Leonardo da Vinci designed the viola organista, a keyboard instrument that produces sound with vibrating strings.
Leonardo’s drawings show a keyboard connected to rotating wheels or cylinders. When a key was pressed, the mechanism brought a wheel into contact with a string, causing the string to vibrate in a way related to a bowed string instrument. The concept combined features of a keyboard, a stringed instrument, and a mechanical organ.
Unlike a conventional organ, the viola organista was not designed primarily to send air through stationary pipes. Unlike a piano, its strings were not struck by hammers. Its proposed sound production depended on friction between the strings and rotating surfaces, allowing a player to control pitch from a keyboard.
Leonardo never completed a known working version. Several modern builders have constructed instruments based on his drawings, and these reconstructions demonstrate that the basic mechanism can function. The name is often written “viola organista,” although Leonardo’s notebooks contain variations in how the concept is described.