What musical instrument did Leonardo da Vinci design using a keyboard and a bow-like wheel?

Leonardo da Vinci designed the viola organista, a keyboard instrument that used rotating wheels to make strings vibrate.

Leonardo’s surviving drawings show a keyboard connected to a set of strings and friction wheels. When a key was pressed, a wheel coated or contacting the string would rotate, producing a sustained sound in a manner related to a bowed string instrument. The concept combined features associated with organs, keyboards, and violas.

Unlike a conventional harpsichord, which plucks strings, the viola organista was intended to sustain tones while the wheel remained in contact with them. Leonardo explored the idea in several designs, but no complete Renaissance instrument is known to have been built from his plans.

The instrument is often confused with a normal organ because of its keyboard. It did not use pipes to produce its sound. Modern builders have reconstructed versions from Leonardo’s drawings, demonstrating that the principle can work even though the original design was never commercially established.