1215: The Magna Carta declares that there should be national standards for the measurement of wine, beer, and cloth.1678: Anglican clergyman and philosopher John Wilkins publishes An Essay towards a Real Character, and a Philosophical Language, which proposes a universal language and system of measurement, based on units of 10.
1790: The National Assembly of France drafts a committee to establish a new standard for weights and measures that would be valid “for all people, for all time,” in the words of mathematician (and revolutionary) Marquis de Condorcet.
1799: The distance of the meter—named after metron, the Greek word for measure—is fixed at 1/10,000,000 of the length between the North Pole and the Equator, arrived at after two French surveyors spent six years measuring the distance between Dunkirk and Barcelona, which was used to calculate the longer distance. A platinum bar officially one meter long is cast.
1840: The metric system becomes compulsory in France.
1875: Seventeen nations (including the US) sign the Treaty of the Meter, creating international bodies to standardize weights and measurements worldwide, according to the metric system.
1975: US president Gerald Ford signs the Metric Conversion Act, declaring the metric system the preferred (but voluntary) system and establishing the US Metric Board, to speed America’s conversion.
1982: US president Ronald Reagan dismantles the Metric Board.
1999: Mars Climate Orbiter, a $328 million satellite, disintegrates over Mars because software produced by Lockheed Martin, the contractor, generated numbers in the English system instead of the metric system, as specified by its agreement with NASA.