The Baker Machine
The machine of the opposite illustration, “the telestereograph,” is the invention of T. Thorn Baker, Esq., of England, and “was used by the London Daily Mirror in July, 1909, and was worked by wire rather regularly between London and Paris, and London and Manchester.” The picture to be sent was “a halftone photograph printed in fish glue on lead foil, and wrapped on a sending cylinder, rotating once every two seconds with a metal point riding on it.”
The receiving cylinder carried “an absorbent paper impregnated with a colorless solution which turns black or brown when decomposed by the incoming electric current.”
What electrolytic solution was employed is not stated in the report, but was probably sodium iodide or potassium bromide judging from the description of its color and behavior.
To synchronize, the receiving drum turns faster than the sending drum, and is caught each revolution until the other catches up. (Smithsonian Report, 1910.)
The Dr. Korn Machine
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.”