Telegraph Using Galvanoscopes
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“Instead of the telephone receivers normally used in telegraphs, substitute with galvanoscopes. When 1 is pressed, the needles at G and G’ will be turned in one direction; when 2 is depressed, teh needles will be turned in the other direction.” -Avery 1895
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Telephone and Telegraph IndustrySource
Elroy M. Avery School Physics (New York: Sheldon and Company, 1895) 563
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