The Importance of the Telegraph The telegraph is an electromagnet connected to a battery via a switch. When the switch is down, the current flows from the battery through the key, down the wire, and into the sounder at the other end of the line. By itself, the telegraph could express only two states, on or off. This limitation was eliminated by the fact that it was the duration of the connection that determined the …
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…History of the Telegraph, www.allsands.com The Library of Congress, Today in History, www.memory.loc.gov References Field, Alexander. "French Optical Telegraphy, 1793-1855: Hardware, Software, Administration." Technology and Culture 35 (1994): 315-47. Nonnenmacher, Tomas. "History of the U.S. Telegraph Industry." EH.Net Encyclopedia, www.eh.net The Household Cyclopedia of General Information, 1881, www.publicbookshelf.com The History of the Telegraph, www.allsands.com The Library of Congress, Today in History, www.memory.loc.gov