Caisson Lighthouse
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A caisson lighthouse (also referred to as a sparkplug lighthouse, or bug light) is a type of
lighthouse A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lens (optics), lenses and to serve as a beacon for navigational aid for maritime pilots at sea or on inland waterways. Ligh ...
whose superstructure rests on a
concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
or metal caisson. Caisson lighthouses were developed in the late nineteenth century as a cheaper alternative to
screwpile lighthouse A screw-pile lighthouse is a lighthouse which stands on piles that are screwed into sandy or muddy sea or river bottoms. The first screw piles, screw-pile lighthouse to begin construction was built by the blind Northern Ireland, Irish engineer Al ...
s. The caisson design was also more efficient as it could better withstand harsh weather, and was not as fragile. Caisson lighthouses usually have living quarters made of
cast iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...
, although some brick examples are known. The two American nicknames were later coined because of the structure's shape.Tim Harrison i Ray Jones, "Lighthouses of the Mid-Atlantic Coast," Globe Pequot Press, 2002


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Lighthouses Caissons {{pharology-stub