Telegraph Key
date: label: date made
content: ca 1900
notes: label: Description (Brief)
content: 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.
label: Description (Brief)
content: This key has a hard rubber base with four mounting terminals across the one end. The lever assembly is mounted in front of these terminals. Both keys have individual adjustment knobs. There are no visible markings. The double key is part of a submarine telegraph testing system mounted on a black-painted wooden base with two switches. Maker unknown, possibly Muirhead.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
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content: Telegraph Keys
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content: Communications
creditLine: label: Credit Line
content: from the French Cable Company
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.336832
label: catalog number
content: 336832
label: accession number
content: 1978.2346
objectType: label: Object Name
content: telegraph key
label: Object Name
content: submarine telegraph key
label: Other Terms
content: submarine telegraph key; Telegraphy
physicalDescription: label: Physical Description
content: wood (switch base material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: metal (overall material)
label: Physical Description
content: rubber (overall material)
label: Measurements
content: key: 1 3/4 in x 4 in x 4 3/4 in; 4.445 cm x 10.16 cm x 12.065 cm
label: Measurements
content: overall unit: 4 in x 11 in x 9 in; 10.16 cm x 27.94 cm x 22.86 cm