Congratulations, JULIAN!!!

That's right everyone, we have a winner!

The correct answer to the question, "Who was the first man to prove mathmatically that the earth was round?" is:

Eratosthenes. He made his calculations and discovery while living in Alexandria, Egypt. Alexandria lies on the Mediterranean Sea. To the south lay the city of Syene. Syene sat on the Tropic of Cancer, the imaginary line around the Earth that delineates the sun's position relative to the tilt of the Earth on the longest day of the yea--in the northern hemisphere. On this day, the summer solstice, the people of Syene could see to the bottom of their wells at noon, when the sun was at its highest point in the sky. This is because at this time, the sun is directly overhead.

Because of increased communication over great distances due to imperialization, this observation was compared across the the Greek Empire. When Greek subjects who lived in Alexandria, further north, realized that they could never see the bottom of their wells, because they were always in shadows, it caused much debate.

Eratosthenes realized that there was a reason for differences in the angle of the shadows at different latitudes. He theorized that two sticks of the same length planted in the ground at a perpendicular, at a great distance apart, but along the same north/south line, would cast shadows of different lengths.

By comparing the shadow lengths, and using the relatively new Pythagorean Theorem, Eratosthenes discovered that the increasing difference in shadow length could only mean that the sticks were being planted perpendicular to the surface of a sphere; thus proving the shape of the Earth.

He didn't stop there. He extrapolated the data from the shadow to determine the size of the earth (very accurately, considering the lack of reliable measurement over great distance). And then he calculated the tilt of the Earth's axis relative to the sun, thereby discovering the true cause for the seasons.

JJ

(P.S. If you would like for me to show you how he did it, come in to Room 203, but you're not leaving 'til I'm done.)