Located in Cork Harbour, to the south of Cobh, Spitbank Lighthouse is set at the end of a long mudbank, marking a 90-degree turn in the shipping channel. Its peculiar form and design make it a striking addition to the maritime heritage, as it differs greatly from the more traditional, stone-built lighthouses that are found along the south coast.
The man behind the design of this curious structure, Alexander Mitchell (1780–1868), was an extraordinary character. (See HI 14.3, May/June 2006, pp 31–3.) Born in Dublin, his family moved to Belfast while he was a child. He was educated at the Belfast Academy, where he showed great mathematical aptitude. His eyesight was failing throughout his teenage years, and he was blind by the age of 23. Amazingly, however, his blindness did not prevent him from becoming a pioneering self-taught engineer.
Apparently inspired by the domestic corkscrew, Mitchell patented the ‘Mitchell screw-pile and mooring’ in 1833, a cast-iron support system that enabled construction in deep water on mud- and sandbanks. Its helical screw flange could be used for difficult shifting foundations in a variety of structures, and its potential was realised in a broad range of projects, including lighthouses in Britain and Ireland as well as more than 150 in North America. Lighthouses using this innovative system were built in Ireland under Mitchell’s supervision at Belfast Lough in 1848, at Spitbank in 1853 and at Dundalk in 1855.
An unlit buoy had previously marked the commencement of the spit bank near Cobh, but the Cork Harbour Commissioners required a more notable structure to take its place. Mitchell won the commission to construct the new lighthouse for £3,450, and moved with his family to Cobh (then Queenstown) in 1851. He immediately set about engaging workmen, testing the ground, and examining the iron for the piles and the wood for the lantern housing. His son and grandson laid the piles, with regular inspections from Mitchell, while he oversaw the construction of the timber structure on shore. The light was exhibited for the first time two years later, and a foghorn was added in the 1890s. With no room for living accommodation, the principal and assistant keeper lived in rented accommodation in Cobh.
Incredibly, surviving accounts describe Mitchell personally overseeing construction, taking trips out to his lighthouses in small boats, even on rough seas (falling overboard twice), and climbing up and down ladders, crawling along planks, examining the wood, iron and rivets. Through touch he checked the quality of the ironwork, sometimes noting flaws that had escaped the workers’ and foreman’s eye. One worker is recorded as exclaiming: ‘Our master may say what he pleases, but I’ll never believe that he can’t see as well as thee or I!’ Mitchell was made an associate of the Institute of Civil Engineers in 1837 and was elected a member in 1848, at which time he received the Telford silver medal for the invention of the screw-pile. He was awarded the Napoleon Medal from the Paris Exhibition in 1855.
The Spitbank Lighthouse remains an iconic structure in Cork Harbour. Described by some as a giant spider in the sea, its curious form and design have attracted much comment and curiosity over the past 150 years. HI
Jane Wales is an Architectural Heritage Officer. Series based on the National Inventory of Architectural Heritage’s ‘building of the month’, www.buildingsofireland.ie.