Scr. XXXV1U. GENERAL LAWS. 387 



force of gravitation are only lines of the second order. 

 The attraction of spheroids, according to any other law 

 of force than that of gravitation, would be raucji more 

 complicated ; and as it is easy to prove that matter might 

 have been moved according to an infinite variety of laws, 

 it may be concluded that gravitation must have been se- 

 lected by Divine Wisdom out of an infinity of others, as 

 being the most simple, and that which gives the great- 

 est stability to the celestial motions. 



It is a singular result of the simplicity of the laws of 

 nature, which admit only of the observation and com- 

 parison of ratios, that the gravitation and theory of the 

 motions of the celestial bodies are independent of their 

 absolute magnitudes and distances. Consequently, if all 

 the bodies of the solar system, their mutual distances, 

 and their velocities, were to diminish proportionally, they 

 would describe curves in all respects similar to those in 

 which they now move ; and the system might be suc : 

 cessively reduced to the smallest sensible dimensions, 

 and still exhibit the same appearances. We learn by 

 experience that a very different law of attraction pre- 

 vails when the particles of matter are placed within in- 

 appreciable distances from each other, as in chemical 

 and capillary attraction, the attraction of cohesion, and 

 molecular repulsion, yet it has been shown that in all 

 probability not only these, but even gravitation itself, is 

 only a particular case of the still more general principle 

 of electric action. 



The action of the gravitating force is not impeded by 

 the intervention even of the densest substances. If the 

 attraction of the sun for the center of the earth, and of 

 the hemisphere diametrically opposite to him, were di- 

 minished by a difficulty in penetrating the interposed 

 matter, the tides would be more obviously affected. Its 

 attraction is the same also, whatever the substances of 

 the celestial bodies may be ; for if the action of the sun 

 upon the earth differed by a millionth part from his ac- 

 tion upon the moon, the difference would occasion, a 

 periodical variation in the moon's parallax, whose maxi- 

 mum would be the T j of a second, and also a variation in 

 her longitude amounting to several seconds, a supposi- 

 tion proved to be impossible, by the agreement of theory 



