Hal Ridings, age 10, of Tulsa, Okla., for his question;

How were the lines of latitude discovered?

Some of the scholars of ancient Greece were quite sure that the world is a globe. They were used to working with circles of 360 degrees. They knew that a globe could be sliced up and down in orange sections and cut into flat circles from side to side.

About 230 B.C., Eratostheries of Greece set about measuring the size of the earth. He measured the angles cast by noon shadows. The angles were different at different cities, and the difference of the angles, he figured, gave him the distance between the cities. The man made lines of latitude were perfected much later. But they are still based on the angles and 360 degree circles figured out by the ancient Greeks.