Foote-Pierson main-line telegraph relay

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.
“Main line” relays like this unit made by Foote, Pierson & Co. were one of the most common types of relay and were typically made with a resistance of 150 ohms. As the name suggests, main line relays served on major intercity circuits several hundred miles long. This unit was used by the Postal Telegraph Company. Originally established by entrepreneur John McKay, Postal merged with Western Union in the 1940s.
Currently not on view
Object Name
telegraph relay
date made
ca 1903
Foote, Pierson & Co.
Skirrow, John F.
Physical Description
wood (overall material)
brass (overall material)
paper (overall material)
metal (overall material)
overall: 3 1/4 in x 7 1/2 in x 4 in; 8.255 cm x 19.05 cm x 10.16 cm
ID Number
accession number
catalog number
Telegraph Relays & Repeaters
See more items in
Work and Industry: Electricity
Telegraph Relays & Repeaters
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
from Western Union
Additional Media

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