464 



NA TURE 



[Sept. 13, 1883 



Every measurement is at least double, and made wiih 

 currents in opposite directions. 



In conclusion I may remark first, that this, like my 

 former note, only deals with part of a larger inquiry ; and 

 secondly, that the results above stated were open to all 

 comers, and were carefully watched by Dr. Percy Smith, 

 Dr. Shepherd, and others of my colleagues and pupils. 



\V. H. Stone 



THE INTERNA TIONAL B UREA U OF H 'E1GH TS 

 AND MEASURES' 



AS the result of an International Convention held on 

 the 20th May, 1875, an International Bureau of 

 Weights and Measures has been created at Paris with the 

 object of securing an international metric system, and 

 which should take account (1) of all comparisons and 

 verifications of the new prototypes of the metre and the 



kilogramme ; (2) of the conservation of the international 

 prototypes ; (3) of periodical comparisons of national 

 standards with the international prototypes, as also of 

 comparisons of thermometric standards ; (4) of the com- 

 parisons of the new prototypes with the fundamental 

 standards of non-metric weights and measures employed 

 in different countries and in science ; (5) of the marking 

 and comparison of geodetical measures ; (6) of the com- 

 parison of standards and scales of precision, the verifica- 

 tion of which may be sought by governments, by learned 

 societies, or even by mechanists and students. 



An international committee of weights and measures 

 composed of fourteen members, comprising physicists, 

 mathematicians, surveyors, and astronomers, all of dif- 

 ferent nationalities, has been intrusted with the supreme 

 direction of the bureau. The president of this committee 

 is General Ibancz, director-general of the Geographical 

 and Statistical Institute of Spain, and its secretary Dr. 



Fig. 



' Cumparatcur " fur Measuring Absolute and Relal.ve Dilatation; 



Hirsch, director of the Observatory of Nenchitel. It 

 meets once a year for the discharge of its functions at 

 Pans. 



Twenty States were represented at the preliminary 

 diplomatic conference of 1875. Of these, seventeen (or 

 nineteen) have signed the international convention which 

 was the result of its deliberations. One alone of these 

 States has not ratified the convention ; and consequently 

 the expenses of the foundation and maintenance of the 

 International Bureau of Weights and Measures have 

 hi herto been defrayed by the following sixteen States: 

 Germ my, Austria-Hungary, Belgium, the Argentine 

 Confederation, Denmark, Spain, the United States of 

 America, France, Italy, Peru, Portugal, Russia, Sweden, 

 Norway, Switzerland, Turkey, Venezuela. These, repre- 

 senting about 351,000,000 of people, have already con- 

 tributed over i,coo,ooo francs towards the foundation of 



1 From La Nature, 



the International Bureau. The Government of Servia has 

 since given in its adhesion to the convention. 



In order to provide for the erection of the necessary 

 structures for the observatory of the International Bureau 

 of Weights and Measures, France made a grant of ground 

 in the park of St. Cloud formerly occupied by the Pavilion 

 de Breteuil, safely removed from all disturbances and sur- 

 face tremors such as would have been experienced in the 

 centre of a large city amidst the whirl of carriages and 

 the working of machines. 



In front of the observatory of the International Bureau 

 are offices set apart for mechanical laboratories. Behind 

 are spacious chambers in which are distributed the various 

 instruments of precision employed in metrological work. 

 These chambers are surrounded by walls of great thick- 

 ness ; they are lighted by skylights so arranged as to pre- 

 vent solar rays from penetrating : and are environed by 

 a lobby i.o'ating them from the exterior. The object 



