pole-changer telegraph relay
date: label: date made
content: ca 1892
notes: label: Description
content: Telegraph relays amplified electrical signals in a telegraph line. Telegraph messages traveled as a series of electrical pulses through a wire from a transmitter to a receiver. Short pulses made a dot, slightly longer pulses a dash. The pulses faded in strength as they traveled through the wire, to the point where the incoming signal was too weak to directly operate a receiving sounder or register. A relay detected a weak signal and used a battery to strengthen the signal so that the receiver would operate.
label: Description
content: This pole-changing relay includes a plate citing "F. W. Jones Patents / April 17, 1888 / April 29, 1890." The citation refers to US Patents 381,251 and 426,819, respectively. Francis W. Jones of New York City received these patents for his inventions related to improvements in operating duplex and quadruplex telegraph devices on "dynamo machines" rather than primary batteries.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
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content: Communications
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content: Telegraph Relays & Repeaters
creditLine: label: Credit Line
content: from Western Union Corporation
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.331739
label: accession number
content: 294351
label: catalog number
content: 331739
label: collector/donor number
content: 13-13
objectType: label: Object Name
content: pole changer relay
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: steel (overall material)
label: Physical Description
content: plastic (overall material)
label: Measurements
content: overall: 4 in x 8 1/2 in x 4 3/4 in; 10.16 cm x 21.59 cm x 12.065 cm