Metronome

Metronome, a small machine for indicating the correct time or speed at which a musical composition should be played. It is essentially an inverted pendulum moved by clockwork. The time is regulated by a weight which can be pushed up and down the pendulum rod, on which is a graduated scale. The metronome as we have it was patented by Mälzel in 1816, but was really invented by Winkel of Amsterdam.