Eratosthenes was a Greek mathematician that conjectured that the earth was a sphere around 250 BC. He did this by measuring the angle of shadows on the bottom of two different wells. One well was in Alexandria, Egypt, and the other was in Syrene, Egypt. The well in Syrene had less of a shadow at noon than the well in Alexandria, meaning that the sun was hitting the wells at different angles. Eratosthanes calculated the circumference of earth to within about 150 kilometers.
My question is: The Greeks had a god named Atlas that carried the weight of the world on his shoulders. Whenever you see a sculpture of Atlas, he is holding a giant sphere on his shoulders. Did the idea that Atlas was carrying a sphere come about before Eratosthenes did his experiment? Or did they make this conclusion after Eratosthenes concluded the earth was a sphere, and not flat?