THE SPIRIT-RAPPERS 



the most useful of our acquired weapons ; they will 

 discharge an electroscope, which serves us for a 

 lacking electrical sense ; they are twisted and turned, 

 pushed or pulled, by a magnet, which supplies our 

 absent magnetic sense; they produce a variety of 

 chemical effects they may produce burns and viru- 

 lent sores, they color glass, generate ozone, make the 

 air and other gases good conductors of electricity, 

 and even transport large quantities of the latter 

 from point to point themselves; for these "radia- 

 tions" are clearly matter, and not merely a new form 

 of ether vibrations, like light. Finally, a way has 

 been found to weigh and count these particles, com- 

 pute their speed, likewise their electrical capacity ; 

 and other of their physical properties are known. 



In short, in four or five years we have learned to 

 know almost as much of these substances which lie 

 out of the reach of our natural senses as though we 

 could taste and see and handle them, like sugar or 

 sand. 



Yet their existence even was not so much as sus- 

 pected until we had come to devise and use instru- 

 ments and processes unknown to Sir Isaac New- 

 ton's age. Until the development of the sciences 

 of chemistry and electricity, and magnetism, and 

 photography, and the physics of molecules, Bec- 

 querel's discovery would not merely have been 

 useless but impossible. It cannot be doubted thru 



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