The metric system had its start in France. During the turbulent days of the French Revolution, the National Assembly directed the Paris Academy of Sciences to Develop an invariable standard for all weights and measures to replace the diverse units then employed throughout the land. For that matter, the many nations had varying weights and measures, all hampering scientific and other communication. The Academy devised a relatively simple and consistent system. In it the meter, a fraction of earth's circumference, was the unit of length. Other elements of the system were based on it. For example, the gram was equal to the mass of a cubic centi-meter of water at its temperature of greatest density.
Necessary studies, surveys and measurements spread over several years. Not until 1799 were metric standards legally adopted in France. Actually, old weights and measures continued in use throughout the country for years. By legislation enacted on July 4, 1837, the use of non metric units was forbidden after January 1, 1840. In time, other nations began using the metric system, until finally the majority had adopted it. Through the years there have been refinements, and in 1960 the General Conference of Weights and Measures resolved minor differences in the use of metric measurements by various countries. From this emerged the International Metric System.