Telegraph Sounder

Description (Brief)
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.
Currently not on view
date made
ca 1875
Physical Description
wood (overall material)
brass (overall material)
rubber (overall material)
nickle (overall material)
overall: 3 3/4 in x 3 in x 5 5/8 in; 9.525 cm x 7.62 cm x 14.2875 cm
ID Number
accession number
catalog number
Credit Line
from Western Union Corporation
See more items in
Work and Industry: Electricity
Telegraph Sounders
Data Source
National Museum of American History


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