THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



SEPTEMBER 1910. 



* 



XXXIX. The Consequences of the Corpuscular Hypothesis 

 of the 7 and X Rays, and the. Range of /3 Rays. By 

 W, H. Bragg, ALA., F.R.S., Cavendish Professor of 

 Physics in the University of Leeds*. 



Introduction, 



IN the following pages I have first restated briefly the case 

 for the corpuscular hypothesis of the X and 7 rays. I 

 have then attempted to show the consequences to be 



(1) A simple view of the history of the X or 7 ray. 



(2) The absence of true secondary radiation. 



(3) A true additive principle in radioactive phenomena. 



(4) The absence of specular reflexion. 



(5) The inability of X and 7 rays to ionize directly ; the 



effect is indirect, the real agents being the secondary 

 cathode and (3 rays. 



(6) The general principle that if one radiant entity («, j3, 



7, X, or cathode ray) enters an atom, one and only 

 one entity emerges, carrying with it nearly all the 

 energy of the entering entity. 



(7) A natural division into three groups of the phenomena 



attending the passage of each radiant entity through 

 matter. These groups relate to {a) rectilinear move- 

 ments during which energy is spent so long as 

 ionization is being produced ; (b) special encounters 

 with atoms on account of which deflexions or scat- 

 terings take place without appreciable loss of energy; 

 (c) transformations (7 into /&, cathode into X, &c). 

 * Communicated by the Author. 

 Phil. May. S. G. Vol. 20. No. 117. Sept. 1910. 2 I) 



