SUN AND THE EARTH'S MAGNETIC FIELD — FLEMING 207 



through the use of high voltages with the electrostatic generator and 

 the cyclotron and at high pressures ma)' give better understanding 

 of relations between the constant generation of subatomic forces in 

 the sun and their terrestrial effects. 



CONCLUSION 



In conclusion, may I hope to have left with you some impression of 

 the interrelationships between the ever changing but quiet variations 

 of the earth's magnetic field and the swirling, tumultuous events on the 

 sun. These interrelationships have made possible the electrical ex- 

 ploration of the high atmosphere far above the limits accessible to air- 

 craft. Less than a decade ago this was thought to be beyond human 

 attainment, and hopes of such exploration forecast by Balfour 

 Stewart, Kennelly, and Heaviside existed only in the speculations of 

 intrepid, persistent scientific investigators. Another great step has 

 tlius been taken toward definite knowledge of the intimate relations 

 between the earth and the sun which play so material a part in our 

 lives. Upon that step even now plans are rapidly developing for ac- 

 curate magnetic exploration at equally great heights to supply the 

 third dimension of the geomagnetic field so long sought to aid in the 

 explanation of the origin of that field. 



Today geomagnetism maintains its key position as a thriving 

 branch of geophysics, not only because of its own intrinsic interest, 

 but mainly because geomagnetic conditions give a complete, a faithful, 

 and an intelligible record of those mighty solar and cosmical influences 

 to which the earth and its inhabitants are subjected. We may well 

 agree with the recent statement of an eminent scholar of earth physics 

 that "as in all branches of science where growth is active, we are only 

 partly satisfied with the new knowledge gained ; long vistas of unex- 

 plored territory invite us onward to 'fresh fields and pastures new.' " 



RECENT LITERATURE PERTAINING TO THE SUN AND 

 THE EARTHS MAGNETISM 



Bekknee, L. v., and McNish, A. G. 



1938. The ephemeral variations of the earth's magnetism. Cooperation in 

 Research, Carnegie Inst. Washington, Publ. No. 501, pp. 223-247. 

 Chapman, S. 



1941a. The sun and tlie ionosphere. Journ. Inst. Electr. Eng., vol. 88, 



pt. 1, No. 11, pp. 400-413. 

 1941b. Charles Chree and his work on geomagnetism. Proc. Phys. Soc, 

 vol. 53, pp. 629-657. London. 

 Chapman, S., and Bartels, J. 



1940. Geomagnetism. 2 vols. Clarendon Press, Oxford. 



