What Leonardo da Vinci invention combined a keyboard with bowed strings to imitate a viola?

Leonardo da Vinci’s viola organista combined a keyboard with bowed strings to imitate a viola.

Leonardo developed designs for the viola organista in the late fifteenth century. The player pressed keys much like those of an organ or keyboard instrument, while a rotating mechanism brought wheels or a continuously moving bowing surface into contact with strings. This allowed the instrument to produce sustained bowed-string sounds without a performer moving a bow by hand.

The concept belongs to Leonardo’s experiments with musical instruments and mechanical transmission. It was not a standard viola, because the keyboard controlled the notes and the machine supplied the bowing action. Leonardo made several related sketches, showing that he refined the mechanism over time.

No original Leonardo viola organista is known to survive. Modern builders have constructed playable versions from the drawings, but details differ because the notebooks do not provide a single complete manufacturing blueprint. The instrument is therefore best understood as a Renaissance mechanical keyboard-string invention.