What instrument did Leonardo da Vinci design that used a keyboard to play bowed strings?

Leonardo da Vinci designed the viola organista, a keyboard instrument that played bowed strings.

The instrument combines features of a keyboard and a stringed instrument. Pressing keys selects pitches, while a rotating wheel or belt rubs against strings to make them sound, much as a bow does on a violin. Leonardo drew several versions between roughly 1488 and 1500.

Unlike a conventional piano, the viola organista does not strike strings with hammers. Its mechanism was intended to produce a sustained, bowed tone while allowing one player to control pitches from a keyboard.

No known original Leonardo viola organista survives. Modern builders have created reconstructions from his drawings, including a playable instrument completed by Polish instrument maker Sławomir Zubrzycki in 2013. The design is sometimes confused with a hurdy-gurdy, but the viola organista is specifically keyboard-controlled.