THE CONSTITUTION OF NATURE. 11 



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

 directions, and a wader, as he approached the place of dis- 

 turbance, would be met by stronger and stronger waves. 

 This gradual augmentation of the impressions made upon 

 the wader's body is exactly analogous to the augmentation 

 of light when we approach a luminous source. In the one 

 case, however, the coarse common nerves of the body suf- 

 fice ; for the other we must have the finer optic nerve. But 

 suppose the water withdrawn; the action at a distance 

 would then cease, and, as far as the sense of touch is con- 

 cerned, the wader would be first rendered conscious of the 

 motion of the wheel by the actual 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 propa- 

 gation 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 round it, each again 

 rotating on its own axis ; and, finally, associated with some 

 of these planets we have dark bodies of minor note the 

 moons. Whether the other fixed stars have similar plane- 

 tary companions or not is to us a matter of pure conjecture, 

 which may or may not enter into our conception of the 

 universe. But, probably, every thoughtful person believes, 

 with regard to those distant suns, that there is in space 

 something besides our system on which they shine. 



Having thus obtained a general view of the present 

 condition of space, and of the bodies contained in it, we 

 may inquire whether things were so created at the begin- 

 ning. Was space furnished at once, "by the fiat of Omnipo- 



