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THE GENESIS OF THE METRIC SYSTEM and THE WORK OF THE INTERNATIONAL BUREAU OF WEIGHTS AND MEASURES HENRI MOREAU International Bureau of Weights and Measures, Sevres, France (Translated by Ralph E. Oesper)
ON
DECEMBER 10, 1949, the meter, the stmdard of length in the metric system, was 150 years old, and May 20, 1950, marked the 75th anniversary of the founding of the International Bureau of Weights aud Measures. These two anniversaries, rrhich vere passed over practically unnoticed, recall important dates in the history of weights and measures, a history which to a great extent may be said to represent the history of civilization itself. The history of the founding of the metric system is intertwined with that of the French Revolution of 1789. At various steps in the genesis of this system one encounters the names of eminent men of science and politics who played leading roles in this fateful period of French history. As for the Bureau of Weights and Measures, its creation was one of the consequences of the development of the metric system dnring the second half of the nineteenth century. This paper will give the broad outlines of the origin of the metric system, that "enterprise whose result should belong some day to the whole world" (Talleyrand), and will describe the essential part of the work of that metrologiral institute of world-wide chararter, namely the International Bureau of Weights and Measures.
To remedy this lack of uniformity and to obviate the consequent inconveniences, royal decrees relative to .the unification and rontrol of measures were issued at various times by the sovereigns, who, at the same time, hoped thus to increase their power over the whole rountry. Such decisions, which sometimes had real effects (Charlemagne, 789; Charles t,he Bald, 864, for instance) unfortunately did not out,live their sponsors. The reform of the system of measures, which was neatly summed up in the motto "One King, olle Lax, one Weight., one Measure" occurring in more t,han one of the cahiers of the Btats GBnFraux (States General),' mas constantly opposed by the interested resistance of the nobles, the influence of the guilds, and, in general, by all vho profited by the prevailing disorder. Added to these hindrances was the innate indifference, if not t,he host,ility, of those accustomed to t,heir local units. In Paris the principal units in use before the establishment of t,he metric system were the Pied de Roi (0.325 m.) for lengths and the Liwe poids de marc (489.5 g.) for weight,^.^ These two units were respectively represented by standards knovn as the Toine du Ch,atelet and the Pile de Charlemagne. The Toise du Ch%telet.( = 6 Pieds de Roi (1.949 m.)) was au iron bar that had been fastened in 1668 to the outer wall, at the foot of the staircase, of the Grand Ch%elet.s At its ends were two notches or projections at right angles; a toke vas supposed to fit precisely between them. This standard toke had served for the adjusting, among others, of the two famous toises, k~oxlnas the Toise du Pgrou and the Toise du Nord, ~ ~ h i cwere h used in measuring the arc of the earth's
DIVERSITY OF ANCIENT MEASURES
At all periods of social intercourse there has heen a need for ireights and measures so that commercial transactions can be carried on conveniently and henestly. This objective was far from attainment, at the end of the eighteent,h century, when a wide diversity of units uroduced inevitable confusion. Furthermore, there was considerable doubt as to the permanence of the standard weights and measures. Without going into the detailed history of the ancient weights and measures, one dominant fart should be noted: the uniformity was illusory. The units varied, not only from country to country, and sometimes (a7in France) from province to province, but even from city to city, and also according to corporation or guild. Of course, t,his stat,e of affairs led to errors, frauds, and continual misunderstandings and disputes, to 8%' nothing of the serious repercussions such a situation mas bound to have on the progress of sriellce, The multiplicity of names given to poorly determined units and the diversity in the multiples and submultiples of the principal measures increased the confusion.
The Etats GPn6raux was the general assembly of the whole F~.enchnation; the representatives \
