PHYSICAL any LITERARY. 51 
a medium which prefles equally undeguaque or - 
quam proxime, will either remain at reft, or 
move with a very flow pace. But this is 
contrary to fact; for the acceleration of  fal- 
ling bodies, within the leaft perceivable di- 
ftance, is perceivable. 
THE power of gravity has a fingular pro- 
perty not commonly attended to, that its 
force is not {pent by being exerted upon any 
fingle body. Its whole force is exerted upon 
a multitude of bodies, all at the fame time. 
Thus,the earth tends at once both to the fun 
and moon ; and the whole force of its tend- 
ency is directed to each, juft as much as if 
the other were annihilated. Thus the fun is 
impelled towards the whole fyftem of pla- 
nets and comets ; and its total impulfe is di- 
rected upon every one of them at the fame 
inftant. It cannot fail to appear fingular 
_ and furprifing, to find a force exerted in fo 
many different and even oppofite directions 
at one time, without being diminithed by di- 
 vifion. Yet all this proceeds from one fingle 
property, that every particle of matter tends 
_ toevery other particle; and confequently, 
_ by encreafing the quantity of matter indefi- 
4 nitely, the fum of the tendencies of any one 
partic | 
