Object Details
- Description (Brief)
- Telegraph keys are electrical switches used to send coded messages that travel as a series of electrical pulses through a wire. Due to special difficulties in sending pulses through long underwater cables, so-called double-current keys were used. Instead of the short dots and long dashes of land-line telegraphs, submarine telegraphs sent positive pulses and negative pulses that made the receiver move right or left. The operator pressed one lever on the key to send a positive pulse and another to send a negative pulse. The code consisted of the sequence of left and right movements recorded on a paper tape.
- This key has a hard rubber base with four mounting terminals across the one end. The lever assembly is mounted in front of these terminals. Both keys have individual adjustment knobs. There are no visible markings. The double key is part of a submarine telegraph testing system mounted on a black-painted wooden base with two switches. Maker unknown, possibly Muirhead.
- Location
- Currently not on view
- Data Source
- National Museum of American History
- date made
- ca 1900
- Credit Line
- from the French Cable Company
- Physical Description
- wood (switch base material)
- brass (overall material)
- metal (overall material)
- rubber (overall material)
- Measurements
- key: 1 3/4 in x 4 in x 4 3/4 in; 4.445 cm x 10.16 cm x 12.065 cm
- overall unit: 4 in x 11 in x 9 in; 10.16 cm x 27.94 cm x 22.86 cm
- Object Name
- telegraph key
- submarine telegraph key
- Other Terms
- submarine telegraph key; Telegraphy
