308 CARNEGIE INSTITUTION OF WASHINGTON. 



Now that the general magnetic survey of the ocean areas and un- 

 explored regions, assigned to the Department of Terrestrial Magnetism 

 as one of its initial great tasks, is coming to a conclusion as regards its 

 first main purpose, efforts are being made to assist in meeting the 

 needs referred to in previous paragraphs. Among the problems 

 specifically mentioned in the plan^ of work of the Department was 

 that relating to observations of the manifold variations in the mag- 

 netic and electric conditions of the Earth, inclusive of its atmosphere, 

 and their correlations with solar and allied phenomena. To this end 

 a magnetic observatory was built at Watheroo, Western Australia, 

 about 120 miles north of Perth, where, since January 1, 1919, con- 

 tinuous observations of the Earth's magnetic changes have been 

 recorded by photographic means; these observations will be supple- 

 mented in the near future by others pertaining to atmospheric elec- 

 tricity and earth-currents. 



The location of the Watheroo Magnetic Observatory is almost 

 diametrically opposite to that of the magnetic observatory of the 

 United States Coast and Geodetic Survey at Cheltenham, Maryland. 

 The comparison of the magnetic variations and disturbances as re- 

 corded at the two stations on opposite sides of the Earth is proving 

 of exceptional interest. During the period May 13 to 16, 1921, there 

 were observed at the Watheroo Magnetic Observatory in the Southern 

 Hemisphere, magnetic disturbances, polar lights (aurora australis), 

 and earth-currents corresponding to those observed in the Northern 

 Hemisphere, as for example, in the United States. 



The second magnetic observatory of the Department, located at 

 Huancayo, Peru, at an altitude of about 11,000 feet and about 125 

 miles east of Lima, is now nearing completion; it is hoped that the 

 magnetic observations may be begun before the end of the year, and 

 that electric observations may be undertaken some time in 1922. In 

 addition, it is hoped that arrangements may soon be made for sys- 

 tematic observations pertaining to atmospheric electricity and earth- 

 currents at other suitable stations in regions for which data are much 

 needed. Among especially desirable regions at present may be 

 mentioned: Northern part of North America, United States, Mid- 

 Pacific Ocean, and South Atlantic Ocean or Africa. 



Various studies concerning the relationships between solar activity 

 and the Earth's magnetic and electric phenomena are in progress. 

 These studies show once more the complexities of the relations. It 

 is not possible always to correlate the intensity of sun-spot activity 

 definitely with magnetic effects. There are well-established cases of 

 severe magnetic storms during complete absences of visual evidence 

 of sun-spots; at times these storms may be related to some other solar 



'Published in the Year Book of the Carnegie Institution of Washington for 1903, pp. 203-212. 



