THE PRESENT PROBLEMS OF TERRESTRIAL MAGNETISM 



BY LOUIS AGRICOLA BAUER 



[Louis Agricola Bauer, in charge of Magnetic Work of United States Coast and 

 Geodetic Survey since 1899 ; Director of Department of Terrestrial Magnetism, 

 Carnegie Institution of Washington, since 1904. b. Cincinnati, Ohio, January 26 , 

 1865. Graduate, C.E., Cincinnati, 1888; M.S. ibid. 1894; special courses, Uni- 

 versity of Berlin, 1892-95 (Ph.D.). Assistant Civil Engineer, C. N. O. & T. P. 

 R. R., 1886-87; Astronomical and Magnetic Computer, U. S. Coast and Geo- 

 detic Survey, 1887-1902; Decent in Mathematical Physics, University of Chi- 

 cago, 1895-96 ; Instructor in Geophysics, ibid. 1896-97; Assistant Professor 

 of Mathematics and Mathematical Physics, University of Cincinnati, 1897-99; 

 Chief of Division of Terrestrial Magnetism, Maryland Geological Survey, since 

 1896; Lecturer injTerrestrial Magnetism, Johns Hopkins University, since 1899. 

 Member (Hon.) of Socfedad Cientifica Antonio Alzate; Permanent Committee 

 on Terrestrial Magnetism and Atmospheric Electricity of International Meteor- 

 ological Conference; also of Committee on Terrestrial Magnetism of Interna- 

 tional Association of Academies; Washington Academy of Science; Washing- 

 ton Philosophical Society, etc. Editor of Terrestrial Magnetism and Atmo- 

 spheric Electricity, and frequent contributor to scientific press, on terrestrial 

 magnetism.] 



IN view of the expansion of the Section from "meteorology," 

 as originally planned, to that of "cosmical physics," I was requested 

 to give a thirty-minute address on the problems of the earth's mag- 

 netism, the two principal speakers dealing chiefly with the investi- 

 gations and problems of meteorology. The time allotted will not 

 permit, however, a presentation of the problems concerning the 

 earth's magnetic and electric phenomena with that completeness 

 and thoroughness the subject deserves. Suffice it, therefore, if we 

 select such concrete examples as shall be typical of the relationship 

 between these problems and those of the related sciences of the 

 earth, and as shall exhibit the role their solutions are destined to 

 play in the unraveling of many of the vexed questions pertaining 

 to the physics of the earth and of the universe. 



While eminent investigators, not directly engaged in magnetic 

 work, have evinced, in one way or another, a conception of the 

 prominence of this r61e, my humble opinion is that the full im- 

 portance is not adequately realized by those concerned with the 

 problems of the physics of the earth and of the universe. The 

 chief reason for this is to be sought in the fact that it is just begin- 

 ning to be recognized that in order to secure a steady advance in 

 our knowledge of the magnetic and allied phenomena of the earth, 

 the subject of the earth's magnetism must be raised to that plane 

 of independent investigation occupied by its sister sciences, astro- 

 physics and meteorology. It must be recognized that this subject is 

 to be studied per se, and not merely as an adjunct to meteorological 

 or geodetic work. The fact must be appreciated that to be an ex- 



