metronome (n.)

mechanical musical time-keeper, 1815, coined in English from Greek metron "measure" (from PIE root *me- (2) "to measure") + nomos "regulating," verbal adjective of nemein "to regulate" (from PIE root *nem- "assign, allot; take"). The device was patented in England in 1815 by Johann Maelzel (1772-1838), German-born civil engineer and showman, who gave it its modern name, but he incorporated the ideas of a device invented in Amsterdam in 1814 by Dietrich Nikolaus Winkel (1777-1826). Related: Metronomic.