instrument for marking musical tempo, erroneously ascribed to the German Johann Nepomuk Maelzel (1772-1838) but actually invented by a Dutch competitor, Dietrich Nikolaus Winkel (c.1776-1826).
It consists of a pendulum swung on a pivot and actuated by a hand-wound clockwork whose escapement (a motion-controlling device) makes a ticking sound as the wheel passes a pallet. Below the pivot there is a fixed weight; above it, a sliding weight. A scale of numbers indicates how many oscillations per minute occur when the sliding weight is moved to a given point on the pendulum.
The notation "M.M. (Maelzel's metronome) = 60" indicates that at 60 oscillations per minute the half note will receive one beat.
The conventional metronome is housed in a pyramidal case.
Pocket and electronic metronomes are also made.