Leonardo da Vinci’s viola organista used a keyboard to press strings against a rotating wheel.
Leonardo developed the design in the late fifteenth century, combining features of a keyboard instrument with the continuous sound production of bowed strings. Pressing a key selected a string, while a rotating wheel rubbed against it and produced vibration. The player could therefore control pitch from a keyboard while obtaining a sustained bowed tone.
The viola organista was never built by Leonardo, and surviving drawings show more than one related concept. The name is modern and describes the instrument’s hybrid character: “viola” refers to the bowed-string idea, while “organista” points to keyboard operation.
It is not a conventional organ and does not use pipes to create its sound. Modern builders have reconstructed versions from Leonardo’s drawings, showing that the basic mechanical principle can work.