Leonardo da Vinci designed the viola organista, a keyboard instrument that used rotating wheels to make continuous musical tones.
The instrument combined features of a keyboard and bowed string instruments. Pressing a key caused a string to contact a rotating wheel, producing sound in a way comparable to a bow moving across a string. Leonardo made several drawings of related mechanisms during the late 15th and early 16th centuries.
The viola organista was never completed by Leonardo, and its exact intended form is debated because the surviving drawings show variations. It is not the same as a conventional organ, which produces sound through pipes, nor is it simply a harpsichord, whose strings are plucked.
Modern builders have reconstructed versions from Leonardo’s sketches. These reconstructions demonstrate that the basic mechanical principle can work, although they necessarily involve interpretation. The design illustrates Leonardo’s interest in combining engineering, acoustics, and musical performance in a single machine.