Rhythmicon

The Rhythmicon, also known as the Polyrhythmophone, was an electro-mechanical musical instrument designed and built by Leon Theremin in 1930 for composer Henry Cowell, intended to reveal connections between rhythms, pitches and the harmonic series. It used a series of perforated spinning disks, similar to a Nipkow disk, to interrupt the flow of light between bulbs and phototoreceptors aligned with the disk perforations. The interrupted signals created oscillations which were perceived as rhythms or tones depending on the speed of the disks. It generated both pitches and rhythms, and has been described as a precursor of drum machines.