2S5 



body for some time from pursuing the course of its 

 gravity ? 



On the other hand, if the motion westward is real t 

 it seems to imply a plain contradiction : for no body 

 can realiy move eastward and westward at one and the 

 same time. 



But though the doctrine of projectiles could be recon- 

 ciled with the motion of the earth, yet what shall we say 

 of self-moving bodies ? That absolute motion which all 

 bodies are supposed to partake of, is not alledged to be 

 maintained iiithcin after they are separated from the earth, 

 by any other means than their vis inertia, or their retain- 

 ing the quantity of motion once impressed upon them. 

 Kon r no body can move in a direction opposite to its 

 vis inertice, till that is overcome. How is it conceivable 

 then, that birds, >r example, after they are separated 

 from the earth, where they acquired their absolute mo- 

 tion, should retain it all ] Certainly avery reluctation 

 of their's in an opposite direction, while on the wing, 

 must destroy part of their absolute motion, as they can- 

 not then have any fresh absolute motion communicated 

 to them. This should imply a great change in the phe- 

 nomena, with regard to the motion of self-moving bo- 

 dies : but in fact, all the phenomena are the same, as if 

 the earth were at rest. In short, the motion which bo- 

 dies have in common with the earth, is something which 

 no re-action has any effect on: therefore, it does not, 

 cannot depend upon the axioms of the present phi- 

 losophy. 



When we come to apply the theory of absolute mo- 

 tion to the secondary planets, in whatever light we con- 

 sider it, it becomes a matter utterly inconceivable, nay, 

 impossible. In the first place, 'we "know of no absolute 

 motion, communicated from greater to smaller bodies, 

 but where they are so intimately connected, that gravi- 

 tation at last, yea soon, destroys all their projectile mo- 

 tion. But such is the distance of the moon from the 

 earth, and so remote is their connection, that her gravi- 

 tation has never gained any thing upon her projectile 

 motion. 



