jca DISSERTATION ON 



of fenfatlon and fponlaneous motion *, But of the heavens, I think, 

 ft is evident, he makes a machine, of which, mdeed, he fays the Deity- 

 is the contriver and fabricator, and the mover, too, if not immediate/}; 

 at leaft mediately y being ultimately the Author of all motion in the 

 univerfe : But the celeftial bodies, being once fct a-going, go on, he 

 fays, of themfclves, mechanically, without the interpofition of Deity, 

 except upon fome extraordinary occafions, when, for certain reafons 

 that he mentions, the machine may need the mending hand of the 

 Creator. With refpe<^, therefore, to the great operations of Nature, and. 

 by far the greater part of the vifible world, there is no Divine Provi- 

 dence, according to Sir Ifaac, conftantly operating ; and the Deity is as 

 much out of the univerfe as the Gods of Epicurus, whom that philofo- 

 pher has placed in certain extra-mundane fpaces, out of the hurry and 

 buftle of his worlds. A phiiofophy of this kind is, at leaft, a ftep to- 

 wards the difbelief of what I call the better part of Theilm, the Pro- 

 vidence of God ; and, if it be extended further, and brought down 

 from the fkies to this our earth, (and I fee no good reafon why it 

 ihould notj, it puts an end to it altogether. It therefore behoves not 

 only every good Chriflian, but every believer in the religion of Na- 

 ture, to examine very fcrupuloufly^ the principles of a phiiofophy which 

 lead to fuch confequences. 



Sir Ifaac's machine of the heavens, and which is exceedingly well 

 reprefented by the machine called an Orrery, is moved by two feveral 

 powers : The one is called the projefiile force^ which is an impulfe, 

 fuch as that by which one body impels another, and by which, there- 

 fore, the planet is neceflarily moved in a ftraight line : The other is 

 called attrat'tion^ or, as I would rather chufe to call it, granjitatioHy by 

 "which the planet is impelled towards its center ; and, from thefe two 

 forces com.bined, refults that motion in an ellipfis, by which the pla- 

 net is carried round its center ; and, as the projedile force, once im- 

 preflcd, continues for ever, and, as the motion towards the center, or 

 centripetal force, as it is called, is every inftant renewed, this elliptical 



motion, 



* Jnjine Principiorum. See page 275. of thia volume* 



