What type of instrument did Leonardo da Vinci design using rotating bows and strings?

Leonardo da Vinci designed the viola organista, a keyboard instrument using rotating bows and strings.

Leonardo developed several sketches for the instrument during the late 15th and early 16th centuries. A keyboard controlled the strings, while rotating wheels or bows rubbed them to produce continuous sound. This combined features of a keyboard with the sound-producing method of bowed string instruments.

Unlike a normal violin, the performer did not hold a bow by hand. Pressing keys selected pitches while a mechanism maintained contact between the strings and the moving bowing surfaces. Leonardo’s surviving drawings show that he explored more than one mechanical arrangement, so reconstructions differ in detail.

The original instrument was never completed by Leonardo, but modern builders have constructed playable versions. The viola organista is therefore an inventive design rather than a standard Renaissance instrument that entered common use. Its name reflects its hybrid character: viola-like strings with organ-like keyboard control.