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}} Point Betsie Light is located on the northeast shore of Lake Michigan — at the southern entrance to the Manitou Passage — north of Frankfort in Benzie County in Northern Michigan. Construction began in 1854, but it was not completed until 1858, and began service in the shipping season of 1859. The lighthouse cost $5,000 to build. In 1875, a life saving station was built for $3,000.〔(Friends of the Point Betsie Light. )〕 ==History== The light was originally equipped with a Fourth Order Fresnel lens with bullseye, which was upgraded to a Third order (with bullseye) in 1880. The latter was visible for , because of the high placement of the tower (focal plane of ) and the efficacy of the lens design.〔See (Third Order Fresnel lens, Terry Pepper, Seeing the Light. )〕 The Fresnel Lens was removed in 1996, and was stored for years 〔(National Park Service, Inventory of historic light stations, Point Betsie. )〕 at Sleeping Bear Dunes National Lakeshore.〔(Sleeping Bear Dunes National Lake Shore Visitors Bureau. )〕 It has since been returned to the original site and sits, non-operational, inside the lighthouse where visitors can see its glass combination of engineering and artistry at close proximity. The cylindrical tower is tall, but sits on a dune. It is attached to the Lighthouse keepers house, which was upgraded to an attractive gambrel roof design.〔(Terry Pepper, Seeing the Light on Point Betsie Light. )〕 This was one of the earliest Life Saving Stations, and was run under the auspices of the U.S. Life-Saving Service. In 1910 the United States Lighthouse Board was reconstituted as the U.S. Lighthouse Service. In 1939 these agencies were merged under the control of the U.S. Coast Guard. Prior to being automated in 1983, the 'wickies' operated the light for 106 years.〔 This was the last manned lighthouse on Lake Michigan〔(Wobser, David, Point Betsie Light at Boatnerd.com. )〕 and the last Michigan lighthouse to lose its keeper.〔(Lighthouse Central, Photographs, History, Directions and Way points for Point Betsie Light, ''The Ultimate Guide to West Michigan Lighthouses'' by Jerry Roach (Publisher: Bugs Publishing LLC - 2005). ) ISBN 0-9747977-0-7.〕 The light is now a Vega VRB-25 system.〔 The new optic would be visible for a range of , depending on the bulb used.〔(Vega VRB-25 250 mm acrylic optic, Terry Pepper, Seeing the Light. )〕 In addition to the lighthouse, the site presently includes a fog signal building and an oil house.〔 Most remnants of the former lifesaving station site have disappeared, including the original boathouse. Some of the former housing units were converted through the years into private cottages and still sit amongst the dunes nearby. Most notable amongst these are the former horse barn which is incorporated into a seasonal cottage to the north of the site, and the sizable 1920's lifesaving personnel dormitory house to the south. A newly constructed building housing a gift shop, public bathrooms and an area for display of related artifacts is slated to open in 2014. Fog signals have received much attention at Point Betsie. In the autumn of 1912, the fog signal building was rebuilt. The locomotive whistles were replaced by 10 inch chime whistles. Meanwhile, the lamp was upgraded to an incandescent oil vapor system, with an intensity of 55,000 candlepower. In 1921, upon being connected to the electrical power grid, aa 110-volt electric bulb was installed, and the fog signal upgraded to twin Type "G" diaphones, driven by electric air compressors. The diaphone doubled the audible radius, and had the added benefit that it could be brought on line immediately, without waiting for steam engines to build pressure. The following April the fog signal's characteristic was changed to a group of two blasts every 30 seconds.〔 Dismantled and sold as junk to the local residents in the 1970s, who hauled it away, all original fog horn apparatus has long since disappeared and is no longer on site. The light is located on Point Betsie, Michigan, which in turn is part of a recognized terrestrial marine near shore ecosystem, dominated by a coastal dune with unique flora and fauna, including Pitcher's Thistle, Lake Huron Locust, and fascicled broomrape.〔(Reid, Ron & Holland, Karen, Environmental Protection Agency. )〕 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「Point Betsie Light」の詳細全文を読む スポンサード リンク
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