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The Equatorial Sextant , also known as Altitude Instrument, was first invented and made by William Austin Burt.〔(Mining and metallurgy, Issues 169-180 By American Institute of Mining and Metallurgical Engineers, p. cccxli Charles S. Burt, the grandson of William Austin Burt )〕 He patented it November 4, 1856, in the United States as patent No. 16,002,〔United States Letters Patent No. 16,002 (Nov. 4, 1856) - Equatorial Sextant〕 which was followed by patents in England, France and Belgium.〔''Michigan Historic Magazine,'' Volume 78, Michigan Department of State, 1994, p. 15〕 The purpose of this type of sextant was to get an accurate position of a ship at sea.〔(Smithsonian - Equatorial Sextant )〕〔(The life and times of William A. Burt )〕 Burt applied the principles of his earlier Solar Compass invention to navigation.〔Farmer, p. 1181〕 == History == One day in 1851 on a return trip to Philadelphia from Europe Burt intentionally took back to America a slower sailing vessel. He wanted to observe what happened out at sea and took notes on this longer ocean trip. He wanted to apply ideas he had to his Solar Compass invention to make a guide for sailors at sea, like he had done for surveyors in the wilderness. Burt noticed on this six week trip that the captain was misguided by the ship's compass, which caused the ship to go off course several times delaying the arrival. He applied his findings and experiments of this return trip to his Solar Compass with the idea to help navigation. The resulting instrument lived up to his expectations. He had considered labeling the new instrument with the names of "Marine Solar Compass", "Computing Sextant", and "Pantalobe" but settled on "Equatorial Sextant" as the original compass was a derivative of the reflecting sextant. He gave to sailors that had no path a means of navigation, just like he gave to surveyors a path to follow when they had no navigation when their normal instruments failed due to large iron ore deposits.〔 Shortly after he had designed his Equatorial Sextant he retired as a surveyor to devote his time to teaching the use of this special navigational sextant. He then moved to Detroit for this purpose. Burt & Bailey company of Detroit built Burt's first prototype by the early part of 1855. Burt had obtained an accurate reading within five degrees on board the ship ''Illinois'' on its historic first journey through the Soo Canal on June 18, 1855.〔Burt, p. 129〕 In March 1856 Burt sent a sample of one of his Equatorial Sextants to the Navy Department. He sent another sample to the U.S. Coast Guard. They both agreed that Burt's Equatorial Sextant met the purpose of its design. His precision instrument was then finalized and approved on a patent November 15, 1856. Burt envisioned a greater worldwide potential for his nautical instrument than for that of his surveying instrument of the Solar Compass.〔Burt, p. 130〕 Burt instructed lake captains in the use of this new sextant and gave them classes in astronomy and navigation. The captains learned valuable knowledge taught from "old salts" and they were able to made successful winter trips across the Atlantic with just their lake schooners. Burt died, however, two years after he patented the Equatorial Sextant and he was not able to perfect his new navigational aid.〔Tuttle, p. 523〕 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「Equatorial sextant」の詳細全文を読む スポンサード リンク
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