What type of instrument did Leonardo da Vinci invent with a keyboard and rotating bow?

Leonardo da Vinci invented the viola organista, a keyboard instrument with a rotating bow.

The viola organista combined a keyboard with bowed strings. Pressing keys selected strings, while a rotating mechanism brought a wheel or bowing surface into contact with them, producing sustained tones. Leonardo developed several versions of the concept in his notebooks, seeking to merge the expressive sound of bowed instruments with the controllability of a keyboard.

The design belongs to Leonardo's broader investigations of musical instruments and mechanical systems. It was not simply a painted idea: his drawings show careful attention to string placement, friction, keys, and the transmission of motion. However, no surviving original instrument proves that Leonardo completed a working version during his lifetime.

Modern builders have reconstructed the viola organista from the drawings. The name is descriptive rather than a label Leonardo necessarily used for one standardized model. It should also not be confused with a conventional viola, which is played with a hand-held bow and has no keyboard.