Continuity 15 



never ultimate but are satisfied with 

 very abstract propositions, and regard 

 mathematical equations as preferable to, 

 because safer than, mechanical analogies 

 or models. 



To use an acute and familiar expression of 

 Gustav Kirchhoff, it is the object of science 

 to describe natural phenomena, not to explain 

 them. When we have expressed by an equation 

 the correct relationship between different natural 

 phenomena we have gone as far as we safely can, 

 and if we go beyond we are entering on purely 

 speculative ground. 



But the modes of statement preferred 

 by those who distrust our power of going 

 correctly into detail are far from satis- 

 factory. Professor Schuster describes 

 and comments on them thus: 



Vagueness, which used to be recognised as 

 our great enemy, is now being enshrined as an 

 idol to be worshipped. We may never know 

 what constitutes atoms, or what is the real 

 structure of the ether; why trouble, therefore, 

 it is said, to find out more about them? Is it not 

 safer, on the contrary, to confine ourselves to a 

 general talk on entropy, luminiferous vectors, 



