that the velocity of a falling body, as far a experiments have gone, will bear no sensible proportion to it. Therefore the effect ought

to be such as it is found to be.

Mr Maclaurin, from whom I have borrowed this objection, mentions it in very few words, and lays no great stress upon it. He thought it improper to determine any thing from hence concerning the cause of gravity*. And he seems to have judged rightly for whoever shall hence determine, that its cause is not mechanical, will undertake the proof of a very extraordinary negative; such as must imply, that he is a complete master of all natural science, acquainted with the utmost extent and power of those mechanical causes, which were contrived and established by a wisdom that comprehendeth all things.

* Maclaurin's Phil. Difcov. p. 241.

CHAP.

CHAP. IV.

An Examination of the Argument for a Vacuum, deduced from resistance and the vis inertia of bodies.

WE

E are now arrived at that part of the subject, where all the admirers of demonstration will expect to see me drop; that is, to the doctrine of a vacuum, and the theory of resistances, upon which it is founded. The learned gentlemen, who object to the sort of philosophy I am now recommending, know very well, without being reminded of it, that if they have proceeded without evidence in this matter, their whole fabric falls to the ground without farther trouble: and if I cannot shew that they have, I am willing to own that all I have yet said, or shall hereafter say, must, in their opinion, go for nothing.

Allowing then that there is a vacuum or void space in the world, their argument is very short, and will stand thus :-Bodies are observed to have motion in such a space; but that motion cannot be the effect of any

material

material cause, no such cause being present - to them.

Should we suppose this to be true, what a confused and heterogeneous mixture of solutions will it necessarily introduce into all our physical discourses? That God does in many cases govern the world by material agents, and conserve the motion of bodies by the activity of secondary causes, is beyond dispute, The support of animal life, by breath, the motion of a ship before the wind, of the sap in vegetables at the approach of the sun's light, of the mercury in a barometer by the pressure of the air, of the fluid in a thermometer by the expanding power of fire, of bodies impelled and driven off again by the flux and reflux of electrical ather, with innumerable other phænomena of nature, all conspire to establish this plain truth. And if it be an axiom in physics, that more causes are not employed where fewer will suffice, how comes it to pass, that those agents which confessedly minister to so many and great effects, are not sufficient for the producing of all? Shall we allow, that God governs the world by a subordinate agency and mechanism in some cases, where that agency appears to us; and deny it in

others,

others, merely because we have lost sight of it, or because it would make against us? A philosophy that labours under this difficulty, and is one while working with a material cause, and in the next breath with an immaterial one, be it ever so ingenioufly put together, will after all be liable to this grand exception, that at best it is inconsistent, and unworthy of God. Every body must see and know, that there are material causes acting in the world; and he that denies it, must deny his senses. If these causes are not sufficient to perform all the stated operations of nature, then the Creator hath made use of such means as are not proportionable to the end. If the Creator himself performs them by the immediate agency of his own substance, then is there no need of any other causes; they are all superfluous. But that there are other causes is abundantly evident; therefore they must be capable of answering their end, and every material effect will be immediately owing to a material cause. What I here say is grounded on this reasonable postulatum, if it may not rather be called an ariom, that the wisdom of God is consistent with itself in its operations, and that he wants neither power nor skill to

avoid the error of inconsistency: grant but this, and the argument amounts to a demonstration. I must confess, it appears to me to be so unanswerable, that if I could not take off the pretended evidence for a vacuum, I should nevertheless be satisfied that it was a sophism, and impute its whole force to a want of skill in myself to lay open and detect the fallacy of it. And now let us proceed to give it a particular consideration.

I have a manuscript-paper by me from a learned and ingenious gentleman of Cambridge, wherein the argument for a vacuum is stated very closely; and he will not be offended with me, if I take the liberty of setting it down in his own. words; for I know how to honour a man of parts and diligence, though we may happen to differ in some of our sentiments.

"You will hardly (says he) deny the vis "inertia of matter, which Sir Isaac Newton, "and every author, but the materialists "think demonstrably essential thereto, and proportionable to its quantity; and there

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fore, that it must hold equally in the most "subtile æther, as in the grossest matter. "Hence it follows, from the different degrees of resistance to bodies moving in different

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"mediums,