250 CARNEGIE INSTITUTION OF WASHINGTON. 



much less in the case of atmospheric electricity than in that of terrestrial 

 magnetism." The conclusion^ referred to by Dr. Chree is that the potential 

 gradient of atmospheric electricity apparently varies during the sun-spot 

 cycle, increasing with increased sun-spot activity, and that the diurnal range 

 of the potential gradient of atmospheric electricity, like the diurnal range 

 of terrestrial magnetism, increases with increased sun-spot activity. 



If there is a relationship between solar activity and atmospheric electricity, 

 it ought to turn out to be a world-wide phenomenon, just as in the case of the 

 recognized relationship between solar activity and terrestrial magnetism. 

 This fact is to be kept in mind, that disturbances, because of local conditions, 

 play a far more predominant role in atmospheric electricity than in ter- 

 restrial magnetism, and may in fact be of such a character as to mask com- 

 pletely any world-wide effect. Accordingly, in atmospheric electricity a very 

 careful selection of stations is necessary for the study of world-wide phenomena. 



After further discussion of the available data, the author concludes : The 

 relationship between sun-spot activity and atmospheric electricity turns 

 out to be, for locally undisturbed stations, as definite as in the case of terres- 

 trial magnetism; the sun-spot influence on the periodic variations of the 

 atmospheric potential gradient is, in general, as great as on the periodic vari- 

 ations of terrestrial magnetism; and as concerns the effects on the absolute 

 values, the sun-spot influence is about 300 times greater in atmospheric 

 electricity than in terrestrial magnetism. The potential gradient of atmos- 

 pheric electricity, and, presumably, the Earth's total negative electric 

 charge, is furthermore subject to an annual or secular change, which may 

 vary in magnitude and sign from one sun-spot cycle to another. 



Transactions of the Rome meeting, May 1922, of the Section of Terrestrial Magnetism and 

 Electricity of the International Geodetic and Geophysical Union. Edited 

 by Louis A. Bauer, Secretary and Director of Central Bureau. Bulletin No. 

 3, 182+viii pages, 3 plates (October 1923). Johns Hopkins Press, Baltimore. 



This volume, containing the transactions of the Rome meeting in May 

 1922 of the Section of Terrestrial Magnetism and Electricity of the Inter- 

 national Geodetic and Geophysical Union, constitutes Bulletin No. 3 of pub- 

 lications by that section. The volume is divided into three parts: Part I, 

 statutes and organization; Part II, reports and communications at the Rome 

 meeting under the subdivisions (a) status of magnetic surveys in 1922, (6) 

 status of observatory work in 1922, (c) magnetic instruments and methods, 

 (d) magnetic curves and characterization, (e) on questions of the agenda, 

 and (/) communications on terrestrial electricity; and Part III, proceedings 

 and minutes of the Rome meeting. 



Earth-current observations by the Department of Terrestrial Magnetism. Louis A. 



Bauer. Bull. 3 Sect. Terr. Mag. and Electr., Internat. Geod. Geophys. 



Union, 1.53 (October 1923). 

 Report of the Chairman of Committee on Comparisons of Magnetic Instruments and 



Methods of Absolute Magnetic Measurements. Louis A. Bauer. Bull. 



3, Sect. Terr. Mag. and Electr., Internat. Geod. Geophys. Union, 75-76 



(October 1923). 

 Report of Secretary and Director of Central Magnetic Bureau, 1919-1922. Louis A. Bauer. 



Bull. 3. Sect. Terr. Mag. and Electr., Internat. Geod. Geophys. Union, 



159-160 (October 1923). 

 On magnetic standards and comparisons of the Department of Terrestrial Magnetism. 



Louis A. Bauer and J. A. Fleming. Bull. 3, Sect. Terr. Mag. and Electr., 



Internat. Geod. Geophys. Union, 84-97 (October 1923). 



This report includes the results of extensive comparisons of magnetic 

 standards at observatories obtained during 1922 and the early part of 1923 

 by the Department. In its final form, it summarizes (1) the data and 



1 Terr. Mag., vol. 27, 30 (March- June 1922); see conclusion (/). 



