weights and measures, units and standards for expressing the amount of some quantity, such as length, capacity, or weight; the science of measurement measurement, determination of the magnitude of a quantity by comparison with a standard for that quantity. Quantities frequently measured include time, length, area, volume, pressure, mass, force, and energy.
..... Click the link for more information. standards and methods is known as metrology.

Crude systems of weights and measures probably date from prehistoric times. Early units were commonly based on body measurements and on plant seeds or other objects from agriculture. As civilization progressed, technological and commercial requirements led to increased standardization. For example, because the length of the human foot or the width of the palm varies from individual to individual, it probably became necessary first to specify a particular individual (e.g., the king) and later to reproduce standards based on this commonly accepted unit of length. Units were usually fixed by edict of local or national rulers and were subdivided and multiplied or otherwise arranged into systems of measurement.

Standards varied greatly in different localities, although conquest and trade stimulated some correspondence between systems, e.g., between the systems of Egypt, Babylon, and Phoenicia. A high degree of standardization was achieved in the Roman Empire, but after its fall considerable diversity returned. The foot, which was one of the earliest units, is believed to have had as many as 280 variants in Europe as late as the 18th cent. Today the chief systems are the English units of measurement English units of measurement, principal system of weights and measures used in a few nations, the only major industrial one being the United States. It actually consists of two related systems—the U.S.
..... Click the link for more information. and the metric system metric system, system of weights and measures planned in France and adopted there in 1799; it has since been adopted by most of the technologically developed countries of the world.
..... Click the link for more information. .

The United States is one of the few countries still using the English system; all other major nations have either converted to the metric system or committed themselves to conversion. The English system is much older and less practical than the metric system, and in the United States there has been considerable discussion in favor of adopting the metric system as the principal system. However, attempts to legislate such a change in the U.S. Congress have failed. The basic units of the English system, the yard yard, abbr. yd, basic unit of length in the customary system of English units of measurement ; all other units in the English system, such as the inch, foot, rod, and mile, are derived from it.
..... Click the link for more information. of length and the pound of mass, are now defined in terms of the metric standards, the meter meter, abbr. m, fundamental unit of length in the metric system . The meter was originally defined as 1/10,000,000 of the distance between the equator and either pole; however, the original survey was inaccurate and the meter was later defined simply as the distance
..... Click the link for more information. of length and the kilogram kilogram, abbr. kg, fundamental unit of mass in the metric system , defined as the mass of the International Prototype Kilogram, a platinum-iridium cylinder kept at Sèvres, France, near Paris.
..... Click the link for more information. of mass.

Before 1960 the meter was defined as the distance between two scratches on a prototype bar kept at the International Bureau of Weights and Measures (est. 1875) at Sèvres, France, near Paris. In 1960 it was redefined in terms of an atomic standard. This new standard is more stable than the old meter bar, is indestructible, and is easily reproduced, eliminating the need for periodic comparison with a single standard. The kilogram is defined in terms of a prototype cylinder kept at the bureau.

In the United States, Congress has the constitutional right to fix standards, but except for purposes of customs and internal revenue, weights and measures legislation has been, for the most part, permissive. Sets of official weights and measures were sent to the states in 1856, but legislation and enforcement are largely state prerogatives. The federal government permitted the use of the metric system in 1866 and established a conversion table based on the yard and the pound; in 1893 the yard and the pound were redefined in terms of the metric prototypes of the meter and the kilogram. The major arguments against total conversion to the metric system in the United States are that it would involve great expense in industry and would cause widespread confusion among the general public.

See the table entitled Common Weights and Measures Common Weights and Measures

Length
Metric System
1 millimeter = 1/1,000 meter
1 centimeter = 1/100 meter
1 decimeter = 1/10 meter
1 meter (basic unit of length)
1 dekameter = 10 meters
1 kilometer = 1,000 meters
..... Click the link for more information. .

Bibliography

See M. Blocksma, Reading the Numbers (1989).

weights and measures

Standard quantities by which comparisons are made between an object to be measured and a known quantity of the same kind (see measurement). Weights and measures are fundamental to the sciences, to engineering, building, and other technical matters, and to much everyday activity. See also foot; gram; International System of Units; metre; metric system; pound.