What Leonardo da Vinci instrument combined a keyboard with bowed strings?

Leonardo da Vinci’s viola organista combined a keyboard with bowed strings.

The viola organista was a keyboard instrument concept Leonardo developed in drawings from the late 15th and early 16th centuries. Pressing keys would select strings, while a rotating wheel or wheels covered with horsehair would rub against them and produce sound. The arrangement borrowed the expressive sustained tone of bowed instruments while retaining keyboard control.

Leonardo made several versions of the idea rather than one single final instrument. His surviving sketches show different approaches to moving the bowing mechanism and engaging the strings. No authenticated Renaissance example of a completed Leonardo viola organista survives, although modern builders have constructed playable interpretations.

The instrument is often confused with a hurdy-gurdy because both use a wheel to sound strings. The difference is control: a hurdy-gurdy uses a crank and keys or tangents, while Leonardo’s concept is explicitly a keyboard instrument in which the wheel acts as the bow.