The Singing Arc (thing)

A very strange invention indeed. To counter the loud humming noise associated with carbon arc lamps used throughout Europe, Duddell attached a keyboard to said lamps and controlled the audible frequencies of the humming by varying the voltage supplied to the lamps.

The music played on a single lamp would also resonate from any other lamps on the circuit. A brilliant, and quite ingenious invention. Unfortunately, Duddell never even filed a patent for what was seen as a purely "novelty" invention.