Henning telegraph relay
date: label: date made
content: ca 1870
name: label: maker
content: Henning, Robert
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 relay was made by Robert Henning, superintendent of the Western Union machine shop in Ottawa, IL. Prior to that Henning worked as manager for the Caton Telegraph Instrument Shop, established by John Dean Caton in Ottawa. Caton had helped found the Illinois & Mississippi Telegraph Company in 1849 and sold out to Western Union in 1867. Apparently the Instrument Shop (and Henning) went to Western Union with the deal.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Communications
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content: Telegraph Relays & Repeaters
creditLine: label: Credit Line
content: from Pennsylvania Railroad Company
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.221145
label: catalog number
content: 221145
label: accession number
content: 41460
objectType: label: Object Name
content: 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 1/4 in x 9 in x 4 1/4 in; 10.795 cm x 22.86 cm x 10.795 cm