William Du Bois Duddell and the "Singing Arc"(1899) Before Thomas Alva Edison invented the electric light bulb electric street lighting was in wide use in Europe. A carbon arc lamp provided light by creating a spark between two carbon nodes. The problem with this method of lighting, apart from the dullness of the light and inneficient use of electricity was a constant humming noise from the arc. The British physicist William Duddell was appointed to solve the problem in London in 1899 and during his experiments found that by varying the voltage supplied to the lamps he could create controllable audible frequencies

A carbon arc streetlamp of the type used in Victorian Britain

By attaching a keyboard to the arc lamps he created one of the first electronic instruments and the first electronic instrument that was audible without using the telephone system as an amplifier/speaker. When Duddell exhibited his invention to the London institution of Electrical Engineers it was noticed that arc lamps on the same circuit in other buildings also played music from Duddell's machine this generated speculation that music deliverd over the lighting network could be created. Duddell didn't capitalise on his discovery and didn't even file a patent for his instrument. Duddell toured the country with his invention which unfortunately never became more than a novelty. It was later recognised that if an antena was attached to the singing arc and made to 'sing' at radio frequencies rather than audio it could be used a continuous radio wave transmitter. The carbon arc lamp's audio capabilities was also used by Thadeus Cahill during his public demonstrations of his Telharmonium ten years later