SI: origins and development
Fundamental Metrological Standards

Two of the fundamental ideas behind the creation and development of the decimal metric system during the French Revolution were the conviction that the proposed new system had to be based on universal notions and solid scientific foundations, and that it had to be disseminated not only throughout France, but throughout the world, "to all times, to all peoples".

The latter idea gained ground throughout the 19th century, in particular at the Universal Exhibitions in London and Paris (1851, 1855 and 1867 respectively), where scientists and politicians alike began to understand the advantages of such a system. In addition to the fact that some countries (e.g. Switzerland, the Netherlands and France) had proclaimed metrology...