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CHAPTER IV. 



SEQUEL TO THE EPOCH OF NEWTON, CONTINUED. 

 VERIFICATION AND COMPLETION OF THE NEWTO- 

 NIAN THEORY. 



Sect. 1. Division of the Subject. 



THE verification of the law of universal gravi- 

 tation as the governing principle of all cos- 

 mical phenomena, led, as we have already stated, 

 to a number of different lines of research, all long 

 and difficult. Of these we may treat successively, the 

 motions of the Moon, of the Sun, of the Planets, 

 of the Satellites, of Comets; we may also consider 

 separately the Secular Inequalities, which at first 

 sight appear to follow a different law from the 

 other changes ; we may then speak of the results 

 of the principle as they affect this Earth, in its 

 Figure, in the amount of Gravity at different places, 

 and in the phenomena of the Tides. Each of these 

 subjects has lent its aid to confirm the general law ; 

 but in each the confirmation has had its peculiar 

 difficulties, and has its separate history. Our sketch 

 of this history must be very rapid, for our aim 

 is only to show what is the kind and course of 

 the confirmation which such a theory demands and 

 receives. 



