MODEEN THEOKIES AS TO ELECTBICITY 293 



Ether, then, is not matter, but something on which many of the 

 properties of matter depend. 



It is curious to note that Newton conceived of a theory of gravita- 

 tion based on the ether, which he supposed to be more rare around 

 ordinary matter than in free space. But the above considerations 

 would cause the rejection of such a theory. We have absolutely no 

 adequate theory of gravitation as produced by ether. 



To explain magnetism, physicists usually look to some rotation in 

 the ether. The magnetic rotation of the plane of polarization of light 

 together with the fact of the mere rotation of ordinary matter, as 

 exemplified by the earth's magnetism, both point to rotation in the 

 ether as the cause of magnetism. A smoke ring gives, to some extent, 

 the modern idea of a magnetic line of force. It is a vortex filament 

 in the ether. 



Electrostatic action is more difficult to explain, and we have hardly 

 got further than the vague idea that it is due to some sort of elastic 

 yielding in the ether. 



Light and radiation in general are explained when we understand 

 clearly magnetic and electrostatic actions as the two are linked together 

 with certainty by MaxwelFs theory. 



Where is the genius who will give us an ether that will reconcile 

 all these phenomena with one another and show that they all come 

 from the properties of one simple fluid filling all space, the life-blood 

 of the universe the ether? 



