The Theremin is a musical instrument controlled entirely without physical contact. One of the most intriguing inventions, it “revolutionised music as the predecessor of the modern synthesiser, among others. When radio waves were still a new phenomenon in technology, a young scientist was experimenting with it in his laboratory at the Physical Technical Institute in Saint Petersburg — then called Petrograd — when he noted that the apparatus made strange sounds when he moved his hands around it. Lev Sergeyevich Termen [d.1993] — who later became famous by the name Léon Theremin — was also a classical musician, trained in the cello, and the strange observations piqued his interest. He “played” with the sounds for a while and concluded that he had created a new musical equipment, one that was played without touching” (Nath). It was the world’s first electronic instrument that came to be known as the Theremin.
Dipanita Nath, Indian Express
More About the Theremin at BBC

Ginan Melodies on Theremin