Eratosthenes of Cyrene

ContentsContents

1...Biography1...Biography2...His work2...His work

3...Earth's circumference measured by 3...Earth's circumference measured by EratosthenesEratosthenes

His Biography

Eratosthenes had birth in Cyrene (today his name is Libya) but he lived , worked and died in Alexandria in Egypt

He studied in Alexandria and he claimed that he had studied for several years in Athens . In 236 B.C. Ptolemeous the 3rd , made him responsible of the famous library of Alexandria . He was there as a librarian and teacher for 40 years

In 194 B.C. he became blind and the next year he stopped eating and died,because he couldn't stand the lack of knowledge

His work

He contributed to the evolution of mathematics . He was friend of Archimedes. He invented the spherical astrolabe

Round the 240 B.C. he measured the periphery of the earth. He used the height of sun during the summer solstice. He chose two diffent places ,Alexandria and Cyene (both in Egypt) because they are in the same meridian

He calculated the periphery almost 252.000 stages which is close to 40.000 km.

He was the first that claimed ,earth was a sphere

He also invented a system to calculate the prime numbers ,known as the Eratosthenes’ sieve

The term Geography is attributed to Eratosthenes.

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