Editing Submarine (section)

====18th century====
By the mid-18th century, over a dozen patents for submarines/submersible boats had been granted in England. In 1747, Nathaniel Symons patented and built the first known working example of the use of a ballast tank for submersion. His design used leather bags that could fill with water to submerge the craft. A mechanism was used to twist the water out of the bags and cause the boat to resurface. In 1749, the [[Gentlemen's Magazine]] reported that a similar design had initially been proposed by [[Giovanni Borelli]] in 1680. Further design improvement stagnated for over a century, until application of new technologies for propulsion and stability.<ref name="vector">{{cite web|url=http://inventors.about.com/od/sstartinventions/a/Submarines.htm|archive-url=https://archive.today/20120709102159/http://inventors.about.com/od/sstartinventions/a/Submarines.htm|url-status=dead|archive-date=July 9, 2012|title=The Invention Of The Submarine|author=Mary Bellis|access-date=16 April 2014}}</ref>

The first military submersible was {{ship||Turtle|submersible|2}} (1775), a hand-powered acorn-shaped device designed by the American [[David Bushnell (inventor)|David Bushnell]] to accommodate a single person.<ref>{{cite web|title=The Submarine Turtle: Naval Documents of the Revolutionary War |url=http://www.history.navy.mil/library/online/sub_turtle.htm |archive-url=https://web.archive.org/web/20080917024301/http://www.history.navy.mil/library/online/sub_turtle.htm |url-status=dead |archive-date=17 September 2008 |publisher=Navy Department Library |access-date=21 May 2013 }}</ref> It was the first verified submarine capable of independent underwater operation and movement, and the first to use [[Propeller|screws]] for propulsion.<ref>[https://web.archive.org/web/20030415051537/http://web.mit.edu/invent/iow/bushnelld.html Inventor of the Week: Archive]. mit.edu</ref>