Which Leonardo da Vinci invention combined a keyboard with strings bowed by rotating wheels?

Leonardo da Vinci’s keyboard instrument with strings bowed by rotating wheels was the viola organista.

Leonardo developed several designs for the viola organista, an unusual instrument that combined features of a keyboard and bowed string instruments. Pressing keys selected strings, while rotating wheels rubbed against them to produce sound. The design aimed to make it possible for one player to control multiple bowed strings from a keyboard.

Leonardo’s sketches show different arrangements, including mechanisms using wheels and continuous bowing surfaces. The instrument was never built by Leonardo, and no surviving original exists. Modern makers have constructed versions based on his drawings, with varying interpretations of the mechanism.

Its name can cause confusion because it is not simply a viola and not an organ in the conventional pipe-organ sense. It belongs to a broader Renaissance tradition of experimenting with automated or mechanically assisted musical instruments.