Alexander Mitchell | Inventor of the Screw-Pile Lighthouse

Happy Birthday to Alexander Mitchell, born 13th April 1780 – The extraordinary Dubliner who invented the screw-pile lighthouse

Alexander Mitchell’s story is inspirational – despite complete blindness he used his incredible engineering talent to help seafarers to see in the dark.

Alexander Mitchell

Alexander Mitchell (1780–1868)

Mitchell was born in Dublin but grew up in Belfast where he attended the prestigious Belfast Academy. His eyesight began to fail at a young age and by 22 he was completely blind. But he didn’t let this sizeable challenge overcome him and would become one of Ireland’s greatest engineers. Over the course of his life he patented several significant inventions and greatly advanced maritime technology with his durable designs with several still in use today.

Alexander Mitchell | Inventor of the Screw-Pile Lighthouse

Mitchell’s plan of Spit Bank lighthouse, Cobh

His most famous invention is the screw-pile lighthouse. His design enabled lighthouses to be built in the difficult soil conditions of shifting sands in deep waters. His design made the lighthouses easy to construct, inexpensive and quick to build. It worked by screwing a central pile surrounded by eight perimeter piles in a hexagonal or octagonal shape into the sea bed.




Mitchell himself was heavily involved with the building process, he supervised all construction and was even seen climbing ladders and scaffolding. The first one was built at the Maplin Sand Lighthouse at the mouth of the Thames. His technology was used all around the country in Belfast, Wexford, Cork and Dundalk.

Alexander Mitchell | Inventor of the Screw-Pile Lighthouse

Screw-pile lighthouse at Spitbank, Cobh

Not all lighthouses were successful though. He tried to build one the perilous Kish Bank but a gale caused the piles to fail and the project was abandoned.

Only four of Mitchell’s iconic lighthouses remain in Ireland at Spit Bank Cobh, Dundalk Bay, Moville, Inishowen Co. Donegal and Passage East, Waterford. Often described as giant spiders at sea these few remaining lighthouses are still operational and acting as unique lights in the dark for mariners at sea.

About the Author

Ann Robinson
Has a passion for coastal heritage and maritime history. Loves sharing the best of the Irish coast online. Contact me ann@coastmonkey.ie or follow me on Twitter @AnnRobinson22

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