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[[File:Eratosthenes.jpg|right]]

[[File:Eratosthenes.jpg|right]]

'''Eratosthenes''' of Cyrene (275-194 B.C.) was a scientific writer, astronomer, geographer and poet. He was the first to calculate the circumference of the Earth. His technique is the earliest known proof that the Earth is round. He also calculated the tilting of the earth's axis during rotation. He used principles of [[Euclid]]ean [[geometry]].  

'''Eratosthenes''' of Cyrene (275-194 B.C.) was a scientific writer, astronomer, geographer and poet. He was the first to calculate the circumference of the Earth. His technique is the earliest known proof that the Earth is round. He also calculated the tilting of the earth's axis during rotation. He was head librarian at the [[Library of Alexandria]].

He also invented the [[sieve of Eratosthenes]], which is a technique for separating composite from prime numbers in a natural series. The sieve appears in the ''Introduction to arithmetic'' by [[Nicomedes]].   

Eratosthenes also invented the [[sieve of Eratosthenes]], which is a technique for separating composite from prime numbers in a natural series. The sieve appears in the ''Introduction to arithmetic'' by [[Nicomedes]].   

Eratosthenes was the third librarian at Alexandria; in addition to his knowledge in many different areas, he was an accomplished mapmaker. Eratosthenes also made a catalogue of stars with 675 stars listed in it.  

Eratosthenes was the third librarian at Alexandria in Egypt. In addition to his knowledge in many different areas, he was an accomplished mapmaker. Eratosthenes also made a catalogue of stars with 675 stars listed in it.  

His followers called him the second [[Plato]].  

His followers called him the second [[Plato]].  

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Eratosthenes died in 194 BC in Alexandria, [[Egypt]].

Eratosthenes died in 194 BC in Alexandria.

== See also ==

== See also ==