What Leonardo da Vinci invention combined a viola’s strings with a keyboard mechanism?

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

The instrument was designed to produce sound when a keyboard controlled strings that were rubbed by rotating wheels or a continuous bowing surface. This gave it a connection to both the viola family and keyboard instruments. Pressing keys would select notes while the mechanical system supplied the friction needed to make the strings vibrate.

Leonardo sketched several versions of the idea, but the instrument was not known to have been completed during his lifetime. The surviving drawings reveal experimentation rather than a single finalized model. Modern builders have created reconstructions based on those sketches, allowing researchers and musicians to test the concept.

The viola organista should not be confused with an ordinary organ. An organ produces sound by sending air through pipes, whereas Leonardo’s design relied on vibrating strings. It also differs from a piano, whose strings are struck by hammers. The invention shows Leonardo combining musical acoustics with mechanical engineering.