|
The metre, American spelling meter, (from the Greek noun μέτρον, "measure") is the base unit of length in the International System of Units (SI). The SI unit symbol is m.〔 〕 The metre is defined as the distance travelled by light in a specific fraction – about one three-hundred millionth – of a second.〔(【引用サイトリンク】title=17th General Conference on Weights and Measures (1983), Resolution 1. )〕 The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. In 1889, it was redefined in terms of a prototype metre bar (the actual bar used was subsequently changed twice). In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. In 1983, the current definition was adopted. In 1959, the imperial inch was re-defined as 0.0254 metres (2.54 centimetres or 25.4 millimetres). One metre is about inches longer than a yard, i.e. about inches. == Spelling == ''Metre'' is the standard spelling of the metric unit for length in all English-speaking nations except the USA, which uses ''meter''.〔The most recent official brochure about the International System of Units (SI), written in French by the ''フランス語:Bureau international des poids et mesures'', International Bureau of Weights and Measures (BIPM) uses the spelling ''metre''; an English translation, included to make the SI standard "more widely accessible" also uses the spelling ''metre''.(BIPM, 2006, p. 130''ff'') However, in 2008 the U.S. English translation published by the U.S. National Institute of Standards and Technology (NIST) chose to use the spelling ''meter'' in accordance with the United States Government Printing Office Style Manual. The Metric Conversion Act of 1975 gives the Secretary of Commerce of the US the responsibility of interpreting or modifying the SI for use in the US. The Secretary of Commerce delegated this authority to the Director of the National Institute of Standards and Technology (Turner). In 2008, NIST published the US version (Taylor and Thompson, 2008a) of the English text of the eighth edition of the BIPM publication ''フランス語:Le Système international d'unités (SI)'' (BIPM, 2006). In the NIST publication, the spellings "meter", "liter" and "deka" are used rather than "metre", "litre" and "deca" as in the original BIPM English text (Taylor and Thompson (2008a), p. iii). The Director of the NIST officially recognised this publication, together with Taylor and Thompson (2008b), as the "legal interpretation" of the SI for the United States (Turner). Thus, the spelling ''metre'' is referred to as the "international spelling"; the spelling ''meter'', as the "American spelling".〕 Measuring devices (such as ammeter, speedometer) are spelled "-meter" in all countries.〔 , s.v. ammeter, meter, parking meter, speedometer.〕 The word "meter", signifying any such device, has the same derivation as the word "metre", denoting the unit of length.〔 , s.v. meter.〕 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「Metre」の詳細全文を読む スポンサード リンク
|