3479486 Diagram of Ader\'s system for transmitting music by telephone, 1881; (add.info.: Diagram of Ader\'s system for transmitting music by telephone which was first used to relay performances from the Theatre Fracais to special rooms in the Palais de 1 Industrie during the Paris Exhibition of 1881. By sending a separate signal to each earpiece, a stereophonic effect was achieved.); Universal History Archive/UIG; out of copyright.