A uniformity of weights and measures...
A
uniformity of weights and measures
Inspired,
among others, by shopkeepers, the registers of grievances of many cities,
including Paris and Orleans, had required the government to settle the
uniformity of weights and measures in the kingdom. All scientists supported
these claims.
The
issue of weights and measures was indirectly tackled in the French National
Assembly for the first time on 15 March 1790. This decree – that the king
sanctionned on 28 March – suppressed seigniorial privileges, of which a
great number was collected "on the pretence of weights, measures, marks,
supply or inspection of measure, or measurement of wares".
Later,
Talleyrand, who was the delegate for the clergy, suggested the unficiation
of measurements. He suggested adopting a "natural" unit, based, either on
the length of the seconds pendulum at the 45° latitude, or on a fraction of
the meridian.
The
Assembly chose the pendulum. As they wanted "to make all France benefit
forever from the advantage which must result from the uniformity of weights
and measures", they voted the 8 May 1790 decree, which was sanctionned by
the king on 22 August. This decree set the principle of standardization.
Besides, it prompted the king to suggest to the king of England inviting the
House of Commons to work with the French National Assembly. In that way, "representatives
from the Academy of Science in Paris could meet in equal number with members
from the Royal Society of London, to set the pendulum length, and to deduce
from it an invariable pattern for all measures and all weights".
The
offer made to England had no upshot. This country must have been too much
attached to its traditional measures to consider adopting another system.
Nevertheless, one has to admit that the declaration of war from France to
England, as soon as February 1793, would have been an obstacle to the
pursuit of a cooperation between scientists from these two countries.
However,
the Academy of Science suggested, in its 19 March 1791 notice, the use of
the length of a quarter of a terrestrial meridian instead of the length of a
pendulum.
The
Assembly came over to the Academy opinion with its 26 March 1791 decree -
sanctionned by the king on 30 March : "by considering that, in order to
achieve setting the uniformity of weights and measures, it is necessary to
set a natural and invariable unit of measure, and that the only means of
extending this uniformity to foreign countries and of committing them to a
new measuring system, is to choose a unit which has nothing abitrary or
peculiar to the situation of one people of the world […] [the Assembly]
adopts the length of a quarter of a terrestrial meridian as a basis of the
new system of measurements ; the processes that are necessary to set this
basis - among others measuring a quadrant between Dunkirk and Barcelona -
will soon be executed."
The
measurement of the quadrant of the earth was left to the astronomers
Delambre and Méchain.
The
operation lasted from June 1792 to late 1798.