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}} The buildings of the St. Helena Island Light complex are the sole surviving structures on St. Helena Island, in Mackinac County in the U.S. state of Michigan. The lighthouse on the St. Helena Island's southeastern point was built in 1872-1873 and went into operation in September 1873.〔National Park Service (Maritime History Project, Inventory of Historic Light Stations, St. Helena Island Light. )〕 It became one of a series of lighthouses that guided vessels through the Straits of Mackinac, past a dangerous shoal that extends from the island.〔(Interactive map on Michigan lighthouses. ) Detroit News.〕 ==History== St. Helena Island, which is in size, is located offshore from Gros Cap, Michigan, west of Mackinac Island in the Lake Michigan approach to the Straits of Mackinac. The island has a natural harbor on its north shore, which provided shelter for both Native Americans and voyageurs, who sought shelter from fierce, foreseeable and notorious southwesterly storms, which would drive waves that gained strength running with the lake's length.〔 During the Civil War years, it became increasingly apparent that a shoal near St. Helena Island menaced maritime traffic through the Straits of Mackinac. At the urging of the United States Lighthouse Board, Congress appropriated $14,000 in 1872 for a lighthouse to be built of limestone and brick on this location and fitted with a 3.5-order Fresnel lens. This work created the St. Helena Island Light. This Light became part of what would be complex of 14 reef lights distributed throughout the shoals and hazardous points of the Straits of Mackinac.〔(Roberts, Bruce; Jones, Ray. (September 2002) ''American Lighthouses, 2nd: A Definitive Guide'' pp. 246-250 Publisher: Globe Pequot Press 304 pp ) ISBN 1-59223-102-0; ISBN 978-1-59223-102-7; ISBN 978-0-7627-2269-3.〕 This essential Light was staffed by either one or two lighthouse keepers from its initial operation in 1873 until 1922. A complex of buildings was constructed around the lighthouse to support its operation, including keepers' dwellings, a boat dock, and a boathouse.〔(Wobser, Dave, ''St. Helena Island Lighthouse'' Great Laker magazine reprinted at Boatnerd.com. )〕 This was the first Michigan lighthouse to lose its keeper.〔(Lighthouse Central, Photographs, History, Directions and Way points for St. Helena Island Light, ''The Ultimate Guide to Upper Michigan Lighthouses'' by Jerry Roach (Publisher: Bugs Publishing LLC - 2007). ) ISBN 978-0-9747977-2-4.〕 In 1922, the lighthouse was automated. The tower was fitted with a tank of acetylene gas, a pilot light, and the "sun valve" recently invented by Nobel Prize-winning engineer Gustav Dalén. When the sun set, the temperature would drop slightly, causing the valve to open and acetylene to be released against the pilot flame. The light would then relight itself and shine throughout the night. With the sunrise the next morning, the valve would close. The St. Helena Island Light innovation was successful, and in the years after 1922, many other Michigan lighthouses would be refitted with sun valves. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「St. Helena Island Light」の詳細全文を読む スポンサード リンク
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