Telegraph Transmitter

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Description (Brief)
Telegraph lines could carry more than one message at a time if designed cleverly. In 1868, Joseph Stearns devised a method of sending two messages simultaneously on a single line. Called a duplex telegraph, Sterns' invention instantly doubled the capacity of a telegraph line. Each station had a transmitter and receiver on the line. This Sterns duplex transmitter sent a series of electrical pulses through the line. Short pulses made a dot, slightly longer pulses made a dash. The sequence of dots and dashes represented letters and numbers. The circuit was designed in such a way that this transmitter activated the receiver at the other end of the line but not the receiver next to the sending operator. The active receiver mades a loud “click” when it struck a crossbar and the operator translated the pattern of sounds into the original language.
Currently not on view
J. H. Bunnell & Co.
Physical Description
wood (overall material)
brass (overall material)
rubber (overall material)
steel (overall material)
overall: 4 1/8 in x 8 1/2 in x 4 3/4 in; 10.4775 cm x 21.59 cm x 12.065 cm
ID Number
catalog number
accession number
collector/donor number
Credit Line
from Western Union Corporation
See more items in
Work and Industry: Electricity
Telegraph Sounders
Data Source
National Museum of American History


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