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The ''Turtle'' (also called the ''American Turtle'') was the world's first submersible with a documented record of use in combat. It was built in Old Saybrook, Connecticut in 1775 by American David Bushnell as a means of attaching explosive charges to ships in a harbor. Bushnell designed it for use against British Royal Navy vessels occupying North American harbors during the American Revolutionary War. Connecticut Governor Jonathan Trumbull recommended the invention to George Washington; although the commander-in-chief had doubts, he provided funds and support for the development and testing of the machine. Several attempts were made using the ''Turtle'' to affix explosives to the undersides of British warships in New York Harbor in 1776. All failed, and her transport ship was sunk later that year by the British with the submarine aboard. Bushnell claimed eventually to have recovered the machine, but its final fate is unknown. Modern functional replicas of the ''Turtle'' have been constructed; the Connecticut River Museum, the Submarine Force Library and Museum, and the Royal Navy Submarine Museum have them on display. == Development == In the early 1770s, David Bushnell, a Yale College freshman and Patriot, began experimenting with underwater explosives. By 1775, with tensions on the rise between the Thirteen Colonies and Great Britain, Bushnell had practically perfected these explosives.〔Diamant, p. 21〕 That year he also began work near Old Saybrook, Connecticut on a small manned submersible craft that would be capable of affixing such a charge to the hull of a ship. The charge would then be detonated by a clockwork mechanism that released a musket firing mechanism, probably a flintlock, that had been adapted for the purpose.〔 According to Dr. Benjamin Gale, a doctor who taught at Yale, the firing mechanism and other mechanical parts of the submarine were manufactured by a New Haven clockmaker named Isaac Doolittle.〔Diamant, p. 23〕 Named for its shape, ''Turtle'' resembled a large clam as much as a turtle; it was about long (according to the original specifications), tall, and about wide, and consisted of two wooden shells covered with tar and reinforced with steel bands.〔Schecter, p. 172〕 It dived by allowing water into a bilge tank at the bottom of the vessel and ascended by pushing water out through a hand pump. It was propelled vertically and horizontally by hand-cranked propellers. It also had of lead aboard, which could be released in a moment to increase buoyancy. Manned and operated by one person, the vessel contained enough air for about thirty minutes and had a speed in calm water of about three miles per hour (5 km/h).〔 Six small pieces of thick glass in the top of the submarine provided natural light.〔 The internal instruments had small pieces of bioluminescent foxfire affixed to the needles to indicate their position in the dark. During trials in November 1775, Bushnell discovered that this illumination failed when the temperature dropped too low. Although repeated requests were made to Benjamin Franklin for possible alternatives, none was forthcoming, and the ''Turtle'' was sidelined for the winter.〔Diamant, p. 27〕 Bushnell's basic design included some elements present in earlier experimental submersibles. The method of raising and lowering the vessel was similar to that developed by Nathaniel Simons in 1729, and the gaskets used to make watertight connections around the connections between the internal and external controls also may have come from Simons, who constructed a submersible based on a 17th-century Italian design by Giovanni Alfonso Borelli.〔Rindskopf et al, p. 29〕 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「Turtle (submersible)」の詳細全文を読む スポンサード リンク
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