METRIC SYSTEM, that system of weights and measures of which the metre is the fundamental unit (adapted from Gr. Orpov, measure). The theory of the system is that the metre is a part of a quadrant of the earth through Paris ; the litre or unit of volume is a cube of A. metre side; the gramme or unit of weight is (nominally) of the weight of a litre of water at 4° C.
The idea of adopting scientific measurements had been sug gested as early as the 17th century, particularly by the astronomer Jean Picard (1620-1682), who proposed to take as a unit the length of a pendulum beating one second at sea-level, at a lati tude of 45°. These suggestions took practical shape by a decree of the National Assembly in 1790 appointing a committee to consider the suitability of adopting either the length of the seconds pendulum, a fraction of the length of the equator or a fraction of the quadrant of the terrestrial meridian. The com mittee decided in favour of the latter and a commission was appointed to measure the arc of the meridian between Dunkirk and Montjuich, near Barcelona. Another commission was also appointed to draw up a system of weights and measures based on the length of the metre and to fix the nomenclature, which on the report of the commission was established in 1795 It was not until 1799 that the report on the length of the metre was made. This was followed by the law of the loth of December 1799 fixing definitely the value of the metre and of the kilogramme, or weight of a litre of water, and the new system became com pulsory in 1801. It was found necessary however to pass an act in 1837, forbidding as and from the 1st of January 1840, under severe penalties, the use of any other weights and measures than those established by the laws of 1795 and 1799. The metric
system is now obligatory in Argentina, Austria, Hungary, Bel gium, Brazil, Chile, France, Germany, Greece, Italy, Mexico, Netherlands, Norway, Peru, Portugal, Rumania, Yugoslavia, Spain, Sweden, Switzerland. Its use is legalized in Egypt, Britain, Japan, Russia, Turkey and the United States. In 1875 there was constituted at Paris the International Bureau of Weights and Measures, which is managed by an international committee. The object of the Bureau is to make and provide prototypes of the metre and kilogramme, for the various subscribing countries.
In England action has frequently been taken both by indi viduals and by associations of commercial men for the purpose of endeavouring to make the metric system compulsory. A Deci mal Association was formed in 1854, but did not make very much headway. A bill was introduced into parliament in 1864 to make the metric system compulsory for certain purposes, but owing to government objections a permissive bill was substituted and subsequently became law as the Metric Act 1864. It was, how ever, repealed by the Weights and Measures Act 1878. In 1871 another bill was rejected in the Commons by five votes. In 1893 a representative delegation of business men pressed its adoption on the chancellor of the exchequer (Sir W. V. Har court), but he declined. But in 1897 a statute was passed, the Weights and Measures (Metric System) Act, which legalized the use in trade of the metric system, and abolished the penalty for having in one's posscssion a weight or measure of that system. (See also DECIMAL COINAGE and MEASURES AND WEIGHTS.)