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English units of measurement
Customary Units of Weights and Measures
Units of Weight
Units of Length and Area
Units of Liquid Measure
Units of Dry Measure
Differences between American and British Systems
Many American units of weights and measures are based on units in use in Great Britain before 1824, when the British Imperial System was established. Since the Mendenhall Order of 1893, the U.S. yard and pound and all other units derived from them have been defined in terms of the metric units of length and mass, the meter and the kilogram; thus, there was no longer any direct relationship between American units and British units of the same name. In 1959 an international agreement was reached among English-speaking nations to use the same metric equivalents for the yard and pound for purposes of science and technology; these values are 1 yd=0.9144 meter (m) and 1 lb=0.45359237 kilogram (kg). In the United States, the older definition of the yard as 3,600/3,937 m has continued to be used in many instances for surveying, the corresponding foot (1,200/3,937 m) being known as the survey foot; the survey foot will become obsolete in 2023.
The English units of measurement have many drawbacks: the complexity of converting from one unit to another, the differences between American and British units, the use of the same name for different units (e.g., ounce for both weight and liquid capacity, quart and pint for both liquid and dry capacity), and the existence of three different systems of weights (avoirdupois, troy, and apothecaries'). Because of these disadvantages and because of the wide use of the much simpler metric system in most other parts of the world, there have been proposals to do away with the U.S. Customary System and replace it with the metric system.
See L. J. Chisholm, Units of Weights and Measure: International and U.S. Customary (U.S. National Bureau of Standards, 1967).
a measure of length used in the national nonmetric systems of units; now used mainly in navigation.
The USSR and most other countries use the nautical mile, which, according to the International Hydrographic Conference of 1929, is equal to 1.852 km, or the average length of 1’ of the arc of a meridian. One nautical mile is equal to 10 cable lengths.
In Great Britain 1 nautical mile equals 1.853184 km, and 1 statute land mile equals 1.609344 km (it is also used in the USA). A geographic mile (German) is equal to 1/15° of the equator, or 7.4204 km. The old Russian mile was equal to 7.46760 km; the old Roman mile, to 1.481 km.