Crossing the Ocean?

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‫המהפיכה המדעית של המאה ה‪17-‬‬
‫נטישתה של תמונת עולם קודמת‬
‫(אריסטוטלית‪ ,‬גיאוצנטרית)‬
‫ואימוצה של ראיית עולם חדשה‬
‫(הליוצנטרית‪ ,‬לא‪-‬אריסטוטלית)‬
‫שקיעתו של העולם האריסטוטלי‬
‫מסעות גילוי‪ ,‬והמהפיכה‬
‫הקוסמוגרפית‬
‫קוסמוגרפיה ומסעות גילוי‬
oikouménē - οἰκουμένη
Modern reconstruction from Herodotus
(S. 5 BC)
oikouménē - οἰκουμένη
Phoenician and Carthaginian voyages
around Africa, according to Herodotus
As for Libya [Africa], we know it to be washed on all
sides by the sea, except where it is attached to Asia.
This discovery was first made by Necos, the Egyptian
king, who on desisting from the canal which he had
begun between the Nile and the Arabian Gulf, sent to
sea a number of ships manned by Phoenicians, with
orders to make for the Pillars of Hercules, and return
to Egypt through them, and by the Mediterranean.
oikouménē - οἰκουμένη
Phoenician and Carthaginian voyages
around Africa, according to Herodotus
The Phoenicians took their departure from Egypt by way of the
Erythraean Sea, and so sailed into the southern ocean. When
autumn came, they went ashore, wherever they might happen to be,
and having sown a tract of land with corn, waited until the grain was
fit to cut. Having reaped it, they again set sail; and thus it came to
pass that two whole years went by, and it was not till the third year
that they doubled the Pillars of Hercules, and made good their
voyage home. On their return, they declared - I for my part do not
believe them, but perhaps others may - that in sailing round Libya
they had the sun upon their right hand. In this way was the extent of
Libya first discovered.
oikouménē - οἰκουμένη
Modern reconstruction from Herodotus
(S. 5 BC)
oikouménē - οἰκουμένη
Phoenician and Carthaginian voyages
around Africa, according to Herodotus
Pillars of Hercules
Strait of Gibraltar
Ptolemy’s
Geographia
‫מפת העולם (מאה ט"ו ) לפי הגיאוגרפיה‬
‫של תלמי (‪ 150‬לסה"נ)‬
Ptolemy’s Geographia
Translated into Latin around 1406
(Jacopo d’Angelo);
First printed edition with maps, in 1475
(Rome) – perhaps the first printed
book with engraved illustrations.
Part of the Humanistic, not the
Scholastic tradition!
Ptolemy’s Geographia
1482
Fra Mauro
(1450)
Fra Mauro (1450)
Under a commission by
king Alfonso V of Portugal.
Orientation with the South at the top, one
of the usual conventions of Muslim maps.
Fra Mauro (1450)
"I do not think it derogatory to Ptolemy if I do
not follow his Cosmografia, because, to have
observed his meridians or parallels or degrees,
it would be necessary in respect to the setting
out of the known parts of this circumference, to
leave out many provinces not mentioned by
Ptolemy.”
Fra Mauro (1450)
“Jerusalem is indeed the center of the inhabited
world latitudinally, though longitudinally it is
somewhat to the west, but since the western
portion is more thickly populated by reason of
Europe, therefore Jerusalem is also the center
longitudinally if we regard not empty space but
the density of population.”
Fra Mauro (1450)
“Jerusalem is indeed the center of the inhabited
world latitudinally, though longitudinally it is
somewhat to the west, but since the western
portion is more thickly populated by reason of
Europe, therefore Jerusalem is also the center
longitudinally if we regard not empty space but
the density of population.”
Fra Mauro (1450)
Basic conventions:
• The world as a sphere
• The continents surrounded by water within
the shape of a disc
• The approximate size of the world ???
Fra Mauro (1450)
“Likewise I have found various opinions
regarding this circumference, but it is not
possible to verify them. It is said to be 22,500 or
24,000 miglia or more, or less according to
various considerations and opinions, but they
are not of much authenticity, since they have not
been tested.”
Johannes de Sacrobosco
(c. 1195 – c. 1256)
‘Tractatus de Sphaera’ )c. 1230)
Ptolemy’s cosmology
and cosmography
Johannes de Sacrobosco (c. 1195 – c. 1256)
‘Tractatus de Sphaera’ )c. 1230)
The accepted Islamic and Latin
medieval view:
A smaller
sphere of earth
rested lightly
and eccentrically
inside the
sphere of water,
surfacing above
it only in the
oikumene
Consequence:
No antipodes
opposite to the
known world
Explanation (Aristotelian):
Jean Burdian (1300-ca. 1358)
Quaestio on De caelo et mundo
)“On the Heaven and the Earth”(
• Center of gravity vs. Center of volume, in the
spherical Earth, because water is of uniform density.
• Sphere of earth emerged from the sphere of water,
and the earth's center of gravity is displaced
downwards.
• The visible surface of the earth is kept dry because
of the heat of the sun and other influences.
Explanation (Aristotelian):
Jean Burdian (1300-ca. 1358)
Quaestio on De caelo et mundo
)“On the Heaven and the Earth”(
• Due to the continual dryness of the upper hemisphere
that showed above the surface of the water, this
condition remained stable.
• Rivers eroded solid pieces of the upper hemisphere,
taking the earth's center of gravity further down.
• In this way, the sphere of earth would be continually
rising out of the sphere of water.
Explanation (theological):
Bishop Paul of Burgos, (1351-1435)
Based on Genesis, 3d day of creation
• In Day 3, God had displaced the sphere
of water in perpetuity away from the
center of the cosmos. This was
countered only once, during the Flood.
Fra Mauro (1450)
“God distributed weight unevenly within the
spheres of earth and water. The resulting
emergence of the inhabited hemisphere of earth
from the sphere of water made it providentially
possible for living beings to inhabit the land.”
[The confinement of the oikumene to one hemi-sphere
resulted simultaneously from God's will and the laws of
celestial physics.]
Portuguese Voyages of
Discovery (1415-1486)
1440: Cape Verde
1474: the equator
1486: Cape of
Good Hope
Basic conceptions
about the oikoumene
start to be doubted.
The idea of a single
habited hemisphere
remained!
Crossing the Ocean?
Cristoforo Colombo - Cristóbal Colón
(1451-1506)
Crossing the Ocean?
Cristoforo Colombo - Cristóbal Colón
(1451-1506)
Contemporaries’ Main Objections:
A Western trip to Asia would take three years,
The Western ocean was boundless and impossible
to sail,
The antipodes do not exist (most of the earth is
submerged in water).
The Size of the Earth
Eratosthenes of Cyrene (276 BCE – 195 BCE)
The Size of the Earth
The Size of the Earth
Eratosthenes of Cyrene (276 BCE – 195 BCE)
http://www.youtube.com/watch?v=F8UFGu2M2gM
Crossing the Ocean?
Cristoforo Colombo - Cristóbal Colón
(1451-1506)
Colón’s )wrong( idea: a low estimate of the
westward distance from Europe to Asia.
• A low estimate of the size of the Earth,
• A high estimate of the size of the Eurasian
landmass,
• A wrong belief that Japan and other inhabited
islands lay far to the east of the coast of China.
Crossing the Ocean?
Cristoforo Colombo - Cristóbal Colón
(1451-1506)
Colón’s relevant knowledge )know-how):
Navigation techniques
The trade winds which would prove to be the key
to his successful navigation of the Atlantic Ocean
Crossing the Ocean?
Cristoforo Colombo - Cristóbal Colón
(1451-1506)
Colón’s right idea
(based on wrong considerations):
“Earth and water together form one round body .”
Crossing the Ocean?
The antipodes do not exist (most of the earth is
submerged in water).
vs.
“Earth and water together form one round body .”
How to decide?
Colón’s trip as the first big
experiment of modern science!!
Crossing the Ocean?
Colón’s trip as the first big
experiment of modern science??
The first unexpected result of
modern science!!!!!
La Pinta, La Niña
y la Santa María
Aug. 2 – Oct. 12, 1492
90 men
Crossing the Ocean?
Colón’s trip as the first big experiment of modern science
The first unexpected result of modern science.
Initially: no clear account of the
situation, no changes in
cosmographical conceptions
Main consequence: many new
exploration trips.
New exploration trips
Vasco da Gama
(1460-1524)
1499: Goa via Cape
of Good Hope.
New exploration trips
Pedro Álvares Cabral
(1467-1520)
1500: with 1,200,
heading Westward to
India
New exploration trips
Fernão de Magalhães
(1480-1521)
1519-22:
Amerigo Vespucci
(1451-1512)
Cosmographer and seafarer:
Mundus Novus (1505)
“Classical authors claim that there is no continent beyond
and south of the equator, but merely sea which they
called the Atlantic; furthermore, if any of them did affirm
that a continent was there, they gave many arguments to
deny that it was a habitable land. But this last voyage of
mine has demonstrated that this opinion of theirs is false
and contradicts all truth.”
Amerigo Vespucci
(1451-1512)
Cosmographer and seafarer:
Mundus Novus (1505)
• There are Southern antipodes
• There is no inhabited “upper hemisphere” )Europa,
Mediterranean Africa, Asia), not covered by water and
“lower hemisphere” )submerged(
• Colón was right: “Earth and water together form one
round body .”
The Cosmographic Revolution!
Martín Waldseemüller
(1470-1520)
Cosmographer and humanist:
Universalis Cosmographia
secundum Ptholomaei traditionem et Americi Vespucii
aliorumque Illustrationes (1507)
• There are Southern antipodes
• There is no inhabited “upper hemisphere” )Europa,
Mediterranean Africa, Asia), not covered by water and
“lower hemisphere” )submerged(
• Colón was right: “Earth and water together form one
round body .”
The Cosmographic Revolution?
• No change in the Aristotelian universe
• A problem with Aristotelian gravity as a
comprehensive principle
The Globe of the Old World. By Johannes Sabius and Albrecht Dürer, 1515.
It does not include the most recent geographical discoveries of the Day.
Nicolaus Copernicus (1473-1543)
1543
De revolutionibus orbium coelestium
Chapter 3:
“How Earth Forms One Single Sphere with Water?”
Colón: “Earth and water together form one round body .”
“We should not heed certain Peripatetics who ...
assert that that the earth emerges from water,
because its weight is not equally distributed due
to its cavities, its center of gravity being different
from its center of magnitude.”
Nicolaus Copernicus (1473-1543)
1543
De revolutionibus orbium coelestium
Chapter 3:
“How Earth Forms One Single Sphere with Water?”
Colón: “Earth and water together form one round body .”
“This will be more clear when we add the islands
discovered in our time under the kings of Spain and
Portugal, and especially America, named after their
finder, a ship’s captain. On account of its still undisclosed
magnitude this is thought to be another inhabited world,
and there are also many other islands, heretofore
unknown. So we should wonder even less that the
Antipodes exist.”
‫שקיעת העולם האריסטוטלי‬
‫מסעות גילוי‪ ,‬והמהפיכה‬
‫הקוסמוגרפית‬
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