CHAPTER VII 



ELECTRONS AND THE AURORA BOREALIS 



The theory of the part probably played by electrons 

 in the production of the phenomenon known as the 

 aurora borealis is one of the most interesting of 

 scientific hypotheses. Regarded in the light of 

 this theory, the aurora borealis may be considered 

 a beautiful demonstration on a large scale of the 

 unity of natural law — indeed, it may be deemed 

 the magnificent luminous signature of the sun to 

 the balance-sheet of the laboratory. 



According to latest scientific theory, the explana- 

 tion of the aurora borealis is as follows : — 



The spectrum of the aurora borealis shows 

 that it is largely produced by the vibrating mole- 

 cules of argon, krypton, xenon, neon, and other 

 rare gases of the air, which, for reasons into which 

 we need not now enter, are likely to collect in the 

 upper layers of the atmosphere. By putting these 

 gases in a Crookes tube and passing an electric 

 current through them we can produce a very 



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