Amy Lonien, age 15, of Eugene, Ore., for her question:

HOW DOES A DIGITAL WATCH WORK?

Power from a tiny battery activates a quartz crystal in the new digital watches. Electronic circuits then translate

vibrations from the crystal into hours,. minutes and seconds. This information is then flashed on the blank face of the watch by means of numbers that light up.

Electric watches were first introduced in the United States by the Hamilton Watch Co. in 1957. In the electric watch, a battery provides the power to move a coil mounted on the balance wheel. As the coil passes through the magnetic field of two permanent magnets, an impulse from the balance wheel sends power to the train  a set of linked mechanical parts.

Did you know that early watches only had an hour hand? A minute hand wasn't added until 1687.