Which Leonardo da Vinci invention combined a bowed string instrument with keyboard controls?

Leonardo da Vinci's keyboard-controlled bowed string instrument was the viola organista.

Leonardo sketched the viola organista in the Codex Atlanticus and other notebooks. The player would press keys while a mechanism caused rotating wheels or a continuous bowing surface to contact strings, producing sound. The instrument combined the expressive idea of bowed strings with the control system of a keyboard.

Unlike a normal violin or viola, it did not require a separate hand-held bow. It also differed from a pipe organ, despite the word “organista” in its name. Leonardo's surviving drawings show several related mechanisms, so the exact intended construction is debated and no single fully preserved original instrument exists.

Modern builders have created playable reconstructions based on Leonardo's sketches. The viola organista is therefore best understood as an experimental musical invention that demonstrates his interest in automating performance and translating familiar technologies into new forms.