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Earth-return telegraph
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[[File:Collins Overland Telegraph Line.gif|thumb|upright=1.5|Part of the [[Russian–American Telegraph]] line bearing the single wire of an earth-return line, c. 1866]]
'''Earth-return telegraph''' is the system whereaby the return path for the [[electric current]] of a [[electrical telegraph|telegraph circuit]] is provided by connection to the [[Ground (electricity)|earth]] through an [[earth electrode]]. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a commensurate saving on the labour required to string it. The benefits of doing this were not immediately noticed by telegraph pioneers, but it rapidly became the norm after the first earth-return telegraph was put into service by [[Carl August von Steinheil]] in 1838.
Earth-return telegraph began to have problems towards then end of the 19th century due to the introduction of [[electric tram]]s. These seriously disturbed earth-return operation and some circuits were returned to the old metal-conductor return system. At the same time, the rise of [[telephony]], which was even more intolerant to the interference on earth-return systems, started to displace electrical telegraphy altogether.
==Description==
[[File:Pole4 of Transaustralien Telegraph Line.jpg|thumb|A disused pole of the [[Australian Overland Telegraph Line]] which used to carry four earth-return lines]]
A telegraph line between two telegraph offices, like all [[electrical circuit]]s, requires two conductors to form a complete circuit. This usually means two distinct metal wires in the circuit, but in the earth-return circuit one of these is replaced by connections to [[Ground (electricity)|earth]] (also called ground). Connection to earth is made by means of metal plates with a large surface area buried deeply in the ground. These plates could be made of copper or galvanised iron. Other methods include connecting to metal gas or water pipes where these are available, or laying a long wire rope on damp ground. The latter method is not very reliable, but was common in India up to 1868.<ref></ref>
==Reason for using==
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.<ref></ref> This advantage was not so apparent in early telegraph systems which often required multiple signal wires. All of these circuits can use a single return conductor for their return paths ([[Unbalanced line#Telegraph lines|unbalanced lines]]) so the cost saving of dispensing with the return wire is a fraction of the total wire cost. Examples of multiwire systems included; [[Pavel Schilling]]'s experimental system in 1832 which had six signal wires so that the [[Cyrillic alphabet]] could be [[binary code]]d,<ref></ref> and the [[Cooke and Wheatstone telegraph|Cooke and Wheatstone five-needle telegraph]] in 1837. The latter did not require a return conductor at all because the five signal wires were always used in pairs with opposite polarity currents until [[code point]]s for [[Numerical digit|numerals]] were added.<ref>Hubbard, p. 63</ref>
The expense of multiwire systems rapidly led to single-signal-wire systems becoming the norm for long distance telegraph. The two most widely used systems up to the time that earth-return was introduced were the Morse system of [[Samuel Morse]] and the Cooke and Wheatstone one-needle telegraph, first put into service, respectively, in 1844<ref>Huurdeman, p. 141</ref> and 1843.<ref>Huurdeman, p. 69</ref> A few two-signal-wire systems lingered on; the Cooke and Wheatstone two-needle system used on British railways,<ref>Hubbard, p. 78</ref> and the [[Foy-Breguet telegraph]] used in France.<ref>Holzmann & Pehrson, pp. 93–94</ref> This reduction in number of signal wires meant that the cost of the return wire was much more significant and earth-return became standard.<ref>Kahn, p. 70</ref>
==History==
[[File:William Watson.jpg|thumb|left|upright|William Watson established the viability of earth-return]]
The first use of an earth return to complete an electric cicuit was by [[William Watson (scientist)|William Watson]] in 1747 if experiments using water as a return path are discounted. Watson, in a demonstration on [[Shooter's Hill]], London in 1747, sent an electric current through 2,800 feet of iron wire, insulated with baked wood, with an earth-return path. Later that year he increased that distance to two miles.<ref>Hawks, p. 421</ref> One of the first demonstrations of a water-return path was by [[John Henry Winkler]],<ref group=note>Full name found from ''Philosophical Transactions of the Royal Society of London'', vol. 9 (1744–1749), p. 494.</ref> a professor in [[Leipzig]], who used the [[River Pleisse]] in this way in an experiment on 28 July 1746.<ref>Hawks, p. 343</ref> The first experimenter to test an earth-return circuit with a low-voltage battery rather than a high-voltage [[electrostatic generator#Friction machines|friction machine]] was Basse of Hameln in 1803.<ref>Schwendler, p. 204</ref> These early experiments were not aimed at producing a telegraph, but rather, were designed to determine the speed of electricity. In the event, the transmission of electrical signals proved to be faster than the experimenters were able to measure – indistinguishable from instantaneous.<ref>Hawks, p. 343</ref>
Watson's result seems to have been unknown, or forgotten, by early telegraph experimenters who used a return conductor to complete the circuit.<ref></ref> 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.<ref>Calvert</ref>
[[File:Carl August von Steinheil um 1857 (cropped).jpg|thumb|Steinheil was the first to put an eaarth-return telegraph into service]]
The first telegraph put into service with an earth return is due to [[Carl August von Steinheil]] in 1838. Steinheil was working on providing a telegraph along the Nuremberg–Fürth railway line, a distance of five miles. Steinheil first attempted, at the suggestion of [[Carl Friedrich Gauss]], to use the two rails of the track as the telegraph conductors. This failed because the rails were not well insulated from earth and there was consequently a conducting path between them. However, this initial failure made Steinheil realise that the earth could be used as a conductor and he then succeeded with only one wire and an earth return.<ref></ref>
The use of earth-return circuits rapidly became the norm. So much so that some telegraph engineers appeared 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.<ref>Bright in Trotter, p. 516</ref>
The introduction of electric power, especially [[tram]] lines, seriously disturbed earth-return telegraph lines. The starting and stopping of the trams generated large electromagnetic spikes which obliterated code pulses on telegraph lines. This was particularly a problem on lines where high-speed automatic working was in use, and most especially on [[submarine telegraph cable]]s. These latter could be thousands of miles long and the arriving signal was consequently small.<ref>Bright, in Trotter, p. 517</ref> [[Repeater]]s were not available for submarine cables until the middle of the 20th century.<ref>Huurdeman, p. 327</ref> Sensitive instruments like the [[syphon recorder]] were used to detect such signals and were easily disrupted by trams.<ref>Trotter, pp. 501–502</ref>
The problem with 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 [[common-mode interference]] can be entirely removed if both parts of the circuit are identical (a [[balanced line]]). In one such case in 1897 in [[Cape Town]], South Africa, the interference was so severe that not only was the buried cable through the city replaced with a balanced line, but a submarine cable was laid for five or six nautical miles out to sea and spliced on the original cable there.<ref>Trotter, pp. 510–512</ref> The advent of [[telephony]], which initially used the same earth-return lines used by telegraphy, made it essential to use balanced circuits as telephone lines were even more susceptible to interference. One of the first to realise that all-metal circuits would solve the terrible noise problems encountered on earth-return telephone ciruits was [[John J. Carty]], the future chief engineer of the [[American Telephone and Telegraph Company]]. Carty began installing metallic returns on lines under his control and reported that the noises had immediately almost enirely disappeared.<ref></ref>
==Notes==
==References==
==Bibliography==
* [[David Brooks (inventor)|Brooks, David]], [https://ift.tt/3b7NMPm "Indian and American telegraphs"], ''Journal of the Society of Telegraph Engineers'', vol. 3, pp. 115–125, 1874.
* Calvert, James B., [https://ift.tt/2ydBVR5 ''The Electromagnetic Telegraph''], retrieved 14 April 2020.
* Commissioners of Patents, [https://ift.tt/3b7NNmo ''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 [https://ift.tt/2yYQ5pz page 584].
* Hawks, Ellison, [https://ift.tt/3b7NNTq "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 .
* Hubbard, Geoffrey, ''Cooke and Wheatstone and the Invention of the Electric Telegraph'', Routledge, 2013 .
* Huurdeman, Anton A., ''The Worldwide History of Telecommunications'', Wiley, 2003 .
* Kahn, Douglas, ''Earth Sound Earth Signal: Energies and Earth Magnitude in the Arts'', University of California Press, 2013 .
* King, W. James, [https://ift.tt/3cndpff "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 .
* Shiers, George, ''The Electric Telegraph: An Historical Anthology'', Arno Press, 1977 .
* [[Carl Louis Schwendler|Schwendler, Louis]], [https://ift.tt/2RCQQew ''Instructions for Testing Telegraph Lines and the Technical Arrangements of Offices''], vol. 2, London: Trèubner & Co., 1878
* Trotter, A.P., [https://ift.tt/2K7AOoG "Disturbance of submarine cable working by electric tramways"], ''Journal of the Institution of Electrical Engineers'', vol. 26, iss. 130, pp. 501-514, July 1897.
** [https://ift.tt/2KaROKF "Discussion of Mr. Trotter's paper"], ''op. cit.'', pp. 515–532.
[[Category:Telegraphy]]
[[Category:History of telecommunications]]
'''Earth-return telegraph''' is the system whereaby the return path for the [[electric current]] of a [[electrical telegraph|telegraph circuit]] is provided by connection to the [[Ground (electricity)|earth]] through an [[earth electrode]]. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a commensurate saving on the labour required to string it. The benefits of doing this were not immediately noticed by telegraph pioneers, but it rapidly became the norm after the first earth-return telegraph was put into service by [[Carl August von Steinheil]] in 1838.
Earth-return telegraph began to have problems towards then end of the 19th century due to the introduction of [[electric tram]]s. These seriously disturbed earth-return operation and some circuits were returned to the old metal-conductor return system. At the same time, the rise of [[telephony]], which was even more intolerant to the interference on earth-return systems, started to displace electrical telegraphy altogether.
==Description==
[[File:Pole4 of Transaustralien Telegraph Line.jpg|thumb|A disused pole of the [[Australian Overland Telegraph Line]] which used to carry four earth-return lines]]
A telegraph line between two telegraph offices, like all [[electrical circuit]]s, requires two conductors to form a complete circuit. This usually means two distinct metal wires in the circuit, but in the earth-return circuit one of these is replaced by connections to [[Ground (electricity)|earth]] (also called ground). Connection to earth is made by means of metal plates with a large surface area buried deeply in the ground. These plates could be made of copper or galvanised iron. Other methods include connecting to metal gas or water pipes where these are available, or laying a long wire rope on damp ground. The latter method is not very reliable, but was common in India up to 1868.<ref></ref>
==Reason for using==
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.<ref></ref> This advantage was not so apparent in early telegraph systems which often required multiple signal wires. All of these circuits can use a single return conductor for their return paths ([[Unbalanced line#Telegraph lines|unbalanced lines]]) so the cost saving of dispensing with the return wire is a fraction of the total wire cost. Examples of multiwire systems included; [[Pavel Schilling]]'s experimental system in 1832 which had six signal wires so that the [[Cyrillic alphabet]] could be [[binary code]]d,<ref></ref> and the [[Cooke and Wheatstone telegraph|Cooke and Wheatstone five-needle telegraph]] in 1837. The latter did not require a return conductor at all because the five signal wires were always used in pairs with opposite polarity currents until [[code point]]s for [[Numerical digit|numerals]] were added.<ref>Hubbard, p. 63</ref>
The expense of multiwire systems rapidly led to single-signal-wire systems becoming the norm for long distance telegraph. The two most widely used systems up to the time that earth-return was introduced were the Morse system of [[Samuel Morse]] and the Cooke and Wheatstone one-needle telegraph, first put into service, respectively, in 1844<ref>Huurdeman, p. 141</ref> and 1843.<ref>Huurdeman, p. 69</ref> A few two-signal-wire systems lingered on; the Cooke and Wheatstone two-needle system used on British railways,<ref>Hubbard, p. 78</ref> and the [[Foy-Breguet telegraph]] used in France.<ref>Holzmann & Pehrson, pp. 93–94</ref> This reduction in number of signal wires meant that the cost of the return wire was much more significant and earth-return became standard.<ref>Kahn, p. 70</ref>
==History==
[[File:William Watson.jpg|thumb|left|upright|William Watson established the viability of earth-return]]
The first use of an earth return to complete an electric cicuit was by [[William Watson (scientist)|William Watson]] in 1747 if experiments using water as a return path are discounted. Watson, in a demonstration on [[Shooter's Hill]], London in 1747, sent an electric current through 2,800 feet of iron wire, insulated with baked wood, with an earth-return path. Later that year he increased that distance to two miles.<ref>Hawks, p. 421</ref> One of the first demonstrations of a water-return path was by [[John Henry Winkler]],<ref group=note>Full name found from ''Philosophical Transactions of the Royal Society of London'', vol. 9 (1744–1749), p. 494.</ref> a professor in [[Leipzig]], who used the [[River Pleisse]] in this way in an experiment on 28 July 1746.<ref>Hawks, p. 343</ref> The first experimenter to test an earth-return circuit with a low-voltage battery rather than a high-voltage [[electrostatic generator#Friction machines|friction machine]] was Basse of Hameln in 1803.<ref>Schwendler, p. 204</ref> These early experiments were not aimed at producing a telegraph, but rather, were designed to determine the speed of electricity. In the event, the transmission of electrical signals proved to be faster than the experimenters were able to measure – indistinguishable from instantaneous.<ref>Hawks, p. 343</ref>
Watson's result seems to have been unknown, or forgotten, by early telegraph experimenters who used a return conductor to complete the circuit.<ref></ref> 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.<ref>Calvert</ref>
[[File:Carl August von Steinheil um 1857 (cropped).jpg|thumb|Steinheil was the first to put an eaarth-return telegraph into service]]
The first telegraph put into service with an earth return is due to [[Carl August von Steinheil]] in 1838. Steinheil was working on providing a telegraph along the Nuremberg–Fürth railway line, a distance of five miles. Steinheil first attempted, at the suggestion of [[Carl Friedrich Gauss]], to use the two rails of the track as the telegraph conductors. This failed because the rails were not well insulated from earth and there was consequently a conducting path between them. However, this initial failure made Steinheil realise that the earth could be used as a conductor and he then succeeded with only one wire and an earth return.<ref></ref>
The use of earth-return circuits rapidly became the norm. So much so that some telegraph engineers appeared 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.<ref>Bright in Trotter, p. 516</ref>
The introduction of electric power, especially [[tram]] lines, seriously disturbed earth-return telegraph lines. The starting and stopping of the trams generated large electromagnetic spikes which obliterated code pulses on telegraph lines. This was particularly a problem on lines where high-speed automatic working was in use, and most especially on [[submarine telegraph cable]]s. These latter could be thousands of miles long and the arriving signal was consequently small.<ref>Bright, in Trotter, p. 517</ref> [[Repeater]]s were not available for submarine cables until the middle of the 20th century.<ref>Huurdeman, p. 327</ref> Sensitive instruments like the [[syphon recorder]] were used to detect such signals and were easily disrupted by trams.<ref>Trotter, pp. 501–502</ref>
The problem with 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 [[common-mode interference]] can be entirely removed if both parts of the circuit are identical (a [[balanced line]]). In one such case in 1897 in [[Cape Town]], South Africa, the interference was so severe that not only was the buried cable through the city replaced with a balanced line, but a submarine cable was laid for five or six nautical miles out to sea and spliced on the original cable there.<ref>Trotter, pp. 510–512</ref> The advent of [[telephony]], which initially used the same earth-return lines used by telegraphy, made it essential to use balanced circuits as telephone lines were even more susceptible to interference. One of the first to realise that all-metal circuits would solve the terrible noise problems encountered on earth-return telephone ciruits was [[John J. Carty]], the future chief engineer of the [[American Telephone and Telegraph Company]]. Carty began installing metallic returns on lines under his control and reported that the noises had immediately almost enirely disappeared.<ref></ref>
==Notes==
==References==
==Bibliography==
* [[David Brooks (inventor)|Brooks, David]], [https://ift.tt/3b7NMPm "Indian and American telegraphs"], ''Journal of the Society of Telegraph Engineers'', vol. 3, pp. 115–125, 1874.
* Calvert, James B., [https://ift.tt/2ydBVR5 ''The Electromagnetic Telegraph''], retrieved 14 April 2020.
* Commissioners of Patents, [https://ift.tt/3b7NNmo ''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 [https://ift.tt/2yYQ5pz page 584].
* Hawks, Ellison, [https://ift.tt/3b7NNTq "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 .
* Hubbard, Geoffrey, ''Cooke and Wheatstone and the Invention of the Electric Telegraph'', Routledge, 2013 .
* Huurdeman, Anton A., ''The Worldwide History of Telecommunications'', Wiley, 2003 .
* Kahn, Douglas, ''Earth Sound Earth Signal: Energies and Earth Magnitude in the Arts'', University of California Press, 2013 .
* King, W. James, [https://ift.tt/3cndpff "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 .
* Shiers, George, ''The Electric Telegraph: An Historical Anthology'', Arno Press, 1977 .
* [[Carl Louis Schwendler|Schwendler, Louis]], [https://ift.tt/2RCQQew ''Instructions for Testing Telegraph Lines and the Technical Arrangements of Offices''], vol. 2, London: Trèubner & Co., 1878
* Trotter, A.P., [https://ift.tt/2K7AOoG "Disturbance of submarine cable working by electric tramways"], ''Journal of the Institution of Electrical Engineers'', vol. 26, iss. 130, pp. 501-514, July 1897.
** [https://ift.tt/2KaROKF "Discussion of Mr. Trotter's paper"], ''op. cit.'', pp. 515–532.
[[Category:Telegraphy]]
[[Category:History of telecommunications]]
April 15, 2020 at 04:57AM
