Manhattan Electric pony telegraph relay
date: label: date made
content: 1903
name: label: maker
content: Manhattan Electric Supply Co.
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: So-called “pony” relays like this unit made by Manhattan Electric Supply Co. serviced private lines and shorter branch circuits. The resistance of a given pony relay varied depending on the length of the circuit. This 20 ohm pony relay would have been used on circuits up to about 15 miles in length. This instrument was used at the American Telegrapher's Tournament Association contest in Philadelphia, on October 30 and 31, 1903. The equipment was donated to the Smithsonian Institution afterwards.
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 Manhattan Electric Supply Co. thru Clarence A. Stimson
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.222129
label: catalog number
content: 222129
label: accession number
content: 41948
objectType: label: Object Name
content: relay
label: Object Name
content: telegraph component
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: steel (overall material)
label: Physical Description
content: iron (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: wood (overall material)
label: Physical Description
content: paper (overall material)
label: Measurements
content: overall: 3 in x 6 3/4 in x 3 1/2 in; 7.62 cm x 17.145 cm x 8.89 cm