Memory of the World; 2012 - unesdoc - Unesco

4th c. 5th c. 6th c. 7th c. 8th c. 9th c. 10th c. 11th c. 12th c. 13th c. 14th c. 15th c. 16th c. 17th c. 18th c. 19th c. 20th c. 21st c.
Introduction of the decimal
metric system, 1790–1837
Inscribed 2005
What is it
Nine items dating from 1790 to 1837, which were central
to the introduction and adoption of the decimal metric
system in France.
Why was it inscribed
The decimal metric system devised and adopted in
France after the revolution of 1789 provided the basis
of today’s international measurement system. It has
since spread across the world to become the standard
official system of measurement in most countries and
has been applied in almost every area.
Where is it
Archives Nationales, Paris, France
The decimal metric system emerged out of the drive for
centralization and uniformity that characterized the French
political establishment during the country’s revolutionary
period from 1789 onwards. The inspirations for this
drive were the ideas that came out of the 18th-century
intellectual movement of the Enlightenment and its
emphasis on the supremacy of reason.
A central part of the ideas of the Enlightenment was
the reform of society. The new decimal metric system
was one part of a manifesto intended to overthrow or
remodel the social systems that existed in France up to
the revolution. The attempted reforms were ambitious
and all-encompassing and took in areas as diverse as
timekeeping and the calendar, measurement, taxation
and the currency and the systems of law and government.
The reformers also attempted to end the monarchy, the
titled aristocracy and religious practice and worship.
These post-revolutionary reforms had varying degrees
of success although in many cases the changes they
brought to both institutions and individual life in France
were profound. The new decimal metric system would
eventually prove to be one of the more enduring reforms.
Before its introduction, there was no agreed principle
for calculating weights and measures in France: it was
estimated that one foot, for example, was measured at
twenty different lengths across the country. In 1790 the
306 Introduction of the decimal metric system, 1790–1837
pragmatic politician Talleyrand, who was at that point the
bishop of Autun, proposed the adoption of a new system
of measurement that was at once universal, invariable,
reproducible and verifiable everywhere and at all times.
In 1791 it was decided that the measure of one quarter
of the earth’s meridian should be used as a natural,
universal unit. Under economic and military pressures, the
measurement first adopted in 1793 was one ten-millionth
of the distance from the North Pole to the Equator, a
distance equal to 3 feet 11 lines and 44 hundredths of a line
as measured by the Académie des Sciences (the French
Academy of Sciences).
A standard metre measurement was built in platinum as
it was less susceptible to shifts in temperature than other
metals. A platinum weight was also made for a standard
kilogram measurement, a gram being based on the weight
and thermodynamic properties of water – one gram was
defined as the mass of one cubic centimetre of water at its
temperature of maximum density.
The new measures were officially approved in 1799 but
were not uniformly popular in France and even Napoleon
once banned the system. They finally became compulsory
in 1840. Over the following centuries, the decimal metric
systems have been adopted for official use in virtually all
areas of activity in line with the International Organization
for Standardization (ISO).
Nine documents and items are considered central
to the introduction of the decimal metric system in France.
The first five, from 1790 to 1795, are documents: the Bishop
of Autun’s initial proposal of weights and measures reform
to the National Assembly; the law, approved by King Louis
XVI, relating to the method of establishing the standards;
a National Convention decree establishing a standard; the
measurements themselves based on the measured length
of the earth’s meridian; and the National Convention
decree to establish the new system.
Two of the items, both dating from 1799, are the metre
length and kilogram weight made in platinum and
deemed to be the standard. A certificate of registration for
both with the National Archives exists for the same year.
Finally, a handwritten law from 1837, signed by King Louis
Philippe, made the new metric system compulsory in
France from 1 January 1840.
Talleyrand, then bishop of Autun, proposed the adoption
of a new system of measurement after the revolution in France. �