What Leonardo da Vinci instrument combined a keyboard with strings like a piano and a viola?

Leonardo da Vinci’s viola organista was a keyboard instrument that used strings to produce a sound related to bowed string instruments.

Unlike a conventional piano, whose hammers strike strings, the viola organista used rotating wheels or bowing mechanisms to rub against strings. Pressing keys selected the notes while the mechanism supplied continuous friction, giving the instrument an unusual sustained tone.

Leonardo drew several versions of the idea in his notebooks during the late fifteenth and early sixteenth centuries. No surviving historical instrument proves that his design entered regular musical use, although modern makers have built playable reconstructions.

The name can cause confusion because the viola organista was not simply a viola with a keyboard. It was an experimental hybrid combining features of keyboard instruments and bowed strings, reflecting Leonardo’s interest in mechanical solutions to musical problems.