NDEJffiD, • 



THE 

 LONDON, EDINBURGH, akd DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



OCTOBER 1907. 



XLI. On the Properties and Natures of various Electric 

 Radiations. By W. H. Bragg, M.A., F.E.S.. Elder 

 Professor of Mathematics and Physics in the University of 

 Adelaide *. 



WE are now aware of the existence of a number of 

 different types of radiation, each of which is able to 

 ionize a gas, to act on a photographic plate, and to excite 

 phosphorescence in certain materials. Of these the a and 

 caual rays consist of positively charged particles of atomic 

 magnitude; the cathode and ft rays are negative rays, and 

 consist of electrons ; the X and 7 rays are supposed to be 

 aether pulses ; and ultra- violet light consists of short aether 

 waves. The 8 rays stand by themselves, for, though they 

 consist of negative electrons like the cathode and ft rays, 

 they have so small a velocity that they possess no appreciable 

 ionizing powers. 



The present paper contains, in the first place, an attempt 

 to find whether there is anything to be learnt from a com- 

 parison of the properties of the various rays ; and, in the 

 second place, a discussion of the possibility that the 7 and X 

 rays may be of a material nature. 



* Communicated by the Author. .Read before the Royal Society of 

 South Australia in two parts ; the first on May 7, 1907, "the second on 

 June 4, 1907. 



Phil. Mag. S. 6. Vol. 14. Xo. $2. Oct. 1907. 2 G 



