American Telephone & Telegraph Company Machine
The picture opposite is one of those sent by the A. T. & T. Company on May 20, 1924, by wire from Cleveland to New York. Some of the pictures sent were from photographs taken earlier, and some were taken only a few minutes before being transmitted.
In the sending machine, “the film picture is inserted in the machine simply by rolling it up in a cylindrical form and slipped into the drum. During operation a very small and intense beam of light shines through the film upon a photo-electric cell within.”
In the receiving machine, “the sensitive film is put on a rotating cylinder and turns like the cylinder record on a phonograph. On this film falls a point of intense white light varied constantly.”
For synchronizing “two separate currents were sent over the wires, one is called the picture channel, the other the synchronizing channel.”
“Forty-four minutes elapsed from the time the picture was taken in Cleveland until it was reproduced in New York.” (New York Times, May 20, 1924.)
It seems unlikely that returns from the daily wire transmission of pictures can equal the day-by-day revenue from the wires used for the transmission of speech when balanced up for the principal circuit, phantom circuits, and carrier circuits.