A HISTORY OF SCIENCE 



then, the physicist has dispossessed the many impon- 

 derables in favor of a single imponderable though the 

 word imponderable has been banished from his vocab- 

 ulary. In this view the ether which, considered as 

 a recognized scientific verity, is essentially a nineteenth- 

 century discovery is about the most interesting thing 

 in the universe. Something more as to its properties, 

 real or assumed, we shall have occasion to examine as 

 we turn to the obverse side of physics, which demands 

 our attention in the next chapter. 



