Philofophy, according to the baron, had its birth in the earliest ages of the world, and owed its origin to that defire of happiness which is fo natural to mankind, that it becomes the motive of all their labours, and the fpring of all their actions.

The firft that made open profeffion of philofophy in Greece, were Thales and Pythagoras, who thought the title of fage too faftidious, and took the more modeft name of philofophers, or lovers of wisdom. Socrates, who followed the career of the earlieft philofophers, turned all his ftudies towards morality, and was the first to reduce the confufed ideas of his predeceffors to fome method; for which reafon he is called by Cicero, the Father of Philofophy. Of all the celebrated men who came out of the school of Socrates, Plato was the moft renowned. He established his school in the Academy, which was a place without Athens, and from thence his followers were called Academics. According to Plato, the foul of man is only an emanation of the divinity. He believed that this particle united to its principle, knew all things; but, when united to a body, contracted ignorance and impurity from that union. He did not follow the example of his master Socrates, in totally neglecting natural philofophy. On the contrary, he enquired into many queftions, which relate to that fcience, and even cultivated aftronomy. The difciples of Plato formed alfo many new fects; of which that founded by Ariftotle is the moft illuftrious. This philofopher was the first who formed a complete fyftem from the feveral parts of philofophy. His difciples and his followers were called the Peripatetics of Lyceum, where he had fixed his fchool. About fixty years after rofe the feats of the Stoics and Epicureans, which at first divided the wits of Greece, and afterwards thofe of all the reft of the world: the founder of the former was Zeno, that of the latter Epicurus. About the twelfth century prevailed a philofophy called the Scholaftic, borrowed, in a great measure from the writings of the Arabs, whom the Scholaftics, who were all attached to Ariftotle, imitated in their fubtle, ambiguous, abftract, and capricious manner of reafoning. About the fixteenth century, men began to throw off the yoke of Ariftotle. Nicholas Copernicus, who was born at Thorn in 1473, had already borne the torch of reafon in mathematics and aftronomy; he had rejected the system of the world that was invented by Ptolemy, and which the Greeks call most wife and most divine; and in its place introduced the fyftem of the fun's being immoveable, and the motion of the earth. Galileo, who was born at Florence in 1564, adopted the fyftem of Copernicus, and improved it by

new

new obfervations. He likewife introduced a new and excellent method of reafoning in philofophical fubjects. At laft René Defcartes appeared, and by a method, but very imperfectly understood before, difcovered more truths in philosophy, than all the preceding ages had produced. Before Defcartes, Sir Francis Bacon had lighted that torch, with which all his fucceffors have illumined philofophy; and in his writings are to be found the feeds of every new difcovery, and every new hypothesis. At length philofophy was carried to its highest perfection by Newton, Leibnitz, and Locke, all living in the feventeenth century, and all cotemporaries.

Thus have we given a general sketch of the hiftory of philofophy, of which our author has enumerated the following branches. . Logic. 2. Morality. 3. Natural theology. 4. Ethics, or moral philofophy. 5. General philosophy, or common prudence. 6. The policy of nations. 7. The law of nature. 8. The law of nations. 9. Metaphyfics. 10. Phyfics, or natural philofophy.-We fhould exceed the limits which we have prefcribed to ourselves, were we to enter into the fubdivifions of thefe branches, or give a particular account of each. With the fame view of avoiding prolixity, we shall pafs over the article of Mathematics, with which this fecond book concludes, as what has been said of the other branches of fcience, is abundantly fufficient to give an idea of our author's manner of treating his fubjects.

Our opinion of this work, upon the whole, is, that, notwithstanding a few errors, which are excufable in a work fo extenfive, it is equally curious and useful;-the author has difcovered a fund of good fenfe equal to his profound erudition; and the tranflator has performed his part with fpirit and fidelity.

[To be continued. ]

IX. An eafy Introduction to Aftronomy, for young Gentlemen and Ladies. The Second Edition. Illuftrated with Copper-plates. By James Ferguson, F. R. S. 8vo. Pr. 5s. Cadell.

AMONG all the fciences it is probable there are very few,

if any, which fo much enlarge the mind and correct the judgment as that of mathematics; by this noble art we are led to truth by the nearest way, and likewife, with the greatest certainty. The ancients held this valuable part of learning in fuch efteem, that their kings were not only encouragers of it, but alfo ftudents in the fence; they accounted that

perfon unfit to govern the world who knew not what the world was, or had not, at least, acquired a general notion of the univerfe and fituation of the parts and extent of the folar and planetary fyftem: nor have there been wanting perfons in early ages, who have cultivated the feveral branches of mathematical knowledge, and in particular aftronomy; for by the writings of Porphyry and Simplicius, it appears, that when Alexander the Great took Babylon, Callifthenes, one of Ariftotle's scholars, by the defire of Ariftotle, carried from thence to Greece, celeftial obfervations made by the ancient Chaldeans and Babylonians of two thoufand years ftanding. And Sir Henry Savil, towards the latter part of his fecond lecture upon Euclid, fpeaking of this, fays, that although the common printed edition of Simplicius mentions but two thoufand years, yet in his manufcript it is thirty-one thousand years; and Cicero, in Jib. 1. de Divinatione, forty-feven thoufand years. But as the Greeks had almost all their aftronomical learning from the Egyptians, whofe obfervations were purely aftrological, and made chiefly with a view to determine the influence of the ftars, Simplicius's account rather ferves to fhew the antiquity than the advancement of aftronomy; nor indeed have we any thing of certainty with refpect to the latter, until about 300 years before the Chriftian æra, when, according to Ptolemy, Tymocris and Aryftillus left feveral obfervations of the fixed ftars, which proved of great ufe to fucceeding aftronomers in determining the' preceflion of the equinoctial points, and other aftronomical phenomena.

The difficulty of arriving at an extenfive knowledge in aftroromy, and the time required for that purpose, have induced feveral very confiderable writers upon this fubject to oblige the world with popular treatifes, whereby a fufficient idea of aftronomy may be obtained, with very little trouble, and without any previous knowledge of algebra or geometry. This feems to be the defign of the work before us, and which may be confidered as excerpta from the writings of thofe celebrated aftronomers Keil, Pemberton, Wallis, &c. wherein the ingenious author has illuftrated the principles of aftronomy by way of dialogue between Neander and Eudofia, in a very eafy and comprehenfive manner. The figure, motions, and dimensions of the carth, the folar fyftem, the nature of eclipses of the fun and moon, &c. are well explained, and rendered clear to the understanding of thofe who are unacquainted with geometry or mathematics.-Our author, in fpeaking of the nature and laws of gravity, at page 61, and of the difference between folar and fydereal time, at page 207, is not quite fo fatisfactory as

in

in the other parts of this performance: the reader will judge of this by the following extracts.

Eudofia. 1 fhould be glad to know the reafon why the fun's attraction decreases in proportion to the fquares of the distances from him; Why do you

fhake

your

head?

• Neander. Because you ask me a queftion which Sir Ifaac Newton himself could not folve; although he was the prince of philofophers.

⚫ E. But can you give me no idea at all of it?

< N. I could; and a very plain one too, if the attractive force, (the effect of which we call gravity) acted only according to the furface of the attracted body.

E. Your if implies that it does not: but, if it did, why Thould it decrease in that proportion?

N. I have drawn a figure for your infpection (Fig. 1. Plate II. in the author's work), which, indeed, is for a quite different purpose: but it would exactly folve your question, if gravity acted as all mechanical caufes do; only upon the furfaces of bodies.

E. But, if gravity acts not according to the quantity of furface, pray how doth it act?

N. Exactly in proportion to the folid contents of bodies; that is, to the quantities of matter they contain; for if gravity acted according to the furfaces or bulks of bodies, a cork would be as heavy as a piece of lead of the fame bulk as the cork.'

This account of gravitation, feems (at least to us) rather defective and confufed; for the folid contents of bodies are not proportional to the quantity of matter they contain, nor are the furfaces of bodies, and their bulks the fame thing. Mr. Ferguson fhould have defined the quantity of matter in a body as Sir Ifaac Newton does, to be the measure of the fame arifing from its denfity and bulk conjun&ly; and then, indeed, the effect of gravity at equal distances from the center of force. would be as the quantity of matter or weight of the body; nor would this vis infita, or vis inertia, probably, be changed by any alteration in the prefent law of gravitation, that is, at the fame diftance from the center of force the proportion between the vis enertia of bodies would ftill remain the fame, namely, that of the quantities of matter or weights of the bodies themfelves, whether the force of gravity acted as it now does, or by We are therefore of opinion, that, even grantany other law. ing the force of gravity upon bodies at equal diftances from the center of attraction to be as their furfaces, it could not be proved from thence that the law of attraction should be reciprocally as the fquare of the diftance from that center, for the

influ

́influence of attraction at different diftances from the center of force remains juft the fame, and increases or decreases in the very fame manner, whether there are any bodies or not within the fphere of its activity; whereas our author (in his hypothefis, makes the force of atrraction propagated from the center, depend upon the magnitude of the furface of the attracted body; confequently by Mr Ferguson's scheme (plate III. fig. 1.) it will appear that the force of gravity upon a body, at the earth's furface, whofe fuperficies is one inch, is no greater than the force of gravity upon a body at two femidiameters from the earth's center, whofe furface is four inches. This we apprehend would fall very fhort of confirming the prefent law of gravitation.

At page 243 it is faid, that 24 folar hours are 3 minutes and 56 feconds longer than 24 fydereal hours. Now as the fydereal day contains only 23 hours 56 minutes and 4 feconds, and the difference between the folar and fydereal year is no more than 20 minutes 17 feconds and, we think Mr. Fergufon fhould have added a line or two, in order to have explained to his readers, the reafon of the folar day being 24 hours.

We have here enumerated the chief, and indeed the only, difficulties we met with upon reading this Introduction to Aftronomy, in which, we apprehend, there is much more to be praised than pardoned; and therefore, recommend it to the. perufal of thofe young gentlemen and ladies, who are defirous of obtaining a competent knowledge of aftronomy, without being obliged to acquire any previous knowledge of geometry or mathematics.

X. A Short Effay on Military First Principles. By Major Thomas Bell. 8vo. Pr. 41. Becket and De Hondt.

IT

T gives us pleafure to behold a performance, in which the principles of the military art treated of in fo clear and rational a manner, as in the Effay before us. We are here prefented, not with dry and arbitrary rules of martial difcipline, drawn from the practice on the parade; but the author lays before us the grand and leading principles of the feveral kinds of military operations, and from thence deduces, by the faireft conclufions, every effential circumftance which regards the improvement of the art. This ingenious fyftem is not only founded on the jufteft principles, but is alfo illuftrated and fupported by examples, both from ancient and modern hif tory..

The