DKPARTMIvNT OI^ TERRIiSTRIAL MAGNETISM. 163 



INTERNATIONAL OBSERVATIONS OF THE VARIATIONS. 



Under this heading is embraced all observations that pertain to the varia- 

 tions and fluctuations of the magnetic elements, such as are included in the 

 work of a magnetic observatory, in the reoccupation of previous stations for 

 secular variation data and special investigations, as, for example, in connec- 

 tion with the total solar eclipse. It has not been possible as yet to undertake 

 any observatory work, but some such work will have to be undertaken within 

 the near future to provide adequately for the needs of the Department. 



The establishment of repeat stations or reoccupation of previous ones is 

 systematically under way, as reported upon under "Magnetic survey of land 

 areas." This work will in the coming year receive further extensive devel- 

 opment, as it is proposed to establish a series of such stations around the 

 globe to permit of regular reoccupation within intervals of not over five 

 years. In connection with this work, which must necessarily keep pace with 

 the magnetic-survey work, all previous data are being collected and suitably 

 arranged, and will shortly be ready for publication. 



The magnetic and electric observations, made in connection with the total 

 solar eclipse of 1905, have now been received from nearly every country that 

 responded to the appeal of the Department for international simultaneous 

 work during this eclipse. It is hoped that before long the results can be sub- 

 mitted for publication. It can only be noted here that the independent 

 researches of various investigators, such as van Bemmelen, Nippoldt, and 

 Nordmann, confirm the result reached from the observations made in the 

 United States during the total solar eclipse of 1900, under the writer's 

 direction, viz, that there is an observable magnetic fluctuation in connection 

 with a total solar eclipse. Professor Oddone, a member of Professor Palaz- 

 zo's Tripoli expedition, conducted in cooperation with the Department, 

 believes he has proved that an appreciable atmospheric electric fluctuation 

 also occurs during a total solar eclipse. 



OBSERVATIONS IN OCEAN DEPTHS AND ATMOSPHERIC REGIONS. 



The work under this head has necessaril}^ not advanced beyond the pre- 

 liminary stages. jMethods and instruments for determining the variations 

 of the magnetic elements with altitude or depth have received some consid- 

 eration, however. Special attention is being paid at present in the course of 

 the survey work to find localities suited for such work. Thus in December, 

 1905, an examination was made of the region around the Grand Canyon of 

 the Colorado; this summer, as elsewhere related, the region about Banff, in 

 the National Park of the Dominion of Canada, was examined by the Director, 

 as also the Yellowstone National Park. The first two localities named 

 appear well suited ; the latter, however, would present difficulties because of 



