Name: Eratosthenes


From: Cyrene (mod. Shahhat, Libya)

Son of: Aglaos


Dates: c. 280-200 BC 

Brief biography: Studied in Athens under Ariston at the Lyceum, under Arkesilaus and Apelles at the Academy, and under Bion the cynic. Went to Alexandria c.245 when invited by Ptolemy III Euergetes to become the second Head of the Library and tutor to Ptolemy IV. Recipient of Archimedes' Cattle Problem and The Method. Solved the problem of doubling the cube by mechanical means. Devised his 'sieve' for finding prime numbers. Established the system of dating by Olympiads. Was an authority on old comedy, epsecially Aristophanes. Wrote three large poems: Hermes, Eripgone and Anterinys. His most famous work was his Geography, in which (amongst other things) he computed the circumference of the earth. Later known as 'the pentathlete' and 'beta'. His Geography was read by Caesar, who was impressed that he knew of the Hercynian Forest.



References: D R Dicks DSB 4.388-93. On dating by Olympiads (and other methods) see A A Mosshammer The Chronicle of Eusebius and Greek Chronographic Tradition (1979) 87. Caesar Gallic War 5. 24.


T E Rihll

Last modified: 11 April 2007