Which musical instrument did Leonardo da Vinci design using a continuous bow mechanism?

Leonardo da Vinci designed the viola organista, a keyboard instrument using a continuous bow mechanism.

Leonardo sketched versions of the instrument during the fifteenth century. Pressing keys would cause strings to be sounded by rotating, rosined wheels or a continuous bow, combining features associated with keyboard instruments and bowed strings.

The idea was unusual because conventional bowed instruments require a player to move a bow back and forth by hand. Leonardo’s mechanism sought to make bowing controllable from a keyboard, potentially allowing a performer to play several notes more easily.

No known original Leonardo viola organista survives. Modern builders have created working reconstructions from his drawings, but the instrument should not be confused with a normal viola, which is played with a handheld bow and has a different body and playing technique.