Speed-control device in an automatic musical instrument. Many different types including: 1. Fan-fly type with rotating fan blades, used in music boxes and certain barrel-operated instruments. 2. Pneumatic type which regulates the speed of travel of a piano roll by regulating the amount of suction to the air motor. 3. Electrical fly-ball type in which rotating weights open and close contacts, as in a Mills Violano-Virtuoso.