What machine did Leonardo da Vinci design to produce music with a continuous bowing action?

Leonardo da Vinci designed the viola organista to produce music through a continuous mechanical bowing action.

Unlike a conventional piano, which strikes strings with hammers, the viola organista was intended to make strings vibrate through contact with a moving wheel or wheels. A keyboard would select the notes, while the mechanism supplied the bowing motion.

Leonardo’s drawings show that he was exploring ways to combine the expressive qualities of bowed strings with the controllability of a keyboard. The result was a hybrid concept rather than a standard organ, despite the word “organista” in its name.

No authenticated original instrument by Leonardo survives as a completed working object. Modern reconstructions interpret his sketches, and their mechanisms can differ because the notebooks leave some construction details unresolved.