Chap. 4.] Laws of Gravitation. 25 



gate of matter, is fuppofed to deftroy the effect of this 

 attraction between fmaller bodies, by forcibly compel- 

 ling them to itfelf. The attraction of mountains, how- 

 ever, upon the balls of pendulums has been found, by 

 repeated obfervations, to be very confiderable *. 



The efficient caufe of this fpecies of attraction is as 

 much a fecret as all the other great principles of na- 

 ture. Some philofophers have fuppofed gravity to be 

 one of the inherent properties of matter ; others have 

 afcribed it to the*~agency of a fubtile fluid; while others, 

 with more modefty, and probably with more truth, 

 have had recourfe to the immediate agency and inter- 

 pofition of the divine power. 



We are generally on fure ground when we defcribe 

 effects. Ignorant as we neceffarily are of the caufes 

 or inftruments by which the fupreme governor of the 

 univerfe effects his purpofes, an attentive obfervation 

 will commonly furniih us with the obvious mode 1 in 

 which they generally take place. What philofophers 

 term the laws of nature, are no other than the modes 

 or forms in which her operations are ufually effected , 

 and this is precifely the cafe with what are called the 

 laws or properties of gravitation. 



Firft, It appears that the gravitating force being 

 proportioned always to the quantity of matter, all bo- 

 dies gravitate from equal diftances with equal velocity, 

 except prevented or impeded by fome refilling me- 

 dium. Thus, though a guinea and a feather will not 

 fall to the ground with equal velocity in the open air, 

 becaufe of the refiftance of that fluid; yet if the air by 

 any means is removed, as in the vacuum of an air 

 pump, they appear to fall at the very fame inflant of 

 time: for though the guinea contains confiderably 



* Nicholfon's IntroJ. to Nat. Phil. V. i. p. 26. 



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