Leonardo da Vinci designed the viola organista, an instrument using a keyboard and continuously bowed strings.
The viola organista combined features of a keyboard instrument and a bowed string instrument. Pressing keys would bring strings into contact with a rotating wheel or wheels, producing sound in a way that resembles the action of a bow. Leonardo drew several versions during the late fifteenth and early sixteenth centuries, but no surviving evidence shows that he completed a playable original.
The instrument is not the same as a hurdy-gurdy. A hurdy-gurdy uses a hand-turned wheel and keys, whereas Leonardo’s concept was intended to use a keyboard to control the sounding strings. It also differs from a harpsichord, whose strings are plucked rather than continuously bowed.
Modern builders have made playable reconstructions from Leonardo’s drawings. The viola organista illustrates his interest in combining mechanisms with musical performance. It also shows why calling every Leonardo sketch an invention can be misleading: some were detailed prototypes, while others remained experimental designs.