THE LAWS OF LIFE. 257 



around the sun, would have less than the actual 

 velocity, and would be, at the aphelion, momen- 

 tarily at rest. 



Two elements have to be supplied to bring the 

 hypothesis into accordance with the facts first, the 

 resistance which turns the gravitating motion into 

 the elliptic form, and secondly, the velocity of the 

 planet at the aphelion. Both of these are supplied 

 by supposing the planet to have gravitated through 

 a resisting medium from a greater distance. An 

 ordinary kite raised above the earth by being drawn 

 through the resisting atmosphere, sufficiently illus- 

 trates the principle upon which the argument is 

 based.* 



It is obvious tha* this hypothesis embraces also 

 the motions of the double stars. Two masses, gra- 

 vitating towards each other through a plenum, di- 

 verge as they approach, and falling beyond each 

 other, continue in a mutual revolution which is in 

 truth but a prolonged vibration. 



* This illustration is suffered to remain, for illustration's sake; 

 but I am aware that the best authorities deny that the velocity 

 really possessed by the planets could be thus derived. 



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