The metric weights and measures were all based on the unit of length. The liter, the unit of capacity, is almost exactly equivalent to a cubic measure 10 centimeters on each edge or 1,000 cubic centimeters (cm' or cc). As greater accuracy could be obtained by basing the unit of capacity upon the unit of mass, the definition was written as follows: *A liter is a unit of capacity equivalent to, the volume occupied by the mass of one kilogram of pure water at its maximum density at a temperature of 4° C. F.) and under the standard atmospheric pressure of 760 rnm.)) One milliliter, equiva lent to 1.000027 cubic centimeters of water, weighs one gram. Technically, however, the gram is one thousandth of the kilogram, .which is the standard for mass or weight.
The equivalents given in this article are based upon the following fundamental equivalents: 39.370000 United States inches = 1 meter 39.370113 British inches =1 meter 0.2641776 United States gallon = 1 liter 0.2199753 British Imperial gallon = 1 liter 1 United States avoirdupois pound= 0.4535924277 kilogram 1 British avoirdupois pound = 0.4535924300 kilogram
A quantity can usually be expressed as a whole number if the proper metric weight or measure is selected. Even when a fraction is needed to express the metric equivalent of another weight or measure, one or two figures to the right of the decimal point generally give sufficient accuracy. Equivalents such as those in the tables here given are intended to be used only to the required degree of accuracy. For example, four inches is equal to about 10 centi meters; if greater accuracy is desired 102 centi meters or 102 millimeters may be taken.
Bibliography.—Adams, J. Q., upon Weights and Measures presented to the United States Senate on 21 Feb. 1822' (Washington, D. C., 1E22) ; American Metric Association, 'Metric Weights and Measures' (New York) ; Bigourdan, (Le systeme Metrique' ; Guillaume, (La Convention du Metre' and et ; Hallock and Wade, of Weights and Measures and the Metric System' ; Mechain and Delambre, 'Base du systeme Metrique) ; Morin, (Notice historique sur le systeme Metrique.)