The metric system was based on a natural concept which assumed the meter to be one ten-millionth part of a meridional quadrant of the earth. Further investigation showed that this concept was wrong and that the original metric standards, kept in the Archives of France, had not been constructed with the precision possible three quarters of a century later. With the United States participating, a series of international conferences were held in the early 1870s to construct new metric standards. A graduated line standard, equal in length to the Metre des Archives at O° centigrade, was chosen as the new basis for the system. Rejection of a natural basis for the meter made international agreement necessary in order to maintain the validity of the artificial meter. The Treaty of the Meter (1875) mandated the establishment of a permanent International Bureau of Weights and Measures, to be located at Sevres, France, which would not only keep custody of the new prototype meter and kilogram when constructed, but make comparisons between them and the fundamental standards of nonmetrical weights and measures in other countries.