THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERI£&] <0 



a 



\" 



SEP TEMBER\~pdU. 



V 



XXXVII. The Connexion betiveen the /3\q&.$ Raiyfepectra. 

 By Sir Ernest Rutherford, F.E.S., Profe^siffof Physics, 

 University of Manchester *. 



THE problem of the nature of emission and absorption of 

 radiation has occupied a very prominent position in 

 modern Physics, both on account of its outstanding- importance 

 and of the great difficulties involved. It is clear that the 

 question of the excitation of X rays and their conversion 

 into /3 rays, and also the spontaneous emission of {3 and 

 7 rays from radioactive substances, must be included in any 

 general theory of radiation. A study of the /3 and 7 rays 

 from radioactive matter is of especial interest in this con- 

 nexion, since the/3 rays are expelled with a very high velocity 

 and a considerable fraction of the energy is emitted in the 

 form of 7 rays of very short wave-length. It is to be 

 anticipated that a close study of the emission of these 

 radiations from radioactive bodies should throw light of a 

 fundamental character on the radiation problem on the high 

 frequency side. 



During the last few years a number of careful investi- 

 gations have been made in this Laboratory bearing on this 

 problem, and it may prove of interest to discuss briefiv the 

 evidence that has so far been obtained and to indicate 

 the general conclusions that can be drawn from it. The 

 problem is much too large and involved to hope for an 



* Conimuuicated by the Author. 

 Phil Mag. S. 6. Vol. 28. No. 1.65. Sept. 1914. X 



