Metric system

A metric unit system, short metric system is a system of units with the meter as the basic unit for the length of a line. Unlike many other systems of units unwieldy large or small details are strictly specified as decimal multiples and decimal fractions in the metric system of units. The purpose of a system of intentions for units

Important examples of metrical unit systems are the SI and the cgs and mks system. The first metric unit system was introduced in 1793 in France during the French Revolution.

Need

The international standardization of the unit system prevents misunderstandings in dealing with quantities and units, making size values ​​immediately exactly comparable. Significantly, this is both for science and technology as well as for industry and trade.

Both the international and the domestic scientific and economic exchange is a unified and self-contained, so consistent system of units of great use, for example, in order to avoid error-prone conversions and misunderstandings by ambiguous information. Thus existed on the territory of the later German Empire until 1870, about 300 different surface dimensions. Units of the same name were or are different. For example, the German horsepower ( hp) is not equal to the British horsepower (HP), and for a mile existed for centuries different definitions in different applications and regions. For the temperature measurement, various scales have been used.

History

In China and parts of India, there was Dezimalmaßsysteme since ancient times. Proposals to create a purely decimal system of measurement, there was in modern Europe since about the end of the 16th century. But one preferred by the end of the 18th century, the highly composite numbers on oriented toward the old systems of measurement. But they were either internationally or value systems. However, the modern economy and administration had both appear to increase efficiency than desirable. Therefore, it resulted in revolutionary France under the reign of terror the civil dezimalmetrische system on 1 August 1793 National Convention a.

In the 19th century only preparations were, for example, in the Confederation of the Rhine made ​​to introduce the French decimal system. Dezimalisierung about by the respective local or introduction of a round, eg, 30 - cm - Fußmaßes Only towards the end of the 19th century, the dezimalmetrische system gradually became established and internationally. So the Metre Convention was signed in Paris on 20 May 1875, a diplomatic treaty among the 17 leading industrial nations agreed therein to uniform standards for the major variables. Without this measure, the further development of the industrialized world might have been impossible, because different national units have international trade and scientific and technical exchanges enormously difficult. The Metre Convention is still valid and is based on the International System of Units (SI). With the maintenance of the conditions laid down in the Metre Convention standards, the international organization " Bureau International des Poids et Mesures ' ( BIPM) was commissioned.

In the UK in 1874 was to "Mega" set the coherent CGS system with three base units, derived units and prefixes "micro". Since the previous units had proved to be too complicated, 1880 " practical sessions " were for the areas of electricity and magnetism additionally introduced, including Ohms, Volts and Amperes.

On the first " Conférence Générale des Poids et Mesures " ( CGPM ) in 1889 meters, kilograms and seconds were defined as an international base units ( MKS system ). The new prototypes for the meter and the kilogram were approved and distributed to the Member States. Here, the so-called International prototype meter replaced the standard meter in 1799. The International Prototype Kilogram (also international prototype kilogram ) is still valid. Both are kept in a vault of the BIPM in Sèvres, near Paris.

The International Electrical Congress introduced in 1893 in Chicago called "international" units for voltage and resistance. The International Conference in London in 1908 confirmed the " international " units volts and ohms.

1946 amperes finally was added ( MKSA system) as a further base unit, and 1954 followed Kelvin and candela. 1971 was decided as the time being last base unit, the mole. The following table shows examples of definitions by which today's SI base units have been established in the past:

Introduction of the metric system

• 1800 ( France)
• 1820
• 1840
• 1860

• 1880
• 1900
• 1920
• 1940

• 1960
• 1980
• No data
• Not yet been introduced

The introduction of the metric system began in France. 1799 meters in Paris was introduced by law. The launch was at times even reversed. However, the radical change of times and calendar to a decimal system not sat through ( inter alia, an week should consist of ten days ).

In the 19th century the metric system was introduced in most European countries: in parts of Germany during the French occupation before 1815 ( for example, the Palatinate, where it remained even after the defeat of Napoleon exist ), in the Netherlands, Belgium and Luxembourg in 1820, in Spain legalized in the 1850s, in Italy in 1861, Germany in 1872 (Act of August 17, 1868 for the North German Confederation, April 29, 1869, the southern German states ), in Austria 1876 ( binding laws publication 1871), in Switzerland in 1877 ( 1868 declared binding by the federal law of 1875, although cantonal introduced some of them already in the Napoleonic era ) and finally in 1907 in Denmark. The last European country is the United Kingdom during the changeover, in Ireland it was completed on 20 January 2005 with the conversion of road signs. In the English-speaking world, the introduction is called " Metrication " or " metrification ".

Today, the metric system is used in almost all countries. Only the United States and Myanmar and Liberia have not yet binding inserted, but it is used in the practice of the latter two. Myanmar decided to transition to the metric system in 2013. In the U.S., metric units are for a parliamentary decision in 1866, a government decree in 1894 recognized units. On December 23, 1975, though the U.S. Congress, approved by the Metric Conversion Act signed in the United States by President Gerald Ford, but is widely held in the traditional system.

Resistance to the introduction, mostly from traditional or aesthetic reasons were, or are there essentially only in the United States, the United Kingdom, Canada (not Quebec ) and Japan. Relics of old systems are found in many countries, partly in the form umdefinierter ( " metrifizierter " ) units (eg, pounds to 500 g ) and partly by the influence of the U.S. economy (customs, eg screen size information ). This approach is indeed common, but contrary to the law. Therefore, Federal agencies usually require the use of the metric system in contract awards (for example, by tender technical documents must be submitted ).