Quotes About Eratosthenes

Eratosthenes of Cyrene, a polymath and one of the first directors of the library

Eratosthenes was the first to use a scientific method to calculate the circumference of the earth

Using his observations of the different shadows cast by sundials along the same meridian and a little number crunching, Eratosthenes made a calculation of the earth's diameter that was amazingly accurate: 7,850 miles, only about 60 off the actual mark.

From the shadow length in Alexandria, the angle A can be measured. But from simple geometry ("if two parallel straight lines are transected by a third line, the alternate interior angles are equal"), angle B equals angle A. So by measuring the shadow length in Alexandria, Eratosthenes concluded that Syene was A = B = 7° away on the circumference of the Earth.

Eratosthenes , the mapmaker who was the first man to accurately measure the size of the Earth, was a librarian.

The size of the Earth has been known for more than two thousand years, although the number was lost or disputed when the Earth went from being round to being flat again in the Middle Ages (under the prodding of Christian heaven-watchers, the Greek philosophers' [Eratosthenes 276-194 BC] work was erased in Europe and preserved only by Muslim scientists in the Middle East and North Africa).