French units of measurement
Encyclopedia
France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 has a unique history of units of measurement
Units of measurement
A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention and/or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of...

 due to radical attempts to adopt a metric system
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

 following the French Revolution
French Revolution
The French Revolution , sometimes distinguished as the 'Great French Revolution' , was a period of radical social and political upheaval in France and Europe. The absolute monarchy that had ruled France for centuries collapsed in three years...

.

In the Ancien régime, before 1795, France used a system of measures that had many of the characteristics of the modern Imperial System of units. There was widespread abuse of the king's standards to the extent that the lieue could vary from 3.268 km in Beauce
Beauce
Beauce is a natural region in northern France, located between the Seine and Loire rivers. It now comprises the Eure-et-Loir département and parts of Loiret, Essonne and Loir-et-Cher. The region shared the history of the province of Orléanais and the county of Chartres, which is its only major...

 to 5.849 km in Provence
Provence
Provence ; Provençal: Provença in classical norm or Prouvènço in Mistralian norm) is a region of south eastern France on the Mediterranean adjacent to Italy. It is part of the administrative région of Provence-Alpes-Côte d'Azur...

. In the revolutionary era, France used the first version of the metric system. This system was not well received by the public. Between 1812 and 1837, the mesures usuelles
Mesures usuelles
Mesures usuelles were a system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements...

was used – traditional names were restored, but were based on metric units: for example, the livre became 500 g. After 1837 the metric system was reintroduced and has remained the principal system of use to this day.

Ancien régime (to 1795)

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. (In England, by contrast, the Magna Carta
Magna Carta
Magna Carta is an English charter, originally issued in the year 1215 and reissued later in the 13th century in modified versions, which included the most direct challenges to the monarch's authority to date. The charter first passed into law in 1225...

 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 3.268 km in Beauce
Beauce
Beauce is a natural region in northern France, located between the Seine and Loire rivers. It now comprises the Eure-et-Loir département and parts of Loiret, Essonne and Loir-et-Cher. The region shared the history of the province of Orléanais and the county of Chartres, which is its only major...

 to 5.849 km in Provence
Provence
Provence ; Provençal: Provença in classical norm or Prouvènço in Mistralian norm) is a region of south eastern France on the Mediterranean adjacent to Italy. It is part of the administrative région of Provence-Alpes-Côte d'Azur...

. 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. 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.

As an example, the weights and measures used at Pernes-les-Fontaines
Pernes-les-Fontaines
Pernes-les-Fontaines is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France.-References:*...

 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 403 g, as opposed to 489 g – the value of the livre du roi. (The Imperial pound is about 453.6 g.)

Revolutionary France (1795–1812)

The French Revolution
French Revolution
The French Revolution , sometimes distinguished as the 'Great French Revolution' , was a period of radical social and political upheaval in France and Europe. The absolute monarchy that had ruled France for centuries collapsed in three years...

 and subsequent Napoleonic Wars
Napoleonic Wars
The Napoleonic Wars were a series of wars declared against Napoleon's French Empire by opposing coalitions that ran from 1803 to 1815. As a continuation of the wars sparked by the French Revolution of 1789, they revolutionised European armies and played out on an unprecedented scale, mainly due to...

 marked the end of the Age of Enlightenment
Age of Enlightenment
The Age of Enlightenment was an elite cultural movement of intellectuals in 18th century Europe that sought to mobilize the power of reason in order to reform society and advance knowledge. It promoted intellectual interchange and opposed intolerance and abuses in church and state...

. 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. Tallyrand, 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. In the end these approaches came to nothing and France decided to "go it alone".

Decimal time
Decimal time
Decimal time is the representation of the time of day using units which are decimally related. This term is often used to refer specifically to French Revolutionary Time, which divides the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal...

 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 2 hr 24 min, the "decimal minute" to 1.44 min and the "decimal second" to 0.864 s.

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. On 1 January 1806, France reverted to the traditional timekeeping.
The metric system of measure was first given a legal basis in 1795 by the French Revolution
French Revolution
The French Revolution , sometimes distinguished as the 'Great French Revolution' , was a period of radical social and political upheaval in France and Europe. The absolute monarchy that had ruled France for centuries collapsed in three years...

ary 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:
  • The metre
    Metre
    The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...

    , for length – defined as being one ten millionth of the distance between the North Pole
    North Pole
    The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...

     and the Equator
    Equator
    An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

     through Paris
    Paris
    Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

  • The are
    Hectare
    The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

     (100 m2) for area [of land]
  • The stère
    Stère
    The stere or stère is a unit of volume in the original metric system equal to one cubic metre. The name was coined from the Greek στερεός stereos 'solid' in 1793 France as a metric equivalent to the cord. The stère is typically used for measuring large quantities of firewood or other cut wood,...

     (1 m3) for volume of firewood
  • The litre
    Litre
    pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

     (1 dm3) for volumes of liquid
  • The gram
    Gram
    The gram is a metric system unit of mass....

    , 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
SI prefix
The International System of Units specifies a set of unit prefixes known as SI prefixes or metric prefixes. An SI prefix is a name that precedes a basic unit of measure to indicate a decadic multiple or fraction of the unit. Each prefix has a unique symbol that is prepended to the unit symbol...

 - "myria", "kilo", "hecta" (100), "deka", "deci", "centi" and "milli". Using Cassini's
César-François Cassini de Thury
César-François Cassini de Thury , also called Cassini III or Cassini de Thury, was a French astronomer and cartographer.- Biography :...

 survey of 1744, a provisional value of 443.44 lignes was assigned to the metre which, in turn, defined the other units of measure.

The final value of the metre had to wait until 1799 when Delambere and Mechain presented the results of their survey between Dunkirk and Barcelona
History of the metre
In the aftermath of the French Revolution , the old units of measure that were associated with the ancien régime were replaced by new units. The livre was replaced by the decimal franc, and a new unit of length was introduced which became known as the metre...

 which 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 18827.15 grains. These definitions enabled reference copies of the kilograms and metres to be contstructed that were to 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
Grad (angle)
The gradian is a unit of plane angle, equivalent to of a turn. It is also known as gon, grad, or grade . One grad equals of a degree or of a radian...

 which in turn was divided in 100 centigrads. An arc on the earth’s surface formed by an angle of one centigrade was one kilometre. The term centigrade was adopted for general use in a number of countries and in 1948 the General Conference on Weights and Measures
General Conference on Weights and Measures
The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures . It is one of the three organizations established to maintain the International System of Units under the terms of the Convention du Mètre of 1875...

 (CGPM) recommended that the degree centigrade (used for the measurement of temperature) be renamed the degree Celsius
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...

.

Mesures usuelles (1812–1839)

The metric system was introduced into France in 1795 on a district by district basis, starting with Paris. However, by modern standards it was 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. This, combined with other excesses of the Revolution and the high level of illiteracy, 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 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. The names of a 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 500 g, each livre comprising sixteen once and each once eight gros and the aune as 120 centimetres.

The metric system restored (1840–1875)

La loi du 4 juillet 1837 (the law of 4 July 1837) effectively revoked the use of mesures uselles by reaffirming the laws of measurement of 1795 and 1799 to be used from 1 May 1840. However many units of measure such as the livre remained in colloquial use for many years.

When this legislation was introduced, the metric system was beginning to take hold across Europe. Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 and the German state of Baden
Baden
Baden is a historical state on the east bank of the Rhine in the southwest of Germany, now the western part of the Baden-Württemberg of Germany....

 had both defined their Fuß (foot) as being 300 mm and the German state of Hessen-Darmstadt
Grand Duchy of Hesse
The Grand Duchy of Hesse and by Rhine , or, between 1806 and 1816, Grand Duchy of Hesse —as it was also known after 1816—was a member state of the German Confederation from 1806, when the Landgraviate of Hesse-Darmstadt was elevated to a Grand Duchy, until 1918, when all the German...

 has defined its Fuß as being 250 mm. Moreover, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

, Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

, Lombardy
Lombardy
Lombardy is one of the 20 regions of Italy. The capital is Milan. One-sixth of Italy's population lives in Lombardy and about one fifth of Italy's GDP is produced in this region, making it the most populous and richest region in the country and one of the richest in the whole of Europe...

 and Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...

 had all adopted the metric system, albeit with local names for the "metre", "kilogram" and so on. The metric system was given a boost when the German Zollverein
Zollverein
thumb|upright=1.2|The German Zollverein 1834–1919blue = Prussia in 1834 grey= Included region until 1866yellow= Excluded after 1866red = Borders of the German Union of 1828 pink= Relevant others until 1834...

(Customs Union) introduced the Zollpfund of 500 g in 1850.

The Great Exhibition of 1851 in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 was followed by international exhibitions in Paris in 1855
Exposition Universelle (1855)
The Exposition Universelle of 1855 was an International Exhibition held on the Champs-Elysées in Paris from May 15 to November 15, 1855. Its full official title was the Exposition Universelle des produits de l'Agriculture, de l'Industrie et des Beaux-Arts de Paris 1855.The exposition was a major...

 and 1867
Exposition Universelle (1867)
The Exposition Universelle of 1867 was a World Exposition held in Paris, France, in 1867.-Conception:In 1864, Emperor Napoleon III decreed that an international exposition should be held in Paris in 1867. A commission was appointed with Prince Jerome Napoleon as president, under whose direction...

. 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.

In 1870, while France was preparing to host an international conference to discuss international cooperation in the sphere of units of measurement, the war
Franco-Prussian War
The Franco-Prussian War or Franco-German War, often referred to in France as the 1870 War was a conflict between the Second French Empire and the Kingdom of Prussia. Prussia was aided by the North German Confederation, of which it was a member, and the South German states of Baden, Württemberg and...

 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:
  • 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
    Pavillon de Breteuil
    Pavillon de Breteuil is a building located in Sèvres, France near Paris. It was inaugurated by Louis XIV in 1672. It is in the park of the former royal Château de Saint-Cloud, which was destroyed in 1870....

    , near Paris
    Paris
    Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

     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.


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
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

 - the poncelet
Poncelet
The poncelet is an obsolete unit of power, once used in France and replaced by cheval vapeur . The unit was named after Jean-Victor Poncelet....

which was defined as being the power required to raise a mass of 100 kg against standard gravity
Standard gravity
Standard gravity, or standard acceleration due to free fall, usually denoted by g0 or gn, is the nominal acceleration of an object in a vacuum near the surface of the Earth. It is defined as precisely , or about...

 with a velocity of 1 kg/s giving a value of 980.665 W. However many other other European countries defined their units of power (the Pferdestärke in Germany, the paardekracht in the Netherlands and the cavallo vapore in Italy) using 75 kg rather than 100 kg which gave a value of 735.49875 W (about 0.985 HP
Horsepower
Horsepower is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the...

). 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 stere and the livre (and amongst others, the German pfund) were proscribed by EEC Directive 71/354/EEC
which required EU member states to standardise on the International System of Units
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...

 (SI).

See also

  • International System of Units
    International System of Units
    The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...

  • Jean-Antoine Chaptal
    Jean-Antoine Chaptal
    Jean-Antoine Claude, comte Chaptal de Chanteloup was a French chemist and statesman. He established chemical works for the manufacture of the mineral acids, soda and other substances...

  • Mansus
    Mansus
    A mansus, sometimes anglicised as manse, was a unit of land assessment in medieval France, roughly equivalent of the hide. In the 9th century AD, it began to be used by Charlemagne to determine how many warriors would be provided: one for every three mansi, with smaller landholders collectively...

  • Mesures usuelles
    Mesures usuelles
    Mesures usuelles were a system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements...


  • Réaumur scale
  • Systems of measurement
    Systems of measurement
    A system of measurement is a set of units which can be used to specify anything which can be measured and were historically important, regulated and defined because of trade and internal commerce...

  • Units of measurement
    Units of measurement
    A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention and/or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of...

  • Units of measurement in France before the French Revolution
    Units of measurement in France before the French Revolution
    200px|thumb|right|Woodcut dated 1800 illustrating the new decimal units which became the legal norm across all France on 4 November 1800Before the Revolution French units of measurement were based on the Carolingian system, introduced by the first Holy Roman Emperor Charlemagne which in turn were...

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