THE FINITE UNIVERSE 



substances of familiar and daily experience, so 

 these cathode particles, variously grouped, make 

 up the seventy or eighty different kinds of ele- 

 mental atoms. It is all so new that one gasps 

 a little, trying to realize the full import of this 

 discovery. If it is confirmed by future experi- 

 ments, there are not many events in the history of 

 science which may compare with it perhaps New- 

 ton's demonstration of the law of gravitation and 

 one or two others. Newton's achievement is de- 

 scribed in this fashion because a good many people 

 have an idea that Newton discovered gravity. 

 The latter was, in some sense, as well known to 

 Plato and to Archimedes and Aristarchus as it was 

 to Newton. So there have been millions of addled 

 heads filled with vague ideas of a primal substance. 

 What Professor J. J. Thomson has done is to 

 bring forward experimental proof. That is all 

 that counts. 



Whether the cathode particles turn out to be 

 urstoff or not, Professor Thomson's researches ap- 

 pear to have added a new physical constant of a 

 rather unexpected sort that is the natural unit 

 of electricity. The charged atoms in an electrically 

 conducting liquid all carry the same quantity of 

 electricity, or a simple multiple of that two or 

 three or four charges. In a word, a chain of rea- 

 soning quite similar to that which leads to the idea 



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