2. His Life
Eratosthenes was born in Cyrene. (in
modern-day Libya). He was the third chief
librarian of the Great Library of Alexandria,
the center of science and learning in the
ancient world, and died in the capital of
Ptolemaic Egypt.
3. Eratosthenes studied in Alexandria, and claimed
to have also studied for some years in Athens. In
236 BC he was appointed by Ptolemy III
Euergetes I as librarian of the Alexandrian library,
succeeding the second librarian, Apollonius of
Rhodes, in that post.[7] He made several
important contributions to mathematics and
science, and was a good friend to Archimedes.
Around 255 BC he invented the armillary sphere.
In On the Circular Motions of the Celestial
Bodies, Cleomedes credited him with having
calculated the Earth's circumference around
240 BC, using knowledge of the angle of
elevation of the sun at noon on the summer
solstice in Alexandria and on Elephantine Island
near Syene (now Aswan, Egypt).
4. Eratosthenes criticized
Aristotle for arguing
that humanity was
divided into Greeks
and barbarians, and
that the Greeks should
keep themselves
racially pure, believing
there was good and
bad in every nation.[8]
By 195 B.C.,
Eratosthenes became
blind. He died in 194
B.C., at the age of 82.
5. His Achiements
Measurement of
the Earth's
circumference.
Eratosthenes
calculated the
circumference of
the Earth without
leaving Egypt.
6. Prime numbers
Main article: Sieve of Eratosthenes
Eratosthenes also proposed a simple
algorithm for finding prime numbers. This
algorithm is known in mathematics as the
Sieve of Eratosthenes.
7. Achievement in astronomy
o Eratosthenes measured the angle of the
shadow to the Earth.
o Eratosthenes believed that the sun was
so far away that its rays were parallel.
o It is also believed that Eratosthenes made
a star catalog with approximately 675
stars and created a calendar that included
leap years.
8. Achievements in History
He decided to work on giving a systematic
chronography of the known world by
figuring out the dates of literary and
political events from the siege of Troy up
until his time. However, this was only a
beginning. Others built on his foundation.
10. Many scholars that preceded Eratosthenes
in the study of the Nile river, tried to figure
out the reason why parts of the river flooded
while other parts did not. It was not until
Eratosthenes that a correct answer was
proposed.
He believed that heavy rains near the
source of the Nile was the cause of Many of
Eratosthenes' peers nicknamed him "Beta"
which is the second letter of the Greek
alphabet, indicating that he just fell short of
first place.
11. Eratosthenes contributed greatly to many
different areas of knowledge, more than I could
cover in this short paper. Maybe in his time
period, his peers did not feel that he contributed
enough in one area or maybe they were jealous
that he had contributed so much to so many
areas.
For a man who was nicknamed Beta, it is pretty
impressive that so much of his work in these
areas is still discussed today, so many years
later.
12. His death & Reasons
"On the Murder of Eratosthenes" is a
speech by Lysias, one of the "Canon of
Ten" Attic orators (Speech 1 in Lamb's
translation, ISBN 978-0-674-99269-6).
The speech is a defense written for
Euphiletos who is charged with the death
of Eratosthenes. The case is heard before
the Delphinion, a court which hears
proceedings for justifiable homicide
13. Euphiletos is accused
of killing Eratosthenes,
who was caught in the
act of adultery with
Euphiletos's wife.
Euphiletos's defense is
that his killing of
Eratosthenes was an
act of justifiable
homicide and therefore
not punishable.
