pole-changer telegraph relay

Description
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.
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.
Location
Currently not on view
Object Name
pole changer relay
telegraph relay
date made
ca 1892
Physical Description
wood (overall material)
brass (overall material)
steel (overall material)
plastic (overall material)
Measurements
overall: 4 in x 8 1/2 in x 4 3/4 in; 10.16 cm x 21.59 cm x 12.065 cm
ID Number
EM*331739
accession number
294351
catalog number
331739
collector/donor number
13-13
See more items in
Work and Industry: Electricity
Communications
Telegraph Relays & Repeaters
Data Source
National Museum of American History, Kenneth E. Behring Center

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