What Renaissance musical instrument did Leonardo da Vinci design using rows of bowed wheels?

Leonardo da Vinci designed the viola organista using rows of bowed wheels.

The instrument combined features of a keyboard and a bowed string instrument. Pressing keys selected strings, while rotating wheels rubbed against them to create sustained sound. Leonardo explored several versions in his notebooks, including arrangements in which a continuous belt or multiple wheels made contact with the strings.

The viola organista was not completed during Leonardo’s lifetime. Its design belongs to his broader interest in mechanical music, in which a machine could reproduce or sustain tones through carefully coordinated motion. The instrument’s name reflects its hybrid character: it was meant to produce the expressive sound of bowed strings while being played from a keyboard.

It should not be confused with a normal viola or an organ. A viola uses a bow moved by a player, while an organ produces sound through pipes. Reconstructions have shown that Leonardo’s concept can work, although builders must interpret incomplete drawings and choose modern materials.