Farmer telegraph repeater patent model

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Description (Brief)
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.
For many years inventors were required to submit models to the Patent Office when they filed for a patent. In 1856, Moses G. Farmer received U. S. patent #14,157 for his “telegraphic repeater”. This is the model Farmer submitted that shows his circuit for an improved way to retransmit telegraph signals. Prior to this invention repeaters had to be switched manually by a telegraph operator. This sometimes led to delays if the operator were otherwise occupied. Farmer's invention allowed for automatic operation of the repeater.
Currently not on view
date made
Farmer, Moses G.
Physical Description
wood (overall material)
cloth (overall material)
brass (overall material)
steel (overall material)
ivory (overall material)
overall: 4 in x 10 in x 12 in; 10.16 cm x 25.4 cm x 30.48 cm
ID Number
catalog number
accession number
patent number
Patent Models
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Work and Industry: Electricity
Telegraph Relays & Repeaters
Data Source
National Museum of American History


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