What musical instrument did Leonardo da Vinci design with multiple parallel bows?

Leonardo da Vinci designed a viola organista with multiple parallel bows in one version.

The instrument was a keyboard-controlled string design. Instead of striking strings like a piano, its keys could bring selected strings into contact with rotating or continuously moving bowing surfaces. Leonardo explored more than one mechanical arrangement, including concepts with several parallel bowed elements.

The goal was to combine the polyphonic control of a keyboard with the sustained tone of bowed strings. This made the design more ambitious than a simple keyboard adaptation of the violin. Because Leonardo’s notebooks contain sketches rather than a preserved working instrument, historians and instrument makers must infer some details.

The name can cause confusion: the viola organista is not a viola, an organ, or a standard Renaissance keyboard. It is a hybrid concept, and modern reconstructions differ in their mechanisms while preserving the central idea of keyboard-operated bowed strings.