CHAPTER IX 



THE ETHER 



It may well be asked, " What is the ether, and 

 why is the ether ? " Yet no questions are more 

 difficult to answer. The ether seems at once 

 everything and nothing ; it is so pervasive that it 

 fills infinitude, and it is so evasive that Lord 

 Salisbury once said that it was nothing more than 

 the nominative case of the verb to undulate. It 

 is essentially that which undulates ; and according 

 to the nature of the undulations it appears in our 

 consciousness as the phenomena light, heat, 

 electricity. These phenomena appear to have 

 periodicity in space and time, like waves in a fluid ; 

 and therefore it has been assumed that they are 

 waves of somethings and this something is called 

 ether, and is given various properties to account 

 for the particular behaviour of its undulations. 

 Of late years ether has also been used to account 

 for gravitation, on hydrodynamical principles. But 

 scientists have found a good deal of difficulty in 



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