|
United States customary units are a system of measurements commonly used in the United States. The U.S. customary system developed from English units which were in use in the British Empire before American independence. However, the British system of measures was overhauled in 1824 to create the Imperial system, changing the definitions of some units. Therefore, while many U.S. units are essentially similar to their Imperial counterparts, there are significant differences between the systems. The majority of U.S. customary units were redefined in terms of the meter and the kilogram with the Mendenhall Order of 1893 and, in practice, for many years before.〔T.C. Mendenhall, Superintendent of Standard Weights and Measures, (Order of April 5, 1893 ), published as Appendix 6 to the Report for 1893 of the Coast and Geodetic Survey.〕 These definitions were refined by the international yard and pound agreement of 1959.〔Astin, A.V., Karo, H.A. and Mueller, F.H. (June 25, 1959). Doc 59-5442, "(Refinement of Values for the Yard and the Pound )." ''Federal Register''. When reading the document note that 999,998 = 3937 × 254.〕 Americans primarily use customary units in commercial activities, as well as for personal and social use. In science, medicine, many sectors of industry and some of government, metric units are used. The International System of Units (SI), the modern form of the metric system, is preferred for many uses by the U.S. National Institute of Standards and Technology (NIST).〔(Laws and Metric Program ). U.S. National Institute of Standards and Technology, 2010〕 ==History== The United States system of units is similar to the British imperial system.〔"English units of measurement". ''The Columbia Encyclopedia'' 6th ed. 2001-2007. (archived copy ).〕 Both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in Roman and Anglo-Saxon units. The customary system was championed by the U.S.-based International Institute for Preserving and Perfecting Weights and Measures in the late 19th century. Advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. An auxiliary of the Institute in Ohio published a poem with wording such as "down with every 'metric' scheme" and "A perfect inch, a perfect pint".〔(Martin Gardner, The Great Pyramid (1957) )〕 One adherent of the customary system called it "a just weight and a just measure, which alone are acceptable to the Lord."〔 The U.S. government passed Omnibus Trade and Competitiveness Act of 1988, which made the metric system "the preferred system of weights and measures for U.S. trade and commerce." The legislation states that the federal government has a responsibility to assist industry as it ''voluntarily'' converts to the metric system, i.e., metrification. This is most evident in U.S. labeling requirements on food products, where SI units are almost always presented alongside customary units. According to the CIA Factbook, the United States is one of three nations (the others being Liberia and Burma) that have not adopted the metric system as their official system of weights and measures. U.S. customary units are widely used on consumer products and in industrial manufacturing. Metric units are standard in science, medicine, as well as many sectors of industry and government, including the military.〔 There are anecdotal objections to the use of metric units in carpentry and the building trades, on the basis that it is easier to remember an integer number of inches plus a fraction than a measurement in millimeters,〔Robyn Williams (February 8, 1998) ("Trouble with the Metric System" ). Australian ''Radio National'', Ockham's Razor.〕 or that foot-inch measurements are more suitable when distances are frequently divided into halves, thirds and quarters, often in parallel. The metric system also lacks a parallel to the foot.〔Ed Tenner, (May 2005). ("The Trouble with the Meter" ) Technologyreview.com〕 Other nations had, or still have unofficially, customary units of their own, sometimes very similar in name and measure to U.S. customary units, since they often share the same Germanic or Roman origins. Frequently, however, these units designate quite different sizes. For example, the mile ranged by country from one-half to five U.S. miles; foot and pound also had varying definitions. Historically, a wide range of non-SI units were used in the U.S. and in Britain, but many have fallen into disuse. This article deals only with the units commonly used or officially defined in the U.S. 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「United States customary units」の詳細全文を読む スポンサード リンク
|