What musical instrument did Leonardo da Vinci invent using a bow moved by a rotating wheel?

Leonardo da Vinci invented the viola organista, a keyboard instrument using a rotating wheel to bow strings.

Leonardo designed the viola organista in the late fifteenth century. Its keyboard operated mechanisms that pressed strings against a continuously rotating wheel, producing sustained tones in a way related to bowed string instruments. The concept aimed to combine the expressive sound of a viola with the controllable layout of a keyboard.

Leonardo drew several versions, but no surviving original instrument is known from his lifetime. Modern builders have reconstructed the design from his manuscripts, and the results show that the mechanism can produce music.

The viola organista is often confused with the hurdy-gurdy because both use a rotating wheel. The hurdy-gurdy is played with a crank and keys, while Leonardo’s design uses a keyboard to control bowed strings. It also differs from an organ, which produces sound through pipes rather than bowed strings.