The Evolution of the Sciences 



panied by a stronger and more extensive 

 illumination of the corona. 



What then can be the mechanism of this 

 illumination? Is the atmosphere of the corona 

 to be likened to the attenuated gases in the 

 Geissler tube which are rendered luminous by 

 the action of electric discharges? Can these 

 electric discharges be Hertzian waves, like those 

 used in wireless telegraphy, but incomparably 

 more powerful? All these problems will no 

 doubt some day find their answer, especially if, 

 by any means, it were proved that radiations 

 of an electrical nature reach our atmosphere 

 from the sun. From this particular point of 

 view the question of the solar corona is con- 

 nected with that of the aurora borealis and 

 with the sudden variations of terrestrial mag- 

 netism, and perhaps at some future time one 

 and the same explanation may be found to 

 apply to these three orders of phenomena and 

 thus demonstrate the close interdependence of 

 all parts of the solar system. 



But the gaseous atmosphere of the corona 



is not the part which is most visible during 



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