244 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1925 



On tlie initiative of Humboldt and Gauss, supported by Herschell, 

 Kupffer, and Sabine, there was developed one of the earliest cases of 

 international cooperation for the study of a world-wide phenomenon, 

 which was remarkably successful when the conditions of transporta- 

 tion and communication at that time are considered. Magnetic sur- 

 veys were undertaken, observers were sent to regions where magnetic 

 observations had not previously been made, including the expedition 

 of Ross to the vicinity of the magnetic south pole, and magnetic 

 observatories were established about 1840, at widely separated points, 

 for the study of the variations of the earth's magnetism. In spite of 

 the imperfect instruments then available, the operation of these 

 observatories served to establish the principal features of the short 

 period variations of the earth's magnetism. Some of them were dis- 

 continued at the close of the limited period for which international 

 cooperation had been arranged, but others continued in operation 

 much longer, some (as the one at Toronto, Canada) even to the 

 present day. It is of interest to recall that, thanks to the zeal of 

 A. D. Baclie, later Superintendent of the Coast Survey, a magnetic 

 observatory was operated at Girard College, Philadelphia, from 1841 

 to 1845, and that variation observations were made in this city from 

 1840 to 1842. One of the observatories established by liussia was 

 at Sitka, Alaska, and was in operation from 1842 to 1867. The re- 

 sults obtained brought out the fact that the variations of the earth's 

 magnetism are different in different magnetic latitudes and called at- 

 tention to the probability of some relationship between thei)resence 

 of sun spots and the occurrence of auroras and magnetic storms on 

 the earth. The desire for more information regarding the connection 

 betAveen the§e two terrestrial phenomena led to further international 

 cooperation m the establishment of a ring of temporary magnetic 

 observatories around the borders of the Arcfic Ocean to be operated 

 for three years from 1882. 



From that time on the interest in the study of the earth's magne- 

 tism steadily increased, not only in the extension of magnetic sur- 

 veys and in the operation of additional magnetic observatories, but 

 also in the discussion of the results and investigations regarding the 

 cause of the phenomenon. 



In most countries the magnetic observatories were established as 

 an adjunct to existing meteorological observatories and gi\en a sub- 

 ordinate position. At the meeting of the International Meteoro- 

 logical Conference held in Paris in 1896, however, recognition was 

 given to the growing importance of the science of terrestrial mag- 

 netism by the appointment of a Permanent Commission for Ter- 

 restrial Magnetism and Atmospheric Electricity. 



A fresh impulse was given to the growth of interest by the ap])ear- 

 ance in 1896 of the Journal of Terrestrial Magnetism edited by 



