Eratosthenes from Kyrene

Greek scholar, * Kyrene (now Schahhat, Libya) about 284 (or 274) B.C., † Alexandria about 202 (or 194) B.C..

Eratosthenes was a student of Zenon and Kallimachos. In 246 B.C. - after stay at Athens - he was nominated to tutor of prince and to head of library of Alexandria by Ptolemaios III. Euergetes.

Besides philosophical, lexicographical, grammatical works as well as poetry he is first known for the introduction of a chronological counting by olympiads and for a three-volume work in which he condensed the geographical knowledge of his time.

Eratosthenes designed a gridded map of the then known world and determined the circumference of the Earth from the known length of the distance Syene-Alexandria and the angle of incidence of the sunbeams at the one place when the sun takes place in zentith at the other place.

As a mathematician he invented among other things a method to find prime numbers (»Sieve of Eratosthenes«).

Eratosthenes who became the incarnation of hellenic scholarship called himself philologistfriend of all intellectual activities«).

  
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