What musical instrument did Leonardo da Vinci design using a wheel to play strings?

Leonardo da Vinci designed the viola organista, a keyboard instrument that used a rotating wheel to play strings.

The concept appears in Leonardo’s notebooks from the late 15th and early 16th centuries. Pressing keys would select strings, while a wheel covered with horsehair or another friction surface would rotate and sound them. The design combined features associated with bowed string instruments and keyboard instruments, potentially allowing sustained tones under keyboard control.

Leonardo did not leave evidence that he completed a working version. The viola organista is therefore best understood as an invention concept rather than a documented Renaissance instrument in regular use. Several modern builders have reconstructed versions from his drawings, with varying mechanisms and materials. Its name reflects the intended hybrid character: “viola” points to bowed strings, while “organista” refers to the keyboard-like method of playing.