English: RCA Theremin and Aeolian/Hammond player organ displayed at the Musical Museum, Brentford.

• RCA theremin AR-1264 (1930, once owned by Musaire (Joseph Whitely 1894 - 1984))

• Aeolian/Hammond player organ Model BA (1938)

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The theremin is one of the earliest electronic musical instruments, and the first musical instrument played without being touched. It was invented by Russian inventor Léon Theremin in 1919. The controlling section usually consists of two metal antennae which sense the position of the player's hands and control radio frequency oscillator(s) for frequency with one hand, and volume with the other. The electric signals from the theremin are amplified and sent to a loudspeaker.

To play, the player moves his or her hands around the antennas, controlling frequency (pitch) and amplitude (volume). The theremin is associated with an eerie sound, which has led to its use in movie soundtracks such as those in Spellbound, The Lost Weekend, and The Day the Earth Stood Still.