What musical instrument did Leonardo da Vinci invent using multiple bowed strings?

Leonardo da Vinci invented the viola organista, a keyboard instrument using multiple bowed strings.

The viola organista combined a keyboard with strings that were sounded by friction from rotating wheels or belts. Pressing a key selected a string and brought it into contact with the moving mechanism, producing a tone somewhat related to that of bowed string instruments. Leonardo drew several versions of the idea in his notebooks.

Unlike an ordinary piano, the instrument did not use hammers to strike strings. Unlike a conventional viola, it could produce notes through a keyboard rather than a player’s bow and fingers. This hybrid design was intended to make sustained, string-like sound available through keyboard technique.

Leonardo’s surviving drawings do not show that he completed a functioning instrument. Modern builders have reconstructed versions based on his plans, but those reconstructions are interpretations rather than original Renaissance instruments.