KINETIC OK MECHANICAL VIKW uK NATURE. 89 



reflexion and refraction and other properties are con- 

 cerned. Luminous waves are now considered !)>- many 

 physicists to be merely electro-magnetic waves of short 

 wave length and great frequency, such as the organ of 

 vision is capable of perceiving in the form of light. 

 The electric and magnetic medium is identical with the 

 luminiferous ether, postulated by Young and Fresnel, 

 and rays of light are merely an electric uiid magnetic 

 disturbance propagated as a periodic or wave motion. 



These discoveries and theories have gone a long m. 



. . Destructive 



wav to destroy the older astronomical view or natural .met ut 



•' '' the new 



phenomena, which explained many effects by the action [};^;"J^jJ^°" 

 at a distance of particles of ponderable or imponderable "lewT' 

 matter. The firm conviction has taken hold of the 

 modern scientific intellect or imagination that space is a 

 plenum tilled with a continuous medium, and that the 

 undoubted atomic nature of ponderable matter may be 

 owino- merely to a specific and unmoditiable form of 

 motion with such properties as Lord Kelvin has shown 

 to belong to vortex lilaments. The ditticulty still re- 

 mains how to explain the phenomenon of gravitation as 

 well as the increased amount of inertia or mass which 

 belongs to all ponderable matter as compared with that 

 material substance which we call ether. 



The reason why Maxwell abandoned his earlier 

 schemes, in which he tried to construct a mechanical 

 model of the electro-magnetic field, is not quite clear.^ 

 The idea has, however, been taken up by others, and 

 elaborate descriptions have been attempted, by whifh the 



1 A suggestion regarding this is given by Dr J. Laruior in ' .Etiier and 

 Matter,' p. 28. 



