Metrication

Metrication, or metrification, is the process of converting from the various other systems of units used throughout the world to the metric or SI (Système International) system. This process was begun in France in the 1790's and spread over the following two centuries to all but four countries, representing 95% of the world's population. The process was completed in most of the world in the 19th and early 20th centuries, replacing numerous historical weights and measures. The countries of the former British Empire completed metrification during the second half of the 20th century, with Ireland recently completing metrication on 20th January 2005. Today only the UK, U.S., Liberia and Burma (Myanmar) have not fully metricated, although Liberia and Myanmar use it in practice and the UK is currently in the process of conversion. Only France, the US, UK and Japan saw any large scale popular opposition to metrication, the main objections being based on tradition, aesthetics and distaste for a 'foreign' system.

Système International

:See main article: International System of Units

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Scientists, chiefly in France, had been advocating and discussing a decimal system of measurement based on natural units at least since 1640, but the first official adoption of such a system was after the French Revolution of 1789. The metric system tried to choose units which were non-arbitrary and practical, merging well with the revolution's official ideology of "pure reason". The original system started with a unit of length, the metre, the gram for weight and a unit of time, the second. Derived units are made from logical combinations of base units. For example, the speed of an object is defined by the number of metres it moves every second — m·s−1. An object that is accelerating has a changing speed, so its m·s−1 changes per second, thus the unit is m·s−2. The force of a moving object can be described by its weight times its acceleration, thus — kg·m·s−2 — which can be abbreviated as N in honour of Isaac Newton. Further base units dealing with electricity, light and quantities of atoms were added later as these sciences became better understood.

Related Topics:
1640 - French Revolution - 1789 - Force

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The current version of this system was agreed in 1971 and is organised and maintained by the International Bureau of Weights and Measures. To avoid confusion over the precise value of base units, this organisation also maintains either an international prototype (in the case of a kilogram, a small object of platinum-iridium dubbed "Le Grand Kilo") or a precise recipe on how to recreate the unit, which is decided at regular conferences.

Related Topics:
International Bureau of Weights and Measures - Kilogram - Conferences

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Time has resisted metrication. During the French revolution there was an attempt at a decimal time system with 100 seconds in a minute, 100 minutes in an hour and 10 hours in a day (100,000 seconds in a day as opposed to 86,400 currently — a metric second would be thus 14% shorter). The proposed system also included a ten-day week, which was probably its main reason for failure. The church and the people objected and the system was dropped. It is also interesting to note that China had an almost identical decimal time system up until the 17th century http://www.decimaltime.hynes.net/history.html.

Related Topics:
Time - Metrication

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