What machine did Leonardo da Vinci design to create a continuous mechanical drumbeat?

Leonardo da Vinci designed a mechanical drum as part of an automated musical machine.

The drum used rotating motion and projecting pins or raised elements to control when beaters struck its surface. By arranging the projections, a repeating rhythm could be programmed mechanically. The concept belongs to Leonardo’s studies of automata, in which a machine performed a sequence without a person directly operating every action.

This kind of device is an ancestor of pinned-cylinder mechanisms later used in music boxes and other automatic instruments. Its significance is not that it was an electronic rhythm machine, but that musical timing could be encoded physically in the arrangement of mechanical parts.

The drum is sometimes confused with Leonardo’s viola organista. The viola organista was a pitched keyboard instrument using bowed strings, whereas the mechanical drum was primarily a percussion and automation concept. Surviving drawings do not establish that Leonardo completed a working original.