What's the difference between i.e. and e.g.?
mechanical musical time-keeper, 1815, coined in English from comb. form of Greek metron "measure" (see meter (n.2)) + -nomos "regulating," verbal adjective of nemein "to regulate" (see numismatics). The device invented 1815 by Johann Maelzel (1772-1838), German civil engineer and showman. Related: Metronomic.
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. Thus, 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 electric metronomes are also made. Metronomes have occasionally been used as musical instruments, e.g., by the Hungarian Gyorgy Ligeti (Poeme symphonique, 1962, for 100 metronomes).