The International Bureau of Weights and Measures
After the original meter was established, it was found that copies made by various countries differed to a greater or less extent from the original, and believing that a copy could be made from which other copies could be more readily made than from the end piece meter, and that better provision could be made for the preservation of the standard, France called a convention of representatives from various States using the system, to consider the matter. The United States representatives, or commissioners, were Messrs. Henry and Hildegard, who met with the general commission in 1870. The commissioners at once set at work to solve the problem presented to them, but the Franco-Prussian war put an end to their deliberations. The deliberations were resumed later, and May 20, 1875, representatives of the various countries signed a treaty providing for the establishment and maintenance, at the common expense of the contracting nations, of a "scientific and permanent international bureau of weights and measures, the location of which should be Paris, to be conducted by a general conference for weights and measures, to be composed of the delegates of all the contracting governments."
This bureau is empowered to construct and preserve the international standards, to distribute copies of the same to the several countries, and also to discuss and initiate measures necessary for the determination of the metric system. The commission adopted a form for the standard as shown in Fig. 1. The lines representing the length of the meter are drawn on the plane _A_, which is the neutral plane, and will not change in length should the bar deflect. The bar is made of 90 per cent platinum and 10 per cent iridium, about 250 kilograms having been melted when preparations were made for the first standard, so that all of the copies made from this cast represent the same coefficient of expansion and are subject to the same changes as the original. The French government presented to the bureau the pavilion Breteuil, opposite the Park of St. Cloud, which was accepted and put into order and is now the repository of the originals of the meter and the kilogram. The expense attending the first establishment of the bureau was about $10,000 to the United States, and since then its share of the annual expense has been about $900. The standards in the possession of the United States were received through the international bureau.