Continuity 37 



on the high velocity of its constituent 

 particles. The apparently discontinu- 

 ous emission of radiation is, I believe, 

 due to features in the real discontinuity 

 of matter. Disturbances inside an atom 

 appear to be essentially catastrophic; 

 a portion is liable to be ejected with 

 violence. There appears to be a critical 

 velocity below which ejection does not 

 take place; and, when it does, there also 

 occurs a sudden rearrangement of parts 

 which is presumably responsible for some 

 perceptible etherial radiation. Hence it 

 is, I suppose, that radiation comes off 

 in gushes or bursts ; and hence it appears 

 to consist of indivisible units. The 

 occasional phenomenon of new stars, as 

 compared with the steady orbital mo- 

 tion of the millions of recognised bodies, 

 may be suggested as an astronomical 

 analogue. 



The hypothesis of quanta was devised 

 to reconcile the law that the energy of a 

 group of colliding molecules must in the 

 long run be equally shared among all 

 their degrees of freedom, with the ob- 



