from μέτρον, measure, and νόμος, rule, a pendulum which marks the times of music by the slowness or quickness of its oscillations. An instrument of this kind was contrived in France in 1698, and several others followed; but the one which has obtained the preference was constructed in 1812 by the celebrated mechanician J. N. Maelzel, inventor of the panharmonicon, the automaton-trumpeter, &c., and who died in America in August 1838, aged sixty-six. The invention of the mechanical principle of this metronome was publicly and successfully claimed by Winkel of Amsterdam; it being proved that Maelzel had contrived only the scale of numbers applied to the pendulum. The mechanism consists of a vertical rod of steel, which is made to oscillate by clockwork, and of which the oscillations are rendered slower or quicker by means of a weight that slides up and down upon the rod. A scale of numbers, from 50 to 160, but with emissions, e.g., 50, 52, 54, &c., is placed behind the rod or pendulum; 50 representing the greatest degree of slowness, and 160 the greatest degree of quickness of the oscillations in one minute of time. The number 60 will thus represent 60 seconds, and all the other numbers, from 50 to 160, so many fractional parts of a minute; the minute being the integer to which all these subdivisions must be referred. The sliding-weight is raised or lowered upon the rod, so that the oscillations of the pendulum may correspond with this or that number indicated upon the scale; each audible beat or tick of the pendulum forming a fractional part of the minute, but not the two beats produced by the pendulum's motion from one side to the other. The musical notes used in manuscript or printed music, along with the numbers of the metronome scale, to indicate the time of a piece of music, are in general a quaver for an adagio movement, a crotchet for an andante, a minim for an allegro, a semibreve for a presto. For example: adagio, Maelzel's metronome \( \frac{L}{=60} \). It is very desirable that composers should always affix metronome numbers to their compositions. In the latest metronomes the scale ranges from 40 to 208. (See MOVEMENT.)**