Chap. I. APPENDIX. 309 



of another Body, and therefore have the fame centrifugal force, de- 

 rived from that law of Nature, by which a Body Impelled, and fet 

 in Motion, has a tendency to go on, and confequently, if reftralned 

 from going on, and made to move in a circle, mufl: have a centri- 

 fugal force *. 



m 

 Thus, 1 think, I have fhown, that the Newtonians cannot prove 



any of the three propofitions above mentioned, viz. imo^ That it is 

 impoffible, by the nature of things, that the Circular or Elliptical 

 Motion fhould be fimple and uncompounded ; 2^0, That, if it 

 were pofFible, the phaenomena would not anfwer, becaufe the Pla- 

 netary Motion, in that cafe, would not have the properties that we 

 know it has : And, laflly. That the Planets do adually gravitate 



towards the Sun. Therefore, I think, I have a light to conclude, 



that the Planetary Motion is fimple and uncompounded, confe- 

 quently no 'vis centriptta or centrifuga^ nor any gra'v'itation^ except 

 where, from fa6l and obfervation, we are fure it is, that is, upon 

 this earth j therefore there is no occafion for Sir Ifaac's Firft Law of 

 Motion, if it were true, nor for the hypothefis of a 'v'u infita in 

 Bodies, by which, of themfelves, and by a Power effential to their 

 nature, they continue in Motion without the agency of Mind : And, 

 if their fyftem of the Planetary Motion be laid afide, I think, mine 

 xnuft neceffarily take place, w^hich at leaft has the merit of being 

 perfectly fimple : For I fay That Body, by its nature, is altogether 

 inert, and that it has no njis at all in it, not even a ins incrtiae ; 

 a very improper exprefli£>n of the Newtonians, as 1 have clfewhere 



obferved : 



* Sir Ifaac accounts for the centdfugal force of the extremities of a wheel, by the 

 cohcfion of the parts of the wheel, as I do for the centrifugal force of Bodies upon 

 ' tlie furface of the earth, by the cohefion of the parts of the earth ; (See the pafTagc 

 quoted. Vol. i. p. 532.) : And the cafe of a wheel, I think, applies very well to the 

 (•a£e of the diurnal Motion of the earth, as the INIotion in both cafes priginates ft-om 

 the centre, and the extremities of both arc moved by their connetftion with the 

 centre. 



