Leonardo da Vinci’s instrument combining a keyboard with strings and a bow was the viola organista.
Leonardo designed the viola organista in the late fifteenth century as a keyboard instrument whose strings would sound through friction. Pressing keys would select notes while a rotating wheel or belt mechanism moved a bowing surface against the strings. This allowed a player to control pitch with a keyboard while producing a sustained, bowed-string tone.
The concept was never completed as a functioning instrument by Leonardo. Several modern builders have constructed playable versions from his drawings, making the idea easier to understand than the original sketches alone. Its name reflects the sound Leonardo wanted to combine: the expressive quality of a viola and the controllability of an organ-like keyboard.
It was not simply a harpsichord. A harpsichord plucks strings, whereas the viola organista uses friction to bow them. Leonardo produced several related designs, so reconstructions differ in their exact mechanisms.