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How the Metric System Works

        Science | Devices

History of the Metric System: Meeting About Meters
Good, old Napoleon, the general famed for spreading war and the metric system wherever his little feet marched.
Good, old Napoleon, the general famed for spreading war and the metric system wherever his little feet marched.
Hulton Archive/Getty Images

Thanks to Napoleon's conquest of Europe throughout the early 19th century, other countries adopted -- some more grudgingly than others -- the metric system as their national system of measurement.

In 1875, a special assembly in Paris brought together representatives from 17 nations, including the U.S. These nations were busy during the assembly, signing the Treaty of the Meter and setting up the International Bureau of Weights and Measures, an International Committee for Weights and Measures to run the bureau and the General Conference on Weights and Measures to consider and adopt changes. The treaty also directed that a lab be maintained in Sèvres, by Paris, to house international metric standards and allowed for these standards to be distributed to each ratifying nation. The U.S. received its copies of the International Prototype Metre and the International Prototype Kilogram in 1890.

In 1954, the 10th General Conference on Weights and Measures initiated a redesign of the metric system to better accommodate the needs of the scientific and technical communities. The revision established seven base units and simplified metric unit definitions, symbols and terminology. The work extended into the 11th Conference, and in 1960, conference members ratified and approved the new system, calling it the International System of Units, or SI for short.

The International System of Units is the modern form of the metric system, and although the two names are used interchangeably, SI is more accurate technically. Up next, we'll look at the building blocks of SI -- the seven base units.


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