Ancestor of the Drum Machine: Leon Theremin's Rhythmicon
The Russian inventor Leon Theremin is best known for the eponymous instrument he created around 1919. But another invention of Theremin's is perhaps even more prophetic of later developments in electronic music: the Rhythmicon, produced in 1931 at the behest of the American composer Henry Cowell. This device allowed for the real-time generation of complex rhythmic patterns thought to be unperformable by humans. Each successive note on the keyboard triggered a division of the basic beat in whole number ratios: the second key beating twice for each basic beat, the third key beating three times, and so on.
This video shows the Russian scholar Andrey Smirnov demonstrating the how the Rhythmicon is played. The device shown in the video is likely the later version, developed in the 1960s and now housed in the Theremin Center in Moscow.