You might not have ever heard of the Theremin, prior to my friend Tom linking me I hadn’t. The wiki article is a fabulous read, but briefly:
“The theremin or thereminvox (originally pronounced [teremi?n] but often anglicized as [?????m?n] ) is one of the earliest fully electronic musical instruments. Invented in 1919 by Russian L?on Theremin, the theremin is unusual in that it requires no physical contact in order to produce music and was, in fact, the first musical instrument designed to be played without being touched. The instrument consists of an array of circuitry including two antennas around which the user moves his or her hands to play.”
If you are interested in hearing some Theremin in action Peter Pringle has some downloads available.