Pamela Edgington, age 10, of Colorado Springs, Colo., for her question:

WHEN WAS THE FIRST CLOCK MADE?

Man's first clock was the sundial, made in the early days of civilization. It was used as a way of charting the sun's daily movement. Next came sandglasses and water clocks.  We don't know who made the first clock with wheels and weights, although it was probably made by the ancient Chinese. In Europe, the first clock was probably made in about 990 A.D. by Gerbert, a monk who became Pope Sylvester II. A clock went into St. Paul's Cathedral in 1286.

A cog wheel clock was installed in Paris in 1379 and it ran for almost 500 years.

Galileo, an Italian, came up with the theory of the swinging pendulum in 1581, but the principle wasn't applied to the clock for nearly a hundred years when the Dutch came up with the idea in 1665.