What Leonardo da Vinci musical invention used bowed strings pressed by keys?

Leonardo da Vinci’s viola organista was a keyboard instrument that used bowed strings.

Leonardo developed drawings for the instrument in the late fifteenth century. Pressing keys would bring strings into contact with rotating wheels or a continuous bowing mechanism, producing sustained tones. The concept combined the expressive sound of bowed string instruments with the control and polyphonic possibilities of a keyboard.

No instrument built by Leonardo is known to survive. Several modern makers have constructed working versions from his plans and related sketches, but the drawings leave room for interpretation about the exact mechanism. The instrument was therefore a design study rather than a standardized Renaissance instrument.

The viola organista is not the same as a pipe organ, which produces sound by sending air through pipes. It is also distinct from the clavichord and harpsichord, whose strings are struck or plucked. Leonardo’s idea was unusual because the keys controlled bowing rather than directly striking or plucking the strings.