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Christianity, if a proper article for a work of this kind, needed not to have been extended through several pages, beside a variety of details under the respective words Popery, Calvinisin, Methodism, Presbyterianism, &c. But it is absurd to spend a number of pages on an historical and geographical account of Hell, at the end of which the reader is referred to the word Elyfium. This reference to contraries, however, frequently occurs; as Cierg), fee Laity; Drink, lee Food ; at the end of the long treasle of Fire we are again sent to Hell.
Among other matter, foreign to either the arts or sciences, we may juftly rank the following: Burning-b:j, that bush wherein the Lord appeared to Moies,' wiih che substance of that chapter in Exodus where the transaction is recoried. • Beard, che hair on the chin, lee Hair. Turning to Hair, we find a long treatise about it, and at length are referred to the word Peruke, which however does not occur in the book.
A minute examination of every article in a production of this kind, is a task which we never proposed to ourselves, and which we are sure our learned Readers would not require at our hands : yet, considering the nature of the work, its price, and the promises made in the Preface, we have been induced to give it as much attention as perhaps it deserves, in order to fulfil, to the utmost of our power, the obligation we are under to the Public, of pointing out the meries or faults of literary performances, especially such as are ro extremely voluminous, and rated so highly as the present. The extensive plan of this Dictionary is one of its greatest faults; and we are perfuaded, that were this enormous work divided into a number of smaller ones, imperfect as the matter is, it would be more useful to the Public, and more advantageous to the proprietors. There are some parts of it which we must acknowledge to be well executed; yet ibe whole is of too great a bulk, as the compilers themselves have evidently experienced; for the first volume contains only three fourths of the letter A, and the tenth S, T, V,U, W, X, Y, Z, beside a copious Appendix and Index. This circumstance alone shews the inequality of the work, and how much the compilers wished to find what they soon found was likely to extend its bounds too far.
In reviewing lo large a work, we think it our duty to say something concerning the manner in which it is printed. To enumerate all the typographical errors that occur, even in the articles we have perused, would be a laborious task; and the many inftances of negligence are evident marks of halte ,and inaccuracy. The continuing to number the pages from the beginning of the work to the end, through the whole sen huge volumes, is une usual. The Editor however has adopted an excellent cons trivance, wbich thews his skill in the bibliopolian art. Although
the pages are numbered from the beginning to the end, yet the several treatises which we have mentioned are paged separately. For instance, N'ufir, which comes in after 5264, is paged 1, and the numerarion goes on to bo, where Mufic ends, and the paye after is 5265; so that the treatise may be taken out of the Dicionary, and not missed, and sold as a book by itself; a complete treatise on Music, on a prefixed title-page, being the only thing wanted to sender it a perfect book. The copper. plates, which are three hundred and twenty. three in number (though the title page only says above iwo hundred'), are, in general, poor engravings; in many instances they are bad representations of the originals; and in some, particularly the botanical ones, material faulis occur.
Upon the whole, we wish that Arts and Sciences had some berier support than they are likely to receive from the present performance; yet for many obvious purposes, the Encyclopædia Britannica may be useful, and afford much instruction. In iis prelene ftare, however, it may, not unapely, be compared to a great garden, abounding with choice trees and plants, but all over-run with weeds.
Tram. ART. V. An Eçay on the Investigation of the first Principles of
Nature : together with the Application thereof to solve the Pha. nomena of the Physical System. Part I. Containing a new philo. • sophical Theory, &c. By Felix O'Gallagher. 8vo. 5s. Boards. » Murray. 1785. T HIS work is delivered in the form of lectures, beginning
with the firit principles of philosophy, and laying down a theory and rules for physical investigations. The first and second seations consist of what the Author calls the first principles and fundamental axioms of natural philosophy, necessary observations, and physical definitions and propositions : but we cannot pretend to give a particular account of these, which would take up too much room.
In the 3d feet. the Author compares the Newtonian rules of philosophizing, as given by Martin in his Philofophia Britannica, vol. i. p. 2. ; with his own rules, or propositions, delivered in the two former sections, whose fole tendency, he says, “is to form accusale distinctions, which is in a great measure the business of philosophy.'
• The spirit of Newton's rules, on the other hand, is to fimplify, aod, if possible, to deduce all effects from the same cause : which me. thod, however juft, was dangerous in its application, as it induced his followers not to search atcer, por admit more principles than one, although more manifestly display themselves in nature. Two examples will shew the different tendencies of both methods.
i Conformably to the spirit of the Newtonian rules, it is said (by Mr. Martin) in the general conclusion, that all bodies consist of one
and the same kind of matter, and that all their varieties proceed from various modifications of the same particles. It is also concluded, in the explanation of the third rule, that gravity, vis inertiæ, &c. are the properties of all bodies. But our rules not only render os more circumfpect in adopting such conclusions, but even induce us to reject them. For as to the first, we know that the immediate and phy. sical causes of all material effects are themselves material ; that there. fore the cause of heat, light, and expansion, or the subitance, producing those effects, is material. Again, as one physical agent, or material cause, cannot produce two contrary effects ; therefore attraction, which draws together, and expansion, which separates, cannot pro. ceed from the same cause. Consequently, as these two operations are seen to obtain in material nature, they have two diltinet material causes, whose essences and propensities are opposite; we therefore disallow the general conclusion above cited from Martin, and pronounce that experience exbibits, at least, two kinds of matter in nature : for opposite propenfities must arise from different essences, i.e. different substances, consequently from different principles.
· Let us now, according to the same method, 'examine the second assertion we have quoted, to wit, “ that vis inertiæ, with the other properties there enumerated, is common to all bodies." _ Certain it is, that a strong centripetal force acts upon bodies throughout the uni. verse. It is also allowed, that there is also another power in nature, namely, that of fire or light, which expands or dilates bodies, separating their parts with a centrifugal force. This principle of expan. fion, according to Boerhaave, is so universal, that there is not a body, or space in nature, which has not its fires, though somețimes latent until excited. ---Wherefore light or fire, the principle of the centri. fugal force, being a material substance, we also conclude, that the centripetal force, which is equally powerful in producing material effects, also arises from a material substance.
• There are, therefore, in nature, cwo material agents, of prodi. gious efficacy, and of opposite propensities or tendencies to act ; these cannot be called inert, because they have in themselves a power of motion and of action, which gives motion to inert matter, and which produces the operations of nature. We must therefore set limits to the property of inertness, which the present generalizing me. thod of philosophizing has rendered too universal.'
So far our Author: but what Newtonian philosopher ever denied the efficacy of gravity, and fire ? As to the inertness of maiter, which Mr. O'Gallagher makes the subje&t of his second lecture, he calls the universality thereof, an unreasonable and false fuppofition; because matter is defined by philosophers to be a substance extended, solid, and perfectly inactive, considering how far this definition is just, he allows it extension and solidity, but not inactivity, for then, he says, we could not be sensible of its existence; at least we should bave no sensation of those bodies which are beyond the reach of feeling: for such diftant bodies only affect our organs, which are of a neutral paflive nature, either by the action of an effluvium, or of some intervening me
phers. Wo frepresents the his metaphysical
dium. Now, our corporeal organs being matter, can only be affected by another material substance, and this cannot be inert as it acts upon them : the matter therefore which gives sensation of diftant bodies cannot be inert.'
But we apprehend that this metaphysical mode of argumenta. tion only misrepresents the meaning of the Newtonian philoro. phers. No sooner is matter in motion, than we suppose they will allow that its inactivity is at an end. Our Author, however, goes further, and will not allow it to be inert even at reft. We cannot pretend to transcribe the whole of what he says upon this subject, or even to abridge it, but must refer to the book it self. He objects, at p. 80, to the usual proof of inertness drawn from the motion of bodies on horizontal planes; and, at p. 83, proposes the following teft, which, he says, admits of mathematical demonstration; we therefore suppose that he looks upon it as his principal argument.
"" Let a box or canister, wherein different weights may be put oca casionally, be suspended like a pendulum, at different lengths proportioned to the weights contained ; if you allow a foot from the point of suspension to the centre of the box, when a pound is in, allow twenty feet for twenty pounds, so that the pendulous lengths shall be as their weights. Let an hook or wire be inserted at the central part of the box or canister, to which a thread is fixed that will stretch horizontally over a free pulley; and at the other end of this thread let a scale be joined, to receive the weights or grains that will draw the box aside from the vertical line of free suspension; then note the weights or grains that will draw the central part of the box, when loaded with each weight, the length of an inch, or even the tenth of an inch from that vertical line, and you have the force of inertness in each weight, expressed by the grains that move it from that line: for whatsoever moves the body overcomes its vis inertiæ.
I Now (p. 86.), when these experiments are accurately made, and every circumstance considered, and duly valued ; if the difference of forces to stir these two bodies, one of a pound, and the other of twenty pounds, whose difference is nineteen pounds, is found to be but a few grains, which may be occafioned by the resistance of the air, or such extrinsic causes, vis inertiæ may be considered as the same in all bodies, and therefore to be neglected in every computation, being a constant invariable quantity in all heavy bodies, great and small, which admits of no various degrees, increment, or force.'
But will not the Newtonian philosophers say that our Author is here combating a mere chimera, a creature of his own imagination, and that they have no other idea of the vis inertiæ, but that the least imaginable impulse, or accelerating force, will overcome it in free space? It is true, they will say, that they suppose it greater as a body is greater, and for this reason, if a heavy perfectly smooth body be laid upon a finely polished bori. zontal plane, any heavy body connected with it by a string pas. ing over a pulley at the edge of the plane, and hanging freely,
may, may, abstracting from fri&tion, move it, nay draw it to the end of the plane : but that the greater the body or weight is that hangs freely, the sooner will it perform this, yet fill in all cases the descending weight would move flower'than it would do if the string were cut and it were liberated from the body that moves along the plane ; consequently the vis inertic acts as a retarding force to the descending body; and this body being supposed given, the greater the other body is, the greater is the retarding force, and is therefore different in bodies of different sizes or quantities of matter. As to this gentleman's proposed demons strative experiment, they will shew that it can be of no use or force at all. For any impulse or force whatever acting hori. zontally upon the body, will be sufficient to draw it from the perpendicular, and the instant it is so drawn, gravity will begin to act upon it, and its own weight and the different positions of the ftring are necessary to be taken into consideracion, in order to determine how far it can be drawn from the vertical line; consequently, the experiment must be very ill contrived to determine with precision the vis inertiæ.
His third and fourth lectures are on the elastic principle in bodies, which he shews to exist in vegetable, animal, and foflil bodies, in fire, air, and water. He endeavours to exhibit the elastic substance separately, to Thew iis uses in nature and mode of operation. He takes into consideration a heap of vegetables 20 hundred weight, which is by fire reduced to a small heap of saline ashes, not 50, perhaps not 20 pounds weight, which when depurated, by wathing, to pure pale ashes, will be much less : and perhaps, says he, 10 pounds of such a residuum would not remain, if the heap originally consisted of paper, or linen. He asks what is become of the weight or gravity of the heap, when its alhes retain not the hundredih part thereof?
• Nineteen hundred weight, he continues (p. 157-), has disap. peared ; shall we therefore conclude, that all this weight has been carried off by smoke and Aame? This seems improbable; for, what. ever be the material cause of gravity, certainly it has not a tendency to ascend, being convergent and centripetal. On the other hand, flame has ever a contrary propensity, viz. to rise and expand; and Smoke, which we find to be the nascent form of fame, is analogous thereto, and should have the same tendency, though in a lower de.: gree ; confequently, when fire dissolved the cohesion of the body, and separated its elements from each other, each pursued the pro. pensity peculiar to its nature; the elastic matter, released from its confinement, Aed into the atmosphere, its proper reservoir ; and the matter of gravity must have sunk with native propensity towards the centre of the earth, a small part of it only fill remaining with the alhes and salts on the surface. And as effences must ever accompany their peculiar substances, the elastic matter in its Aight, carried off the elasticity, fnell, taste, and other lively qualives peculiar thereto, along with the oils and spirits, on which, according to all chemists,