Earth-return telegraph
Earth-return telegraph is the system whereby the return path for the
Earth-return telegraph began to have problems towards the end of the 19th century due to the introduction of
Description
A telegraph line between two telegraph offices, like all
Reason for use
The advantage of the earth-return system is that it reduces the amount of metal wire that would otherwise be required, a substantial saving on long telegraph lines that may run for hundreds, or even thousands, of miles.
The expense of multiwire systems rapidly led to single-signal-wire systems becoming the norm for long-distance telegraph. Around the time earth return was introduced, the two most widely used systems were the Morse system of
Telegraph system | Number of wires required or proposed |
---|---|
Steinheil (1838)[13] | 1
|
Cooke and Wheatstone (1837)[14] | 5
|
Schilling (1832)[15] | 8
|
Sömmerring (1809)[16] | 35
|
Ritchie (1830)[17] | 52
|
Ampère (1820)[18] | 60
|
Sömmerring's telegraph was an electrochemical, rather than an electromagnetic telegraph and is placed out of chronological order. It is shown here for comparison because it directly inspired Schilling's electromagnetic telegraph, but Schilling used a greatly reduced number of wires.[19]
History
Early experiments
The first use of an earth return to complete an electric circuit was by
Watson's result seems to have been unknown, or forgotten, by early telegraph experimenters who used a return conductor to complete the circuit.[24] One early exception was a telegraph invented by Harrison Gray Dyar in 1826 using friction machines. Dyar demonstrated this telegraph around a race course on Long Island, New York, in 1828 using an earth-return circuit. The demonstration was an attempt to get backing for construction of a New York to Philadelphia line, but the project was unsuccessful (and is unlikely to have worked over a long distance), Dyar was quickly forgotten, and earth return had to be reinvented yet again.[25]
First earth-return telegraph
The first telegraph put into service with an earth return is due to
Steinheil realised that the "galvanic excitation" in the earth was not confined to the direct route between the two ends of the telegraph wire, but extended outwards indefinitely. He speculated that this might mean that telegraphy without any wires at all was possible; he may have been the first to consider wireless telegraphy as a real possibility. He succeeded in transmitting a signal 50 feet by electromagnetic induction, but this distance was not of practical use.[29]
The use of earth-return circuits rapidly became the norm, helped along by Steinheil declining to patent the idea – he wished to make it freely available as a public service on his part.[30] However, Samuel Morse was not immediately aware of Steinheil's discovery when he installed the first telegraph line in the United States in 1844 using two copper wires.[31] Earth return became so ubiquitous that some telegraph engineers appear not to have realised that early telegraphs all used return wires. In 1856, a couple of decades after the introduction of earth return, Samuel Statham of the Gutta Percha Company and Wildman Whitehouse tried to patent a return wire and got as far as provisional protection.[32]
Problems with electric power
The introduction of electric power, especially electric
The problem caused by electric trams was so severe in some places that it led to the reintroduction of return conductors. A return conductor following the same path as the main conductor will have the same interference induced in it. Such
The advent of
See also
- Single-wire earth return, used for electric power distribution.
Notes
- ^ Full name found from Philosophical Transactions of the Royal Society of London, vol. 9 (1744–1749), p. 494.
References
- ^
- Schwendler, pp. 203–206
- Brooks, pp. 117–120
- ^ Wheen, p. 22
- ^ Darling, p. 378
- ^ Fahie, pp. 346–347, citing Steinheil
- ^
- Schwender, p. 204
- Kahn, p. 70
- ^
- Huurdeman, p. 54
- Shiers, p. 286
- ^ Hubbard, p. 63
- ^ Huurdeman, p. 141
- ^ Huurdeman, p. 69
- ^ Hubbard, p. 78
- ^ Holzmann & Pehrson, pp. 93–94
- ^ Kahn, p. 70
- ^ Fahie, pp. 344–345
- ^ Burns, pp. 128–129
- ^ Artemenko
- ^ Fahie, pp. 230–231
- ^ Fahie, pp. 303–305
- ^ Fahie, p. 275
- ^ Huurdeman, p. 54
- ^ Hawks, p. 421
- ^ Hawks, p. 343
- ^ Schwendler, p. 204
- ^ Hawks, p. 343
- ^
- Schwendler, p. 205
- Charles Bright, in Trotter, p. 516
- ^ Calvert
- ^ Fleming, p. 511
- ^
- For example,
- Stachurski, p. 80
- Wheen, p. 22
- ^
- Hawks, p. 421
- King, p. 284
- Calvert
- ^
- Fahie, pp. 4–5
- Fleming, p. 511
- ^
- Stachurski, p. 80
- Calvert
- ^ Prescott, p. 272
- ^ Bright in Trotter, p. 516
- ^ Margalit, p. 69
- ^ Bright, in Trotter, p. 517
- ^ Huurdeman, p. 327
- ^ Trotter, pp. 501–502
- ^ Trotter, pp. 510–512
- ^
- Hendrick, p. 102
- Kahn, pp. 70–71
Bibliography
- Artemenko, Roman, "Pavel Schilling - inventor of the electromagnetic telegraph", PC Week, vol. 3, iss. 321, 29 January 2002 (in Russian).
- Brooks, David, "Indian and American telegraphs", Journal of the Society of Telegraph Engineers, vol. 3, pp. 115–125, 1874.
- Burns, Russel W., Communications: An International History of the Formative Years, IEE, 2004 ISBN 0863413277.
- Calvert, James B., The Electromagnetic Telegraph, retrieved 14 April 2020.
- Commissioners of Patents, Patents for Inventions: Abridgements of Specifications Relating to Electricity and Magnetism, Their Generation and Applications, George E. Eyre and William Spottiswoode, 1859. Statham and Whitehouse's claim for a return wire is on page 584.
- Darling, Charles R., "Field telephones", The Electrical Review, vol. 77, no. 1,973, pp. 377–379, 17 September 1915.
- Fahie, John Joseph, A History of Wireless Telegraphy, 1838–1899, Edingburgh and London: William Blackwood and Sons, 1899 LCCN 01-5391.
- OCLC 561016618.
- Hawks, Ellison, "Pioneers of wireless", Wireless World, vol. 18, nos. 9 & 11, pp. 343–344, 421–422, 3 & 17 March 1926.
- Hendrick, Burton J., The Age of Big Business, Cosimo, 2005 ISBN 1596050675.
- Hubbard, Geoffrey, Cooke and Wheatstone and the Invention of the Electric Telegraph, Routledge, 2013 ISBN 1135028508.
- Huurdeman, Anton A., The Worldwide History of Telecommunications, Wiley, 2003 ISBN 9780471205050.
- Kahn, Douglas, Earth Sound Earth Signal: Energies and Earth Magnitude in the Arts, University of California Press, 2013 ISBN 0520257804.
- King, W. James, "The development of electrical technology in the 19th century: The telegraph and the telephone", pp. 273–332 in, Contributions from the Museum of History and Technology: Papers 19–30, Smithsonian Institution, 1963 OCLC 729945946.
- Margalit, Harry, Energy, Cities and Sustainability, Routledge, 2016 ISBN 1317528166.
- Prescott, George Bartlett, History, Theory, and Practice of the Electric Telegraph, Boston: Ticknor and Fields, 1866 LCCN 17-10907.
- OCLC 637561329
- Shiers, George, The Electric Telegraph: An Historical Anthology, Arno Press, 1977 OCLC 1067753076.
- Stachurski, Richard, Longitude by Wire: Finding North America, University of South Carolina, 2009 ISBN 1570038015.
- Trotter, A.P., "Disturbance of submarine cable working by electric tramways", Journal of the Institution of Electrical Engineers, vol. 26, iss. 130, pp. 501–514, July 1897.
- "Discussion of Mr. Trotter's paper", op. cit., pp. 515–532.
- Wheen, Andrew, Dot-Dash to Dot.Com: How Modern Telecommunications Evolved from the Telegraph to the Internet, Springer, 2010 ISBN 1441967605.