Farmer telegraph repeater patent model

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
Object Name
telegraph receiver
telegraph register
telegraph relay
telegraph repeater
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
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
Additional Media

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Selected comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about the history, rarity, or value of your personal artifacts.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Enter the characters shown in the image.