Editing Ground (electricity) (section)

== History ==
{{main|Earth-return telegraph}}
Long-distance electromagnetic [[Electrical telegraph|telegraph]] systems from 1820 onwards{{efn|
name="Harvard1|
An 'electrochemical telegraph' created by  physician, anatomist and inventor [[Samuel Thomas von Sömmering|{{nobr|S.T. von Sömmering}}]] in 1809, based on an earlier, less robust design of 1804 by [[Països Catalans|Catalan]] [[polymath]] and scientist [[Francisco Salva Campillo|{{nobr|F.S. Campillo}}]], both employed multiple wires (up to 35) to represent almost all Latin letters and numerals. Messages could be conveyed electrically up to a few kilometers (in von&nbsp;Sömmering's design), with each of the telegraph receiver's wires immersed in a separate glass tube of acid. An electric current was sequentially applied by the sender through the various wires representing each digit of a message; at the recipient's end the currents electrolysed the acid in the tubes in sequence, releasing streams of hydrogen bubbles next to each associated letter or numeral. The telegraph receiver's operator would watch the bubbles and could then record the transmitted message.<ref>
{{cite web
 |last      = Jones |first = R. Victor
 |title     = Samuel Thomas von&nbsp;Sömmering's "space multiplexed" electrochemical telegraph (1808-1810)
 |website   = people.seas.harvard.edu
 |place     = Boston, MA
 |publisher = [[Harvard University]]
 |url       = http://people.seas.harvard.edu/~jones/cscie129/images/history/von_Soem.html
 |archive-url = https://web.archive.org/web/20121011042334/http://people.seas.harvard.edu/~jones/cscie129/images/history/von_Soem.html
 |archive-date=2012-10-11
}}
: Cited source :
{{cite report
 |title = Semaphore to Satellite
 |year = 1965
 |publisher = [[International Telecommunication Union]]
 |place = Geneva, CH
 |url = https://books.google.com/books?id=Oxc7AAAAMAAJ
 |via = Google books |access-date = 2009-05-01 |df = dmy-all
}}
</ref>
}}
used two or more wires to carry the signal and return currents. It was discovered by German scientist [[Carl August von Steinheil|{{nobr|C.A. von Steinheil}}]] in 1836–1837, that the ground could be used as the return path to complete the circuit, making the return wire unnecessary.<ref>
{{cite web
 |first1=J. B. |last1=Calvert
 |date=19 May 2004
 |title=The Electromagnetic Telegraph
 |website=du.edu
 |publisher=[[University of Denver]]
 |url=http://www.du.edu/~jcalvert/tel/morse/morse.htm
 |url-status=dead  |access-date=2004-09-20
 |archive-url=https://web.archive.org/web/20070804113714/http://www.du.edu/~jcalvert/tel/morse/morse.htm
 |archive-date=2007-08-04
}}
</ref>
Steinheil was not the first to do this, but he was not aware of earlier experimental work, and he was the first to do it on an in-service telegraph, thus making the principle known to telegraph engineers generally.  However, there were problems with this system, exemplified by the transcontinental telegraph line constructed in 1861 by the Western Union Company between [[St. Joseph, Missouri]], and [[Sacramento, California]]. During dry weather, the ground connection often developed a high resistance, requiring water to be poured on the [[ground rod]] to enable the telegraph to work or phones to ring.

In the late nineteenth century, when telephony began to replace telegraphy, it was found that the currents in the earth induced by power systems, electric railways, other telephone and telegraph circuits, and natural sources including lightning caused unacceptable interference to the audio signals, and the two-wire or 'metallic circuit' system was reintroduced around 1883.<ref>
{{cite book |last=Casson |first=Herbert N. |url=https://www.gutenberg.org/files/819/819-h/819-h.htm |title=The History of the Telephone |pages=Chapter IV |type=public domain electronic copy |quote='At last', said the delighted manager [J.J. Carty, Boston, Mass.], 'we have a perfectly quiet line.' |via=[[Gutenberg.org]]}}
</ref>