Woodcut dated 1800 illustrating the new decimal units which became the legal norm across all France on 4 November 1800Table of the measuring units used in the 17th century at Pernes-les-Fontaines in the covered market at Provence-Alpes-Côte d'Azurregion of southeastern France
In the Ancien régime and until 1795, France used a system of measures that had many of the characteristics of the modern Imperial System of units but with no unified system. There was widespread abuse of the king's standards, to the extent that the lieue could vary from 3.268km in Beauce to 5.849km in Provence. During the revolutionary era and motivated in part by the inhomegeneity of the old system, France switched to the first version of the metric system. This system was not well received by the public, and between 1812 and 1837, the country used the mesures usuelles – traditional names were restored, but the corresponding quantities were based on metric units: for example, the livre (pound) became exactly 500g. After 1837, the metric system was reintroduced and progressively became the only system of use, with other units now in only residual use.
In the pre-revolutionary era (before 1795), France used a system of measures that had many of the characteristics of the modern Imperial System of units, but there was no unified system of measurement. Charlemagne and successive kings had tried but failed to impose a unified system of measurement in France.[1] (In England, by contrast, the Magna Carta decreed that "there shall be one unit of measure throughout the realm.")
The names and relationships of many units of measure were adopted from Roman units of measure and many more were added – it has been estimated that there were seven or eight hundred different names for the various units of measure. In addition, the quantity associated with each unit of measure differed from town to town and even from trade to trade to such an extent that the lieue (league) could vary from 3.268km in Beauce to 5.849km in Provence. It has been estimated that, on the eve of the Revolution, a quarter of a million different units of measure were in use in France.[2] Although certain standards, such as the pied du roi (the king's foot) had a degree of pre-eminence and were used by savants across Europe, many traders chose to use their own measuring devices, giving scope for fraud and hindering commerce and industry.[1]
As an example, the weights and measures used at Pernes-les-Fontaines in southeastern France differ from those catalogued later in this article as having been used in Paris. In many cases, the names are different, while the livre is shown as being 403g, as opposed to 489g – the value of the livre du roi. (The Imperial pound is about 453.6g.)[citation needed]
The French Revolution and subsequent Napoleonic Wars marked the end of the Age of Enlightenment. The forces of change that had been brewing manifest themselves across all of France, including the way in which units of measure should be defined. The savants of the day favoured the use of a system of units that were inter-related and which used a decimal basis.
There was also a wish that the units of measure should be for all people and for all time and therefore not dependent on an artefact owned by any one particular nation. Talleyrand, at the prompting of the savant Condorcet, approached the British and the Americans in the early 1790s with proposals of a joint effort to define the metre.[3] In the end, these approaches came to nothing and France decided to "go it alone".[4]
Decimal time was introduced in the decree of 5 October 1793 under which the day was divided into 10 "decimal hours", the "hour" into 100 " decimal minutes" and the "decimal minute" into 100 "decimal seconds". The "decimal hour" corresponded to 2hr24min, the "decimal minute" to 1.44min and the "decimal second" to 0.864s.
The implementation of decimal time proved an immense task and under the article 22 of the law of 18 Germinal, Year III (7 April 1795), the use of decimal time was no longer mandatory.[5] On 1 January 1806, France reverted to the traditional timekeeping.[6]
The Paris meridian, which passes through the Observatoire de Paris. The metre was defined along this meridian using a survey that stretched from Dunkirk to Barcelona.
The metric system of measure was first given a legal basis in 1795 by the French Revolutionary government. Article 5 of the law of 18 Germinal, Year III (7 April 1795) defined five units of measure. The units and their preliminary values were:[7]
The metre, for length – defined as being one ten millionth of the distance between the North Pole and the Equator through Paris
The gram, for mass – defined as being the mass of one cubic centimetre of water
Decimal multiples and submultiples of these units would be defined by Greek prefixes - "myria", "kilo", "hecta" (100), "deka" - and Latin prefixes - "deci", "centi" and "milli". Using Cassini's survey of 1744, a provisional value of 443.44 lignes was assigned to the metre which, in turn, defined the other units of measure.[8]
The final value of the metre had to wait until 1799, when Delambre and Mechain presented the results of their survey between Dunkirk and Barcelona that fixed the length of the metre at 443.296 lignes. The law 19 Frimaire An VIII (10 December 1799) defined the metre in terms of this value and the kilogram as being 18,827.15 grains. These definitions enabled the construction of reference copies of the kilogram and metre, which were to be used as standards for the next 90 years.
At the same time, a new decimal-based system for angular measurement was implemented. The right angle was divided into 100 grads, which in turn was divided in 100 centigrads. An arc on the earth’s surface formed by an angle of one centigrad was one kilometre.
The Mesures usuelles were introduced by Napoleon I in 1812
The metric system was introduced into France in 1795 on a district by district basis, starting with Paris. However, the introduction was by modern standards poorly managed. Although thousands of pamphlets were distributed, the Agency of Weights and Measures, which oversaw the introduction, underestimated the work involved. Paris alone needed 500,000 metre sticks, yet one month after the metre became the sole legal unit of measure, there were only 25,000 in store.[9] This, combined with other excesses of the Revolution made the metric system unpopular.
Napoleon ridiculed the metric system, but as an able administrator, he recognised the value of a sound basis for a uniform system of measurement. Under the décret impérial du 12 février 1812 (imperial decree of 12 February 1812), he introduced a revised system of measure – the mesures uselles or "customary measures" for use in small retail businesses. However, all government, legal and similar works still had to use the metric system and the metric system continued to be taught at all levels of education.[10] The names of many pre-metric units were reintroduced, but were redefined in terms of metric units. Thus the toise (fathom) was defined as being two metres with six pied (feet) making up one toise, twelve pouce (inches) making up one pied and twelve lignes making up one pouce. Likewise, the livre (pound) was defined as being 500g, each livre comprising sixteen once and each once eight gros and the aune as 120 centimetres.[11]
The metric system restored (1840–1875)
La loi du 4 juillet 1837 (the law of 4 July 1837) of the July Monarchy effectively revoked the use of mesures usuelles by reaffirming the laws of measurement of 1795 and 1799 to be used from 1 May 1840.[1] However, many units of measure, such as the livre, remained in colloquial use for many years and the livre still does to some extent.
When this legislation was introduced, the metric system was beginning to take hold across Europe. Switzerland and the German state of Baden had both defined their Fuß (foot) as being 300mm and the German state of Hessen-Darmstadt has defined its Fuß as being 250mm. Moreover, the Netherlands, Belgium, Greece, Lombardy and Venice had all adopted the metric system, albeit with local names for the "metre", "kilogram" and so on.[12] The metric system was given a boost when the German Zollverein (Customs Union) introduced the Zollpfund of 500g in 1850.
The Great Exhibition of 1851 in London was followed by international exhibitions in Paris in 1855 and 1867. The 1867 exhibition had a stand showing how the diverse units of measure were converging onto the metric system – a system that had been developed in France and whose standards were in the custody of the French government, but available for world use.[13]
In 1870, while France was preparing to host an international conference to discuss international cooperation in the sphere of units of measurement, the war broke out. France was humiliated by Prussia's military action, but in 1872 France seized the diplomatic initiative and re-issued the invitations for the 1870 conference. The conference met in 1875 and concluded with the signing of the Treaty of the Metre. The principal agreements under the treaty were:[14]
A three-tier organisation would be put into place to provide political (CGPM), scientific (CIPM) and secretarial (BIPM) support for coordinating calibrations of national standards against an international standard.
One of the eighteen seats on the CIPM would always be filled by a Frenchman.
France would provide premises for the secretariat. These premises, at the Pavillon de Breteuil, near Paris would have a diplomatic status.
New prototypes of the kilogram and metre would be manufactured. These were ultimately made in England and delivered in 1889.[15]
Thus the French metre and kilogram passed into international control.
International era (1875 onwards)
During the early part of the twentieth century, the French introduced their own units of power – the poncelet, which was defined as being the power required to raise a mass of 100kg against standard gravity with a velocity of 1m/s giving a value of 980.665W.[16][17] However, many other European countries defined their units of power (the Pferdestärke in Germany, the paardekracht in the Netherlands and the cavallo vapore in Italy) using 75kg rather than 100kg, which gave a value of 735.49875W (about 0.985HP). Eventually, the poncelet was replaced with the cheval vapeur, which was identical to equivalent units of measure in neighbouring countries. In 1977, these units, along with the stère and the livre (and amongst others, the German Pfund) were proscribed by EEC Directive 71/354/EEC[18] which required EU member states to standardise on the International System of Units (SI) and therefore to use the watt and its multiples.
The kilogram is the base unit of mass in the International System of Units (SI), the metric system, having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. It means 'one thousand grams'.
The litre or liter is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). A cubic decimetre occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre.
Metrication or metrification is the act or process of converting to the metric system of measurement. All over the world, nations have transitioned from their local and traditional units of measurement to the metric system. This process began in France during the 1790s, and continues more than two centuries later—with the modern SI system—as the metric system has not been fully adopted in all countries and sectors.
The Metre Convention, also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations. The treaty created the International Bureau of Weights and Measures (BIPM), an intergovernmental organization under the authority of the General Conference on Weights and Measures (CGPM) and the supervision of the International Committee for Weights and Measures (CIPM), that coordinates international metrology and the development of the metric system.
The pound or pound-mass is a unit of mass used in British imperial and United States customary systems of measurement. Various definitions have been used; the most common today is the international avoirdupois pound, which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces. The international standard symbol for the avoirdupois pound is lb; an alternative symbol is lbm, #, and ℔ or ″̶.
The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and based on the metre as the unit of length and either the kilogram as the unit of mass or the kilogram-force as the unit of force.</ref> and the world's most widely used system of measurement. Established and maintained by the General Conference on Weights and Measures (CGPM), it is the only system of measurement with an official status in nearly every country in the world, employed in science, technology, industry, and everyday commerce.
The metric system is a system of measurement that succeeded the decimalised system based on the metre that had been introduced in France in the 1790s. The historical development of these systems culminated in the definition of the International System of Units (SI) in the mid-20th century, under the oversight of an international standards body. Adopting the metric system is known as metrication.
Metrology is the scientific study of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th General Conference on Weights and Measures (CGPM) in 1960.
The gram is a unit of mass in the metric system.
The quintal or centner is a historical unit of mass in many countries which is usually defined as 100 base units, such as pounds or kilograms. It is a traditional unit of weight in France, Portugal, and Spain and their former colonies. It is commonly used for grain prices in wholesale markets in Ethiopia and India, where 1 quintal = 100 kg or 105g.
Myria- (symbol my) is a now obsolete decimal metric prefix denoting a factor of 104 (ten thousand). It originates from the Greek μύριοι (mýrioi) (myriad). The prefix was part of the original metric system adopted by France in 1795, but was not adopted when the SI prefixes were internationally adopted by the 11th CGPM conference in 1960.
Mesures usuelles were a French system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements. The system was restricted to use in the retail industry and continued in use until 1840, when the laws of measurement from the 1795 and 1799 were reinstituted.
The "Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States" was a report submitted to the U.S. House of Representatives on July 13, 1790, by Secretary of State Thomas Jefferson.
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units or SI, the British imperial system, and the United States customary system.
The spread of metrication around the world in the last two centuries has been met with both support and opposition.
The grave, abbreviated gv, is the unit of mass used in the first metric system which was implemented in France in 1793. In 1795, the grave was renamed as the kilogram.
The hectare is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectares and one hectare contains about 2.47 acres.
Before the French Revolution, which started in 1789, French units of measurement that were founded on the Carolingian system, introduced by the first Holy Roman Emperor Charlemagne (AD 800–814), which in turn were based on contemporaneous Byzantine and ancient Roman measures. Charlemagne brought a consistent system of measures across the entire empire. However, after his death, the empire fragmented and many rulers introduced their own variants of the units of measure.
The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a century. Other measures with unity ratios were added, and the system went on to be adopted across the world.
The following outline is provided as an overview of and topical guide to the metric system – various loosely related systems of measurement that trace their origin to the decimal system of measurement introduced in France during the French Revolution.
↑ Adler. pp.349–357.{{cite book}}: Missing or empty |title= (help)
↑ Wolfgang Appell (2002). Amtliche Maßeinheiten in Europa 1842[Official units of measure in Europe 1842] (in German). ISBN3-7686-1036-5. Retrieved 2011-02-10Website based on Alte Meß und Währungssysteme aus dem deutschen Sprachgebiet{{cite book}}: CS1 maint: postscript (link)
↑ Thiery Thomasset, Universitié de Technology, Compiègne (December 2010). "Jean Victor Poncelet (1788-1867)"(PDF). Tout sur les unités de mesure (in French). Archived from the original(PDF) on 2016-03-03. Retrieved 2011-02-17.{{cite web}}: CS1 maint: multiple names: authors list (link)
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