Editing Lock (water navigation) (section)

===Caisson lock===
[[File:Caisson lockenglish.svg|thumb|Operation of caisson lock]]
{{Main|Caisson lock}}
Around 1800 the use of caisson locks was proposed by [[Robert Weldon]]<ref>[https://canalrivertrustwaterfront.org.uk/heritage/speedy-invention/ Robert Weldon]</ref> for the [[Somerset Coal Canal]] in England. In this underwater lift, the chamber was {{cvt|80|ft|m|1}} long and {{convert|60|ft|m|1|abbr=on}} deep and contained a completely enclosed wooden box big enough to take a barge. This box moved up and down in the {{convert|60|ft|m|1|abbr=on}} deep pool of water. Apart from inevitable leakage, the water never left the chamber, and using the lock wasted no water. Instead, the boat entered the box and was sealed in by the door closing behind it, and the box itself was moved up or down through the water. When the box was at the bottom of the chamber, it was under almost {{convert|60|ft|m|1}} of water – at a pressure of {{cvt|3|atm|kPa psi|sigfig=3|spell=in|lk=on}}, in total. One of these "locks" was built and demonstrated to the Prince Regent (later [[George IV of the United Kingdom|George IV]]), but it had various engineering problems and the design was not put into use on the Coal Canal.<ref>{{cite web|title=The Somerset Coal Canal|work=Bath Royal Literary and Scientific Institution |url=http://www.brlsi.org/proceed03/transport200201.htm |access-date=6 October 2006 |url-status=dead |archive-url=https://web.archive.org/web/20061114001751/http://www.brlsi.org/proceed03/transport200201.htm |archive-date=14 November 2006}}</ref><ref>{{cite web|title=History of the Caisson Lock On the Somersetshire Coal Canal |work=The Somersetshire Coal Canal (Society) |url=http://rtjhomepages.users.btopenworld.com/caishist.html |access-date=6 October 2006 |url-status=dead |archive-url=https://web.archive.org/web/20061011094639/http://rtjhomepages.users.btopenworld.com/caishist.html |archive-date=11 October 2006 }}</ref>