[PT032AAHx], Technical Note, Thomas Alva Edison, July 25th, 1887


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[PT032AAHx], Technical Note, Thomas Alva Edison, July 25th, 1887

Editor's Notes

Dyer Patent Railway signals-- I put a large permanent magnet on Locomotive with poles of iron flush with Rail in center track In a closed box between the ties is an electromagnet the box is poured full insulating compound-- The poles project above box & are about 3 or 4 inches from the polar faces of magnet on Locomotive-- when Loco is running the passage of the permanent magnet induces a powerful current into the fixed rail magnet & the current passing along the track to any required distance to control a semaphore signal when the train enters it sets up a current which blocks both one energizing the magnet that is fixed has its coils reversed & hence sends reverse current to unblock-- An electromagnet could be used on Loco energized by battery or dynamo-- and any form of fixed magnet could be used-- I want claim broad principle of actuating signals by induced current without electrical or mechanical contacts & by motion of train.




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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