NOMOS. 103 



position differed only 52' from the position as- 

 signed by M. Leverier, and only 2 27' from that 

 determined by Mr. Adams, and only 47' from the 

 mean of the two calculations. Now those calcula- 

 tions were made upon the assumption that the law 

 of gravitation was universal, and the prophetic result 

 is therefore thought to be a convincing proof of this 

 universality. 



The sun, moreover, is considered to be the subject 

 of the same law, for his centre is found to move in an 

 orbit in which the original projection is modified by 

 the united influence of the several bodies which circu- 

 late around him. So are the comets, whether these 

 be permanent members or occasional visitants of 

 our system ; and so, apparently, are the stars them- 

 selves. But at each successive step outwards the 

 difficulties of the demonstration accumulate, from 

 the want of data, from the number of perturbing 

 causes, from the inconceivable vastness of the dis- 

 tance, and so on ; but as far as we can go with cer- 

 tainty, so far the evidence is not wanting. 



This, then, is the conclusion up to this point 

 that all bodies and all parts of bodies attract each 

 other with a force which is inversely proportional to 

 the square of the distance. But this is not all. We 

 have already seen that the attractive power of the 

 sun is greater than that of the earth, and this is only 

 one instance out of many of similar differences in 

 this respect. Measured in feet, indeed, a body falls 

 through 16-08 feet in the first second at the Earth, 

 through 8-04 feet at Mercury, through 14*63 feet at 

 Venus, through 8-04 feet at Mars, through 39-40 feet 



H 4 



