Semi‐elec. instr. developed in 1938 by Marshall Moss, leader of the Nat. SO, Washington, and William Bartley, an engineer. The vn., which has no sound‐board, is played in the usual way, the mechanically‐prod. vibrations being picked up by electro‐magnets or a microphone and amplified through a loudspeaker. Similar instr., and a vc., was developed by Vierling, and there is a 5‐string electric vc. by Karapetov.