"Looks like a spinet, with a keyboard of 5 octaves but can produce only one note at a time. Uses oscillating valves like the theremin but is operated by a wire across the keyboard, the player producing the desired pitch by manipulating the wire which moves a variable condenser, the keyboard serving as a guide. The signal is amplified through a loudspeaker. Tone‐colour and timbre are obtained by pressing a button, and vol. is controlled by a key.
"First demonstrated in Paris, 20 April 1928; first composition to use it was Poème symphonique by Dimitri Levidis, 23 Dec. 1928."
- Oxford Music Online
Thomas Bloch performs his own composition, "Formule," in a live performance in London, October 2007.