us.

-They pretended to give no evidence for this affertion, but the difciples of each party had recourfe to the Ipfe dixit of their mafter; our philofophers produce no agents fufficient to perform the actions they fay are done, but expect we should take their words, and ask no questions.We have got no farther, by the help of gravity, than the poor Indian philofopher did, by means of his elephant, which he found out to support the earth. -But what fupports this elephant?-Oh!-a tortoife! Sir Ifaac Newton too, not to be behind hand in difcoveries, has provided a tortoise to support his elephant; though it is generally thought the building is weakened by this underprop, and that the first is a queftion not to be answered.

BUT I fhall be told, that the existence of these powers, attraction and gravity, is confirmed by repeated experiments, and the deductions from them mathematically proved.

But what is confirmed by repeated experiments?

periments? Only an effect of fome unknown cause.A ftone defcends to the earth ; the earth is carried round the fun; the moon round the earth; and fo of the planets, which are carried in their orbits round the fun, and their fatellites round each of them. This effect we call gravity, and attraction, or the attraction of gravity: but fympathy, or any other term, will serve as well; and the phenomena will as much prove that fympathy is the power which acts, and that all things fympathize to each other, as that they gravitate to each other. One thing tending to another, does not prove that the tendency is in the body tending or tended to; because it may be pushed or impelled by a force ab extra. And this, in reality, is the point in debate between the Newtonian and Mofaic philofophy, viz. Whether the power which makes things gravitate is inherent in matter itself? or, Whether the air, in its different conditions of light and fpirit, does not act upon every the least particle of matter, and press and impel each to each other?

INDEED the efpousers of Sir Ifaac's philosophy seem now fenfible of the absurdity of the doctrine of attraction. And the ingenious Mr Maclaurin, who is the last perfon that has undertaken to clear him of that abfurdity, acquaints us, "That Sir Ifaac

never imagined that bodies could attract "each other, without being impelled or "acted upon by other bodies;- that he

never affirms or infinuates, that a body "can act upon another at a distance, but by the intervention of other bodies; and "that he has plainly fignified, that he thought those powers arofe from the impulfes of a fubtile ethereal medium that " is diffufed over the universe, and pene"trates the pores of groffer bodies that "it appears from his letters to Mr Boyle, "that this was his opinion early; and if he

did not publish it fooner, it proceeded "from hence, that he found he was not "able from experiments and obfervation to

give a fatisfactory account of this me

dium, and the manner of its operation, "in producing the chief phenomena of na"ture.". -But where has he published

this his opinion, except only by way of query? and this in direct contradiction to his Principia. And even this is done, after the manner of his famous Greek and Phonician philosophers, tacitly. For in the first edition of his Principia, 1687, there is no mention of his subtile spirit: and in his other editions, although he sometimes fays, that, for ought he knows, gravity may be caused by impulse; and, at the end of his book, talks about a most subtile spirit penetrating, and lying hid in bodies; yet in his calculations and demonftrations throughout the Principia, he neglects the confideration of this medium, and fuppofes the planets to move by gravity, in places void of all fenfible resistance, and confequently void of all fenfible matter.

FROM whence it is evident, he could not there nor then confider gravity as the impulse of any medium; because a medium which cannot refift, cannot impel; and a medium that can impel, must likewise refift. And though, in his Optics, he introduces an ethereal medium, yet he rejects a dense one; although

although he could not be ignorant, that it is the dense or groffer part of the aereal medium which is the caufe of motion to fuch bodies as are confeffedly moved by the fluid of the air.It is the denfe or groffer parts of the aereal fluid that impel the bullet from the wind-gun.It is the dense or groffer parts that impel, and continue a ship under fail in motion.It is the dense or groffer parts of the air which rush into those which are thinned by the firing of gun-powder, and purfue and carry the ball.

AND, from Mr Cotes's preface to the second edition of the Principia, it is very eafy to gather, that it was not then designed that gravity fhould be looked upon as caufed by the impulfes of any medium: for the points he labours. to establish, are the impoffibility of motion in a plenum by impulse of a fluid medium, and consequently the neceffity of a vacuum; and to divest people of the notion they had then got into their heads, that gravity was no better than one of the occult qualities of the fchoolmen. "There can be no room for

"the