THE CONSTITUTION OF NATUKE. 5 



over, once heated there, would continue for ever heated ; 

 a sun or planet once molten, would continue for ever 

 molten. For, the loss of heat being simply the ab- 

 straction of molecular motion by the ether, where this 

 medium is absent no cooling could occur. A sentient 

 being on approaching a heated body in this region, 

 would be conscious of no augmentation of temperature. 

 The gradations of warmth dependent on the laws of 

 radiation would not exist, and actual contact would 

 first reveal the heat of an extra ethereal sun. 



Imagine a paddle-wheel placed in water and caused 

 io rotate. From it, as a centre, waves would issue in 

 all directions, and a wader as he approached the place 

 of disturbance would be met by stronger and stronger 

 waves. This gradual augmentation of the impression 

 made upon the wader is exactly analogous to the aug- 

 mentation of light when we approach a luminous 

 source. In the one case, however, the coarse common 

 nerves of the body suffice; for the other we must have 

 the finer optic nerve. But suppose the water with- 

 drawn; the action at a distance would then cease, and, 

 as far as the sense of touch is concerned, the wader 

 would be first rendered conscious of the motion of the 

 wheel by the blow of the paddles. The transference of 

 motion from the paddles to the water is mechanically 

 similar to the transference of molecular motion from 

 the heated body to the ether; and the propagation of 

 waves through the liquid is mechanically similar to the 

 propagation of light and radiant heat. 



As far as our knowledge of space extends, we are 

 to conceive it as the holder of the luminiferous ether, 

 through which are interspersed, at enormous distances 

 apart, the ponderous nuclei of the stars. Associated 

 with the star that most concerns us we have a group 

 of dark planetary masses revolving at various distances 



