The accompanying illustration shows the work of a machine developed by
Dr. Korn, of Germany, and first used by the Daily Mirror between London
and Paris in 1907. “On a revolving glass cylinder” a transparent picture
was put. He used a Nernst lamp and “selenium cells on opposite sides of
a Wheatstone bridge” to overcome the inherent lag of the selenium cell.
Signals were sent over a wire and received on photographic film on a
cylinder, using “two fine silver strings free to move laterally in a
strong magnetic field.” A light was focused on the obstructing “silver
strings,” which the incoming electric signals, passing through the
“strings,” separated to a greater or lesser degree “to widen or thin the
photographed line.”
“When the film is developed it is laid out flat, and the spiral line
becomes resolved into so many parallel lines.” The sending and the
receiving machines were synchronized by “well calibrated clocks which
released the cylinders at end of every five seconds.” (_Mr. Baker in
Smithsonian Report_, 1910.)
[Illustration: [Machines]]