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The second voyage of HMS ''Beagle'', from 27 December 1831 to 2 October 1836, was the second survey expedition of HMS ''Beagle'', under captain Robert FitzRoy who had taken over command of the ship on its first voyage after the previous captain committed suicide. FitzRoy had already thought of the advantages of having an expert in geology on board, and sought a gentleman naturalist as a supernumerary who could be his companion while the ship was at sea. The young graduate Charles Darwin had hoped to see the tropics before becoming a parson, and accepted the opportunity. By the end of the expedition he had already made his name as a geologist and fossil collector, and the publication of his journal which became known as ''The Voyage of the Beagle'' gave him wide renown as a writer. The ''Beagle'' sailed across the Atlantic Ocean, and then carried out detailed hydrographic surveys around the coasts of the southern part of South America, returning via Tahiti and Australia after having circumnavigated the Earth. While the expedition was originally planned to last two years, it lasted almost five. Darwin spent most of this time exploring on land: three years and three months on land, 18 months at sea. Early in the voyage he decided that he could write a book about geology, and he showed a gift for theorising. At Punta Alta he made a major find of gigantic fossils of extinct mammals, then known from only a very few specimens. He ably collected and made detailed observations of plants and animals, with results that shook his belief that species were fixed and provided the basis for ideas which came to him when back in England, and led to his theory of evolution by natural selection. ==Aims of the expedition== The main purpose of the expedition was to conduct a hydrographic survey of the coasts of the southern part of South America as a continuation and correction of the work of previous surveys, to produce nautical charts showing navigational and sea depth information for the navy and for commerce. An Admiralty memorandum set out the detailed instructions. The first requirement was to resolve disagreements in the earlier surveys about the longitude of Rio de Janeiro, which was essential as the base point for meridian distances. The accurate marine chronometers needed to determine longitude had only become affordable since 1800; the ''Beagle'' carried 22 chronometers to allow corrections. The ship was to stop at specified points for four-day rating of the chronometers and to check them by astronomical observations: it was essential to take observations at Porto Praya and Fernando de Noronha to calibrate against the previous surveys of Owen and Foster. It was important to survey the extent of the Abrolhos Archipelago reefs, shown incorrectly in Roussin's survey, then proceed to Rio de Janeiro to decide the exact longitude of Villegagnon Island. The "real work of the survey" was then to commence south of the Río de la Plata, with return trips to Montevideo for supplies; details were given of priorities, including surveying Tierra del Fuego and approaches to harbours on the Falkland Islands. The west coast was then to be surveyed as far north as time and resources permitted. The commander would then determine his own route west: season permitting, he could survey the Galápagos Islands. Then the ''Beagle'' was to proceed to Point Venus,Tahiti and on to Port Jackson, Australia which were known points to verify the chronometers. No time was to be wasted on elaborate drawings; charts and plans should have notes and simple views of the land as seen from the sea showing measured heights of hills. Continued records of tides and meteorological conditions were also required. An additional suggestion was for a geological survey of a circular coral atoll in the Pacific Ocean including its profile and of tidal flows, to investigate the formation of such coral reefs. 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「Second voyage of HMS Beagle」の詳細全文を読む スポンサード リンク
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