Could Eratosthenes have calculated the Earth's curvature as concave?
After watching this video my Carl Sagan on how Eratosthenes calculated the curvature of the Earth, I thought what if Eratosthenes had calculated the curvature as a concave Earth rather than a convex one.
Some interesting things about Eratosthenes was a that he was called Beta because he was the second best in the world in many subjects. Also he was the librarian in Alexandria where at one time there was the biggest library in the world and was burnt to the ground. Accident or deliberate I'm not sure probably was deliberate.