Leonardo da Vinci’s keyboard machine for continuous bowed-string music was the Viola organista.
Leonardo developed drawings for the instrument during the late 15th and early 16th centuries. It combined features of a keyboard instrument and a bowed string instrument. Pressing keys selected strings, while a rotating mechanism caused a wheel or belt to rub against them, producing sustained tones.
The idea addressed a musical problem: ordinary bowed instruments could sustain notes, but playing many strings simultaneously was difficult. A keyboard offered control of multiple pitches, while the moving bow supplied continuity. Leonardo produced several related designs rather than one single finalized instrument.
The viola organista is often mistaken for an ordinary organ because of its keyboard. It did not use pipes and air in the normal organ manner. Modern builders have constructed working versions from Leonardo’s drawings, demonstrating that the concept can produce sound, although the surviving sketches leave details open to interpretation.