Eratosthenes of Cyrene

Eratosthenes was born in Cyrene which is now in Libya in North Africa.Eratosthenes also studied under the poet and scholar Callimachus who had also been born in Cyrene.Eratosthenes then spent some years studying in Athens.Ptolemy II Philadelphus appointed one of Eratosthenes' teachers Callimachus as the second librarian.One rather surprising source of information concerning Eratosthenes is from a forged letter.Although the letter is a forgery, parts of it are taken from Eratosthenes' own writing.Other details of what Eratosthenes wrote in Platonicus are given by Theon of Smyrna.Eratosthenes also worked on prime numbers.Eratosthenes made a surprisingly accurate measurement of the circumference of the Earth.It is less good if 166.7 metres was the value used by Eratosthenes as Gulbekian suggests in .