Telegraph repeater for ocean telegraphy
name: label: associated user
content: Farmer, Moses G.
label: maker
content: Farmer, Moses G.
notes: label: Description
content: 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.
label: Description
content: 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.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Telegraph Relays & Repeaters
label: See more items in
content: Communications
creditLine: label: Credit Line
content: from Sarah J. Farmer
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.181955
label: catalog number
content: 181955
label: accession number
content: 2015.0173
objectType: label: Object Name
content: relay
label: Object Name
content: telegraph repeater
label: Object Name
content: telegraph relay
label: Other Terms
content: relay; Telegraphy
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: steel (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: copper (overall material)
label: Measurements
content: overall: 3 1/2 in x 13 in x 6 3/8 in; 8.89 cm x 33.02 cm x 16.1925 cm