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SCIENCE 



[N. S. Vol. XXXVII. No. 958 



collecting its own data and forwarding it 

 to the central bureau in London. 



I can not pass away from this type of 

 international cooperation without express- 

 ing regret that a proposal which was made 

 by the late Professor Simon Newcomb has 

 not been adopted hitherto. When the first 

 program of the Carnegie Institution of 

 Washington was being discussed, he pro- 

 posed that there should be some central 

 computing bureau established at one place 

 where accumulated data of observation, 

 which required scientific treatment, could 

 be discussed and treated in that way. The 

 number of instances which have come to 

 my own notice within the last few years, 

 in which the existence of such a bureau 

 would have been of the greatest assistance 

 to the progress of science is considerable; 

 and I feel very little doubt that others have 

 also felt the want. 



The problems which fall into the third 

 category are mainly those belonging to the 

 important and much neglected subject of 

 geophysics. The time is past when we 

 could separate the physics of the labora- 

 tory from that of the earth, and that again 

 from the physics of the universe. The ex- 

 perimenter who now studies the structure 

 of the atom must keep an eye on the sun 

 and stars in order to detect whether celes- 

 tial observations destroy his theories or 

 give them strength. 



Atmospheric electricity and terrestrial 

 magnetism, treated too long as isolated 

 phenomena may give us hints on hitherto 

 unknown properties of matter. A meteor- 

 ologist, finding out at last that space has 

 three dimensions, and that the motion of 

 air is governed by the laws of mechanics, 

 has converted what hitherto has been a 

 sport into a science. 



Before enumerating the international 

 associations which are dealing with these 

 problems of geophysics, let us say a few 

 words as to the problems themselves. 



We have, first, to study the shape of the 

 earth and the variations in the gravita- 

 tional forces which are observed on its 

 surface. We have further to take account 

 of the secular variations of level and of 

 the more or less violent disturbances which 

 accompany earthquakes and earth tremors. 

 By comparing the indications of instru- 

 ments placed in different localities, we can 

 deduce the rate of propagation over the 

 earth and through the earth of the seismic 

 waves. This yields us important informa- 

 tion on the physical properties or material 

 composing the interior of the earth. The 

 cause of terrestrial magnetism is at present 

 unknown, and we have no means at our 

 disposal to attack the problem directly, but 

 the study of the diurnal and secular varia- 

 tions may give us a clue, and deserves our 

 closest attention. 



In a similar way, the study of the higher 

 atmosphere and of the high electric con- 

 ductivity which the air is now known to 

 possess at heights which we can not reach, 

 is also a subject which can only be studied 

 by combined efforts. How are these ques- 

 tions dealt with at present ? 



We have, first, an International Asso- 

 ciation of Geodetics, which is an exceed- 

 ingly efficient body, with a bureau at Pots- 

 dam, under Professor Helmert. That asso- 

 ciation is successful, perhaps, partly be- 

 cause its work has been facilitated in that 

 it had to build on virgin soil. Nothing 

 had been done, to a very great extent at 

 any rate, internationally before that asso- 

 ciation came into being. On the other 

 hand, we have the International Associa- 

 tion of Seismology, a related subject, which 

 was only founded at the beginning of the 

 present century, with a central bureau at 

 Strassburg. This association had to over- 

 come more serious difficulties. It entered 

 into the field when there was already a less 

 expensive organization in existence, which 

 had been originated by Professor Milne 



