168 SUMMARY OF ELECTRON THEORY [CH. XVIIL 



Solar Corona, Magnetic Storms, and Aurorce. 



Another subject on which it is tempting to enlarge 

 is the explanation of various astronomical and 

 meteorological phenomena by the electron theory. 



The theory of Aurorse has recently been elaborated 

 by Arrhenius ; but the whole doctrine of emanations 

 from the sun, and of repulsion of small particles both 

 by his light and by his probable electrification, is a 

 matter that has been familiar to me for many years, 

 through conversation with FitzGerald and others. 

 See, for instance, Larmor, Phil. Trans., 1894, vol. 

 185, p. 813; Lodge on Sunspots, Magnetic Storms,. 

 Comets' Tails, Atmospheric Electricity, and Auroras, 

 in the Electrician for December 7, 1900, vol. 46, p. 

 250; FitzGerald, Electrician, December 14, 1900, 

 with reference to his review of a Heaviside volume in 

 1893 (Electrician, vol. 31, p. 390). See also Fitz- 

 Gerald's collected "Scientific Writings," at date 1882. 



The earth is in fact a target exposed to cathode 

 rays, or rather to electrons, emitted by a hot body, 

 viz. the sun. The sun is evidently intensely radio- 

 active : and the result of its discharge of electrons 

 into the approximate vacuum of its immediate 

 neighbourhood is not unlikely to be the appearance 

 known as the corona. The gradual accumulation 

 of negative electricity by the earth is a natural 

 consequence of this electron bombardment extending 

 to greater distances across space, where no residual 

 matter exists ; and the fact that the torrent of particles 

 constitutes an electric current of fair strength gives an 

 easy explanation of one class of magnetic storms ; 

 these storms having long been known, by the method 

 of concomitant variations, to be connected with sun- 

 spots and aurorse. The electric nuclei, when they 



