260 CARNEGIE INSTITUTION OF WASHINGTON. 



The formulae for the function G, used chiefly in this investigation, were 

 developed in the author's article on "The Local Magnetic Constant and Its 

 Variations."* 



The chief purpose of the present investigation is to find out, if possible, 

 how the intensity of magnetization of the Earth may vary and how these 

 changes may be related to changes in solar activity. 



It is stated in conclusion that when the present sun-spot maximum has 

 been well passed and thus a few more years of observations of both magnetic 

 and solar quantities are available, it will be more easily possible to determine 

 the magnetic effects to be associated respectively with sun-spot activity and 

 solar-constant changes. 



It would seem that we have ample evidence that the Earth's absolute 

 magnetic state at any time is dependent upon solar conditions, and that an 

 appreciable portion of the secular variation of the Earth's magnetism may be 

 associated with changes in solar activity. In general, the effect of increased 

 solar activity is to cause a decrease in the Earth's intensity of magnetization, 

 though there may also at times be reverse effects. 



Results of magnetic and allied observations made during the solar eclipse of June 8, 1918. 

 L. A. Bauer, H. W. Fisk and S. J. Mauchly. Terr. Mag., vol. 23, 95-110, 

 151 (Sept. and Dec. 1918), Washington. 



The solar eclipse of Jime 8, 1918, offered an exceptional opportunity for 

 magnetic and allied observations, since somewhat over one-third of the belt 

 of totality was situated in the United States. An interesting circumstance 

 was also the fact that this eclipse was the repetition of the one of May 28, 

 1900, in connection with which systematic observations according to the 

 first author's directions, for the study of a possible magnetic effect during 

 a total solar eclipse, were made. The belt of totality of the latter eclipse 

 passed through the southeastern part of the United States during the morning 

 hours, whereas that for the eclipse of June 8, 1918, passed through the United 

 States from northwest to southeast during the afternoon hours. Thus con- 

 ditions were, in a certain sense, reversed for the two eclipses, as far as the 

 regular diurnal variation of the earth's magnetism is concerned. 



In response to the appeal sent out by the Department of Terrestrial Mag- 

 netism of the Carnegie Institution of Washington, cooperation was received 

 from various magnetic observatories, institutions, and universities situated 

 within the entire zone of visibility, as well as from certain places outside of 

 this zone. As the result of this appeal magnetic data are available at present 

 from 7 stations within the belt of totality, 16 stations outside of the belt but 

 within the zone of visibility of the ecHpse, and 3 stations outside of the zone; 

 the stations covered the region of the Earth from China, Australia, and the 

 Philippines to Porto Rico. Of this list the Coast and Geodetic Survey con- 

 tributed data at 8 stations, and the Department of Terrestrial Magnetism 

 at 7 stations, besides the data at 5 university stations working in cooperation 

 with the Department. Canadian governmental institutions contributed data 

 at 3 stations in Canada; the data at the remaining stations were received 

 from the observatories at Kakioka, Japan, Lukiapang, China, and Antipole, 

 Philippine Islands. 



At Lakin, Kansas, where was located the Smithsonian Institution party, 

 a temporary magnetic observatory was established by the Department, and 

 a full program of magnetic and atmospheric-electric observations was carried 

 out; this station was in charge of S. J. Mauchly. At Mr. Fisk's station, 

 Goldendale, Washington, where the Lick Observatory party was located, 



*Terr. Mag., vol. 19, 1914, p. 114. 



