Leonardo da Vinci’s wheel-driven instrument for continuous bowed sound was the viola organista.
Leonardo developed several designs for the viola organista, especially in manuscripts from the late fifteenth and early sixteenth centuries. The instrument combined a keyboard with strings and a rotating wheel. Pressing keys selected strings, while the wheel rubbed against them in a way comparable to a bow.
This arrangement aimed to combine the controllability of a keyboard with the sustained sound of bowed instruments. It was not simply a keyboard version of a harpsichord: a harpsichord plucks strings, while the viola organista was intended to make sound through friction.
Leonardo’s design was never widely adopted during his lifetime. Several modern builders have reconstructed versions from his drawings, but those reconstructions should not be confused with an original surviving Leonardo instrument. The name is also sometimes written with a space as “viola organista.”