Which Leonardo da Vinci invention combines a keyboard with bowed strings to produce music?

Leonardo da Vinci’s invention combining a keyboard with bowed strings is the viola organista.

Leonardo described the instrument in several notebooks during the late fifteenth and early sixteenth centuries. Pressing keys caused wooden or covered wheels to contact strings, producing sound in a way related to a bowed string instrument. The keyboard allowed one player to control the pitches more easily than with a conventional hand-held bow.

The viola organista was never known to have been completed by Leonardo himself. It belongs to a group of imaginative musical-machine designs that explored how mechanical motion could replace or assist human performance. Its name is modern and reflects its mixture of viola-like strings and organ-like keyboard control.

Modern builders have constructed playable versions from Leonardo’s drawings. The instrument is sometimes confused with a hurdy-gurdy, but a hurdy-gurdy uses a crank to turn a wheel continuously, while the viola organista uses keyboard-controlled action on its strings.