Williams-Farmer duplex telegraph patent model
Social Media Share Tools
Object Details
- associated person
- Farmer, Moses G.
- Woodman, Asa F.
- Charles Williams, Jr.
- Description
- 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.
- This is the model that inventor Moses Farmer of Salem submitted along with the application that resulted in US Patent #160,581. Issued in 1875 the patent for an "improvement in Duplex-Telegraph Apparatus." A duplex telegraph sends two messages simultaneously through a single wire. Farmer found that on long lines a static charge built up and interfered with the operation of the circuit. He designed this apparatus with a relay, a duplex transmitter, a rheostat and special induction coils to counter that static charge. It is unclear how much of this device Farmer himself actually constructed since the relay bears the marking of Charles Williams, Jr., a noted telegraph and telephone maker in Boston.
- Location
- Currently not on view
- 1875
- ID Number
- EM.252638
- catalog number
- 252638
- accession number
- 49064
- patent number
- 160581
- Object Name
- relay
- telegraph relay
- Object Type
- Patent Model
- Other Terms
- telegraph relay; Telegraphy
- Physical Description
- wood (overall material)
- metal (overall material)
- cloth (overall material)
- ivory (overall material)
- Measurements
- overall: 5 in x 12 in x 12 in; 12.7 cm x 30.48 cm x 30.48 cm
- See more items in
- Work and Industry: Electricity
- Communications
- Telegraph Relays & Repeaters
- National Museum of American History
- Record ID
- nmah_712407
- Metadata Usage (text)
- CC0
- GUID (Link to Original Record)
- http://n2t.net/ark:/65665/ng49ca746a5-395e-704b-e053-15f76fa0b4fa
This image is in the public domain (free of copyright restrictions). You can copy, modify, and distribute this work without contacting the Smithsonian. For more information, visit the Smithsonian's Open Access page.
International media Interoperability Framework
IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more.