Vol. 6, 1920 
GEOPHYSICS: L. A. BAUER 
579 
activity of the volcano. He furthermore found that the action of Vesuvius 
was such as to mask the diurnal variation in the observations of earth 
currents. 
Reference may also be made to the investigations by Folgheraiter and 
others in Italy, B. Brunhes and P. David, in France, with regard to the 
magnetization of lava beds. 
10. Laboratory Problems in Terrestrial Magnetism and Electricity: One 
of the prime purposes of the Section of Terrestrial Magnetism and Elec- 
tricity should be to stimulate research in these fields as widely as possi- 
ble so as to increase the number of workers, especially at our universi- 
ties. About the middle of the last century very much of the investiga- 
tional work in the United States in the subjects here considered was car- 
ried out by university professors. It must be one of our endeavors there- 
fore to present and suggest problems which might be advantageously 
taken up at universities, either in connection with laboratory work or field 
investigations, over a region of greater or less extent. 
Among some of the problems for experimental and theoretical investiga- 
tion may be mentioned those with regard to the origin of the earth's 
magnetic field, origin and maintenance of the earth's electric field, im- 
provement of instrumental appliances for magnetic and electrical measure- 
ments on the surface of the earth and at altitudes above, the effect of 
pressure upon the critical temperature of magnetization, studies in mag- 
netism, in general, etc. 
In conclusion, let it be stated that the incompleteness of this sketch of 
some of the chief problems of concern and interest to the Section of Ter- 
restrial Magnetism and Electricity is fully realized. Other topics of im- 
portance could profitably have been dilated upon, especially with regard 
to the question of the origin of the earth's magnetic field and as regards 
certain outstanding problems in the fruitful subjects of atmospheric 
electricity, earth currents, polar lights, upper-air electric phenomena 
bearing upon radio-telegraphy, etc. It must suffice, owing to the limits 
imposed upon the present paper, merely to have called attention to these 
additional problems, and to reserve fuller treatment for a subsequent 
occasion. It is hoped, however, that enough has been said to show the 
intimate relation of the various problems not only to the sister branches 
of geophysics represented by the other sections of the American Geo- 
physical Union, but also to the general subjects of physics, astronomy 
and geology. 
^ See Terrestrial Magnetism and Atmospheric Electricity, 9, 1904 (127, 128). 
2 Philosophical Magazine for December, 1919 (669-684). 
^Proceedings Royal Society, A, 95, 1918 (61-83); also Monthly Notices of R. A. S., 
Nov., 1918 (70-83); and Observatory, London, 42, No. 539, May, 1919 (196-206). 
4 See L. A. Bauer's "Resume of Observations Concerning the Solar Eclipse of May 29, 
1919, and the Einstein Effect," Science, March 26, 1920 (201-311). 
5 See article by S. J. Mauchly and A. Thomson, Terrestrial Magnetism and Atmos- 
pheric Electricity for June, 1920. 
