CHAPTER VII 



RADIO-ACTIVITY 



To watch the abysm-birth of elements. 



— Keats, Efidymion. 



Scientific investigation, which usually proceeds 

 unmarked by most of those not directly engaged 

 in it, is from time to time forced on the attention 

 of the public by some discovery of immediate and 

 striking advantage to mankind, or by the attain- 

 ment of some theoretical result, which, from its 

 novelty and interest, fires the imagination of 

 every thinking man. 



To those who follow closely the course of 

 research, these brilliant advances in knowledge 

 rarely come suddenly. The slow and patient 

 work of many observers through long years often 

 leads up to and suggests the particular step from 

 which follows, almost of necessity, the practical 

 application or the far - reaching theory. The 

 mathematical genius of Clerk Maxwell, the experi- 

 mental skill of Hertz, laid the foundations on 

 which, years afterwards, was reared the super- 

 structure of wireless telegraphy. The observa- 

 tions of Crookes, Lenard, J. J. Thomson, and 

 many others, on electric discharges through 

 rarified gases, had given to the physicist an 

 extended insight into the nature of these pheno- 

 mena, before Rontgen's almost accidental dis- 

 covery — that photographically active rays thus 



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