Telegraph repeater for ocean telegraphy

Description
Telegraph repeaters 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, limiting the distance a message could travel. Repeaters remedied that problem by detecting a weak signal and using a local power source to re-energize and re-transmit the signal down the line.
This unusual repeater was made by noted electrical inventor Moses Farmer and is one of the devices bequeathed to the Smithsonian by his daughter Sarah in 1917. The records indicate the repeater was "devised and used by Farmer" in experiments related to underwater telegraphy. The unit features a four-plate compound magnet and a set of electromagnetic coils connected by a series of wires.
Location
Currently not on view
Object Name
relay
telegraph repeater
telegraph relay
associated user
Farmer, Moses G.
maker
Farmer, Moses G.
Physical Description
wood (overall material)
steel (overall material)
brass (overall material)
plastic (overall material)
copper (overall material)
Measurements
overall: 3 1/2 in x 13 in x 6 3/8 in; 8.89 cm x 33.02 cm x 16.1925 cm
ID Number
EM*181955
catalog number
181955
accession number
2015.0173
subject
Telegraph Relays & Repeaters
Communications
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 Sarah J. Farmer
Additional Media

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