The accompanying “photoradiogram” is a development by the Radio
Corporation of America, and was transmitted from London to New York on
November 30, 1924.
“The transparent picture film is placed on a glass cylinder. An
incandescent lamp inside the cylinder is focused in a minute beam onto
the film as the cylinder rotates, and this transfers the light values of
the picture into electrical impulses, in a General Electric Company
photo-electric cell.
“The receiving cylinder has white paper placed thereon, and the incoming
dots-and-dashes, amplified in passing through a bank of vacuum tubes,
are recorded in ink on this paper with a special vibrating fountain pen,
drawn down by magnet coils to record the picture much in the style of an
artistic stippled engraving.” The cylinders of both the sending and the
receiving machines are “rotated back and forth, the electric camera
itself advancing down the length of the picture one notch at a time.”
“The necessary synchronism of the two machines is maintained by the use
of special driving motors, and a special controlling mechanism based on
the constant pitch of a tuning fork.” (_See Radio News, February,
1925._)
[Illustration:
By courtesy of “The World,” New York.