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Système Usuel

In France, 1812 – 1839, a system of weights and measures introduced to satisfy public resistance to the adoption of the metric system.

This process began as early as 1800 with a decree¹ by First Consul Napoleon, that permitted the substitution of traditional names for the names of a number of metric units and decimal multiples and submultiples.

Notice that the meter itself was not renamed.

A decree of February 1812 carried this accommodation much further, and established the Système usuel. While calling for the teaching of the “Système legal,” that is, the metric system, and its continued use by officials, the decree authorized use of traditional names but now with values much closer to their traditional ones. For most units, defining such values required the use of common, not decimal, fractions of the metric base units, thus breaking a fundamental principle of the metric system. For example:

The Système Usuel was abolished in 1837 by a law² forbidding the use of non-metric units after 1 January 1840.

1. Arrêté relatif au mode d'exécution du Système décimal des poids et mesures du 15 Brumaire. An 9. (15 November 1800)

2. Décret concernant les poids et mesures. Du 12 Févier 1812.
Arrêté du ministre de l'intérieur pour l'exécution du décret du 12 Février 1812. Du 28 Mars 1812.

3. Loi relative aux poids et mesures.
Bulletin des lois No. 515.
Signed 4 July 1837.
Promulgated 8 July 1837.

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Last revised: 27 August 2001.