Science: Taping the Earth

The U.S. Army has succeeded in shrinking the circumference of the earth by about half a mile. To make the new estimate, according to a paper submitted to the American Geophysical Union by Bernard Chovitz and Irene Fischer of the Army Map Service, the Army's scientists used the latest instruments, but their basic method was the one the Greeks invented more than 2,000 years ago.

Bones & Lions. About 200 B.C. the Greek mathematician Eratosthenes ran a geometrical tape measure about the earth by estimating the distance between Syene in southern Egypt and Alexandria in northern Egypt.*Then he measured shadows cast by...