What musical instrument did Leonardo da Vinci redesign with a keyboard and bow?

Leonardo da Vinci redesigned a keyboard instrument with bowed strings, a concept now called the viola organista.

The instrument combines features of a keyboard and bowed string instruments. Pressing keys selects notes, while rotating wheels or a continuous bowing mechanism rubs against strings to produce sound. Leonardo explored several versions in his notebooks during the late fifteenth and early sixteenth centuries.

Unlike a conventional piano, the viola organista does not strike strings with hammers. Unlike a violin, it does not require the player to move a bow by hand across each string. Leonardo’s goal was to create an instrument capable of sustaining tones while retaining keyboard control.

The design was not completed as a standard Renaissance instrument. Modern builders have constructed working interpretations from Leonardo’s drawings, but these reconstructions are not identical to a surviving original instrument.