Pony-type telegraph relay
date: label: date made
content: 1848
name: label: maker
content: unknown
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 used by Charles Heaton serviced private lines and shorter branch circuits. The resistance of a given pony relay varied depending on the length of the circuit. This 10 ohm pony relay would have been used on circuits about 7 miles in length.
label: Description
content: The donor reported in 1902 that: "these instruments were first put in use at South Bend, Indiana, in March 1848 on the Erie & Michigan Telegraph line, the first line that ever touched the states of Michigan, Indiana, Illinois, and Wisconsin. This line was constructed under the immediate direction of Ezra B. Cornell (founder of Cornell University) and Col. John F. Speed, with W. B. Wood as superintendent of construction of the Western Division, which extended from Detroit to Milwaukee. Construction began at Detroit and Milwaukee. The builders from the Western end came over into Indiana and established the first office in the state at Michigan City. A few days later the builders from Detroit struck the state at South Bend and there established the second office ever in Indiana. The instruments ... were put in use, my father being operator from March 1848 to June 1861. From the latter date to March 1865 [in] war operation. The instruments remained in use until about 1872 with Thoe. D. Baird as operator since which they were in our family as relics until the date they [came to the Smithsonian]."
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 Charles M. Heaton, Jr.
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.215497
label: catalog number
content: 215497
label: accession number
content: 39777
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: silk (overall material)
label: Physical Description
content: ivory (overall material)
label: Physical Description
content: steel (overall material)
label: Measurements
content: overall: 9 in x 5 5/8 in x 5 3/4 in; 22.86 cm x 14.2875 cm x 14.605 cm