Editing Alexander Mitchell (engineer) (section)

==Career==
[[File:Belfast Lough Screwpile Lighthouse.jpg|thumb|upright|Plan from the late 1840s of Mitchell's lighthouse in Belfast Lough]]
[[File:Hopper barge apparatus 2.jpg|thumb|Illustration of Mitchell's screwpile method]]
Originally working in brickmaking in [[Belfast]], he invented machines used in that trade, before patenting the [[Screwpiles|screw-pile]] in 1833, for which he would later gain some fame.<ref name="boi">{{cite web|url=http://www.buildingsofireland.ie/Surveys/Buildings/BuildingoftheMonth/Archive/Name,1402,en.html |publisher=Buildings of Ireland: National Inventory of Architectural Heritage |title=Building of the Month – Spit Bank Lighthouse, Cobh, County Cork |date=November 2009 |access-date=23 February 2016}}</ref><ref>{{cite journal|first=Alan J. |last=Lutenegger |title=Historical development of iron screw-pile foundations, 1836–1900 |journal=International Journal for the History of Engineering & Technology |publisher=[[Newcomen Society]] |volume=81 |year=2011 |pages=108–28 |doi=10.1179/175812109X12547332391989 |s2cid=109521534 }}</ref> The screw-pile was used for the erection of [[lighthouse]]s and other structures on mudbanks and shifting sands, including bridges and piers. Mitchell's designs and methods were employed all over the world from [[Portland, Maine|Portland]] breakwater to [[Bombay]] bridges. Initially it was used for the construction of lighthouses on [[Maplin Sands]] in the [[Thames Estuary]] (the first light application, in 1838), the [[Wyre Light]] at [[Fleetwood]] in Lancashire (the first such beacon lit) completed, in 1839), and at [[Belfast Lough]] where his lighthouse was finished in July 1844.

In May 1851 he moved to [[Cobh]] to lay the foundation for a [[Spit Bank Lighthouse|lighthouse on the Spit Bank]];<ref name="wales">{{cite journal|url=http://www.historyireland.com/18th-19th-century-history/spitbank-lighthouse/ |journal=History Ireland |author= Jane Wales |title=Spitbank Lighthouse |issue=  2 | volume = 18 |date=April 2010 |access-date=23 February 2016}}</ref> the success of these undertakings led to the use of his invention on the breakwater at [[Portland Harbour|Portland]], the viaduct and bridges on the [[Bombay, Baroda and Central India Railway]] and a broad system of Indian telegraphs.

While in Cork, Mitchell became friendly with [[astronomer]] [[John Thomas Romney Robinson]], and [[mathematician]] [[George Boole]].