that, in fo great a field, the moft material parts are in a curfory manner related; but the history is fo scattered under the various words Longitude, Clock, Watch, Pendulum, Time keeper, Harrison, Navigation, &c. that it is no easy matter to collect all that is laid upon the fubject. The application of pendulums to clocks is here afcribed to Galileo; yet it is certain, that we have accounts of clocks fimilar to ours, being made in the time of Edward the Third, who granted, in 1368, a licence to three artists to come from Holland, and practice their occupation in England; and of clocks made of brafs in the reign of Charlemagne, to whom one was presented by Aaron King of Perfia, in the year 807. As to watches, our compilers affirm that the invention of of pocket watches belongs to the prefent age.' We are furprised to fee fuch an affertion when so many proofs of their greater antiquity are upon record. Mr. Barrington gives a full and fatiffactory account of a pocket watch, belonging to Robert Bruce, who began his reign in 1305, of which we gave an account in our Review for April 1780. We have accounts of repeating pocket watches as early as the time of Charles the Fifth, who had one stolen out of his pocket, and the thief was detected by its ftriking the hour. In Shakespear's Twelfth Night, Malvolio fays, I frown the while, and perchance wind up my watch, or play with fome rich jewel.' Guy Fawkes had one found upon him, with which he and Percy used to try the times of the burning of touchwood, for fetting fire to the train of powder.

We find in this work, however, a very good account, drawn from the Supplement to the first edition of the Biographia Britan nica, of Mr. Harrifon's labours and contrivances; and the great degree of perfection to which these inftruments have been brought by him, and by Arnold, copied, literally, from our Review, Vol. LXIII. p. 198-207. The various methods in which time-keepers are used for finding the longitude of a fhip at fea are fufficiently defcribed; but the great improvement which navigation has received by the methods of finding the longitude from the distances of the moon from the fun and fixed ftars, is not any where to be met with.

of

We have several inftances of extraordinary definitions occurring in this performance :-perhaps none is more curious than the following: Artist, a person poffeffing an habitual power becoming the cause of fome effect.' Query, are fuch things below criticism, or above it?

Hanging, we did not expect to find in a Dictionary of Arts and Sciences, and are yet at a lofs to determine whether it is an art or science. In the article Drowning we meet with the methods made ufe of for the recovery of people apparently drowned, hanged, or fuffocated; which are judicious, and may be ferviceable.

Chriftianity,

Chriflianity, if a proper article for a work of this kind, needed not to have been extended through feveral pages, befide a variety of details under the refpective words Popery, Calvinism, Methodifm, Prefbyterianifm, &c. But it is abfurd to spend a number of pages on an hiftorical and geographical account of Hell, at the end of which the reader is referred to the word Elysium. This reference to contraries, however, frequently occurs; as Clergy, fee Laity; Drink, fee Food; at the end of the long treatife of Fire we are again fent to Hell.

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Among other matter, foreign to either the arts or sciences, we may juftly rank the following: Burning-bufh, that bufh wherein the Lord appeared to Moles,' with the fubftance of that chapter in Exodus where the tranfaction is recorded. • Beard, the hair on the chin, fee 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 fure our learned Readers would not require at our hands: yet, confidering the nature of the work, its price, and the promifes made in the Preface, we have been induced to give it as much attention as perhaps it deferves, in order to fulfil, to the utmoft of our power, the obligation we are under to the Public, of pointing out the merits or faults of literary performances, efpecially fuch as are fo extremely voluminous, and rated fo highly as the prefent. The extenfive plan of this Dictionary is one of its greateft faults; and we are perfuaded, that were this enormous work divided into a number of fmaller ones, imperfect as the matter is, it would be more useful to the Public, and more advantageous to the proprietors. There are fome parts of it which we must acknowledge to be well executed; yet the 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, befide a copious. Appendix and Index. This circumftance alone fhews the inequality of the work, and how much the compilers wifhed to finish what they foon found was likely to extend its bounds too far.

In reviewing fo large a work, we think it our duty to fay fomething 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 tafk; and the many inftances of negligence are evident marks of hafte and inaccuracy. The continuing to number the pages from the beginning of the work to the end, through the whole ten huge volumes, is unufual. The Editor however has adopted an excellent contrivance, which fhews his fall in the bibliopolian art. Although

the

the pages are numbered from the beginning to the end; yet the feveral treatifes which we have mentioned are paged feparately. For inftance, Mujic, which comes in after 5264, is paged 1, and the numeration goes on to to, where Mufic ends, and the page after is 5265; so that the treatife may be taken out of the Dictionary, and not miffed, and fold as a book by itself; a complete treatife on Mufic, on a prefixed title page, being the only thing wanted to render it a perfect book. The copperplates, which are three hundred and twenty-three in number (though the title page only fays above two hundred'), are, in general, poor engravings; in many inftances they are bad reprefentations of the originals; and in fome, particularly the botanical ones, material faults occur.

Upon the whole, we wifh that Arts and Sciences had fome better fupport than they are likely to receive from the present performance; yet for many obvious purpofes, the Encyclopædia Britannica may be ufeful, and afford much inftruction. In its prefent ftate, however, it may, not unaptly, be compared to a great garden, abounding with choice trees and plants, but all over-run with weeds.

ART. V. An Efay on the Investigation of the first Principles of - Nature: together with the Application thereof to folve the Phanomena of the Phyfical Syftem. Part I. Containing a new philofophical Theory, &c. By Felix O'Gallagher. 8vo. 5s. Boards." Murray. 1785.

TH

HIS work is delivered in the form of lectures, beginning. with the first principles of philofophy, and laying down. a theory and rules for phyfical inveftigations. The first and fecond fections confift of what the Author calls the firft prin-. ciples and fundamental axioms of natural philofophy, neceffary obfervations, and phyfical definitions and propofitions: but we cannot pretend to give a particular account of these, which' would take up too much room.

In the 3d fect. the Author compares the Newtonian rules of philofophizing, as given by Martin in his Philofophia Britannica, vol. i. p. 2.; with his own rules, or propofitions, delivered in the two former fections, whofe fole tendency, he fays, is to form accurate diftinctions, which is in a great measure the bufinefs of philofophy.'

The fpirit of Newton's rules, on the other hand, is to fimplify, and, if poffible, to deduce all effects from the fame caufe: which method, however juft, was dangerous in its application, as it induced his followers not to fearch after, nor admit more principles than one, although more manifeftly difplay themselves in nature. amples will fhew the different tendencies of both methods. Conformably to the fpirit of the Newtonian rules, it is faid (hy)

Two ex

Mr. Martin) in the general conclufion, that all bodies confix of one

and

3

and the fame kind of matter, and that all their varieties proceed from various modifications of the fame particles. It is alfo concluded, in the explanation of the third rule, that gravity, vis inertia, &c. are the properties of all bodies. But our rules not only render us more circumfpect in adopting fuch conclufions, but even induce us to reject them. For as to the first, we know that the immediate and phyfical caufes of all material effects are themselves material; that therefore the caufe of heat, light, and expanfion, or the fubftance, producing thofe effects, is material. Again, as one phyfical agent, or material caufe, cannot produce two contrary effects; therefore attraction, which draws together, and expanfion, which feparates, cannot proceed from the fame caufe. Confequently, as these two operations are feen to obtain in material nature, they have two diftinct material caufes, whofe effences and propenfities are oppofite; we therefore difallow the general conclufion above cited from Martin, and pronounce that experience exhibits, at least, two kinds of matter in nature for oppofite propenfities muft arife from different effences, i. e. different fubftances, confequently from different principles.

Let us now, according to the fame method, examine the fecond affertion we have quoted, to wit, "that vis inertia, with the other properties there enumerated, is common to all bodies."- Certain it is, that a ftrong centripetal force acts upon bodies throughout the univerfe. It is alfo allowed, that there is also another power in nature, namely, that of fire or light, which expands or dilates bodies, feparating their parts with a centrifugal force. This principle of expanfion, according to Boerhaave, is fo univerfal, that there is not a body, or fpace in nature, which has not its fires, though fometimes latent until excited. Wherefore light or fire, the principle of the centrifugal force, being a material fubftance, we also conclude, that the centripetal force, which is equally powerful in producing material effects, alfo arifes from a material fubftance.

There are, therefore, in nature, two material agents, of prodigious efficacy, and of oppofite propenfities 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 fet li mits to the property of inertnefs, which the prefent generalizing method of philofophizing has rendered too univerfal.'

So far our Author: but what Newtonian philofopher ever denied the efficacy of gravity, and fire? As to the inertness of matter, which Mr. O'Gallagher makes the subject of his fecond lecture, he calls the univerfality thereof, an unreafonable and falfe fuppofition; becaufe matter is defined by philofophers to be. a fubftance extended, folid, and perfectly inactive, confidering how far this definition is juft, he allows it extenfion and folidity, but not inactivity, for then, he fays, we could not be fenfible of its existence; at least we should have no fenfation of those bodies which are beyond the reach of feeling: for fuch diftant bodies only affect our organs, which are of a neutral paffive nature, either by the action of an effluvium, or of some intervening me-.

dium. Now, our corporeal organs being matter, can only be affected by another material fubftance, and this cannot be inert as it acts upon them: the matter therefore which gives fenfation of diftant bodies cannot be inert.'

But we apprehend that this metaphyfical mode of argumentation only mifreprefents the meaning of the Newtonian philofcphers. No fooner is matter in motion, than we fuppofe 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 rest. We cannot pretend to tranfcribe the whole of what he fays upon this fubject, or even to abridge it, but muft refer to the book itfelf. He objects, at p. 30, to the ufual proof of inertnefs drawn. from the motion of bodies on horizontal planes; and, at p. 83, propofes the following teft, which, he fays, admits of mathematical demonftration; we therefore fuppofe that he looks upon it as his principal argument.

Let a box or canister, wherein different weights may be put occafionally, be fufpended like a pendulum, at different lengths proportioned to the weights contained; if you allow a foot from the point of fufpenfion to the centre of the box, when a pound is in, allow twenty feet for twenty pounds, fo that the pendulous lengths fhall be as their weights. Let an hook or wire be inferted 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 fcale be joined, to receive the weights or grains that will draw the box afide from the vertical line of free fufpenfion; 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, expreffed by the grains that move it from that line: for whatfoever moves the body overcomes its vis inertiæ.—

'Now (p. 86.), when thefe experiments are accurately made, and every circumftance confidered, and duly valued; if the difference of forces to ftir thefe two bodies, one of a pound, and the other of twenty pounds, whofe difference is nineteen pounds, is found to be but a few grains, which may be occafioned by the refiftance of the air, or fuch extrinfic caufes, vis inertia may be confidered as the fame in all bodies, and therefore to be neglected in every computation, being a conftant invariable quantity in all heavy bodies, great and fmall, which admits of no various degrees, increment, or force.'

But will not the Newtonian philofophers fay that our Author is here combating a mere chimera, a creature of his own ima gination, and that they have no other idea of the vis inertia, but that the leaft imaginable impulfe, or accelerating force, will overcome it in free space? It is true, they will fay, that they fuppose it greater as a body is greater, and for this reafon, if a heavy perfectly fmooth body be laid upon a finely polifhed hori-zontal plane, any heavy body connected with it by a fring paffing over a pulley at the edge of the plane, and hanging freely,

may,