Leonardo da Vinci invented the viola organista, a keyboard instrument that used rotating wheels to bow strings.
The player would press keys, which selected the strings, while a crank or pedal turned a wheel or wheels coated with friction material. The rotating surface acted like the bow of a string instrument, producing sustained tones without a conventional hand-held bow.
Leonardo drew several versions of the instrument in his notebooks, especially during the late fifteenth and early sixteenth centuries. No surviving original instrument by Leonardo is known, but modern builders have made playable reconstructions from his drawings. The design belongs to his broader interest in combining mechanics, music, and performance.
The viola organista is not simply a keyboard version of a harpsichord. A harpsichord plucks strings, whereas Leonardo's mechanism bows them. Its name reflects its intended relationship to bowed viol instruments and organ-like keyboard control.