What musical instrument did Leonardo da Vinci design with a bow moved by wheels?

Leonardo da Vinci designed the viola organista, a keyboard instrument with a bow moved by wheels.

The instrument combines features of a keyboard and a bowed string instrument. Pressing keys selects strings, while a rotating wheel or wheels continuously rub against them, producing sustained tones. Leonardo explored several versions in his notebooks, including designs with multiple strings and rotating elements.

The viola organista was never known to have been completed by Leonardo himself. It is therefore better described as an invention he designed rather than a Renaissance instrument that entered regular performance. Modern makers have built playable reconstructions from his drawings, though details vary because the surviving sketches do not provide a single fully specified construction plan.

The name can cause confusion: the viola organista is not simply a viola with a keyboard. It is closer to a mechanical bowed-string keyboard, using continuous friction from a wheel instead of a player’s bow.