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dations of the Newtonian astronomy, creating a new science of
optical astronomy, composed of the motion of the stars and the
phenomenon of light by which it is perceived--perfecting, by
this application of optics to astronomy, the theory of ecliples,
making discoveries which seemed to require the use of the te
lescope, before that inftrument was invented-associating natural
philosophy to astronomy-applying the principles of metaphysics
to explain the phenomena of motion-with many other essential
operations and improvements in astronomical science, which the
curious Reader will certainly be desirous of perusing in the work
itself.

M. BAILLY suspends his account of the labours of Kepler, ia
order to introduce his cotemporary and rival Galilei, who was
born at Pisa, in 1564, who laid the foundations and unfolded
the elementary truths, on which Newton created the fublime
theory of motion, discovered the laws of accelerated motion in
falling bodies, and enriched astronomical science with a multi-
tude of other discoveries, which were greatly facilitated by his
invention of the telescope, or at least by his application of it to
astronomical uses. It is one of those circumstances that would
afflict humanity, if man's principal destination looked no farther
than the present itate of things, that Kepler lived and died in
indigence, and that Galilei was persecuted.

In the third book our Author treats, first, of the astronomers that were the cotemporaries of Kepler and Galilei, and afterwards of their successors. Here we meet with an account of the Jabours of Longomontanus, a Dane, Albert Curtius, Father Scheiner, a Jesuit (who was the first that attended to, or at leaft explained the elliptical form that the fun assumes in his approach to the horizon), de Rheita, Bayer of Augsburg, Robert Fludd, and Horrox, the first who observed the passage of Venus, and seemed to have been born for that object alone. Horrox lived in the obscurity of retirement, and the silence of study, and at the age of twenty-two, when he died, he had already the soundeft notions and the inoít extensive knowledge of physical astronomy. Vendelinus, Snellius, Blaeu, Hortensius, Cavalieri, Fontana, the learned and indefatigable compiler Riccioli, Peyresc, and others of inferior note, are also treated in this book.

Book fourth. Descartes (says M. Bailly), who taught us to think, who broke the yoke of authority, and would admit no truths before they were examined with precision and ascertained by evidence, is one of those philosophers who produced the greatelt number of errors. The parallel, or rather contrast, in which he represents the different methods followed by Bacon and Descartes in the investigation of truth, is beautiful, ingenious and solid; and though it contains, in substance, what has been often said of these two great men, yet it has an aspect of

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novelty by that luminous arrangement of ideas, and that unequalled felicity of expression, that reign through this whole . work, and are particularly conspicuous in this fourth book. As to the merit of Descartes in astronomical science, it is confiderable ; he opened a path to the most interesting discoveries by his geometrical inventions, and he discovered, in effect, that centrifugal force which is an agent of such importance in the motion of the celestial bodies; but he neither decompounded it, nor investigated the forces that conspire to produce it, 'nor difcerned the power that retains, counterbalances, and modifies it. His hypotheses in dioptrics and other branches of natural philosophy are admirably appreciated and criticised in the rest of this book'; in which we find interesting digreffions from the main subject of the work before us.

The fifth book contains an account of Bouillaud, Hevelius, Huygens, and some other astronomers, such as Ward, Street, Rook, Wing, Mercator, Linemann, and Langrenus. The celebrated Christian Huyghens appears here in all his lustre;-his improvements of the telescope, his discovery of Saturn's ring and of one of his satellites; his pendulum, his writings, give him an eminent rank among astronomers.

The fixth book exhibits the erection of academies, and the invention of instruments, and in the seventh our Author treats of the methods of observing the heavenly bodies. - This book is learned, full of matter, and incapable of being even superficially abridged. The principal object of the eighth book is the cele brated 7. D. Casini, who was born at Perinaldo in the county of Nice, in the year 1625, whose tables of the motions of the fatellites, and other astronomical discoveries and improvements, procured him a high reputation, and an honourable settlement in France, under the protection of Lewis XIV, and Colbert. In the ninth book M. Bailly treats of the measure of the earth, and of the voyages that have been undertaken in France for the improvement of astronomy; and in the tenth he enumerates the Jabours and discoveries of many eminent astronomers about the fame time. The eleventh book contains the labours of Flamstead, Halley and Hook (which laid the foundations of aftronomy in England), and the discoveries that were made in that science from the year 1672 to 1686.

Newton, and Newton alone, employs the head, heart, imagination, and pen of our excellent Author in the twelfth book, which contains above one hundred and ten pages, and in which, not only, nothing is omitted, but all the rays, that were blended in the lustre of that immortal man, are distinguished by M. BAILLY, and are collected here in all their glow of light and truth. There is a certain tone of eloquent fimplicity, gravity and dignity in this book, that is worthy of its subject, and does

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fingular: honour to its Author. He praises Newton with pleas fure, knowledge, admiration and ease. He considers all studied ornaments in his expressions, as beneath the dignity of the Englith philosopher, who was fingularly modeft, did great

things with fimplicity, and followed Nature. Newton, no doubt, is well known ;-but those who know him most will certainly peruse this part of M. BAILLY's, work with the greatest pleasure; and what ample instruction, what a fund of admiration will it not yield to those who are not acquainted with all the wonders of this man's genius, and all the excellence and simplicity of his heart? -"I Thall say nothing of his studies (these are the words of our Author); he seems rather to have discovered, than ftudied, and it may be almost said, that he acquired knowledge by intuition. He ran through the elements of Euclid : the bare mention of the theorems laid open to him their demonftration, and he proceeded to the geometry of Descartes, where he difcerned the language of a great genius, and ideas proportioned to his own capacity and powers. No mistake, no errors have yet been discovered in his writings ; accordingly, Fontenelle applies to him the witty thought of an ancient writer concerning the majestic river that fertilizes Egypt, and whose fource was so long unknown, il n'a pas été permis aux hommes de voir le Nil foible et naisant.

After having remarked, that it was reserved for Newton to de monstrate the causes of gravity, and to secure that important dircovery upon the foundation of mathematical certainty, M. Bailly enters into an ample detail concerning the system of attraction, and all the other discoveries of that transcendent genius. « His researches were admired-many, however, entertained doubts with respect to their results : time and long study were requisite in order to understand him, and to render even the most knowing worthy to receive his lessons." --We need not enter into our Author's enumeration of the sublime contents of the Newtonian philosophy; but we cannot resist the pleafure of making a few extracts from the portrait of the Eng. lish philosopher, with which the Author concludes this twelfth book.

“ Newton, says he, is as singular by the character of his genius, as by his fublime discoveries ; it was gold without alloy, perfectly pure. Genius, by its nature, is ardent, vehement, and the need in which it stands of motion, seems to be the spring which makes it foar. But the genius of Newton was valt without the arcor of pallion, and calm without losing aught of its activity. The objects and ideas which other mortals pursue with such agitation, pain and effort, seem to have offered themselves to the intuition of this great man, who exhibits to us the image of an obferver, fixed and motionless, who fees fuc6

ceffively ćessively the whole heavens' unfolding, around him, their pro perties and powers.-The genius of Newton seems to have transported him to the center of nature-to the point where all the rays

of truth converge and terminate ; there he becamie a fimple spectator, and has related what he saw. What a distance is there between him and his great forerunners, both with respect to extent and accuracy of ideas! Their lustre was always more or less tarnished by errors--Newton produces nothing but truths.”_

" The fimplicity and modefty of Newton were the consequences of his superiority; men of that order execute with facility the most difficult things; how then should they admire what has cost them so little pain and effort ?-Men applaud themselves most, when they are surprised at their productions ; they set a high value on the fruits of painful efforts ;-pride is the indication of mediocrity, and the acknowledgment of our weakness."

66 One of the circumstances that shew Newton's discoveries were (to him) as easy, as they were in themselves important and sublime, is the little pains he was at to insure to himself the honour of having made them. He suspended the publication of a curious discovery, because he saw that Mercator was also in the way to find it out, and if truth was investigated, it was equal to him who made the discovery. The first hints that were thrown out, questioning the originality of his ideas of light and colours, made him put off, for a great number of years, the publication of his Treatise on Optics, which is a work truly original and full of genius. The dispate, relative to the invention of the method of Auxions, gave him pain, not on account of his being obliged to share the honour of this invention with Leibnitz, but because his tranquillity was ruffled in the contek: Newton was desirous of that tranquillity, which is as necessary to the contemplation of nature as to the enjoyment of life.--Are those minds fit to be employed about the grand objects of nature and the universe, which are always acceflible to the petty interests of vain-glory, and the fumes of literary faction? Time glides along amidst these shameful divisions, genius pines, and truth escapes through the tumult. Newton defired tranquillity, because he knew what was the true employment of time; he was indifferent about fame, which followed him fpontaneously, and remains inseparably attached to his memory : If, as Plato thought, there is a fcale of beings which terminates in the highest degree of finite perfection, the nearett approach to Deity, the human species has many great men to present in this series; but Newton, accompanied with his pure, intellectual truths, would undoubtedly exhibit the highest degree of force and pera fection to which the human mind has ever arisen, and would be

sufficient

sufficient, alone, to aflign the place, which human nature ought to hold in this grand scale.”

The thirteenth book treats of the researches and observations relative to the planets and the progress of astronomy, since the discoveries of Newton, or from the year 1687 to 1730. The fourteenth contains researches relative to comets and stars, and the progress of astronomy during the period last mentioned.

This volume is terminated by M. BAILLY's discourse concerning the nature of luminous and obscure bodies in the universe, and a vocabulary designed to explain certain astronomical terms, which may escape the knowledge of numbers, whom the beauty, perspicuity, science and amenity, that jointly adorn this excellent work, will engage to peruse it.

ART. VII. Lettres du Docteur DeMESTE, Correspondant de la Societé Royale de la

Medicine, au Docteur Bernard, &c. Sur la Chymie, &c. -Letters concerning Chymistry, Christallography, Decimasticks *, Lithology, Mineralogy, and Natural Philosophy in general, addressed to Doctor BERNARD, first Professor of Phylic at Douay, and Fellow of the Royal Society of London, by Dr. DEMESTE, Correspondent of the Royal Society of Medicine, &c. with this Inscription : Novus rerum nafitur ordo. Vol. I. Paris. 1779. HESE letters are the production of a masterly writer,

and an accurate observer.- Perspicuity and precision, method and order, distinguish the manner in which the Author expresses his ideas; but his discussions, like many others of modern times, thew us, that physical theories are as little ascertained, and are not a whit more susceptible of evidence in the analytic line, than metaphysical ones.

The title shews the kind of entertainment, which the philosophical, and more especially the chymical Reader, is to expect in these letters. The first discussion we meet with turns upon elementary substances, among which some will be surprised to find, neither fire, nor air, as our Author adopts the hypothesis of Sage, considers these as mixed bodies, of which the former (composed of phlogiston and elementary acid) contributes to the formation of the latter, by a combination with the aqueous principle. You see, gentle Reader, how far the air is from being an element, or fimple principle, upon this hypothesis ; it is so far from being fimple, that it is a double-compound. This notion is illustrated and confirmed with great sagacity and depth of reasoning in three of the letters that compose this volume, to which we refer the curious Reader.

These elements, which we still look upon as dusky beings after all these illustrations, lead our Author to treat of affinities,

A new French term for experimental chymistry, and more especially mineralogical experiments.

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