9th April, 1918. 



DISCONTINUITY IN THE PHENOMENA OF 

 RADIATION. 



By Mr. James Eice, M.A. 



The idea of continuity has been of supreme importance in 

 the development of all departments of Science. Let us be clear 

 at the outset as to what this idea implies. It certainly does not 

 preclude the possibility of sudden changes, i.e., changes in the 

 properties of bodies taking place at rates which are to be regarded 

 as very much greater than the normal values for such rates. To 

 take a simple example, the impact of two billiard balls offers an 

 illustration of the fact that a change may be sudden without 

 being discontinuous ; for we have no reason to suppose that the 

 laws of motion, to which the balls are subject at the other 

 periods of their motion, are inoperative during the brief interval 

 when they are in contact and their surfaces are being progressively 

 strained from their normal shapes and restored to it. A dis- 

 continuity in a natural occurrence implies the existence of a 

 period of time, long or short, in which laws, previously assumed 

 to be of a general character, are found to fail and cease to explain 

 the occurrence in a manner consistent with established principles. 



It is in the realm of Biology that the notion of continuity 

 has made its most signal contribution to the advancement of 

 science. The assumption of the evolutionary growth of all living 

 forms from protoplasm without the intervention of "special 

 creations " is the most striking example of the application of the 

 principle of continuity to which one can direct the attention of a 

 general audience. Yet even in this department of science pheno- 

 mena in which discontinuities appear to be present have been 

 plentiful ; so much so that the particular theory of variation of 

 species which is associated with the name of Darwin has had to 



