J 



08 



A P P 1^ N D I X. Chap. I. 



which It both beguis and continues Motion, it Is, even upon that hy- 

 pothefis, impoffible that the Motion of the Planets Qiould be compound- 

 ed'; for, how can we conceive that a Planet, or any other Body, 

 not aaed upon by any external force, Ihould move itfelf two dif- 

 ferent ways at the fame time, and fliould not perform the circular 



or elliptical Motion, in the moft fmiple and dired manner? And 



fo much with refped to the Motion of the Planet round its centre. 



The Newtonians, unwilling to part with their favourite /^r^jVc:- 

 i'lon, gravitation, and centrifugal force, alledge that thefe muft at 

 lead take place in the diurnal Motion of the earth round its axis ; 

 for from that Motion it is evident that there refults a centrifugal 

 force, by which the Bodies upon the furface of the earth have a 

 tendency to fly off In the tangent. If they were not reftrained 



by the power of gravitation. But to this I anfwer, imo, That 



no argument drawn from the Motion of the earth, or any 

 other planet, upon its axis, can apply to the cafe of a Motion fo 

 different as tliat of the planet round the fun. 2^5, The centrifu- 

 "•al force, which makes Bodies upon the furface of the earth have a 

 tendency to fly off, is the very fame which makes the ftone in a 

 fling have that tendency ; and the two cafes are exadlly the fame : 

 Por in both It is the adion of Body upon Body, not the immediate 

 adion of Mind upon Body ; the fl:one, in the cafe of the fling, 

 being moved im.medlatcly by the fl:ring and the hand, and only me- 

 diately by Mind. In the fame manner, the Bodies upon the furface 

 of the earth are not immediately moved by Mind, but by the Earth 

 itfelf: For the Motion by Mind is upon that part of the earth that 

 is nearefl: to the centre, as the Motion by Mind, in the cafe of a 

 fling, is upon the extremity of the fling which is held in the hand 

 of the flingcr ; and the parts of the earth cohering together, as the 

 fl.ring of the fling does, the Bodies on the furface of the earth are 

 jnoved in the fame way as the fl:one is, that is, by the intervention 



