What musical instrument did Leonardo da Vinci design with a keyboard and bowing wheel?

Leonardo da Vinci designed the viola organista with a keyboard and bowing wheel.

The viola organista combines features of a keyboard instrument and a bowed string instrument. Pressing keys selects strings, while a rotating wheel or belt rubs against them to create sound. Leonardo developed several versions of the idea in his notebooks during the late fifteenth and early sixteenth centuries.

Unlike a conventional piano, the strings are not struck by hammers. The concept instead sought to let one player produce sustained, bowed tones through a keyboard. It belongs to Leonardo’s wider interest in mechanical music and practical engineering.

Leonardo’s instrument was never completed as a working original. Modern builders have constructed versions from his drawings, including a playable instrument made by Polish musician Sławomir Zubrzycki, who presented it publicly in 2013.