Editing London Underground (section)

==== 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" />