Mr. M. is likewife clearly of opinion that all the parts of 171 á fluid lie perfectly clofe to each other, without any cavities interfperfed; it is impoffible there can be any; confequently there is not the leaft particle of air contained in fluids.' Can any thing be more unphilofophical and abfurd than this notion ? Whence then arifes the difference in denfity between one fluid and another? or, How can he evade the exploded doctrine of a Cartefian plenum? Again, I am fully convinced that the pores in glafs, &c. are of thofe ingenious Gentlemen's (Newtonians) own creating; who, when they are at a lofs for proof of certain hypothefes (for want of better) imagine bodies to poffefs fuch and fuch qualities as may beft anfwer their purpose. But are thofe chimeras, of their own fertile imaginations, to pafs on the world for real exiftencies? Are the conclufions drawn from fuch premifes candid? By no means, they are very difingenuous, infomuch, that I deny it to be in the power of any man to give ocular or other demonftrative proof, that there are pores in glafs or tranfparent ftones; and I do believe that the most pellucid fubftances are the freeft from pores; for all porous bodies are compreffible into lefs compafs, which neither glass nor ftones can poffibly be; nor water, which is perfectly transparent.The real caufe of tranfparency, and how vifion is conveyed through tranfparent bodies, are (I am firmly perfuaded) among the hidden myfteries of nature, which is not given man to explore.'

Were we not afraid of incurring the charge of prefumption. for pretending that any of thefe myfteries have been already explained, we would refer the Author to fome very modern and ingenious difquifitions on the fubject of his difficulties, which he feems not yet to have heard of: particularly to thofe of the late Mr. Canton, on the Materiality of Light and the Compreffibility of Water, &c. publifhed not long fince in the Philofophical Tranfactions. An account of which may be seen in the Monthly Review, vols. xxix. xxxiii. and xlii.

Having already recited fome of the leading opinions propofed by our Author in the first book, we fhall give an analysis of the contents of the three remaining books, in which he explains the theory and practice of perspective, by a great variety of important and ufeful propofitions and problems. In the three first fections of the fecond book, Mr. M. defines the terms made ufe of in this fcience; and premifes feveral general obfervations on the points, lines, and planes about which this art is converfant, by way of introduction to the theory and practice of it. He then proceeds, in the fourth and fifth fections, to demonftrate the principal theorems, that lie at the foundation of rectilinear and curvilinear perspective; deducing from them a number of corollaries, which farther illuftrate and establish the

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principles of the art. The fixth fection is intitled, a full re futation of feveral errors and abfurd opinions which many artifts entertain of perfpective; and therefore look upon it as an imperfect and fallacious fcience.'

The third book contains feveral problems and examples to affift the practitioner in this art; and they are fo numerous and various as readily to apply to every cafe that can occur. Our Author begins with determining the projection of lines under different pofitions, with respect to the eye and picture. He then goes on to find the reprefentations of plane and folid figures, both rectilinear and curvilinear and he directs how to make perfpe&ive delineations of buildings, furnishing various outfide and infide views of them, and defigned as models for other fimilar cafes that may offer. There are likewise many drawings, according to the rules of this art, of chairs, tables, book-cafes, &c. as alfo of coaches and fundry other machines. The plates and figures are throughout accurately and elegantly executed.

The fourth book treats of the perspective of fhadows projected from a number of different objects, variously fituated with refpect to the luminary and the obferver. The whole is terminated with useful obfervations on the effect of reflected light on objects perfpectively delineated; and alfo on the effect of diftance, ufually known by the term keeping, but more properly aerial perspective.

Mr. M. advertises an Appendix to this work; containing a brief analysis of the various authors who have written on perfpective; and the methods used by the ancients compared with the prefent; with other interefting matters in the art of delineating, not neceffarily connected with the fubject of this book.

In works of this nature, elegance of ftyle is not expected, as the fubjects will not admit of it; but we are forry to obferve a great number of inaccuracies, befide a general negligence with refpect to language, of which no notice is taken in the long lift of errata. The Author, we apprehend, might have reduced the work into lefs compafs without contracting his plan, had he guarded againft ufelefs repetitions, and against a prolixity and minutenefs in many of his demonftrations and folutions, which confound rather than aid the learner or the practitioner, Nevertheless, on the whole, this treatife is comprehenfive, intelligible, and useful: it is the most complete work on the fcience of perfpective which has yet been publifhed: the execution of it must have been laborious and expenfive; and we heartily wish that the Author may meet with fuitable encouragement.

ARTI

ART. II. Difcourfes on various Subjes. By William Samuel Powell, D. D. late Archdeacon of Colchester, and Mafter of St. John's College in Cambridge. Published by Thomas Balguy, D. D. 8vo. 5's. L. Davis.

THE

HE Author of thefe Difcourfes has been long known on account of his "Defence of Subfcription," publifhed in 1757 for the character of which we refer our Readers to the Monthly Review, vol. xvii. p. 607. The Editor has, in this volume, collected fixteen fermons more, befide three charges, and a Latin thefis on the Author's admiffion to his degree. He has likewife prefixed fome facts and dates for the fatisfaction of Dr. P.'s friends. The fubjects of thefe difcourfes are, for the most part, the various evidences of Chriftianity; fuch as, the authenticity of the books of the New Teftament-the credit due to the facred hiftorians-the infufficiency of Mr. Hume's objection to the credibility of miracles-the ufe of miracles in proving the divine miffion of our Saviour and his apoftles-the evidence arifing from the prophecies of the Old Testament→ the argument drawn from the fwift propagation of the gospelthe character given by Heathen writers of the first Chriftiansand a recapitulation of the arguments brought in fupport of Christianity befide thefe, there are other difcourfes, on the vices incident to an academical life-on the martyrdom of Charles I.-intemperance in the gratification of our appetites not confiftent with fpiritual improvements-the prodigal fonthe nature and extent of infpiration, illuftrated from the writings of St. Paul-the diverfity of character belonging to dif fererent periods of life-public virtue-and that on fubfcription.

Concerning the influence of God's fpirit (fays our Author) men have fallen into two mistakes: which, though founded on the fame false principle, are yet oppofite to each other; and, though oppofite, are equally dangerous: the one to religion, the other to morals. Some men, virtuous in their conduct, and ferious in their faith, neither perceiving the operation of the fpirit within themselves, nor hearing that others, of a fober and rational piety, pretend to fuch fenfations, impute this whole notion to enthufiafm, and fuppofe that the promises of the feripture are either mifunderstood, or extend not to thefe times. Others, having a temper more affected by religious fubjects, and, being fully convinced that good Chriftians, in alf ages, may expect the divine afittance, eafily fancy that they perceive it, and are very apt to mistake the fuggeftions of a warm imagination for the dictates of the Holy Spirit. The two errors feem to be derived from this one principle, that, whenever our minds are influenced, we cannot be ignorant by whom, and in what manner, they are influenced; a principle contradictory to conftant experience. We are perpetually confcious of changes in our fentiments and inclinations, without knowing or attending to the causes of the charges. We even proceed to actions, the motives to which efcape

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obfervation. When the origin of any opinion is within our own minds, we frequently do not remark it. When it is without them, we are as frequently unable to difcover it. The difpofitions of those a man converfes with, the ftudies he is engaged in, the amufements he follows, imperceptibly alter his fentiments upon fubjects, with which they seem to have little connexion. The ftate of his body, every external accident, even the weather, affects his mind more than he can believe, till repeated experience has convinced him. If all these trifles can influence us, and if the influence of caufes fo cbvious is often unnoticed; can it be a queftion, Whether we may not be fecretly guided by an omnipotent and fpiritual director? It is equally irrational to conclude, either because we are not fenfible of his affiftance, that none is given, or because we rely on God's promifes, that the affillance given must neceffarily be perceived. Difficulties of the fame kind have been the occafion of fimilar miftakes in natural religion.' The preacher inftances in the doctrine of Providence: But as we are ignorant how the infliucts of animals, the powers of vegetation, and even the forces of brute matter are communicated, fo mufl we be content to be ignorant of the nature and particular effects of the divine illuminations. It is fufficient for us to understand the means of obtaining them. These are, humble prayers to God, ferious attention to the importance of the bleffings we afk, and carneft endeavours to prepare both our fouls and bodies for their reception. Thus may our bodies become the temples of the Holy Ghoft. But whether they fhall be confecrated to him, or remain the finks of vice and corruption, is the fubject of our free choice. If there be any difficulty in the determination, we may submit it to the judgment of a fenfible Heathen. In the reign of Alexander Severus, a difpute arofe at Rome, between fome Chriftians and a company of vintners, about a piece of wafte ground, upon which the Chriftians wanted to build a church, and the others a tavern. The title was doubtful; the parties obftinate; the cause came on at last before the Emperor, who, when the grounds of justice could not be afcertained, decided it upon a religious confideration. Though little acquainted with Christianity, he judged in favour of the Chriftians. "It is better, faid he, that the ground be employed for the worship of God, in any manner, than for luxury and excess." So did a Heathen determine, even of an unhallowed place. And furely a Chriftian will think it an impious profanation to make that body a receptacle for wine, which was chofen for a tempie for the living God.'

In his fermon on public virtue, our Preacher introduces his fubject with fome pertinent obfervations, obviating the charge of defect in this particular urged against Chriftianity.

Had Chriftians been farther feparated from the Heathen world, and united under one civil government, and had that government been conftituted on fuch principles of liberty, that all or many of them might have had fome influence in it, fome power of promoting the general welfare; thefe would have been additional bonds of love, and the peculiar regard which they were taught to fhew to their fellow Chriftians, had then been directed to their fellow citizens.

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We might then have expected to find in the writings of the apoftles as warm exhortations to love our country, as high praifes of public virtue, as in any Greek panegyrift, or among the boats of the ar rogat Roman.'

In fpeaking of the Reformation and Revolution, and of the miferies and dangers, which either actually involved or threatened us at thofe important periods, our Author thus reasons :

What relieved us from thefe miferies and thefe dangers, but the patriot fpirit of our countrymen, their generous concern for the common good, for the fecurity of the prefent and future ages? Had not the reformers of religion, influenced by a fenfe of their duty to God and man, refolved to deliver out of darkness and error their deluded brethren, we might now perhaps have been groaning under the tyranny of an inquifition. Had not the danger of long the ellablished religion and laws animated fome of the laft age with a zeal which deipifed all other dangers; inftead of living under a well conflituted government, mild and regular beyond the example of any age or kingdom, we fhould either have been fubject to an arbitrary and illegal dominion at home, or, which is more probable, have long ago fubmitted, with all the nations round us, to thofe powerful enemies, who for a century past have been attempting to enslave the world. And what other human bleflings can be compared with that, which is the fecurity and prefervation of them all, the liberty of laws? What other, except that, which fecures to us more than human bleflings, the liberty of religion? What praife and elicem, and veneration, are due to those who obtained them for us? And let it not be imagined that this merit is confined to the great. Every Briton may deserve well of his country. A fpark of public virtue, fcarce difcerned, among men in obfcure ftations, will fometimes fpread, and enlighten the whole kingdom. Who were the firit, the chief inftruments of the reformation? Poor begging fcholars. Who opened the way for the revolution? The clergy. The univerfities, Nay, a fingle college of honest and refolute men carried more force than an army.'

The Author well expofes the hypocrites in this virtue and he adds,

There is another fort of men who difgrace public virtue as much as the falfe pretenders to it; men equally wicked, and more foolish : who, in their writings and converfation, maintain, that this boasted virtue is but an empty name; that a wife man fhould take care of himself only; or, if he regard his private connexions, fhould confider himself as unconnected with the Public. And this falfe doctrine they ground on as falfe a fact that in this nation the common ties are diffolved, that no man has any concern for his country; but whatever difguifes he may put on, each purfues a feparate intereft, and fells, though in different forms, and with different fuccefs, that fhare of power, with which the community has entrusted him. It is not true. The thought is a reproach to human nature. Let it fall on those only, who confefs, that they know no exception to it. But let us turn our thoughts from these men, and view the noblest fpectacle the world affords; a true lover of his country, who, for the

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