United Telegraph "Bruce" type cable relay
date: label: date made
content: ca 1918
notes: label: Description
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. This unit was designed for use on submarine telegraph cables.
label: Description
content: This unit was received by the Western Union Museum from the company's Multiplex Department Laboratory in New York, in April 1933. Wooden base with connectors on either side and the relay set on top. Glass and wood cover hinged to open to the back. Right side connectors labeled "Aux Coil" and "Main Coil", left side connectors labeled: "T", "C", "VIB", "DOT", "DASH", and "VIB / COND". Main section is a 5-layer laminated horseshoe magnet set on four posts with a suspension unit mounted between the poles. Two connector posts are set inside the magnet and two more are just outside the poles. A small electromagnet coil is mounted in front of the suspension and two more are mounted on a separate stand at left front. An adjustable post is set in front of the suspension and can be adjusted vertically with a knob on the post, or forward horizontally with a knob that extends to the right and outside the cover. Unit appears mostly complete.
label: Description
content: Nameplate on front reads: "The United Telegraph and Cable Co. / Springfield, Ohio, U.S.A. / Bruce Relay / .S. Patent No. 1240306, Others Pending / Instrument No. B.11". Stamp on front: "W. U. Tel. Co. / 1712- / Cable Lab". Reference: US patent 1240306, "Telegraphy" issued 18 September 1917, to William M. Bruce, Jr., assignor to United Telegraph & Cable Co. Patent describes a relay for "high resistance and capacity lines, such as for submarine telegraphy." Includes mercury contacts to minimize induced vibration (no sign of mercury contacts on this specimen).
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Communications
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.332153
label: accession number
content: 294351
label: catalog number
content: 332153
label: collector/donor number
content: 31-10
objectType: label: Object Name
content: cable relay
label: Object Name
content: telegraph relay
label: Other Terms
content: telegraph relay; Telegraphy
physicalDescription: label: Physical Description
content: glass (case material)
label: Measurements
content: overall: 13 3/4 in x 19 1/2 in x 14 1/2 in; 34.925 cm x 49.53 cm x 36.83 cm