Leonardo da Vinci invented the viola organista, a keyboard instrument using friction wheels and strings.
The viola organista combined a keyboard with the continuous sound of bowed strings. Pressing a key caused a wheel or rotating surface to contact a string, producing vibration in a manner related to a bowed viola. Leonardo drew several versions of the instrument, with designs dating mainly from the late 15th and early 16th centuries.
Unlike a conventional piano or harpsichord, the viola organista did not pluck or strike the strings. Its sound was intended to resemble string instruments while allowing a keyboard player to control several notes. The design shows Leonardo’s interest in adapting mechanisms from one musical technology to another.
No authenticated original instrument by Leonardo survives. Several modern builders have made playable reconstructions, and their results show that the concept can produce a sustained, string-like tone. The instrument should not be confused with a standard organ, because its sound-producing mechanism relies on strings and friction rather than pipes.