Leonardo da Vinci designed the viola organista, a stringed keyboard instrument played with a bow.
The instrument used a keyboard to control strings while a rotating wheel or wheels supplied continuous friction, functioning somewhat like the bow of a string instrument. Pressing keys selected the notes, allowing a player to produce sustained tones without directly moving a bow by hand. Leonardo drew several versions of the concept during the late fifteenth and early sixteenth centuries.
The viola organista was not a standard keyboard instrument built in large numbers during Leonardo’s lifetime. It survives mainly through drawings and later reconstructions. Its design combines features associated with the organ, keyboard instruments, and bowed strings, which is why it is sometimes confused with the hurdy-gurdy.
Modern builders have made playable versions based on Leonardo’s plans. These reconstructions demonstrate the unusual sound-producing principle, but they do not prove that Leonardo completed a working original. The instrument illustrates his interest in translating one performer’s gestures into a mechanical process.