THEORIES OF AETHER AND ELECTRICITY. 



CHAPTEK I. 



THE THEORY OF THE AETHER IN THE SEVENTEENTH CENTURY. 



THE observation of the heavens, which has been pursued con- 

 tinually from the earliest ages, revealed to the ancients the 

 regularity of the planetary motions, and gave rise to the 

 conception of a universal order. Modern research, building on 

 this foundation, has shown how intimate is the connexion 

 between the different celestial bodies. They are formed of the 

 same kind of matter ; they are similar in origin and history ; 

 and across the vast spaces which divide them they hold 

 perpetual intercourse. 



Until the seventeenth century the only influence which was 

 known to be capable of passing from star to star was that of 

 light. Newton added to this the force of gravity ; and it is now 

 recognized that the power of communicating across vacuous 

 regions is possessed also by the electric and magnetic attractions. 



It is thus erroneous to regard the heavenly bodies as isolated 

 in vacant space; around and between them is an incessant 

 conveyance and transformation of energy. To the vehicle of this 

 activity the name aetlier has been given. 



The aether is the solitary tenant of the universe, save for 

 that infinitesimal fraction of space which is occupied by ordinary 

 matter. Hence arises a problem which has long engaged 

 attention, and is not yet completely solved : What relation 

 subsists between the medium which fills the interstellar void 

 and the condensations of matter that are scattered throughout 

 it? 



B 



