20.7

DEAD MEDIA: THE TELEGRAPH 4/5
In This Issue: Inductive Telegraphy

//Source: *The Progress of Invention in the 19th Century* by Edward W. Byrn Munn and Co., Publishers, Scientific American Office, 361 Broadway, New York 1900//

page 25

"*Telegraphing by induction,* i.e., without the mechanical connection of a conducting wire, is another of the developments in telegraphy in recent years, and finds application to telegraphing to moving railway trains. When an electric current flows over a telegraph line, objects along its length are charged at the beginning and end of the current impulse with a secondary charge, which flows to the earth if connection is afforded. It is the discharge of this secondary current from the metal car roof to the ground which, on the moving train, is made the means of telegraphing without any mechanical connection with the telegraph line along the track.

"(...) a rapid series of impulses, caused by the vibrator of an induction coil, is made to produce buzzing tones of various duration representing the alphabet, and these tones are received upon a telephone instead of a Morse register. (...)

"In 1881 William W. Smith proposed the plan of communicating between moving cars and a stationary wire by induction (U. S. Pat. No. 247,127, Sept 13, 1881). Thomas A. Edison, L. J. Phelps, and others have further improved the means for carrying it out. In 1888 the principle was successfully employed on 200 miles of the Lehigh Valley Railroad."

(((bruces remarks: Inductive telegraphy, being wireless, would seem to have been a precursor of radio ("wireless telegraphy"). Note the use of telephone receivers, which produced specialized buzzes instead of Morse code. Inductive telegraphy, used only on moving trains (and requiring a moving train in order to produce its signal) is another striking example of the symbiosis of telegraphs and railroads.)))