44 FERGUSON'S LECTURES. 



LECT. order to preserve that just balance which takes place 

 \^~v-^ among them. For, the planets being as inactive and 

 dead as the above balls, they could no more have put 

 themselves into motion than these balls can ; nor have 

 kept in their orbits without being balanced at first with 

 the greatest degree of exactness upon their common 

 center of gravity, by the Almighty hand that made them 

 and put them in motion. 



Perhaps it may be here asked, that since the center 

 of gravity between these balls must be supported by the 

 fork E in this experiment, what prop it is that supports 

 the center of gravity of the solar system, and conse- 

 quently bears the weight of all the bodies in it ; and by 

 what is the prop itself supported ? The answer is easy 

 and plain ; for the center of gravity of our balls must 

 be supported, because they gravitate towards the earth, 

 and would therefore fall to it : but as the sun and pla- 

 nets gravitate only towards one another, they have no- 

 thing else to fall to ; and therefore have no occasion for 

 any thing to support their common center of gravity : 

 and if they did not move round that center, and conse- 

 quently acquire a tendency to fly off from it by their 

 motions, their mutual attractions would soon bring them 

 together ; and so the whole would become one mass in 

 the sun : which would also be the case if their velocities 

 round the sun were not quick enough to create a cen- 

 trifugal force equal to the sun's attraction. 



But after all this nice adjustment, it appears evident 

 that the Deity cannot withdraw his regulating hand from 

 his works, and leave them to be solely governed by the 

 laws which he has impressed upon them at first. For if 

 he should once leave them so, their order would in time 

 come to an end ; because the planets must necessarily 

 disturb one another's motions by their mutual attrac- 

 tions, when several of them are in the same quarter of 

 the heavens ; as is often the case : and then, as they 



