Cathy Ingram, age 15, of Las Vegas, Nev., for her question:

WHO INVENTED THE METRONOME?

A metronome is a musician's device, usually in the shape of a pyramid, that clicks audibly at exactly timed intervals as an aid to keeping correct tempo.

In 1816 the metronome was patented by a German musician and inventor named Johann Nepomuk Maelzel. However, the instrument was actually conceived about 1812 by a Dutch inventor named Dietrich Nikolaus Winkel.

A metronome functionally is an upside down pendulum, the upright, oscillating hand bearing a small counterweight that can be raised or lowered vertically according to the tempo desired. This adjustment regulates the number of beats per minute in models that are wound by hand. Other models operate electrically.

The metronome is often used by music teachers. With the steady tempo registered by the instrument, students can quickly pick up the required rhythm.