Leonardo da Vinci designed the viola organista, a keyboard instrument whose strings were sounded by rubbing them with a wheel.
The instrument combined a keyboard with the continuous friction of bowed strings. Pressing keys selected strings, while a rotating wheel covered in horsehair or another friction material acted like a bow. This arrangement allowed a player to produce sustained tones without directly handling a bow.
Leonardo drew several versions of the idea, especially in notebooks from the late 15th century. The viola organista was never established as a standard Renaissance instrument, and surviving evidence consists mainly of designs rather than an original Leonardo-built example.
Its name can cause confusion because the device is not simply a viola and is not an organ in the ordinary pipe-organ sense. It belongs to a family of experimental keyboard instruments that sought to combine keyboard control with the expressive sound of bowed strings. Modern builders have constructed working interpretations from Leonardo’s drawings.