Telegraph Key

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Description (Brief)
Telegraph keys are electrical switches used to send coded messages that travel as a series of electrical pulses through a wire. Due to special difficulties in sending pulses through long underwater cables, so-called double-current keys were used. Instead of the short dots and long dashes of land-line telegraphs, submarine telegraphs sent positive pulses and negative pulses that made the receiver move right or left. The operator pressed one lever on the key to send a positive pulse and another to send a negative pulse. The code consisted of the sequence of left and right movements recorded on a paper tape.
Curator George Maynard, who collected this key in 1897, reported: this key was "used to determine differences of longitude between principal meridians of the British Islands and the principal meridians of the United States by means of telegraphic cables from Brest, France, to Duxbury, Mass., to Cambridge, to Washington, D.C., 1869-1872."
Currently not on view
date made
ca 1868
Charles Williams, Jr.
Physical Description
wood (overall material)
rubber (overall material)
ivory (overall material)
brass (overall material)
overall: 3 1/2 in x 7 in x 8 3/4 in; 8.89 cm x 17.78 cm x 22.225 cm
ID Number
catalog number
accession number
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Work and Industry: Electricity
Telegraph Keys
Data Source
National Museum of American History


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