Editing London Underground (section)

===Early years===
[[File:GWR broad gauge Metropolitan Class.jpg|thumb|The Metropolitan Railway opened in 1863 using GWR broad-gauge locomotives.{{sfnp|Peacock|1970|pp=37–38}}]]

==== Sub-surface lines ====
The idea of an underground railway linking the [[City of London]] with the urban centre was proposed in the 1830s,{{sfnp|Day|Reed|2010|p=8}} and the [[Metropolitan Railway]] was granted permission to build such a line in 1854.{{sfnp|Jackson|1986|p=19}} To prepare construction, a short test tunnel was built in 1855 in [[Kibblesworth]], a small town with geological properties similar to London. This test tunnel was used for two years in the development of the first underground train, and was later, in 1861, filled up.<ref>{{cite book |last1=Bextor |first1=Robin |title=A History of the London Underground |date=2013 |publisher=Demand Media Limited |isbn=978-1909217379 |page=34}}</ref> The world's first underground railway, it opened in January 1863 between [[Paddington]] and [[Farringdon, London|Farringdon]] using gas-lit wooden carriages hauled by steam locomotives.{{sfnp|Day|Reed|2010|pp=8, 14}} It was hailed as a success, carrying 38,000 passengers on the opening day, and borrowing trains from other railways to supplement the service.{{sfnp|Simpson|2003|p=16}} The Metropolitan District Railway (commonly known as the [[District Railway]]) opened in December 1868 from [[South Kensington]] to [[Westminster]] as part of a plan for an underground "inner circle" connecting London's main-line stations.{{sfnp|Day|Reed|2010|pp=18–24}}  The Metropolitan and District railways completed the [[Circle line (London Underground)|Circle line]] in 1884,{{sfnp|Day|Reed|2010|pp=27–28}} built using the [[cut and cover]] method.{{sfnp|Day|Reed|2010|pp=10–11}} Both railways expanded, the District building five branches to the west reaching [[Ealing]], [[Hounslow]],{{sfnp|Day|Reed|2010|p=26}} [[Uxbridge]],{{sfnp|Day|Reed|2010|p=33}} [[Richmond, London|Richmond]] and [[Wimbledon, London|Wimbledon]]{{sfnp|Day|Reed|2010|p=26}} and the Metropolitan eventually extended as far as {{rws|Verney Junction}} in [[Buckinghamshire]] – more than {{convert|50|mi}} from [[Baker Street tube station|Baker Street]] and the centre of London.{{sfnp|Day|Reed|2010|p=32}}

==== Deep-level lines ====
For the first deep-level tube line, the [[City and South London Railway]], two {{convert|10|ft|2|in}} diameter circular tunnels were dug between [[King William Street, London|King William Street]] (close to today's [[Bank–Monument station|Monument station]]) and [[Stockwell]], under the roads to avoid the need for agreement with owners of property on the surface. This opened in 1890 with electric locomotives that hauled carriages with small opaque windows, nicknamed ''[[padded cell]]s''.{{sfnp|Day|Reed|2010|pp=40–45}} The [[Waterloo and City Railway]] opened in 1898,{{sfnp|Day|Reed|2010|pp=50–51}} followed by the [[Central London Railway]] in 1900, known as the "twopenny tube".{{sfnp|Day|Reed|2010|pp=52–56}} These two ran electric trains in circular tunnels having diameters between {{convert|11|ft|8|in}} and {{convert|12|ft|2.5|in|2}},{{sfnp|Day|Reed|2010|pp=50, 53}} whereas the [[Great Northern and City Railway]], which opened in 1904, was built to take main line trains from [[Finsbury Park station|Finsbury Park]] to a [[Moorgate station|Moorgate terminus]] in the City and had {{convert|16|ft|adj=on}} diameter tunnels.{{sfnp|Day|Reed|2010|pp=60–61}}

While steam locomotives were in use on the Underground there were contrasting health reports. There were many instances of passengers collapsing whilst travelling, due to heat and pollution, leading for calls to clean the air through the installation of garden plants.<ref name=":4" /> The Metropolitan even encouraged beards for staff to act as an air filter.<ref>Mason, M. (2013). ''Walk the Lines: The London Underground, Overground.'' London: Arrow Books. p.126.  {{ISBN|978-0-099-55793-7}}</ref> There were other reports claiming beneficial outcomes of using the Underground, including the designation of Great Portland Street as a "[[sanatorium]] for [sufferers of ...] [[asthma]] and bronchial complaints", [[tonsillitis]] could be cured with acid gas and the Twopenny Tube cured [[anorexia (symptom)|anorexia]].<ref name=":4" />

==== Electrification ====
With the advent of electric Tube services (the Waterloo and City Railway and the Great Northern and City Railway), the [[Volk's Electric Railway|Volks Electric Railway]], in [[Brighton]], and competition from electric trams, the pioneering Underground companies needed modernising.<ref name=":5">{{Cite book|title=The London Underground|last=Emmerson|first=Andrew|publisher=Shire Publications Ltd.|year=2010|isbn=978-0-74780-790-2|location=London}}</ref>  In the early 20th century, the District and Metropolitan railways needed to electrify and a joint committee recommended an [[Alternating current|AC]] system, the two companies co-operating because of the shared ownership of the inner circle. The District, needing to raise the finance necessary, found an investor in the American [[Charles Yerkes]] who favoured a [[Direct current|DC]] system similar to that in use on the City & South London and Central London railways. The Metropolitan Railway protested about the change of plan, but after arbitration by the [[Board of Trade]], the DC system was adopted.{{sfnp|Day|Reed|2010|pp=62–63}}