When and where was Eratosthenes born?
Eratosthenes arrived in the world during 276 BC within the city of Cyrene. This settlement now exists as part of modern Libya and was founded by Greeks during the second half of the 7th century BCE.
Eratosthenes arrived in the world during 276 BC within the city of Cyrene. This settlement now exists as part of modern Libya and was founded by Greeks during the second half of the 7th century BCE.
Strabo records he learned Stoicism from Zeno of Citium who died shortly after his arrival. Apelles of Chios taught him while Aristo of Chios instructed him on Cynic philosophy and Bion of Borysthenes provided eclectic training before Arcesilaus of Pitane led the Platonic Academy.
Eratosthenes described an arc measurement technique using shadows cast by vertical rods called gnomons at Alexandria and Syene. Multiplying the distance between cities reported by professional bematists at roughly 5,000 stadia by fifty yielded approximately 250,000 stadia total circumference.
His three-volume work Geography described and mapped his entire known world with grids of overlapping lines. The second book contained calculations on Earth's circumference while third covered political geography using parallel lines to divide maps accurately.
An algorithm separated prime numbers from odd natural numbers less than or equal to given limits though Hans-Joachim Waschkies claims he did not invent it. He coined the term sieve and Hipparchus credited him with inventing the armillary sphere model featuring spherical frameworks of rings.