What automatic musical instrument did Leonardo da Vinci design using a rotating cylinder?

Leonardo da Vinci designed a mechanical drum that could play automatically using a rotating cylinder.

The instrument was intended for military or ceremonial use. A cart carried a large drum, while a rotating cylinder with projecting pegs activated beaters. As the cylinder turned, the pegs struck the drum in a programmed sequence, producing a repeating rhythm without a human drummer.

This design illustrates Leonardo's interest in translating music into mechanical timing. The pegs acted like a simple program: changing their positions could change the pattern of beats. Similar pinned-cylinder principles later appeared in music boxes and other automatic instruments.

The device was not an electronic instrument and did not record sound. It was a mechanical automaton powered by a human-operated crank or other mechanical source. Reconstructions have shown that the design can produce rhythms, although exact details depend on how the surviving drawings are interpreted.