Note from Simon Barber:
The Theramin was THE futurist instrument of the 1930’s. Ancestor to all the synthesisers of modern times, it was played by moving one’s hands through a magnetic field generated by two aerials on the box. In modern terms, think “Kraftwerk doing the hand-jive”. Note that [the German experimental group mentioned in the Songmark Diaries] “V-Gerat” probably is “Versuchtes Gerat”, meaning “Experimental Device”. )