Metre Convention - Background

Background

In England in 1215, clause 25 of the Magna Carta set out the standards of measure that were to be applied throughout the realm. Five centuries later, when in 1707 England and Scotland were united into a single kingdom, the Scots agreed to use the same units of measure that were already established in England. During the eighteenth century, in order to facilitate trade, Peter the Great, Czar of Russia adopted the English system of measure.

Abuse of units of measures were one of the causes of the French Revolution and its reform was one of the items on the agenda of National Assembly. Talleyrand, an influential leader of the Assembly invited British and American participation in the establishment of a new system, but in the event, the Assembly went it alone and introduced the metre and the kilogram which were to form the basis of the metric system, manufacturing prototypes which, in 1799, were lodged with Archives.

Between 1850 and 1870, a number of countries adopted the metric system as their system of measure including Spain, many South American republics and many of the Italian and German states (the Netherlands had adopted the system in 1817). In 1863, the International Postal Union used grams to express permitted weights of letters.

In the 1860s, inspections of the prototype metre revealed wear and tear at the measuring faces of the bar and also that the bar was wont to flex slightly when in use. In view of the doubts being cast on the reproducibility of the metre and the kilogram and the threat that a rival standard might be set up, Napoleon III invited scientists from all the world’s nations to attend a conference in Paris. In July 1870, two weeks before the conference was due to start, the Franco-Prussian War broke out. Although the delegates did meet (without a German delegation), it was agreed that the conference should be recalled once all the delegates (including the German delegation) were present.

France was defeated in the war, Napoleon went into exile and Germany and Italy, now unified nations, adopted the metric system as their national system of units, but with the prototype copy of the kilogram and metre under the control of the Third French Republic. In 1872 the new republican government reissued the invitations and in 1875 scientists from thirty European and American countries met in Paris.