rays parallel to ta nge n t 0 70 2 98 . . , , . . . , , . . ’ , , ‘ , , , . ' . . , . ' . to the revolved sectio n o f the ellipsoid at a l f an d bl f Whe n the plan e A is revolved b ack to its former positio n these tange n t poin ts are at a an d b I n the fron t proj ection then ai bf is the maj or axis of the ellipse of shade I n the horizo n tal proj ectio n o f h h the ellipsoid a b is the min or axis of the ellipse of shade an d h h h h perpe n dicular to a b is the maj or axis e i The shadow o f the ellipsoid o n the horizo n tal plan e P is the shadow ca st by a sec ti on of the ellipsoid i n cluded b y the ellipse of shade T 0 fi n d this shadow determi n e the i n tersectio n s with the plan e P o f rays through the poin ts 0 a b e an d f These poi n ts determi n e the maj or an d mi n or axes a b an d e f of the elliptical shadow E X E R CI SES Fin d the shadow of an ellipsoid o n a vertical plan e Fi n d the shadow of a sphere (a ) o n a pla n e b elow an d parallel to th e hori z o n tal plan e ; ( b) o n an o blique plan e D raw the shadow of a dormer wi n dow o n a roof D raw the shadow o f a chi m n ey o n a roof The stair ramp show n i n the figure i s parallel to the slope The i n cli n atio n o f the stairway i s 1 ver o f the steps tical to 2 hori z o n tal C o ns truct the shadow o f the I m p o n the ste ps . ’ . , , . , , . , , . , , , , ’ , . ’ ’ , ’ , . . , . . . . . ' . Draw the cap an d column i n Fig 5 5 with the axis ho ri z o n tal i n stead of vertical S how the shade an d shadow Make a simple drawing o f a sectio n of an e n gin e cyli n der through the cen ter li n e Represe nt the whole p isto n i n the cylin der b y showin g the shadow o n the i n s i de o f the cyli n der o f the po rtio n that proj ec ts b e y on d the se ctio n . . . . . CHA PTE R VI I W A R PE D W arped S U R FACE S are distinguished from plan e surfaces and surfaces of si n gle curvature ( co n es cyli n ders an d co n volutes ) b y a differen t positio n of the ele me n ts with respect to each other I n all the surfaces that have been discussed a plan e could always be passed through at least tw o o f the co n secutive eleme n ts This property was very serviceable for the solutio n of pro blems I n warped surfac es however n o two co n secutive eleme n ts lie i n the same plan e ; t hat is li n e s draw n th rough an y tw o co n s ec utive h f h i n n n n t s e e a h r n ositio tr a t li e r ti t m ith r s o e e a e e e r a g g g p p allel n o r i n te rse ctin g E xamples o f warped surfaces are show n i n Figs 5 7a 5 7 b an d 58 A Warpe d su rf ace therefore may be ge n erated by a s trai gh t lin e movi ng so th at it al w ays to u ch es tw o giv en lin es an d rem ai n s * n l a n e n i e n l g The fixed li es which the movi g li e r e l t o a v n a a l p p touches are called t h e di re ctri ces an d the plan e is called the pl an e di re cto r 99 . su rf ac es , , . , ' . . , , , . , , . . , , . . . The h yperb oli c parab o l o i d is a warped surface with a plan e director an d two straight li n e directrices which are n o t i n the same plan e It takes its n ame from the fact that curved sectio n s made by plan es cuttin g the surface are either hyperb olas « i s A para olas cf F the directrices approach paral b r o ( g This l el is m the surface approaches a pla n e as a l i mi ti n g surface surface is o f some practical importan ce as it is used i n maso n ry co n structio n an d the cow—catcher o f a locomotive ( Fi g 60) is usually o f this form 1 00 . . . . . , , . . Th of e re is a ge n e rati o n a n v d p p of w ar e rti es ; b u t ro t h a t w i l l b e d i s c u sse d y ari e t r t e a g . p ed th i s e s u r f a c e s , al l x pl an ati o n is d i ff e ri n g i n th e i r m o de s uffi c i en t f o r th e s u rf aces a hyperb olic parab oloid any plan e parallel to a plan e director will o u t each directrix i n a poin t an d the l in e j oi n i ng these two poi n ts will b e an eleme n t o f the surface The eleme n ts may be regarded as lyi n g i n a series o f pl an es which are paral lel to the plan e director an d dividing the two directrices proportio n ally If the n an y two straight li n es n o t i n the same plan e are divi ded i n to proportio n al parts the straight li n es j o i n in g the correspo n d i n g poi n ts o f divisio n are elemen ts o f the surface o f the hyperb olic 9 parab oloid In , , . . , , , . The characteristic properties o f this surface can b e mos t co n ve n ien tly i n vestigated by refere n ce to a pictorial drawi n g showi n g the directrices an d the plan e director I n Fig 61 we shall take for simplicity of represe n tatio n the horizo n tal plan e marked H for the pla n e di recto r The li n es a c and b d shall be the di r ectri ces From poi n ts o n these li n es the elemen ts o f the surface a b and c d are drawn parallel to the plan e director H Fo r the n ecessary co ns tructio n draw through the directri x a c a vertical plan e V 1 parallel to b d an d cutti n g the plan e director Then draw an other vertical plan e V2 parallel i n the lin e x1 1171 to V I through b d cutti ng the plan e H i n the li n e x2 The lin e c f is draw n perpe n dicular to xl x1 an d d g is draw n perpe n dicular to x2 x2 ; therefore i g will b e parallel an d equal to c d Through o n a c draw i j parallel to the pla n e director H an d an y poi n t i cutti n g b d i n j ; the n i f is an other eleme n t o f the surface The li n e i h is drawn perpe n dicular to x2 x2 an d i t perpe n dicular to rallel an d equal to i i A lso x1 ; the n l k will b e p a 101 . . . , . . , , , . , , , , , . , , . , , , , . , . } 4 235— ' c Therefore a t b h , 1 l an d I t f foll ows that l ie f 9 cut an d a b In same poi n t r N ow draw a plan e parallel to V I cutti n g a b i n poin t n the n its i n tersectio n wi th H w i ll b e parallel to xl x1 , . , , W l ll cut lh In 0 , jg In m, an d n o - 5771 li — c also 0 9 is parallel th e an y an d an d e qual to ti an d is parallel mp which proves three elemen ts a b portion ally so tha t , i j n i s qp an d c , d, equal an d to i Therefore a . a straight lin e i n tersectin g the , an d dividi ng these elemen ts r o p , a n n b i q cp = d qj p ' If the elemen ts a b an d c d are take n as directrices an d the vertical plan e V1 as a plan e director the surface which is ob tain ed will be ide n tical with that havin g a c and b d as directrices an d the plan e The elemen ts a b i j etc are called H as its plan e d i rector eleme n ts o f the fi rst gen e rati on an d those o f the other set as a c which are parallel to the vertical plan e VI are call ed n p etc eleme n ts of the sec on d gen eratio n We have show n the n that every eleme n t of eith er ge n eratio n i n tersects all those of the other Th is surface is do u bl y ru l ed; that is it h as two s ets o f straight li n e eleme n ts an d through an y poin t o n the surface two straight lin e eleme n ts can b e always drawn E ach elemen t o f o n e ge n eratio n i n tersects n o eleme n t of its o w n se t b u t meets all the eleme n ts of the other set The lin es o n the surface i n Fig 5 8 show t h is doub le ruli n g very plai nl y , , , . . , , . , , , , , , . , , . , - , - . , . . . a hyperb olic parab oloid are represe n ted i n Figs 62 an d 63 Two straight li n es a b an d c d o f defi n i te le n gth an d n o t i n the same pla n e are divided i n to th e same n umb er of equal parts The lin es j oin in g correspon din g poi n ts A n eleme n t marked my o f divisio n are eleme n ts o f the surface is shown i n each figure O b serve that the di ffere n ce b etween the two figures is merely that the same poi n ts of division o n a b I n Fi g 62 the method of j oin i n g an d c d are j oi n ed up di ffere ntly the poi n ts of divisio n is the same as shown i n the pictorial drawi ng 102 E lemen ts . of the surface of . . , , , . . . . i n Fi g 61 . . . r r e r c f w a d s e rec i If the e s o a f a c i n ge eral are di t u n no t 3 p limited i n l en gth it is n ecessary to have give n the directrices o f “ b oth systems o f rulin g o r the directrices an d plan e director o f ' 19 . , sy stem This las t case is il lustrated i n Fi g 64 The lin es q r an d s t are the direc trices an d th e pla n e director is give n b y its To draw an elemen t of the surface then tr aces H P an d F P Through this poin t s ome poi n t as e o n the directrix s t is assumed draw two lin es d l bl an d cl d l parallel to a b an d c d which are The in tersection o f the plan e an y two lin es i n the pla n e director o f the tw o lin es through e with the directrix q r i s a poi n t i n the required eleme n t of the surface This i n tersection can b e fou n d very simply with out fi n di ng the traces o f the plan e of the lin es First pass through the li n e q r a plan e perpen a l bl an d c l d l di cu l ar to the fro n t pla n e an d fi n d the in tersection s o f the li n es The i n tersectio n o f a l bl with a ; b1 an d c l d l with this pla n e th i s plan e has of course its fro n t proj ectio n i n the fro n t trace at f n e determ i n es the horizo n tal proj ectio n a proj ecti n g li n a d g S i milarly cl d l i n tersects th e pla n e of q r at f an d the plan e o f The th e lin es a l bl an d c l d l i n tersects the directrix q r at i lin e c i is in a plan e parallel t o the plan e director an d touches the two directrices It is therefore an eleme n t of the surface through B y this process any n umb er o f eleme n ts c an an assumed poin t e b e draw n o ne . . . , , . , . , . . . . , , . , ' , , , , . . . . If o ne proj ectio n o f a poin t o n any warped surface is k n own an other proj ectio n may b e located b y drawi ng through the give n proj ectio n a li n e perpe n dicular to the plan e of projectio n Through this per i n which the give n proj ectio n is represe n ted i l r li n e pass a pla n e which will i n tersect the eleme n ts o f n c a e d u p the surface i n poi n ts which whe n j oin ed will give a lin e o n the surface The in tersectio n of this li n e with the other proj ectio n of the perpe n dicular li n e is the required proj ectio n o f the poin t 1 04 . , . , , . . The h ype rb o l oi d o f revolution is a warped surface ge n e rated by a straight lin e revolvi n g ab out an axis n o t lyin g i n the same plan e wi th it Usually a vertical lin e is take n for the axis P roj ectio n s o f this surface showi n g a n umb er o f eleme n ts are represe n ted i n Fi g 65 The method for co nstructi ng this surface is shown i n Fi g 66 The axis a b is vertical A n elemen t of th e 105 . . . . . . . . surface as m n is called a gen eratrix b ecause the surface can be gen erated by revolvi n g this lin e a b out the axis E ach poin t i n T he m n as it revolves ab out the axis descri b es a hori z o n tal circle true radius o f each circle is seen i n the horizo n tal proj ec tio n Thus the poin t r o n the ge n eratrix n earest the axis descri bes the circle of which the diameter is shown i n the fro n t proj ectio n of the surface as u f rf vf This smallest circle described by a poin t i n the ge n eratri x i called the ci r cl e o f the go rge The diameter of the circle describ ed by a poi n t p is gl f (M which is equal to , , , . . . . s . , h h 2 >< b p The hyperb oloid o f revolutio n is a dou bl y ru led surface as it h as tw o sets o f straight li n e eleme n ts O n e eleme n t o f each set A n eleme n t o f c an b e draw n through an y poi n t o n its surface o n e ge n eratio n c an b e produced to i n tersect all those of the other gen eratio n for the s imple reason that they lie upo n the same sur face If the n an y three eleme n ts of either ge n eratio n are taken as directrices an y eleme n t o f the other ge n eratio n may b e take n as a ge n eratrix which when movin g will produce the same surfa ce The method for drawi n g a plan e tan ge n t to a hyperb oloid o f revolutio n is show n i n Fig 67 The plan e P shown i n the figure i f o n ly o n e proj ectio n O f is ta n ge n t to the surface at the poi n t e h draw an eleme n t of th e surface d 6 through 0 is give n as s ay c f n n c b y proj ectin g to the fro n t proj ectio n of d e d fi d O ne c a o f the other se t of eleme n ts passi n g throug h the poi n t is show n b y f g The two eleme n ts determi n e th e pla n e t ange n t to the surface at the poi n t e , - . . , , , . , , , . . . , , , . , , . . . u rf ace is a surface ge nerated by a straight lin e moving so that it is always touchi ng tw o h el i cal d i rec trices lyi ng upo n co n ce n tric cyli n ders I n Figs 68 an d 69 tw o cy l i n ders of revolutio n are shown O n each is a port i o n o f a helix The straight lin e m n ge n erates the surface o f the helicoid I n bot h fi gures The differe n ce is merely i n the slope of th e ge nerating lin e Whe n b oth o f the directi n g helices of a helicoid h ave the same pi tch i t is called a helicoid of u n i for m pi tch If the pitches ar e n o t the same the surface is called a h elicoid o f va ryi ng pi tch 106 . A h eli co i d or screw s . . . . . . , . . The tw o examples of helicoids of un iform pitch in Figs 68 and 69 di ff er o nly in the relative positio n o f the movin g o r ge n erati n g lin e I n b oth cases this lin e moves un iformly aroun d the vertical axis while at the same time all the poi n ts o n it move u n iformly I n either figure the poin t b in a directio n parallel to the axis i n the ge n eratin g li n e m n will describ e the helix a b c d lyi ng o n the inn er cylin der an d the po in ts m an d n will describ e helices o f the same pitch lyi ng o n the outer cyli n der These helices traced by m an d n are marked respectively c i g an d h i j The ge n eratin g li ne m n will always lie i n a plan e tan ge n t to the i nn er cyli n der an d will in tersect the vertical eleme n t at the poin t o f ta nge n c y at a co n stan t angle I n the helicoid o f Fi g 68 t h e ge n erati ng lin e m n is always perpen dicular to the vertical eleme n ts o f the i nn er cylin der an d is called a ri ght heli coi d The helicoid of Fi g 69 has the gen erati ng lin e m n i n cli n ed to the vertical eleme n ts of the i nn er cylin der an d is called an o bl i qu e hel i co i d Whe n the elemen ts o f a helicoid are perpen di cu l ar to the axis the surface i the same as that o f a square threaded screw (Fig an d whe n th e a n gle is less it i s that of a V — thr eaded screw ( Fig Fo r the V thr ead of the U n ited S tates stan dard screw th e an gle b etwee n the elemen ts and the axis is . . , , , . , . . , . . , , , ‘ . , . , , . , . - s . . - a satisfactory represe n tation of a helicoid it is not Usu n ecessary to draw a large n um b er of eleme n ts of the surface ally i t is shown b etter b y drawi n g a few elemen ts for a small portion I n Fi g 7 2 an ob lique helicoid is sho w n resemb li ng o f the surface the o n e i n Fi g 69 The small po rti o n o f the outlin e that is repre sen ted is easily recog n ized as like that i n the groove of an auger or a twist drill If o n th i s surface it is required to locate say the fro n t pro draw n o f a poi n t whe n the hori z o n tal proj ectio n is give n i o ec t j the hori z o n tal proj ectio n of the eleme n t o f the surface at the poi n t The requi red fro n t proj ectio n of the poi n t is the n foun d by projectin g to th e fro n t proj ectio n of the eleme n t If o nly the fro n t proj ection o f a poin t is k n own the horizo n tal proj ectio n 1 07 . Fo r . . . . . - . , , , . . , determi n ed by drawin g a lin e through the fro n t proj ectio n parallel to the horizo n tal plan e A n y plan e passed through this li n e will cut the eleme n ts i n poi n ts determin i ng a curve The h ori z o n tal proj ectio n of this curve will i n tersect the correspo n d i n g proj ectio n of the li n e at a poi n t which is the required pro is . . j ecti o n . If the surface of the helicoid i n the last figure is cut b y a vertical n n n n la e h the a is d perpe dicular the fro t pla e the n h r o u a t o t g y x sectio n cut out will be like the shaded drawi n g at the ri ght h a n d side of the figure Half o f the curve shown i n the sectio n i s marked 3 1 x1 y1 This figure is easily co n structed by drawi n g eleme n ts The poin ts i n which the eleme n ts are i n tersected o f the surface Thus by the cutti n g pla n e determi n e the curve of the sectio n an eleme n t i j i n tersects the cutti n g pla n e at x This poi n t is located On the curve i n the sectio n b y proj ecti n g hori z o n tally from xf and layin g o ff from the axis the len gth 0 1 x1 equ al to h k as The other poi n ts n eeded to determi n e the curve are fou n d o i n the same way S uch a sectio n cut from the surface by a plane through the axis is called a meri di a n secti o n , - . . . . . . . . A plan e is drawn tan gen t to the surface of a helicoid at a n t b y drawi n g an eleme n t through the give n poi n t an d ive poi n g a ta n ge n t to the helix lyi n g i n the surface an d passi n g through the l n es determi n e the required t a n ge n t w i ive po t These t i n n o g plan e As the surface is warped the pla n e w ill n o t be tan ge n t throughout the le ngth of an eleme n t an d will n o t co n tai n there fore a tan ge n t to the b ase at its i n tersectio n with an eleme n t p assi n g through the poi n t 1 08 . . . , , , . The i n tersectio n of the helicoid with an y give n plan e is fou n d by passin g hori z o n tal auxiliary pla n es through it These ” “ plan es will cut from the surface S pirals equ al to the base an d from the give n plan e horizo n tal li n es The in tersectio n s O f these li n es will give poi n ts o n the required li n e of i n tersectio n The ” “ proj ectio n s of the differe n t S pirals are no t n eeded if a curve of the b ase is made o n a tra n spare n t shee t 1 09 . . , . . . E X E R CI SES Locate a poi n t o n the surface o f a hyperb olic parabo l o id give n b y two limited lin es Draw a tangen t plan e through thi s poin t Three o b lique li n es are give n as b elo n gin g to o n e set o f eleme n ts o f a hyperb olic parab oloid Fin d three ele me n ts o f the other set S how several elemen ts of the surface of a hyperboli c parab oloid give n by tw o directrices and a plan e director Draw the proj ectio n s o f a hyperb oloid o f revolutio n an d assume a poi n t o n the surface Draw a plan e tan ge n t to the surface at thi s poi n t A ssume the proj ectio n s of an o blique helicoid Locate a poi n t o n the surface an d draw a tan ge n t plan e at thi s poin t Take the proj ectio n s o f the h elicoid co nstructed for th e preceding exercise an d draw a meri dian sectio n an d three tra nsverse sectio ns Draw the proj ectio n s of ( a) a sq uare thre ad ed screw ( b) — a V thre aded sc re w . . . . ) . . . . . . - , . CHA PT ER V II I PE R S P E CT I VE the art of represen ti ng ob j ects as they appear to the eye The pri n ciples are n o t diffi cult for a stude n t who u n derstan ds the methods of orthographic proj ectio n The sig n ifican ce o f perspective drawi n g can be explain ed b est by Showi ng i n what way it di ffers from orthographic proj ectio n I n perspective the eye o f the o b server is at a fi n ite dista n ce from the o bj ect I n orthographic proj ectio n the views r eprese n t the o bj ect as see n whe n the eye is i n fi n itely distan t B y the per Specti ve method the ir the li n es drawn from poi n ts o n the o b j ect to the eye co n verge an d i n tersect at the poi n t o f sight I Io . P E RSP E CT I V E Is . . . . . , , , . A perspective drawi ng represen ts an o bj ect as s ee n through a vertical plan e which is assumed to b e tra nspare n t I n Fig 7 3 the eye at S the o bj ect ( a square pyramid v a b c) an d the perspe c tive proj ectio n v a? bp 0 are plai n ly shown The light solid li n es i n the figure represe n t the rays from the corn ers o f the o b j ect to the eye The straight li n es j oi n i n g the i n tersectio n s o f these rays with the vertical plan e form the outli n e o f the o b j ect If this perspec tive picture is shaded an d co lored it will exactly represe n t the o bj ect as see n from the viewpoi n t The vertical plan e o n which the perspective drawi n g is made is called the pi ctu re pl an e and the positio n of the eye is called the poin t o f si gh t The simplest co n structio n o f a perspective drawi ng is o b tai n ed by the use of two proj ectio ns o f the poi n t o f si ght together with the two correspo n di ng proj ectio ns o f the obj ect T he method is i l lustrated i n Fi g 74 The light solid li n es show the horizo n t al an d fro n t projec tion s o f a rectan gular c ard held n early hori o n tally T w o 1 1 1 . . , . , 19 i? . . . , ‘ . , . , . . . , z . corn ers are marked a an d b The proj ectio ns of the poi n t of sight " f n are S a d S Dotted li n es are drawn j oi ni ng the corn ers o f the " card i n the horizo n tal proj ectio n with S an d j oi ni ng the corn ers i n the fro n t proj ectio n with Sf These are respectively the hori z o n tal an d fro n t proj ectio ns of rays from the corn ers to the poi n t From the poi n ts where the hori z o n ta l proj ectio ns of o f sight these rays i n tersect th e X axis li n es are drawn perpe n dicular to the axis to i n tersect the correspo n di n g fro n t proj ectio n s o f the rays The corn ers of the perspective proj ectio n are thus deter mi n ed an d by j oi n i ng these corners the outli n e of the card show n Fi g 75 shows a perspective by the heavy solid li n es is o b tai n ed “ drawi ng of a scree n with three blades made by this method The poi n ts a b and c are marked tomake the co n structio n plai n er Usually whe n represe n ti ng an o b j ect i n perspective the horizo n tal plan e o n which the o b j ect rests is shown I n the figure the li n e marked GL is the fro n t trace o f the horizo n tal pla n e throug h th e If a house is to be represe n ted i n a b ottom edges o f the scree n drawi n g the level o f the grou n d is represe n ted by a hori z o n tal plan e The fro n t trace is the n very properly called the grou n d l in e This n ame is give n however to the fro n t trace of any hori z o n tal pla n e o n which an o b j ect is imagi n ed to b e placed . . . . , s . , . . , , . , . . , . . , , . A picture may be made very simply by the met h od de scrib ed if there are n o t ma n y details to b e shown I n practical drawi ng however this method is n o t ofte n used The difficulty is that for a picture o f suitab le proportio n s the horizo ntal proj ect i o n h must be usually lo cated so far from the X o f the poi n t of S ight S axis that it is b eyo n d the limits o f th e drawi ng board Al so f o r an o b j ect with ma n y details the n umb er o f co nstructio n li n es It is the n ofte n difficul t b ecomes so great as to b e very co n fusi n g to decide which poi n ts are to be j oi n ed Fo r these reas o ns the n an ab ridged method o f perspective drawi ng is commo n ly used h k f f n a n b i n b a a a li n e is show its proj ec t o s a b d b i n F 76 I y g This lin e is parallel to the horizo ntal plan e an d makes an a n gle of 4 5 with the fro n t plan e B y the method tha t h as bee n j ust explained its perspective proj ectio n is fou n d at a' bp The other 1 12 . . , , , . , , - . . . , , . . . ° . , . gen eral method for co ns tructi n g perspective drawi ngs may be illustrated with this figure The lin e a b i s produced i n defi n itely h as shown i n b oth proj ectio n s A proj ectin g li n e from S to the en d of the li n e through a b must b e represe n ted parallel to it an d makin g an a ngle of 4 5 with th e X axis This proj ecti n g li n e meets the X axis at u ; an d th e perspective of a poi n t o n a b at an i n fi n ite distan ce is at M The perspective of an y poi n t o n the li n e produced through a an d b is therefore b etwee n af an d M I n i h = = f r n v t t u H orizo n tal l i n es this co ns tructio O b se e that S S M maki ng the same angle with the fro n t plan e b u t slopi n g i n the opposite directio n would co n verge toward a similar poi n t located at an equal distan ce to the left of S It follows the n that all h ori z o n tal li n e s at 4 5 to the pictur e p l an e ( fro n t plan e ) c o n verge i n p e r sp ective to w a r d poin ts o n e it h er si de o f Sf an d at a distan ce from th i s p roj ectio n e qu al to th at o f th e poi n t o f si ght from th e i n h n n ce t e n i ture la e locatio of the poi t M depe ds o ly S n c n p p an y hori z o n tal 4 5 o n the di recti o n of a b an d n o t o n its po s i ti o n li n e i n the drawi n g will co n verge toward M Th i s po rn t is called the m easuri n g poi n t S ome dimen sio n lin es are shown i n Fig 76 to Show how this poin t can b e used for layi n g o ff distan ces Fo r example the perspective proj ectio n of the poi n t b could be fou n d by layi ng h to the X axis o n the left—han d side o f bf o ff the d ista n ce from b an d b? would b e fou n d at the i n tersectio n of this li n e with the proj ecti n g li n e j oi n i n g bf an d S7 I n the same way the perspective h of a poi n t e is fou n d by layi ng o ff the distan ce from c to the X axis o n the left—han d side o f cf an d locati n g c at the i n tersectio n of this li n e with cf Sf If the measuri n g poi n t ll had b ee n located o n the left ha n d side of Sf the n i n these same cases the dista n ces me n tio n ed would b e laid o ff o n the right ha n d side of the fro n t proj ectio ns This method o f co ns tructi ng perspective drawi n gs with the help of measuri n g poi n ts is shown also i n Fig 7 7 A perspective drawi ng o f a cub e with circles i n scrib ed i n its sides is illustrated The measuri n g poi n t M is located b y maki n g Sf M equal to the h distan ce from the poi n t of sight to the picture plan e (S to the . , . 0 . . , , . , , , . , , ° . . . ° , , . - . . . , , . ? - . " - , - . - . . . - X axis ) O bserve that there are a n umb er of parallel lin es i n a cub e The co nstructio n can b e simplified if we n otice that all “ parallel li n es must co n verge or van ish at the same poi n t E very se t of parallel li n es has the n a v an i sh i n g oi n t The li es which n p are perpe n dicular to the picture plan e have of course their van ish i ng poi n t at S 7 ; an d hori z o n tal 4 5 li n es van ish at M Fo r an y drawi n g the van ishin g poi n ts the measuri n g poi n ts an d th e fro n t proj ectio n o f S must b e i n a li n e parallel to the X axis The j udicious u se of measuri n g an d van ishi ng—poi n ts saves much lab or i n maki n g perspective drawi ngs I n Fi g 77 the va n ishin g poi n ts of the horizo n tal edges o f the cu b e are at V 1 an d V 2 E ach i s located by drawi n g an edge fo r which the dirc o tio n has b ee n determi n ed to i n tersect the li n e through Sf parallel to the X axis . . ” . - . , , 0 - . - - , , . . . - . , . The perspective drawi ng o f the cub e illus trates also a very satisfactory I ii eth o d for drawi ng the perspective proj ectio n s of circles P oi n ts i n the perspective drawi n g of the circles are fou n d by locati n g diago n als o f the circumscri bi n g squares formed O ther li n es are also draw n parallel to by the edges o f the cu b e the sides o f the same square through the i n tersectio n s of the diago h als with the circle The i n tersectio ns of these straight li n es locate usually en ough poi n ts to determin e the perspective of the circle The ( o nstru cti o n for tw o poi n ts a and b o f the circle are illustrated i n the figure 1 1 3 . . . . . . The pri n ciples o f perspective are n o t di fficult to apply i n a mecha n ical way b y those who have n o artistic trai n i n g ; bu t distorted results are o b tai n ed from ab solutely correct applicatio n s whe n ab surd co n ditio n s are assumed If for example a large house is represe n ted with the poi n t of sight ab out twe n t y feet from the fro n t of the house o b viously a poor result is o b tai n ed N evertheless fo r such a case the pri n ciples can b e applied as well as to an y other A perspective draw i n g should show the ob j ect as it appears to the eye If is importan t therefore that the b est viewpoi n t is 1 14 P e rspe ctiv e D i sto rtio n — . . . , , . ‘ . . , , , ob tai n ed ; and care i n selecti ng the viewpoin t is as esse n tial as a kn owledge o f the rul es If a house ab out forty feet high is to be sketched the poin t o f sight should b e taken ab out eighty feet from the picture plan e A good rule to follow is to make this distan ce a b out twice the greatest di m ens ro n When large o bj ects are to b e represe n ted the most satisfactory results are o b tai n ed usually when the poi n t o f sight is take n n early i n fro n t o f the o bj ect It is preferable the n tha t the plan drawi ng should b e shown i n cli n ed to the picture plan e . , . . , . , , ) . 1 1 5. P erspecti ve Sk et ch es f r om “Wo rk in g ” D raw in s g — A very pro fi tabl eappli catio n of the methods o f perspective draw i n g ” “ “ ” — i s fou n d i n maki n g free ha n d sketches from worki n g or s h O p drawi ngs show n i n orthographic proj ectio n The worki n g drawi ng represe n ts certai n i n formatio n ab ou t an o bj ect by a co ll ecti o n of views S everal views are n ecessary to represe n t the obj ect completely I n perspective drawi ng the same i n formatio n i s sho w n i n a si n gle sketch When b egi n ni ng a perspective draw i ng which is to b e made from an y proj ectio n drawi n gs it is n eces sary to acquire a thorough k n owledge of the form an d details T h e work ot herwise ca n n ot b e do n e i n tellige n tly o f the o b j ect The perspective sketches for most o bj ects should an d rapidly b e comm e n ced by drawi n g i n perspective the edges of either — circumscri bed o r i n scrib ed solids usually square prisms Mos t machi n es an d architectural forms are easily treated i n this way The pri n cipal edges of the o b j ect should b e the n grouped i nto three syste ms correspo n di n g to three n o n parallel ed ges o f the prism O n e of these will b e represe n ted b y vertical li n es an d two o thers must b e show n with their proper co n vergen ce A fter the pri n cipal edges of the o bj ect have b ee n drawn the other li n es are very e as ily represe n ted Whe n deali n g with complicated forms it is ab solutely n ecessary to follow some defi n ite system to o b tai n results showi n g reaso n able accuracy E ve n with simple drawi ngs some care shoul d b e exercised i n selecti n g the poi n t of sigh t It should b e take n so that th e details which are co nsidered most import an t will appear i n the ' . . . . , . , , . . , . - , , . . , . . . perspective sketch as plai nly as possible A drawi n g is o f little value i n which the importan t parts are crowded so that they are n o t clearly show n . . P 1 93 RA C T ICAL E X E RCI SES “ . Make a perspective drawi n g o f a scree n with four blades usi n g for the co ns tructio n measuri ng an d vanishi ng poi n ts Make a perspective drawi n g of the end co nn ectio n o f a truss as shown i n the figure , . 1 94 . . Make a perspective draw i ng of a s i mple wooden b ridge . Draw a cottage i n perspective S how i n perspective the flight o f steps an d the ramp i n th e figure i n E x 1 83 Make a perspective drawi ng of a locomotive b oiler Make a perspective drawi n g of the mil l b uildi n g shown i n the figure S how also a tall chim n ey b ehi n d the b ui ld . . . . . I ng . I ND E X . No te — I n r O th e In x de al l figu art rc l e s , e xe rc rse s , o r fi gu re s re s re fe r to r s, , , r r s , - r 74 , 76 , , , , , 126 , B th t b P b l m 1 30 1 34 B l ti g P b l m 1 36 B t Pl t C 1 5 6 1 57 ti B v l f R ft 7 4 7 6 B t P bl m 66 7 0 B il h Fl 1 34 B i l P bl m 1 4 2 1 4 4 1 58 1 5 9 B tf S t v p i p 1 32 B i dg Pi P b l m 90 B i dg P b l m 32 7 8 80 84 90 B tt P b l m 1 62 1 63 e n ro u ro en e e s oa s, e o nn e c a or ro er- o u se ue, o er ro s, r e r e u e o ro re ss e e e , , e, s, ro , , e- ro er , , o or a on , ers , s, e , s, e a e oo , , , , , , , Cam -w h eel , 56 P o b l em 1 58 Ch i m n ey P o b l em 1 34 Chi mn ey Sh ad o w o n a Roo f Ce il i ng r , r , , Ci rc l e , 1 70 th e G o rge , 1 80 of Ci rcl es in O bl i qu e an Pl an e Pro j ecti o n s o f , Co n e , 1 00 Co n e to th e . rs - no ne , A ngle A ngl e A ngl e o f R efl ecti o n 7 2 A ngl e fo R afte s o f R o o fs A h c h u te H ead 1 62 1 65 A uxil i a y Pl an es 4 0 4 6 5 2 a age s ; be tw een a L i n e an d a Pl an e 68 be tw een a Pl ane an d a Pl an e o f P o j ecti o n betw ee n I n te e cti ng L i n e 64 66 An gl e s p of Co n i c al R y a A rc h , 1 30, 1 32 , 1 34 , 1 36 14 6 v T N o le Co n i c a l E a Co ni cal s, e zz , ro u l gh O u t 148 et , 1 58 , 8 0— 84 n um be rs of l lR l To we Co ni c a Roo f Co nn ecti o n , 1 30 1 34 Co ni ca o o f P r o b em , 1 4 6 Co ni c a . l Ro o f r on a 1 32 , Co nn ecti ng- ro d , 1 38 L in e s 9 8 Co n to u re d P l an Ou t b y P l an es Co nvo lu te S u rface 1 1 8 Co n to u r Co n , 98 , , v o l u te s , 1 02 , 1 1 4 Co ordi n ate s , System E xp l i ned R p f a Le ngth o f G u y o es Cu be P ro b l em 56 1 9 4 1 9 7 Cu ve o f I n terse cti o n 1 2 6 Cyli n der 1 00 Cran e , , , 12 , 92 o r, , r , , D e rri c k P bl k P bl v l pm v l pm v l pm v l pm D es De De De De ro em s , em s , ro 68 , 9 4 4 4 , 54 , 1 30 e o e nt o f a Co n e , 1 4 2 e o ent o f a Cy li n de r , 1 28 e o ent o f a e o en t o f a D i re cti o n R of ‘ S l o pe Sh ee t 1 59 Steam D o m e 1 59 , , 1 67 , 1 68 ay s , W p S u rface 1 7 2 betw ee n P arall el Pl an e 56 betw een T w o L i ne s 9 2 f ro m a Po i nt t o a L in e 90 f ro m a P o i n t to a Pl an e 54 D i re ctri ce s D i stan ce of a ar ed , s, D i stan ce , , D i sta n ce , D i s tan ce , D i stan ce s ” tru e ) Measu re d , 4 8 , 50 D o m e w i th E igh t Si des , 1 56 D o tte d i n e s , 1 4 L D o rm e r Wi P o b l em s n do w r , 1 70 b ved S u rf ace s 1 00 D o u b l y R u l e d S u rf ace s 1 7 6 1 80 D ry D o c k P ro b l em 86 D o u l e Cu r , , , , v T Ea e l O u t et , 1 58 r o u gh E l e m e n ts S u rf ace of a v ti n D w i ng E l li p i d S h d w E l li p t i l C m w h E le a ra o so a , ca a ee l , - “ E n d Co n n e cti o n y x H e ad r e P o j ect i o n s r of a T ru s s , r r P o b l m 1 38 ” i i I n te rse cti o n Fan 1 68—1 7 0 , 56 1 98 P o b lem i n Sh ado w s P o b l em 1 4 8 1 50 E ngi n e C li n de r , E h au st ” 1 00, 1 26 38 , o f, o , s, , , 12 Fi rst Gen e rati o n , 1 7 6 , Mi l l bu i ldi ng 1 98 - , Mi n e Pro bl em 1 5 6 Mirro r Pro b l ems 4 4 , 72 , Negative D irecti o n N o tati o n 1 0 1 2 Nut P o b l em 1 38 , , 12 , r , O b li qu e Co n e , 1 02 O b l i qu e Cy lin d e r , 1 02 el i c o i d , O b i qu e H l O b li qu e ( Li n e s ) P l ane to s of Pro j ecti o n O ff se t B o o t f o r a Fu r n ace , 1 62 O i l -c an P r o b l em , 1 58 , 1 60 O n e Pro e cti o n o f a L i n e i n a Plane gi O ri gi n , 2 j p v pp O rth o gra h i c P r o j e cti o n , 1 , 4 “ — O al S to e i e , Co nn ecti ng v B oot ” , 16 ven , t o Fi n d th e O th fo r , 1 32 Pa al l l Lin e a Pl an e th o ugh 28 P a a l l e l L i n P o j e ti o n f 2 6 2 8 Pa all el (L i n ) to P lan o f P o j ecti o n 1 6 Pa al l el Pl an D i tan e betw een 56 Pa al l l P l an e D aw n at a G iven D istance A p art 62 94 Patte n fo an A ch S to n e 1 46 Perp n di cu l a (L in e ) to a Plan e 54 Pe pe ctive D aw i ng 1 1 88 Pe pe ctive f a Cu be 1 9 4 1 9 7 Per pective o f a Ci le 1 9 4 1 9 7 Pe p ective D i t rti o n 1 9 4 Pe p ective Sketch e fro m Wo k i ng D rawi ngs 196 Pi ctu re Pl an 1 88 Pi p e fi tti ng P o blem s 1 4 2 1 44 1 52 Pi pe P bl em s 2 4 4 6 5 4 1 30 1 32 1 34 146 1 48 1 56 Pi tch o f a H elix 1 1 6 1 2 0 Pi t h o f S cre w Su rface 1 80 Pl an D aw i ng 38 Plan e D i e to o f a Warp ed Su rf ace 172 Pl ane o f P o j ecti o n 2 Pl an e 1 0 Pl an e S u f a e 1 00 Pl an T angent to a Co n e o r a Cyli nder 1 08 1 1 2 Pl an e T angen t to a Co nvo lu te Su rf a 1 22 Pl an T angen t to a H yp e b o lo i d o f R vo lu ti n 1 80 1 8 3 Pl an T ang n t to a Sph ere 1 1 2—1 1 4 Plan e th ro ugh a Po int Perp endi cu l a to a Li ne 60 r r s, e es, r es r es , s r r r , s r , , o , , , rc s rs , , r rs , , r e , , c s r rs s o es s e r c r r , , s o , , s rs r , e, r - ro , , , , , , , , , , , , , , s, c r , r c s r r , , s, r c , e , , ce , r e e e e o , , , r , : , er , 16 P late Co nnecti o n fo r Steel Rafters 1 56 1 57 P o i nt o f S i gh t 1 88 Po rtal o f a B idge 32 Po i ti ve D i ecti o n 1 2 P o j ect a L i n e u p o n a Plane 56 Pro j e ti ng L i ne 4 1 4 2 2 Pro j ecti o n s o f I nte se cti ng L i nes 28 P o j e cti o n o f a L i n e 1 2 1 6 P o j ecti o n o f P a al l el L i n es 2 6 2 8 P o j ecti o n o f a P o i n t 2 1 0 P o j ecti o n o f P o i nt n a Co n e 1 04 P o j ecti o n s o f P o in t o n a Co nvo l u te S u f a e 1 2 0 Pro j e ti n o f P o i n t o a Cyl i n de 1 04 P ro j ecti n o f P o ints o n a D u b l e cu ved S u rface Pro j e ti n o f P i n t o n H l i co i d o r S c ew S u rf ac Pu l l y P o b l em 9 6 9 8 1 36 1 62 Pu l ley P o j ecti on o f 9 6—9 8 , , , r s , r , r , c s, , , r r s r s r s r s , , , r , , , , s o r , s c c o s o s o s o - e s , , e rs a ro a 1 04 , r es , 1 82 , s r r cu or, s oo s, - , r s R ft o f R f A ngle f 7 4 R i l d t P o blem 9 8 R igh t C n 1 02 R igh t Cy li n d 1 02 R igh t H l i i d 1 82 1 85 1 87 R o o f P bl m 2 2 38 39 56 a c r, o s, s, rr s r e r , 76 , e, o er , co e San d b o x of a - Sco o s, e ro p P bl ro , em , re 7 4 , 1 30, 1 32 , 1 34 , 1 4 6, 1 5 6 , 1 62 , 1 70 1 56 , 1 58 , 1 58 , 1 60 B l ade Sc re e n w i th Fo u r qu a , , , L o co m o tive - Sc rew , S , , , s Perspe cti ve . , 1 90, 1 9 3 , 1 9 8 — th re ad e d , 1 2 0, 1 82 , 1 8 5 Scre w , V th re ad e d , 1 8 2 , 1 8 5 - Sec o n d G e n e r ati o n , 1 7 6 Se w e r P o bl r Sh a de f o r an d m , 1 54 E l e ctri c an S h ade L i n e Sh ad es e L amp S h ado w s of a Cap Sh ad o w of a Co ne S h ado w of Shado w of a an 1 66 , on a E lli Co so i d , S ph ere , r e s, mn , 1 68—1 70 P l an e on a p l u , , , 1 36, 1 44 , 1 45 Sh o rte st Se am , 1 30 ” I nterse cti o n , 1 2 si l 1 68 , 1 69 1 70 - Si de , 1 70 1 68 — P o bl m s 7 0 — 6 98 m 56 9 P b l e o Sh aft m etal P attern s 1 30 Sh eet— r 1 60 1 66 , Sh ad o w Sh ado w , Verti cal P ro j ecti o n , 2, 4 -cu rv e d Su rf ace e n i S g , 1 00 1 56, 1 5 8- 1 65 k B P o b l m 3 2 7 8 80 84 S l o pe S h eet o f a L o c m tiv 1 5 6 1 5 9 S p h ere Sh ad o w o f 1 70 S p h e ri cal Hu b fo a Fan 1 38 S p i al S p i ng P o b l em 1 2 2 Squ a e th ad e d S ew 1 2 0 1 8 2 1 85 S ew ri dge s, e r o o r r , s, cr re - R e, , r r Stai r , , , r , , m a p , , , 1 70, 1 9 8 , P o b l em 1 4 2 Ste am I i p P b l em 4 6 54 1 70 St p P o b l m i n S h ado w p i pe E l bo w 1 62 Sto v — S t ve p i p e P o b l m 1 32 Stu b E n d f a Co n n cti ng o d 1 38 S u fa f R vo l uti o n 1 02 Ste am D rum r ro e e s, , e r s, s, s e o , r - e , o e ce o r , - e r , , T l p h P b l m ( S h t t Li ) 9 2 Th P i t D t mi Pl 28 T 1 38 T w P bl m 1 4 6 10 1 2 T f Pl T C i t t f m T Angl f Pl T i ti C 1 64 ti T i gl P b l m 56 68 T A gl b tw I t ti g L i 64 66 T w P i t 50 T Di t b tw T L gth f L i 50 T S i f Pl S f 62 T l P b l m 1 56 1 00 Tw i t d S f one e e ro o n s re e ne o r es e an e , ne a e er , o ru s , e ro er o , r ac e s o ane s , ra ce s o an e s r an e ru e n ro en ru e ru e o ze o a ro e u n ne n e r se c e een a ne , ane o , g s , r , r V e rte x , 1 38 Co n e , 1 00 of a Sc V th re ad ed - re w , 1 8 2 , 1 85 W pdS f 1 00 1 7 2 W t p ip P bl m 2 4 W i L p P bl m 1 60 W d B i dg P bl m 1 9 8 ar u r ace s , e a e rre oo Y ” e oo ro en fo r r a , e ro e , , e ro e Blo w pip - e, n es , o n s, u r ace , V an i h i n P o i n t 1 9 4 Va l t P o b l em 1 58 Ve n ti l ati ng Fan P o b l em u n u r ace s , s e r ue es , , ee n e e ro on, s, e s a nce ru e o rs r u c . o n n ec on r an s , , 144 , 145 , SH O RT - C A T A LO G U E T I T LE O F TH E PU B L I C A T I O N S WI LEY J O HN SO N S N E W Y O RK L ON D ON C H A P MA N : HA LL , LI MI TE D A RRAN G E D U N D E R SUBJ E C T S v i t p i D escri pti d sol l ppli ti A ll b k b e c r c u ar s s en t o n a a t ne r c es o n ly ca s are oo . on k d w i th th l th l B k oo . o un d in m ar s e u n ess o c o a n a s te ri s i e rw se s ta te AG RI CULTU R H O R TI CULTU R O RE STRY P i ipl f A i m l N t i ti A m by 8 B dd d H A m i H ti l t l M l d I mp v m P t I P p g ti C l t t 12m P t I I S y t m ti P m l gy 12 m i gf L d 12 m E lli t t E gi P ti l F m D i g ( S d Edi tion Rew i tte 12m ti G v F tM 8 P i ipl f A m i G 12m f M d D i y P ati G t f l t P i ipl 12m (Wll H i k D t d I d t i l Al h l 8 K m p d W gh L d p G d i g ( N w E d i ti R w i tt I P p ti ) f B tt MK y d L P i ipl d P ti m ki g 8 M y d L d p G d i g A ppli d t H m D ti l 2m I i t S t pl C p S d t I j 12m dl I d H t I j i t G d C p (I P p S d ti ) S h w z L gl f P i i Vi gi F t 12m R k d S il St k b i d g 8 Mi py f V g t b l F d Wi t 8 W ll H d b k f F m d D i ym 1 6m — E r ’ s r nc s ’ an u a n se n s ar o ca ' ’ ro ' en e ' er r c au c ' n ar a an an ' er so n s n se c ar c oc ’ e s r ’ n on s o ' a r sc a co ce o . . o en n ar e c r . on, e . e r en , 0 , o , v0 , ” us r a e s an en n ar n ur ous ’ r ac as o . o er - a 0 , 0 , v0 , n ec o r a e v0 , n on o, . s ro e u ce o e a o n ur o us n s ec s ee s oc oo ne ea s an c r o sc o an s . o o, en ar o ro s . n re a . on s n r , . r nc e s o, . ea on ra n an s sc a erso n an ’ or a rs e n s an s ec o n . e rn o ’ an a en e e r c an on ar a re ro on” es o ’ an u a u ra an e . yo o o ra n a en a u r e s cu d are . on r u r e , an o or r nc an e c es o 5 u or u e n s u ra r nc r een s a ar o re s es s on , n e er n n 5 a — E F a e r c an s e . r ac ra a ro . ar ’ n es o k ar o res s 0 , vo , s e a e n r o o or n e ers a n v0 , s oo en a r 0, AR CHI TE CTURE B l dwi S t m H ti g f B il di g f Am i R il B g B i l di g d S t t d d Bi kmi A h i t t l I C m p d Ri v t d G i d A ppli d B il di g P l i g d C t ti f A m i Th t P l i g d C t ti f H igh O ffi B ildi g Sk l t C t ti i . ' a er ea n s ’ ’ re 5 r o n s an n u s ea o un u ru c u r es o ec u ra rc or ers as r e e an o n s ru c on o an n n an o n s ru c on o o n s ru c 1 2 mo , 4 to , 8 vo s e r c an a ro a s . ro n an an n n e e on n on n e In e r can ce u ea u n . s . re s ” n . s . . . , 8 vo 8 v0 8 vo 8 v0 , , , . 2 5 3 2 3 3 3 50 00 50 00 00 50 00 B i gg By C p ' s s r ’ rn e s M d S l B i l di g A meri can c h o o ateri a s an d I n spec ti o n o f o ern M l n u s Worman shi p E mplo y e d i n . C o nstru c ti o n 1 6m 0 , 8 vo , 1 2 mo g d V ti l ti g f B i l di g D p F d ti w bl P C th l l l F i t g A hi t t F i p fi g f S t l B ildi g 8 th E d i ti E ti ly R G h d G id t S i t y I p ti (F vi d d E l g d ) 12m M d B th d B th H 8 S i t ti f P b li B ildi g 12m d P Th t F i i 1 2m S pply S w g d P l m b i g f M d C i ty B ildi g Th W t 8 Jh S t ti b y A lg b i d G ph i M th d 8 d K ll w y H w t L y O t S b b H m G 8 Ki dd A h i t t s d B i ld P k t b k 1 6m m ti M ill S t f B ildi g d D 8 M kt S t i b ildi g 4t P t t P t i l T ti F d ti 8 P b dy N v l A h i t t 8 Ri C t bl k 8 Ri h y H d b k f S p i t d n tsOf C t ti i6m m B ildi g F m P k t B k d R dy B ildi g M h i R dy R f S i C p t d w k E di ti d W 1 6m m C m tW k E di ti d Pl t 1 6m m d Ti P l m b S t m F i tt E di tiOi 1 6m m St E d i ti d B i k m 1 6m m H S bi 12m d B iggi M d rn Stone tti g aid M ry Si b t 8 S w P i ip l S p e i f W d 8 Tw L k d B ild H dw 18m m W i t E gi i g d A hi t t l J i p d 8 Sh p L w f C t t f Op L w P li m i y t C t ti i E gi i g d ti A hi t t 8 Sh p Ai C Wi l di ti i g 12m W d A tki S m ll H pi t l E t b li h m t d M i t t S gg ti f H pi t l A hi t t w i th P l f S m ll H pi t l H A ll eati n ’ en t er s ar e or re ’ s s rc re ro o a ’ ar er ’ n e a a a s ’ er s ’ e rr a on s ea o ’ ce s c s a ’ e an c s e rs en no ers a . s o . s yo , v0 , v0 , or , . . ’ e vo e rs ’ or e rs ea , r c a so n s - . vo , . vc , . v0 e rs ’ o , or o, or . . o , or . . 0 , or . . 0 , or . on ’ on n n ers an , on s n 5 r nc n s o a ’ . . ’ r . . on oo er s u neer n an n cu e c es o s an oc ’ v0 , vo , . ar e ar rc aso n r ru ur s u ra ec o en c e or , . . on o a r ac o s rc n ar re o n s ru c o n on n n eer n an v0 , u re ec , . ons era ee ’ so n s on n on r a n so n s u ons es or a s, os a os s a en s a n e n an c e . an s ec ur e , rc an AR MY or a NAV Y A ND s o se ’ c re o a t ern ro ’ ’ unn er s ’ ra re s ar n e s s ec a a ’ rac u er s se o n s ’ e ’ u ra n a e ’ a n er Ce ll u 1 2 m0 , 1 2 mo 8 v0 , 8v 0 8 vo , u s on ro . . ' ss er s e os ta r a an oo o e rn er s ex ’ o n an “ on r u es e ro ra t . , . , ’ s . a rr . ro c e . . r s u re o ar e e a . ar o e u s on o . on . a es o oo . ‘ os - ro n o o -c ar e u an er s o ” es s an c e a n 5 n o ar a r 5 ’ a o n er ’ re a e eo r e u o re a n u u o se , an n a a e ro -ce er , er s a n e s te n e s o o ec u e rt o ase s e e ss o a . 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Z mo r 1 2 mo , . . 8 v0 8 v0 8 v0 , , , . , 8 v0 1 2 m0 es or ’ u n n er s ca a ec on s . . . ar e 1 2 m0 1 8 mo , , A St i ss o c i a t o n o f N ti a te an d a lF d on a D iyDp an d oo a r e H f d ar tm e n ts , ar t o r M ti g 1 9 06 8 J m t w M ti g 8 A t N t f Ch mi l St d t 12 m B k vill C h m i l E l m t— ( I P p ti ) B d S m k l P w d N i t ll l d Th y f th C ll l 12m B il tz I t d tio t In g i C h m i t y ( Hal l d P h l 12m L b t y M th d f I g i C h m i t y ( H ll d B l h d ) 8 B l h d S y th ti I g i C h m i t y 12m B w i g I t d ti t th R E l m t 8 Cl B t g M f t d R olf ) 8 ( H ll Cl Q ti t tiv C h m i l A ly i b y E l t ly i ( B l tw d 8 d T t p p C h I di t T t dR g t 8 D l El t h m i t y (M i m 12m D th M th d f T x til C h m i t y 12 m D h m Th m d y m d Ch m i t y 8 (B g Efi t d th i A ppli ti E zym tt 8 (P Ei l M d H igh E xpl iv 8 E dm I t d ti t Ch m i l P p ti 12m ( D l p) F i h P h y i l gy f A li m t ti L g 1 2m Fl t h P ti l I t ti Q ti t tive A yi g w l th th B l w pip 12m m F wl S w g W k 12m F i M l f Q li t tiv C h m i al A n aly i ( W ll 8 M l f Q li t tiv C h m i l A ly i P t I D ip tiv ( W ll ) 8 Q ti t tiv C h m i l A ly i ( C h ) 2 v l 8 Wh S ld S p t ly V l I $6 V l I I 88 d P b li H F t Wt l th l 2m F m M l f P ti l A yi g ( S ix th E di ti d P d R vi d d E l g d ) 8 G t E x i i P hy i l C h m i t y 12m G ill G l A ly i f E gi d F 12 m f Q O tli li t tiv C h m i l A ly i G d B w i g h L g 12m G t f lt P i i pl f M d D i y P ti 12m G th I t d l C y t ll g phy ( M h ll ) ti t Ch m i 12 H mm T x t b k f P h y i l gi l C h m i t y ( M d l ) t 8 H k Mi py f T h i l P d t 8 H ki l d O g i Ch m i t y d M 12m H i g R dy R f T bl (C v i F t ) 1 6m m H i k D t d I d t i l Al h l 8 Hi d I g i Ch mi t y 8 l 2m Lb t yM l f St d t H ll m Lb t y M l f O g i C h m i t y f B gi 12m 8 T xt b k f I g i C h m i t y d M tt T t b k f O g i Ch m i t y ( W lk 8 H ll y L d d Z i P igm t L g 12m H ll y d L dd A ly i f Mix d P i t C l P igm t d V i h L g 12m H pki O i l h m i t H db k J k D i ti f L b t y W k i P hy i l gi l C h m i t y 8 Jh l A ly i f S p i l S t l S t l th C h m i R p i d M th d f d G phi t L g 12m m ki g A ll y L d S p t m A ly i ( Ti gl ) 8 f A l mi m i V g t bl P d L gw thy d A t O 8 A im l P d t d N t l W t t L C h A ppli ti f S m G l R ti t I v tig ti i 12m O g i C h m i t y ( Ti gl ) L h I p ti ly i f F d wi th Spe i al Ref en e t S t t d A 8 E l t h mi t y f O g i C m p d ( L z 8 L b L dg N t A yi g d M t ll gi l L b t y E xp i m t 8 8 L w T h i l M th d f O n ee a u s en s as n es o ’ o es or e s ou s ca ca en e e e ss o en u o er s s o . n . ara re on $ 3 00 3 00 1 50 , . u o se , a n ro - 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A y ii g k d Mi lle Nt d l Di i f ti d th P v ti f F d S w g d th B t i l P i fi ti f S w g Rigg E l m t y M l f th C h m i l L b t y R bi gl C y id I d t y ( L d L i P R d dim I m p ti b ili ti ip ti Wh y i P h m y R E l m t f M tal lo gaphy ( M th w ) S b i I d t i l d A t i ti T h l gy f P i t d V i h S lk w ki P hy i l gi l d P th l gi l C h m i t y ( O d ff ) S hi m pf E ti l f V l m t i A ly i M l f V l m t i A ly i ( F ifth E di ti R w i tt ) Q li t tiv C h m i l A ly i d Ch m i t M lf A y S m ) (I P S m i th L t N t Ch mi t y f D t l St d t Sp H db k f C S g M f t 1 6m H d b k f Ch m i t f B t g 1 6m S t k b i d g R k d S il d G St P t i l T ti g f G M t " D i p tiv G l Ch mi t y f Till m El m t y L i H t T d w ll Q li t tiv A ly i ( H l l ) Q ti t tiv A ly i Ri c e tts Ri e a s 0 v0 a te r an 3 ’ o un ar o ca en e ’ oo u re ue s ec e o , v0 , . e ar an an s er o ns o o or , . s e nc u . uct o n ro ’ e . s n . ean n t n s o cat o n o . o e r o an ’ c s an c oo n era s, es a o an s r e es o o s r e sc o es t ca s tr e e n a gc s a o : en a a c to r e s es u rea e ’ r ac er s e rc a o ur . ts ro s . n ee r s w oun s t n en t on o ons on ersa an ’ ar s t es o n o t e or . ’ eo r e s an or o “ ar - en o u s e . . s tw a o un ar se s tr s tr an e s u n o u r ca ec ca et or o u t o n s an or e u str a n e e o s tr o o . r sco w en eo r en era en s o s ca e s to r u r s ’ oo a c u a t o n s u se o rse s u t e e ts an a cu a t on s en ts o e ut nu n ca ec . 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RAWI NG . o , o , . n e m ati cs o f 8 vc 8 vo 8 vo l D wi g C lidg l f D wi g p p 8 C lidg d F m El m t f G l D fti g f M h i l E gi Ob l g 4 t D l y Ki m ti f M h i 8 E m h I t d ti t P j tiv G m t y d i t A pp li ti 8 F h d I v St t my 8 H ill T x t b k S h d dSh d w p tiv d P 8 J mi A dv d M h i l D w i g 8 El m t f M h i l D wi g 8 J M hi D ig P t I K i m ti f M h i y 8 f P t P t I I F m S t gth d P p ti 8 K i m b ll d B M hi D ig 8 M C d El m t f D i t pi G m t y 8 K i m ti ; P ti l M h i m 8 M h i l 4t V l i ty Di g m 8 ML d D ip t iv G m t y L g 12m M h D i p tiv G m t y d S t t ti g 8 I d wi g t i l D 8 ) ( Th m p M y D ip tiv G m t y 8 k t hin g R d T p g phi l D w i g d S 4t R id C M h i l D wi g 8 T xt b k f M h i l D w i g d E l m t y M h i D i g 8 R bi 8 P i ipl f M h i m 8 S h w mb ill E l m t f d M 8 S m i th ( A W ) d M x M hi 8 l f T p g phi l D win g ( M Mi l l ) Sm i th ( R S ) M T t w th E l m t f M h i l D w i g Ob l g 8 12m W D fti g I t m t d O p ti d P 8 E l m t f D i p tiv G m t y S h d w p tiv d 8 E l m t f M hi C t ti h 12m El m t f Pl dG m t i l d S lid F 8 l P bl m f Sh d d Sh d w G M l f E l m t y P b l m i th Li P p tiv f F m d l 2 Sh d w l 2m M l f E l m t y P j ti D w i g l 2m Pl P bl m E l m t y 8 P b l m Th m d E x m pl D i ptiv Ge m t y d mi i f T W i b h K i m ti d P w (H m Kl i Wi l ( H M ) T pg phi S v yi g Wil ip ti v G m t y (V T ) D F h d L tt i g F h d P p tiv W lf E l m t y C D i p tiv G m t y L g 8 ar M M s e an ra c , an . on e D B ts o ’ ’ en , s ra o n s tr u c ro a a cs o on c u ro a n e en co n o 5 a cu a o vo . ’ e tt s ’ oo ec h a n i c a an u a e s e an oo n ra o ’ an s ree n ra . vo . en s o e en e r a n ra or on . ’ ur e ’ c a n ro 5 en e ’ o n es s ne ar ’ or ne a eo s e sc r an s n er 5 ’ ee ’ e o n so n 3 a I . 5 ’ an s e r vo , vo , vo , vo , vo , o , vo , o , vo , . vo , . vo , o , . en n ra s o en s o e sc r e en s o ac e en s o a n e an an u a a o an e ro ’ ac eo r e en e ar ac ne n es . ” ra ca e r s n e n o . ’ so n 5 . r ee an r ee - an en ec o e ra on s , an er s ec a an o e r ca eo s n ea r er s ec e o vo n es I n e sc r o r an s e ss o n . o e r er , , vo , vo , o , vo , vo , o , vo , s an or . er . e ar s , an vo , an n rn o , o , o , vo , an . ’ . ro . . an a vo . o vo . . o n an e s an e a . on ons , re e o an c . n e ra o n s ru c ro ra ra an c a eo e cs a ne e an ne e ar s In e s so n s n s an ar en e s, e vo , o an u a ro en e o o a . . n en s o e n s o ec ne e . e c an s o n s ru ro so n ac o o n e- cu an ra s e s ec an en e ar e e n e ra oo eo ra ec es o an u a 5 ar r e n s ’ , . ” an c a ec . or ’ e s an c a an . s s . ar n ec e rr . e r eo ’ an ' ar s ons o or ve o . ra r nc vo , vo n es e r ca o , vo , . e r eo e oo ’ c . . ro ca eo n ra ra o e o e s e o u r se I n s an ne rac e sc r e sc r s n ec n er e sc r e us r a ’ o ra , s o ra a ’ a n er s . e oc c vo , on ca an c a ec ’ s , an o ra ac ac o r, cs a an c a re n , en e es a n cs o a ar r s s s n ’ an an e r eo , vo an ca es or . e ” ec ne . o , vo ro e c a ec s o ac ar ac on an c e so n 5 a o e re o oo ’ a ’ es e s on o n es ac cs o uc an r en c ’ ne s , n an c a ec , er , a , o ra e sc r . e en ar c ur e eo e n e r . er n e rs , ec e . o u r se I n esc r e 10 eo e r ar e y o , 2 MATHE MATI CS . B k E llip ti F ti 8 B igg E l m t f P l A ly ti G m t y ( B o h ) 12 m d S ph i B h Pl l T ig m t y 8 By l y H m i F ti 8 C h d l E l m t f th I fi i t i m l C l l 12m C ffi V t A ly i 12m C m p t M l f L g i thm i C m p t ti 12m Di k C ll g A lg b L g 12m I t d t th Th y f A lg b i E q ti L g 12m ti Em h I t d P j tiv G m t y d i t A ppli ti ti t 8 f F i k F ti C m pl x V i b l 8 H l t d E l m t y S y th ti G m t y 8 8 El m t f G m t y 12m R ti lG m t y 8 S y th ti P j tiv G m t y H yd G m S p A ly i 8 Jh p l L g i th m i T b l V t p k t iz p p ( J B ) Th 1 00 pi M t d h vy d b d 8 X 1 0 i h 10 pi f Diff ti l d I t g l C l Jh l ( W W ) Ab idg d E di ti L g 12m 1 l 12m C v T i g i C t i C di t Diff t l E q ti 8 E l m t y T ti Diff ti l C l l L g 12m E l m t y T ti I t g l C l l L g 12m th 12m Th ti l M h i Th y f E d t h M th d f L t Sq 12m T ti Diff ti l C l l L g 1 2m T ti th I t g l C l l L g 12m T ti O di y d P ti l Diff ti l E q ti L g 12m K E gi i g A ppli ti f H igh M th m ti p t ff ti (I P p ) tt d Em L pl P hil phi l E y P b b ili ti ( T y ) 12m L dl w d B E l m t f T ig m t y d L g i th m i d O th 8 T bl T ig m t y d T b l p b li h d p t ly E h L dl w L g i thm i d T ig m t i T b l 8 M f l V t A ly i d Q t i 8 MM h H yp b li F ti 8 d th i R p M i g I ti l N m b t ti by S q d 12m S i M th m ti l M g ph E di t d b y M fi ld M i m d R b t h S W dw d Otv N y f M d M th m ti b y D vid E g S m i th 1 Hi t N P j tiv G m t y b y G g B H ltd 2 S y th ti by L G iff d W ld N t N 4 H yp 3 D t mi N F ti by J m M M h H m i F 5 b li ti b y Willi m E B y ly N 6 G m S p A ly i b y E dw d W H yd N 7 P b b i li t y d Th y f E b y R b t S W dw d N 8 V t A ly i d Q t i N by Al x d M f l D iff ti l E q ti by 9 Willi m W l y J h N S l ti f Eq ti 1 0 Th f b y M fi ld M i m N 1 1 F ti C m pl x V i b l b y Th m S F i k M T" h i l M h i 8 M i m M th d f L t S q 8 S l ti f E q t i 8 Ri d J h D iff ti l d I t g l C l l i 2 v l L g 12m th D ifi E l m t y T ti l L g 12m ti l C l S m i th H i t y f M d M th m ti & V bl d L I t d ti l I fi i t i m l A ly i f O t th R ’ a er s ' r s s en e an a n s ’ er e ’ an er s n s o ’ so n s c ’ unc e s s ’ a s e s en e e en a ona n e ’ . u o o , ar e o , vo , vo , vo , 1 vo , o , o, . ons a e c an e r eo o ns ua ra c e ar a e eo e ac e an n s n so n s a cu us on ca s e e r eo . ec ’ o e ar o es : a c es oc - 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. , vo , . e r ’ ra ss e s a o e n e r ro c eo r o eo eo ar . . ro ec ar s o es c e a e r $ 1 50 1 1 1 2 2 1 1 1 2 1 o . . o ons o ono er ra o on uc n ar e on uc n ro s o e e o n ro ’ o r c . vo , n e s s e r eo o ns unc na an u a on s c er c a s o ec o r ' o en e ’ na an e on c vo , . . an e a n ar s ons s o ’ uc c un c c an uc e e re n e a n e on a ra a c u u s. o s . a c u us a . n o ne ar e o , ar e o , v0 , cs o . e 12 ea n n es a na s s o ne 2 00 b y V t P k t H d —b k f M h E l g d E di i I l di g T b l mi W ld D G m f C W d El m di y W d d P b b ili ty d Th y f E W a te r ’ ur n ar ’ ’ oo s ’ oc t e on an e nc u , a n at o oo e m at i cs fo r 2% E gi n X5 % n ee r s i h nc . mor mo r es , es n a n ts e n ts o e w ar oo es e te r s e s a ro s n a te o -o r eo r an rro r s o ME CHANI CAL . 8 vo 8 vo , 8 vo , e tr eo . . . 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i h m E l g d E di ti I l di g T b l m d th Ki m ti P w f T mi i W i b h m (H Kl i ) 8 M hi y f T m i i d G v 8 (H m W d T bi 8 Ri c h a r d s s Ro i n s o n s ’ ’ wa c r nc . ’ t ’ o re es an . s ’ ar u re t n ar s ts en e ac s re s s- w o r s an s ec ’ err an t r re ss e o n an vo , ne es n vo , vo , . on n co n o n es ’ u rs o n s es t n a n w ar oo . ar . r ac t c a one s as an o as a ac , an s r e s to n ’ vo ec us o , o e a s o o e te r s as n e an e r a e e o , y o , et cs n er s o o re a t s e o n ’ so n s ’ ts w o r t ’ a te r ts oc n er an or o n s tru c an oo - on ra w n o n an a o a e cs n or n eers nc n ar ’ ac e s on e e n ’ oo an cs a e . er s s o n an r an s n es e ’ ’ u rc s I ’ o ’ e ea 3 an e o ' a n so n s na 5 te e s, n so n s ee ’ s . ro n as ’ an a s a re s et . a n ts , s o n a an c s ec en ern o , or . or . , R I NG ru c t u r e s i l f E gi n or e ra s an o on o n s ru c , , . 8 vo 8vo 8vo 8 vo i g n ee r n , , , L g 12m C lo P igm t d V i h L g 12m C h m i l A ly i f S p i l phi t L g 12m ar en r o s , an na ca o a rn s ar e e s s e es o o e , . , ec a ar e o , 8 vo , 12mo , o , o , vo , o , o , . . e ' s e a er a s o . St f a te r a s o e s s o - o . en a ’ o an c s nc . . te e vo vo . n ee r n ec a ’ o n tru c tu r a re e n e s eo r e s s ta n c e o an an c s o ec , . t s an c es e e r l M h M T hi i M im M h i fM t i l f M t i l St 12m gth M t lf S t l A M l f St l 12m S b I d t i l d A ti ti T h l gy f P i t d V i h 8 S m i th ( ( A W ) M t i l f M hi 12m S m i th ( H E ) S t gt h f M t i l 12m Th t M t i l f E gi i g 8 3 v l P t I N —m t lli M t i l f E gi i g 8 P t II I d St l 8 P t I I I A T ti B B z d O th A ll y d th i C ti t t 8 W d ( D V ) E l m t f A l y ti l M h i 8 f M t i l T ti d A pp dix th R i t th P v ti f Ti m b 8 d E l t ly i f I W d ( M P ) R tl C ti g C i d ’ a u re r s ’ er r an s * ’ ’ in s r a us an ’ s ' s ’ u rs o n s on ar ar u en o ns ’ oo s e se o n r ea reser oo ’ s . . an arn s . n es n e er n o s a er a s o ee n vo , , n eer n . . . se o n r a sse s , ro n es an er s an o en na s o ca e s s an c e on o us vo , vo ec a o an c s y o . an er a s an en on ess n oa o rr o s o n s: an ec ro s s o ro n , , e vo er , e r vo e a a n o s e . u se r s a er a c r ea - no o ec ac n o e a . c o ro n a n . ee er a s o a er a s . s ren . . ar a . . or r . . an u a ee n a er a s a er a s o s an c s ec an c s o ec r en e ca a nca ec , an 8 vo , S TE AM E NG INE S - B y Tm t R fl i C Ch A t f P t err a rn o ’ t ’ ’ a se s ec t o n s o n e s r py Di g m M tiv P w th M ki g r a u re en e p e s o a t ern tro a a e o e n ra . A ND , o er o f H ea t B O ILE R S . ( Th . u r s to n 3 00 3 50 . 1 3 1 1 7 00 00 50 25 50 1 00 l 50 an n e rr an n er . O F E NG NE E a te r a s an o t as t c u rr s vo vo r en s ss o n . B v y S t gth f M i l d Th y f th M B El i i y d R i C h h M h i f E gi i g G S lM h i H ll y L d nd Z i P igm t H ll y d L dd A ly i f Mix d P i Jh th ( C M ) R pi d M h d f S l S l M ki g A ll y d G f C t ti Jh (J B ) M t i l K p C tI L z A ppli d M h i M i M d P igm t d h i V hi l o r an s o e rn o rs o MATE R IALS ’ es , es o , vo o ur s n 00 00 00 00 . . n er ac a ne s nc u , , o raw n an c a , vo . n s r u c to r ne e ac n or e ec ac es s o o e n ts o ’ ur en e s e a rr e n s u to e e o o st o n an r c 3 3 3 3 an . o r , an o $ 1 50 5 00 5 00 2 50: A lyti l M h i f M h im S b M h i P bl m mb d M S h ill E l m t f M h i W d E l m t f A ly ti l M h i P i ipl f E l m t y M h i Mi hi R bi El m t P i ipl ’ s of , $4 00 8 vo 1 2 mo 8 vo 8 vo , 12 mo 3 00 1 8 3 8 3 8 1 8 Ab d h l d Ph y i l gi l C h m i t y i Thi ty L t d ( H ll B h i g S pp i f T b l i ( B ld ) 12m I mm B ld S 12m B d t S t di i I m m i y ( G ) 8 D v p S ti ti l M th d w i h S p i l R f B i l gi l V i ti m 1 6m E h li h C ll t d S di Imm i y ( B ld 8 F i h P hy i l gy f A li m t ti L g 12m ff M l f P y hi y ( R L g 12m d F d C lli ) T x b k P hy i l gi l C h m i y H mm 8 J k Di i f L b y W k i P hy i l gi l C h m i t y 8 L C h P i l U i y A ly i ( L z ) 1 2m M d l H d b k f th B i C h m i l L b y 12m P li P hy i l C h m i t y i h S vi f M di i ( Fi h ) 1 2 m P zzi E t T xi m d h i A i b di 12m d V R ki S m Di g i 12m R d di m I m p i b ili ti ip ti 8 i P Why i P h m y 12m S lk w ki P hy i l gi l d P h l gi l C h m i y ( O d ff ) 8 f H m 12m S l O li E m b y l gy Sm i h L N Ch mi t y f D l S d t 8 Whippl T h id F v L g 12m W dh ll Mili y H ygi f f O ffi f h Li L g 12m 12m P l H ygi W S m ll H pi l E b li h m t d M i d A ki f i f H pi l A hi w i h Pl S m ll d S gg H pi t l 12m 1 25 c ' n so n s o ’ r nc o rn s an an ’ s oo en r nc es o ’ ca s e s na s o es o L g ar ca an s m ec a er vo n en s ' r n e s ’ u an s o or ’ e u s es n ta s ’ o rt s en a un e s r e re s s o n o u . , u . n er c u o s s r u an o . u r es ec a . r c ’ t un ca ay . e ’ . . t s o ec a to e e r en c e ’ a r s te n s a ’ ac a ssa r an ' ’ e ’ au o - an s ’ sc o - ’ o s to s ’ an s a ’ s o ca o o t ut ’ e s ’ u oo tes an a os ca er o r en . , . e , ar e o , ar e o , . vo , . vo , o , o , o , o , . ca s r . . c ne e n e r t es o er sc . r esc r . . on s ca o o . an r e o , vo , o , rn . or e n ta tu en en e t c ers o o . s er e . . vo , o , vo , o o or s r s tr e ne e ar e o , ar e o , o , . n so n s a or ta os s ta ta s os te c t u r e , rc a n te n a n c e , an en s t an s or a a o . ME TALLU R G Y . vo o r a to r a t ns s o o ce o s an at on es t o n s u e e s tr n s s n an ’ t vo . u en e e r so n a o rc e s t e r an t n es ca po ta r s , ac o y o or , . o e or o- an ca na en o n es o tu r e ec s e no s s s o o a tte r e e s r n ar at ar o sa n o . o r a to r s r a s , ar a u an o on s o o n s an o n co ’ ’ a e s n s or or e ru s on oo s ca s u o ns oo rac t c a n s o - t r ec so n s a a tr c s t- e en o t un es o n o an u a u r sa c s e tu e s o o er s sc o era o ec o s an . ons ’ , an c s ec ca s o o e , , ME D I CAL ’ . an c s : ec 8 vo . . s o e n ar e . . en e an c s ec an s ec ro e rr e na an c s ec wa c en e e s , . L d R fi i g b y E l t ly i B ll d E y l p di f F di g d Di ti y f F d y T m d i h P i f 12m I F d 12m S ppl m 12m D gl U h i l A dd T h i l S bj t 12m l Mi l d M t l A R f B k G L d m l ti g Il 12m Jh R pid M h d f th C h m i l A ly i f Sp l S l S t l m ki g A ll y d G phi t L g 12m K p C I 8 — B H igh m p M B d d g ) m L Ch t l i t ( 12m 12m M t lf S l A M l f St l 12m Mi P d i f A l mi m d i t I d i l U R f M 8 El m ll g phy ( M h 12m S mi t h M t i l f M h i 12 m Tt dS F dyP i 8 M t i l f E gi i g I Th P t h Th P t I N m t lli M at i l f E gi i g C ivil E gi i g pg 9 P t II I d St l d O th P t I I I A T ti o B a B z A ll y d th i B e tts ’ ea s ’ an o nc s n t ro n ec ro n n e c o a o e ’ o e se ea es s ’ n so n s ee e ’ e ca tee s net s u er s s ar ’ ar e . e s an u o e ta oo ec , . o , . o , o , s ” na ca e ra e o un s ee nu an ra o s s . . tee ec I a o ar e - en u s ers s . s ou . ur o u ar ess u s tr a at e w so n se . . c . er a s o n r ee n ar ts n ee r n , n see o , o , o , vo , o , o , vo , . n ee r n n , vo , . n , s, o r ac t c e r e a eas u re or n es ac n e er n , . ro n an . or an u a on- . s er a tu re a er a s o s a ar te . ’ u o . - to n e o o a er a s o a e an s u se er o e n ts o e r . uc t on ro ’ u rs o ro n n ca ec e er en c e e a s: n er s ’ ’ a ’ a e o un o t res se s o n et - as t s o n ar c n a ee ’ n ca e s - en e n e r a s an s ' o n tec as s an er u ou n o un . r ac t c e o e o un ’ s s r ea ee se n r sses , ro n es , an er o s an e r M d E l t ly ti C pp W t A m i F d y P ti M ld T x t B k U lk e ’ s ’ es e rn o ec er c a n s ers ou ’ ro c o un r ac r Re fin er o ce i g n . . oo e MI NE RA LO GY . B k vill C h m i l E l m t ( I P p i ) B i g I t d i t th R El m 8 B h M l f D t m i iv Mi l gy ( P fi l d 8 B l P k t H d b k f Mi l 1 6m m Ch C t l g f Mi l p p 8 Cl h d S ilv G ld C D F i t A pp dix D N w Sy m f Mi l gy L g 8 D S d A pp dix D N w Sy m f Mi l gy L g 8 M l f Mi l gy d P t g phy 12m Mi l d H w S dy Th m 12m S y m f Mi l gy L g 8 h lf l h T x —b k f Mi l gy 8 D gl U h i l A dd T h i l S bj 12m E kl Mi l T b l 8 t U Ekl S d i E gi i g ( I P p i ) d Cl y P d Mi l d M l A R f B k l G m l fim d ti t C h m i l C y ll g phy ( M h ll ) I h 12m G H y H db k f F i ld G l gi i 6m m ’ ’ ro w n n ’ ru s an u a s ’ u t er s oc ’ es t er s u ct o n n ro s an e ar a t o n re ar e r . e n ts e n e ra o e en . e -. n era s o n er a s ue o n . e nat oo - s o e er o a a o en e ca e e s er as o vo . an o r an e s ’ ’ an u a to n e ra s an ' ’ c ’ e ’ o e se ’ t ro to n e s ’ a , ’ I d d i n gs Ro c e t , Ro c l n e ra s e vo , ar e vo , o , o vo e n ca ec ec ts u uc s o e or e k s n se n eat a , e e ren c e ca s ta r n re a ra t o n oo o ra o a rs vo , o , vo , or , o o or , . . 8 vo 8 vo 8 vo . , . , k f i g Mi l i Thi S ti Wi th Th m b I d x M ti L b t y G i d t Q li t tiv A ly i w i th th B l w pip 1 2m M ill N m t lli Mi l Th i O d U 8 ti S t f B ildi g d D 8 Nt D t m i tiv Mi l gy d R d f Mi l T t fi ld P 8 p p T b l f Mi l I l di g th U f Mi l d S t ti t i f D m ti P d t i 8 d R k Mi R k l Pi 12m S y p i f Mi l Ri h d 12m m C l y Th i O P p ti d U Ri 8 H i t y f th C l y w ki g I d t y f th U i t d Ri d L igh t 8 Ti l l m T t b k f I m p t t Mi l d R k 8 W hi gt M l f th C h m i l A ly i f R k 8 J i i e te r m n a t o n ’ o h an n se n s of Ro c —o r m n n era s n n o ns ec . u o ra o r a n s ar e ua o a s s na e e e rr ’ e a s es o ’ ’ e s an n er a o n an se e ec o r n e ra s o n era o an , vo , 4 vo . 5 00 , a a s cs n er a s o o o s or er ro o e e s an a - se s n or or , . . us n r o n e . er , vo c c u rr en c e , on 3 o es s vo n er a ’ e . on oc e r ses , , . vo , ex an s ’ o r an o an u a on s n as oo - e o n e r a s an ca e na s s o MI NI NG B d Mi C G ld ’ e ar ne s ’ r an e s o G ases an d E xpl an d S ilv er o si o n s oc s vo , oc s vo , . . d x f Mi i g E gi i g L i t t M i i g M th d ( I P ) D gl U t h i l A dd T h i l S bj t M d H igh E xpl iv Ei l Mi l d M l A R f B k l G M l f Mi i g Ihl g L d S m l ti g Il C m p d A i P l t f Mi P l S h f t Si ki g U d Diffi l t C di ti i ga d P Ri m (C W v Mili t y E xpl iv w i tt Wi l H yd li d P l Mi i g 2 d di ti T ti P ti l d Th ti l Mi V til ti In e n n n as s ’ ss e r s o es e ’ ’ ’ ee e s r ea r au se o n u s ec es ‘ e e r en c e oo . an r n n ca nes or cu er os c an r ac n ca ec . ar er 5 so n 5 n n a ’ ’ n n r esse er s ea e ta s u re . res se s o n o e o ’ r e ss os an u a e ra n ee r n n . n ca ec ea es s n n er a s a n s ’ s o . ern o s s en e e ’ ou n n o on ons n o rn n . es ac e r n n an eo r e e . ca 17 ne on . en en r re a on . 12mo 8vo e e l e ) 8 vo 8 vo 12mo , 1 2 mo , , . , . . 1 2 1 5 8 8 8 8 e vo , ’ 3 00 1 25 1 50 5 00 5 00 , o on e nc u s s o s: a es s s an no s 5 ar c na uc ro c c u r re n c e a n e r ec o r a e er c oc r s so n s an n e ra s , o ’ n es o n o es n era s : c u or o n es en e a on- s , e e ’ 2 00 1 50 1 2 50 4 00 1 00 1 25 5 00 1 50 60 n u ’ 50 00 00 00 25 00 00 . a s ts eo o , er, . n eer n 1 4 3 1 1 5 1 . . e ta s : oo n eo u s ar . ro on uc g k Mi D I s . er , es a an es s a a an n tro s , ra re ss e s o n n e ra s a n s tu n e ra o o ar n ca n er a e s a e ro to s te e an n era o o n tec as s ou an a s n era o o n e ra o oo ’ s te e ’ to o o t e an a s n e ra o o s te ’ en ec o n an a s vo er en rs an a s , or , o ’ vo . 2 8 2 8 2 8 S A NI TA RY S CI E NCE A St i i sso c a t o n o f N i a te an d at o n a lF d D iyD p an d oo . a r e art m e n ts H f d ar t o r , M ti g 1 9 06 8 J m t w M ti g 1 9 07 8 f P ti 12 m O tli l S i t ti B h S i t ti f C t y H 12m S i t ti f R C mp d P k 12m ti g ( D ig i g C t ti d M i t 8 F lw l l S w ) 8 Wt pply E gi i g F w l S w g W k A ly 12m F t W t fi l t ti W k 12m Wt d P b li H l th 12m 12m i t y I p ti G h d G id t S M d B th d B t h H 8 12m S i t ti f P b li B ildi g S pply S w g d P l m bi g f M d C i ty B i ldi g Th W t 8 d H w t G t It H z Cl W t L g 12m 8 F il t ti f P b li W t ppli P i fi ti f S w g ( I P p ti ) d P tt Ki i t Wi l w t h I p ti ly i f F d w i th S p i l R f St t d A L 8 C t l 12m M E x m i ti f W t ( C h m i l d B t i l gi l ) W t pply ( C id d p i ip lly f m S i t y S t dp i t) 8 8 M i m E l m t f S i t y E gi i g S w C t ti 8 O gd S w D ig 12m Di p l f M i ip l R f P 8 P l w E l m t f W t B t i l gy w i h S p i l R f d Wi tt S i t y W t A ly i t 12 m P i H d b k S i t ti 12m C t f Cl 12m Ri h d C t f F d A S t dy i Di t i 12m C t f Livi g M di fi d b y S i t y S i 1 2m C t f Sh l t 12 m Di t y C m p t d W i l li m Ri h d 8 Ai d F dm W t d f m S it y St d d W Ri h d pi t 8 Pl mb S t m fi tt d Ti E di ti ( B ildi g Ri h y M h i R dy R f S i ) l 6m m v ti f F d d th P Ri d l Di i f t i 8 S w g d B t i l P fi ti f S w g 8 S p Ai d V til ti f S bw y 12m d R ll P b li W t ppli T 8 V bl G b g C m t i i Am i 8 M th d d D vi f B t i l T tm t f S w g 8 W d d Whippl F h w t B i l gy ( I P ) Wh ippl Mi py f D k g w t Typh id F v V l fP Wt Wi l w S y t m ti R l ti hip f th C n ee a ’ as o n es o a on o an a on o e s e n a er su - ’ a e er s o ’ a e r an ’ ar er u s o e rn an a a en s ra nn c u ’ eac ar ns ns o n ro ’ an s en s on er e an r esc o ' ’ ar c os o os o os o c e rn o u ar e c ea s on o o a e e n . on a ra re e eren c e ec a oo ca e r nc ar a an a an as er e o ac ca er o o an a ro a er na n s s a r es e an e ’ e ar s s ’ an s ers r, en a e s e ar ac er a u rI ’ a er , an er o o oo an ar t , o n . G eo o n e rn a err e ’ o p u ar s ’ er a ’ an n e a a ar a ’ a n es s an au se s er ca ’ s . vo , o , vo , . , vo , vo , vo , o , vo , o , o , o , o , o , o , vo , an on e or , er a e es en r ea n . . vo , oo a 2 00 , n u s o o In ’ er c a n a er rI n a e o r ess yo , o , vo , vo , vo e , . a er - a er e a c ca u o na o ns o se o n ac ca oo e- on r ea os on s s s . u re s e s , e er o on o a e r - su ac or n n er s o c c a c ea e e l gi l G i d b k f th R ky M I t ti l C g s f G l gi t F l P l T ti th Wi d Fi tzg ld B t M hi i t G tt S t ti ti l Ab t t of th W ld Hi A m i n R ilw y M g m t k H T h e Mi py f T h i l P d t E mmon s , . ec a an 8 ro MIS CE LLANE O US ’ vo o er es on o a o r es o er e a ue o s , . er an , ca c res c r o sc o ’ a u u c es e o s re e e s ’ o c en c e u r e ser on o a ’ e s , . ar e e r en c e , e u sse an ’ o . o ers - an ac an ns o ea on a ea , en ar o ’ an c s u rn ea u r e a n ’ , vo r an er s o . oo e an ’ , on a o a u a o vo , e u se a er u s n ec e , a e o n ee r n n en s o e . n s s vo e a n n e ss oo ec ’ , e o n ’ vo n on on o an s o . ca . an ar s an ar ar c ’ an oo os s s s s un c o o an r ce s . es er e s o ns o en c e , n o sa s a rs o n s s en o n s ru c es ’ n . ur s a er o ons e er e ’ na . ’ ’ e n an c e a n . a er - s u e rr an , . na a aso n s on u e o ra an on o s o a er - s u an , s e , an o c u o ons ec era e a e r an ec o n s ru c n u , ns o ar o u se s a u on o , s an c , s o u ea n or . s an a er ' on ea a o s es c e s an , u on o e n n na s ra a er - u er e s s a on n ee r n or e , on a , vo o u se es . an ca r ec r ea er a e r ac o un a . . , n es o an ’ n ee u o re s vo . , res o o e oc eo o s s . i Ex o u n ta n n s L g ar “ e i c u rs o n o f . a c ro sc o e an a a o ec e or en . . . n ca ro 18 uc s 8 vo 8 vo 18mo e . n s s ra c th e . ( Wi , , 24 mo , 1 2 mo , n to n ) 8 vo -8 4 . n8 a H8 8 K 8 0 8 ) 1 ,