What Leonardo da Vinci machine combined a keyboard with strings played by rotating wheels?

Leonardo da Vinci’s viola organista combined a keyboard with strings sounded by rotating wheels.

Leonardo sketched several versions of the instrument in the late fifteenth and early sixteenth centuries. Pressing a key would select a string, while a rotating wheel covered with horsehair or another friction material would rub against it. This gave the instrument a sustained, bowed-string sound while retaining the layout of a keyboard.

The viola organista was never completed as a functioning instrument by Leonardo. It belongs to a family of Renaissance experiments that tried to combine the expressive qualities of bowed strings with the control of keyboard instruments. Its name reflects that hybrid character rather than a claim that it was an ordinary viola.

The design should not be confused with a harpsichord, whose strings are plucked, or a pianoforte, whose strings are struck. Modern builders have created playable reconstructions based on Leonardo’s drawings, but surviving notebooks contain multiple versions rather than one finalized model.