The history of telecommunications -Ader page 382

Thanks to improvements introduced by French Ader allows 881 from the spread of 'THEATROPHONE' first form of cultural diffusion, the

spread of this service will continue until the advent of commercial radio 1932.
The service promoted by the company of "THEATROPHONE" was transmitted in stereo (two channels phone) works, and other comedies by various theaters of the Paris Chafe, hotel lobby or even at home. In 1891 the service has spread to London.

Clément Ader