Mesures usuelles (French pronunciation: [məzyʁ yzɥɛl], customary measurements) 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 1795 and 1799 were reinstituted.[1]

Rationale behind the new system

The ordinary measures were introduced by Napoleon I in 1812

In the five years immediately before the French First Republic introduced the metric system, every effort was made to make the citizens aware of the upcoming changes and to prepare them for it.[2] The administration distributed tens of thousands of educational pamphlets, private enterprise produced educational games, guides, almanacs and conversion aids, and metre standards were built into the walls of prominent buildings around Paris.[2] The introduction was phased by district over the next few years, with Paris being the first district to change. The government also realised that the people would need metre rulers, but they had only provided 25,000 of the 500,000 rulers needed in Paris as late as one month after the metre became the sole legal unit of measure.[2] To compensate, the government introduced incentives for the mass-production of rulers. Paris police reported widespread flouting of the requirement for merchants to use only the metric system.[2] Where the new system was in use, it was abused, with shopkeepers taking the opportunity to round prices up and to give smaller measures.[2]

The Mesures usuelles were abolished by Louis-Philippe in 1839

Napoleon I, the French Emperor, disliked the inconvenience of surrendering the high factorability of traditional measures in the name of decimalisation, and recognized the difficulty of getting it accepted by the populace.[3] Under the décret impérial du 12 février 1812 (imperial decree of 12 February 1812), he introduced a new system of measurement, the mesures usuelles 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.[4][5]

The prototypes of the metric unit, the kilogram and the metre, enabled an immediate standardization of measurement over the whole country, replacing the varying legal measures in different parts of the country, and even more across the whole of Europe. The new livre (known as the livre métrique) was defined as five hundred grams, and the new toise (toise métrique) was defined as two metres. Products could be sold in shops under the old names and with the old relationships to one another, but with metric-based and slightly changed absolute sizes. This series of measurements was called mesures usuelles.

Napoleon's decree was eventually revoked during the reign of Louis Philippe by the loi du 4 juillet 1837 (law of 4 July 1837), which took effect on 1 January 1840, and reinstated the original metric system. This brought the system of mesures usuelles to a legal end,[4] though the livre remains in some informal use to this day.

Permitted units

The law authorised the following units of measure:[6]

The mesures usuelles did not include any units of length greater than the toise - the myriamètre (10 km) remaining in use throughout this period.[8]

See also


  1. ^ "History of measurement". Métrologie française. Retrieved 2011-02-06.
  2. ^ a b c d e Alder, Ken (2002). The Measure of all Things - The Seven-Year-Odyssey that Transformed the World. London: Abacus. ISBN 0-349-11507-9.
  3. ^ Napoleon I (19 December 1809). "Letter to Général Clarke, duc de Feltre". Correspondance de Napoléon Ier: publiée par ordre de l'empereur Napoléon III. Retrieved 2011-02-10. Je me moque des divisions décimales [I don't care about decimal divisions]
  4. ^ a b Denis Février. "Un historique du mètre" (in French). Ministère de l'Economie, des Finances et de l'Industrie. Retrieved 2011-03-10.
  5. ^ For example the engineering textbook, Stéphane Flachat (1835). Traité élémentaire de méchanique industrielle. Paris. Retrieved 2011-02-17.
  6. ^ Hallock, William; Wade, Herbert T (1906). "Outlines of the evolution of weights and measures and the metric system". London: The Macmillan Company. pp. 66–69.
  7. ^ Thierry Sabot (1 October 2000). "Les poids et mesures sous l'Ancien Régime" [The weights and measures of the Ancien Régime] (in French). histoire-genealogie. Retrieved 2011-02-10.
  8. ^ a b Appell, Wolfgang (2009-09-16) [2002]. "Königreich Frankreich" [Kingdom of France]. Amtliche Maßeinheiten in Europa 1842 [Official units of measure in Europe 1842] (in German). Archived from the original on 2011-10-05. Retrieved 2011-02-10.. (Website based on Alte Meß- und Währungssysteme aus dem deutschen Sprachgebiet, ISBN 3-7686-1036-5.)