284 



or any figure, ever prove the gravitation, which is con- 

 tinually wasting and spinning out into a cobweb thread, 

 will at any point recover a superiority to the projectile 

 force, and grow at last a cable, massy and powerful 

 enough to bring home the wandering star again. 



14. I would add some thoughts on the motion of the 

 satellites. It is no wonder that notwithstanding all the 

 arguments for the motion of the ear ih, yet the greatest 

 part of astronomers have not pronounced it absolutely 

 certain, but only probable in a high degree. Among the 

 perplexities which attend this highly probable system, 

 the doctrine of alsolute motion is not the smallest. It 

 is certain all the phenomena of relative motion, ure the 

 very same as if the earth were at rest. And it is not 

 easy to conceive how this can possibly be, on the suppo- 

 sition of the earth's motion. 



The phenomena of bodies moving in the same direc- 

 tion with the absolute motion of the earth may be com- 

 prehended : that motion of bodies cross the absolute 

 motion of the earth is also intelligible. But it is no 

 easy matter to satisfy one's self about the phenomena 

 of bodies moving westward, or in an opposite direction 

 to that of absolute motion. If we should suppose that 

 a ball fired pointed blank west, does not really move 

 westward, but it is only resisted by the explosion from 

 moving so fast east as the earth goes in her absolute 

 course ; may it not be asked, What is it that keeps the 

 ball suspended, while the earth proceeds in her absolute 

 motion ] For the resistance given to the progressive 

 motion of the ball, can be no resistance to its following 

 the course of its gravity : as we have no example to ex- 

 plain how resistance applied horizontally will prevent a 

 body's falling to the ground in the same time as if it 

 was not so resisted. If the ball's absolute motion is 

 only the force of its vis inertice, derived from the earth's 

 motion, and its apparent motion in a contrary direction 

 is only from another vis inertice, derived from the ex- 

 plosion. What possible conception can be framed of 

 the ttvo opposite vis inertite's, acting so as to prevent a 



