Eratosthenes of Cyrene, chief librarian at the Library of Alexandria was a polymath, a music theorist, poet, astronomer, geographer (generally considered the founder of that science) and mathematician. He calculated both the circumference of the earth and the tilt of its axis with astonishing accuracy. (He also calculated the circumference of the sun with much less success) Eratosthenes also developed a calculation for dating the sacking of Troy, which he figured began on the 11th of June 1184 BC, or... Read more