the former, are more promoted by the obfervation of facts, ⚫ than by the moft ingenious reafonings and difputations. To a diligent, and even fometimes to a careless enquirer, many valuable experiments, no doubt, occur; and thefe would enrich our collections, tho' without this method of convey⚫ance, they would be entirely loft to the public. The united judgments too of men, correct and confirm each other by ⚫ communication; their frequent intercourfe excites emulation, and from the comparison of different phænomena, remarked by different perfons, there often refult general truths, of which, from one of thefe phænomena, no man of the greatest fagacity could entertain any fufpicion. Tho' the collection of experiments feems continually, by means of the learned focieties, and the labours of individuals, to be • augmenting, we need not entertain any apprehenfions, that ⚫ the world will ever be overwhelmed by the number of con• fused and independent obfervations. The heap does not always go on increafing in bulk and diforder, through every age. There arife from time to time bold and happy genuifes, who introduce method and fimplicity into particular branches of fcience; and reducing the fcattered experiments to more general theorems, abridge the science of nature. Hints of this kind, we hope, may pafs through our hands; and at worft our collections will be a fpecies of magazine, in which ⚫ facts and obfervations, the fole means of true induction, will be depofited for the purposes of philofophy.'

Having given this fhort account of the establishment and views of this fociety, we shall now proceed to the work itself, which confifts of twenty-two articles; the firft of which is, Of the laws of motion; by the hon. Henry H me, efq; one of the fenators of the college of justice.

The author of this diflertation has endeavoured to prove, that matter is endowed with an active quality, and on that principle accounts for all the phænomena obfervable in moving bodies. He obferves, that when a being moves itself, or moves, we conceive the being as acting, and in this view motion is a species of action. But when a body is moved by being acted upon, we conceive the motion of the body as an effect produced by a proper caufe. In this cafe, the body does not act, but is acted upon. This, tho' an evident diftinétion, does not exclude self-motion from being alfo confidered as an effect in a certain light, viz. An effect produced by a being upon it elf. He also observes, that every thing which moves, and is not

barely

barely moved or acted upon, must be endued with a power of

motion.

Mr. Home then proceeds to examine this famous question, • Whether matter in any cafe be endued with a power of motion?' and determines it in the affirmative. We shall give the fubftance of his reafoning on this head, and, as near as poffible, in his own words.

Matter, he obferves, is generally reprefented as altogether unactive and inert; and, indeed, in a fuperficial view, the fact appears to be fo. The bulk of the things about us, feem to be at reft, and we fuppofe they will continue in that state, unless acted upon by fome external force. If we lock up any moveable object, we truft to find it in the fame place; and, if miffing, we afcribe our lofs to thieves, not to felf-motion in the body. Matter, fo far as we can difcover, is certainly not endued with thought or voluntary motion; and yet, that it is endued with a power of motion in certain circumstances, appears to me an extreme clear point. Dropping a ftone from an high tower, it falls to the ground without any external impulfe, fo far as we can difcover. Here is an effect produced, which every one, who has not ftudied philofophy, will attribute to a power in the ftone itself. One would not hesttate to draw this conclufion, fhould the ftone move upwards; and yet, fetting afide habit and cuftom, it will be evident, that a stone can as little move downwards as upwards, without a vis motrix. And that this is a just as well as natural way of thinking, will appear by analogy. When a man is in motion, we readily afcribe the effect produced to a power, which he poffeffes to move his limbs. Why then do philofophers deny to the ftone, in the act of falling, the power of beginning motion, a power which they fo readily afcribe to the man? If it be objected, that man is endowed with a power of moving himself, and of moving other things, the plain anfwer is, that these are facts which we learn no other way than by experience; and we have the fame experience for a voucher, that a ftone fet free in the air will move itself. And if it be farther urged, that man is a thinking being, the anfwer will readily occur, that a power of beginning visible motion is no more connected with a power of thinking, than it is with any other property of matter or fpirit. Nay, Mr. Locke holds, that matter may be endowed with a power of thinking; and, fuppofing this power fuperadded to the other properties of matter, it cannot be maintained, that matter would be rendered thereby more or lefs capable of beginning or continuing visible motion,

But

1

But this is not the only inftance in which we difcover an agency or active power in matter. A billiard-ball ftruck against the ground, rebounds with a confiderable force. A bow bent by the hand, reftores itself with violence when the ftring is let go. In both there is an inftant of reft betwixt the oppofite direction of the motion. The ball rebounds, and the bow reftores itself to its former shape, without any external force, by an inherent power, which is known by the name of elasticity. But we need not dwell upon particular inftances. Chemistry difcovers various powers in matter of the most active kind; and every man who is converfant with the operations of chemistry, must have a ftrong impreffion, that matter is extremely active.

For the fake of illuftration, let us fuppofe a fubftance or thing having the following properties; that it makes no refiftance to bodies impinging upon it; that when carried along in a man's hand, even with the most violent motion, it does not increase the momentum of the hand, and that it stops short the inftant the hand ceases to move. This would certainly be the most inert of all conceiveable things. And if fo, matter cannot be abfolutely inert or paffive, when its properties differ fo widely from thofe defcribed. In many circumftances matter begins motion, and acts often with great violence. It has a conftant endeavour, when once fet in motion, to preserve itself in the fame degree of motion, and, when at reft, it is not motion without refiftance.

But it is maintained by the bulk of our philofophers, that matter is altogether incapable of active powers; that activity is confined to immaterial íubftances, and that inertness is implied in the very conception of matter. This moves them to afcribe to fome invifible agency, all that activity we discover in matter. In every one of the above inftances they say mat ter does not act, but is acted upon by the deity, who interpofes, by general laws, to preferve the uniformity of nature, Thus, when a ftone falls, it is not the ftone which acts, but the deity. It is the continual action of the deity, which keeps the planets in elliptical orbits: and when a plague infefts the world, it is the deity which fpreads the infection, and directs the inert matter to ravage and deftroy. Arfenic is not of itself a poifon; it is the immediate finger of God which makes it fo.

The author next proceeds to afcertain the meaning of the terms material and immaterial, which, he fays, has not yet been done with fufficient accuracy. All beings and exiftences must be either material or immaterial; or, in other

• words,

words, must be matter, or not matter: therefore, if we 'know what is matter, we cannot be at a lofs about what is not matter. I take it for granted, that we have no conception of matter, but as fubftance or body, endued with colour, figure, extenfion, impenetrability, or other properties of fuch a nature as to be objects of our external senses. The direct oppofite muft of course be an accurate description of an immaterial fubftance, viz. that which has pro'perties of fuch a nature, as not to lie open to any of our external fenfes, more than colour to one born without fight. • Thus it comes out, that immateriality is merely a negative C term, comprehending every thing that is not matter. And it is of confequence to be obfeived, that the diftinction be<tween material and immaterial, not being founded on the nature of the things which are fo diftinguished, but on the • limited nature of our external fenfes, has not the least ten<dency to explain the nature or properties of immaterial fubftances, farther than barely, that these properties are of such ⚫ a kind, as not to be the objects of any external fenfe.

From these premifes the following reafoning will, it is hoped, be found entirely conclufive. Size, figure, motion, weight, &c. are qualities of matter which are perceived by 6 our external fenfes : but there is none fo foolish to maintain, that matter can have no qualities but what are objects ⚫ of an external sense. It would be the fame as to deny the ex<iftence of immaterial fubftances, because thefe do not exhi• bit themselves to our fenfes. Power is a property or quality ⚫ of which none of our external fenfes afford us the percep

tion; and therefore our want of perception of power, does • not more conclude a negation of power to matter, than to fpirit. In general, we have no means to come at the know ledge of a caufe, but by the effect produced. We cannot a priori, conclude, that animate beings are endued with any fort of powers, more than inanimate. Experience is here our only guide. We find by experience man to be a reafoning being, endued with many powers and faculties: and by the fame experience, we find matter to be endued with ⚫ certain powers and faculties. Both are discovered by the effects produced; and we have no other means to make a difcovery. We see a stone fall without any external im→ pulfe. From that effect we have a just foundation to con clude, that the ftone has a power of moving itself. And if we have not a juft foundation to make this conclufion, we have not a juft foundation to make this other conclufion,

• that

that a man has a power of felf-motion, when we see him 'walking.'

After endeavouring to fhew, that by enduing matter with a power of acting according to certain and invariable laws, a more beautiful and complete fyftem is exhibited than by leaving it abfolutely inert, to require a continual interpofition of the deity, he concludes, That the doctrine of the abfolute ⚫ inertness of matter, is not only repugnant to truth, but tends ⚫ in an indirect manner, to arraign the deity of want of power, or of wisdom, or of both.'

Having thus fuppofed matter endued with an active principle, our author proceeds to examine fuch of the powers of matter as are productive of the most remarkable effects: as the vis infita, or vis inertia, the communication of motion, action and re-action, gravity, and the force of bodies in motion, deducing all thefe powers from the activity of matter. II. Some remarks on the laws of motion, and the inertia of matter. By John Stewart, M. D. fellow of the royal college of phyficians, and professor of natural philofophy in the univerfity of Aberdeen.

The doctrine of the activity of matter advanced by Mr. Home, in the foregoing article, is here confuted, and the suppofition of Sir Ifaac Newton, on which that illuftrious author founded his laws of motion, the inactivity of matter, fully established. In order to this, the doctor fupposes a fubftance, quite inactive of itself, which is extended, impenetrable, finite, and confequently moveable; and fhews, that the fame refiftance to motion must be expected from such a substance, as is actually met with from common matter.

Place,' fays he, any mafs of fuch a fubftance at reft. It 'cannot begin motion of itself by the fuppofition. But an ⚫ active animated being, as for example, a man, can move it. Some effort muft certainly be made, fome power exerted, to produce this effect. It will never be pretended, that the iame effort can move the mafs either with a great velocity or a small velocity; that being as abfurd as to fay, that a great velocity and a small velocity are one and the fame thing. In like manner, it must require one effort to move a fmall quantity of this fubftance with a certain velocity, and a different effort to move a great quantity with the fame velocity. The fame energy of the agent, will never serve to < move a given quantity of this fubftance, or double the quantity of this fubitance, with the fame velocity; no more than it will move the fame fubftance with different velocities. By