Telegraph Sounder
date: label: date made
content: ca 1875
notes: label: Description (Brief)
content: Telegraph sounders convert electrical pulses into audible sounds and are used to receive Morse code messages. The message travels as a series of electrical pulses through a wire. Short pulses make a dot, slightly longer pulses make a dash. The sequence of dots and dashes represent letters and numbers. The pulses energize the sounder’s electromagnets which move a lever-arm. The arm makes a loud “click” when it strikes a crossbar and the operator translates the pattern of sounds into the original language. The date for US Patent #165156 is stamped on this sounder. That patent was issued to Patrick B. Delany of Jersey City, NJ., on 6 July 1875 for an "Improvement in Automatic Telegraphs." Delany's patent was intended to address the issue of induced currents in a telegraph line that created "false records or signals" by activating the sounder during the pauses between dots and dashes. This became a problem with the adoption of automatic sending devices that could transmit messages faster than human operators.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
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content: Communications
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content: Telegraph Sounders
creditLine: label: Credit Line
content: from Western Union Corporation
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.332364
label: accession number
content: 294351
label: catalog number
content: 332364
objectType: label: Object Name
content: telegraph receiver
label: Object Name
content: telegraph sounder
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: rubber (overall material)
label: Physical Description
content: nickle (overall material)
label: Measurements
content: overall: 3 3/4 in x 3 in x 5 5/8 in; 9.525 cm x 7.62 cm x 14.2875 cm