telegraph relay
date: label: date made
content: ca 1876
name: label: maker
content: Charles Williams, Jr.
notes: label: Description (Brief)
content: 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.
label: Description (Brief)
content: This duplex relay was made by Charles Williams, Jr. of Boston and used in experiments by Moses Farmer. Duplex relays operated in a system designed to send two messages simultaneously over the same wire. Williams had made duplex devices for Joseph Stearns who devised the first practical duplex system in 1868 and also made early telephone devices for Alexander Graham Bell.
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.181950
label: catalog number
content: 181950
label: accession number
content: 2015.0173
objectType: label: Object Name
content: relay, relegraph, duplex
label: Object Name
content: telegraph key or relay
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: brass (overall material)
label: Physical Description
content: wood (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: ivory? (overall material)
label: Measurements
content: overall: 4 1/2 in x 6 1/2 in x 7 3/4 in; 11.43 cm x 16.51 cm x 19.685 cm