What instrument combining a keyboard and bowed strings did Leonardo da Vinci invent?

Leonardo da Vinci invented the viola organista, a keyboard instrument using bowed strings.

Leonardo drew several versions of the instrument, including designs from the late fifteenth and early sixteenth centuries. Pressing keys would bring rotating wheels or bows into contact with strings, producing a sustained sound related to that of a viola or other bowed instrument.

The viola organista combined features normally found in separate instruments. A keyboard controlled which notes sounded, while continuous friction from the moving bows supplied the tone. Leonardo never completed a surviving original instrument, so modern makers have reconstructed it from his drawings.

The viola organista is often confused with an organ because of its keyboard, but it does not produce sound through pipes. It is also different from a harpsichord, whose strings are plucked, and a clavichord, whose strings are struck.