rays had each its own colour inherent in it, that rays falling in the same angle of incidence, have alternate fits of reflection and refraction; that bodies are rendered transparent by the minuteness of their pores, and become opaque by having them large; and that the most transparent body, by having a great thinness, will become less pervious to the light. However, what had thus employed his assiduous researches for so many years, was far from being confined to the subject of light alone. On the contrary, it seemed to comprehend in it all that we know of natural bodies. He had discovered, that there was a mutual action at a distance between light and other bodies; by which both the reflections and refractions, as well as inflections of the former were constantly produced. To ascertain the force and extent of this principle of action, was what had all along engaged his thoughts, and what, after all, by its extreme subtlety, escaped even his most penetrating spirit. But, though he has not made so full a discovery of this principle, which directs the course of light, as he has of the power by which the planets are kept in their courses; yet he has given the best directions possible for those who may be disposed to carry on the work, and furnished abundant matter to animate them to the pursuit. By this means he has opened a way of passing from optics to an entire system of physics; and if we look upon his queries as furnishing us with the history of a great man's first thoughts, even in that view they must be entertaining and curious. He was very anxious that his true meaning in them should be rightly understood, which was, to furnish sufficient motives for making further enquiries; but, in the mean time, not to determine any thing. Hence it was, that when Dr. Friend, a few years afterwards, published his "Lectures on Chemistry," and, in explaining the phænomena of chemical experiments, assumed attraction for a principle, which in the queries was only stated as a conjecture, our author complained of it as an injury done to him. With the approbation of Newton, the learned Dr. Samuel Clarke translated the "Optics" into Latin; and our author was so well pleased with the accuracy and elegance of his version, that he made the doctor a present of five hundred pounds, or, a hundred pounds for each of his children. This translation was published at London, in 1706, quarto; and our author printing a second edition of his book, with improvements, in 1718, octavo, the second edition of Dr. Clarke's translation was

VOL. VII.

likewise published, in 1719, quarto. A French translation of it, by Mr. Peter Coste, was published at Amsterdam, in 1720, in two volumes, 12mo.; and reprinted at Paris, in 1722.

With the first edition of his " Optics," the author also published his "Quadrature of Curves" by his new analysis; to which he subjoined, "An Enumeration of the Lines of the Third Order :" both contained under this title, "Tractatus duo de Speciebus et Magnitudine Figurarum curvilinearum." This was the first appearance in print of his "Method of Fluxions." We have already seen that this invention was intended for the public so long before as the year 1672; but was then laid by in order to prevent the author from being engaged in any dispute about it. However, notwithstanding his solicitude to avoid controversy, its publication at present proved the source of an altercation that continued many years. Ever since the year 1684, Mr. Leibnitz had endeavoured to impress the world with the persuasion, that Newton had borrowed this invention from his "Differential Method." Of this design our author was aware, and on that account inserted his right to the invention, in the scholium to the second lemma of the second book of his first edition of the "Principia," in 1687; and, as he now published his "Method," he took occasion to acquaint the world, that he had discovered it in the years 1665 and 1666. In the account which was given of this treatise in the "Acta Eruditorum" of Leipsic, this invention was ascribed to Leibnitz, and it was intimated that Newton borrowed it from him. In our life of Dr. Keill, professor of astronomy at Oxford, we have entered into a particular account of the zeal and success with which that mathematician vindicated the honour of his illustrious countryman. When referring to this dispute, Fontenelle says, "Sir Isaac was by many years the first inventor. Mr. Liebnitz, on the other side, was the first who published this method of calculation; and if he took it from sir Isaac Newton, he resembled Prometheus in the fable, who stole fire from heaven, that he might communicate it to men." In the year 1705, queen Anne, influenced by the consideration of his extraordinary merit, was pleased to confer upon our author the honour of knighthood. Two years afterwards, Mr. Whiston, by our author's permission, published his algebraical lectures, under the title of "Arithmetica Universalis, sive de Compositione et Resolutione Arithmetica Liber,"

3 C

octavo; which was translated into English by Mr. Raphson. A second edition of it, with improvements by the author, having been printed under the care of Mr. Machin, professor of astronomy at Gresham College, and secretary to the Royal Society, Raphson's translation was revised and corrected by Mr. Cunn; and an improved edition of it, illustrated with notes, was published by Dr. Wilder, of TrinityCollege, Dublin, in 1769, in two volumes, octavo. A Latin edition of the same work, with a commentary, by Castilion, afterwards made its appearance at Amsterdam, in two volumes, quarto. Dr. Pemberton tells us that the author called this work, which exhibits another specimen of the extraordinary force of his genius, by the name of "Universal Arithmetic," in opposition to the injudicious title of "Geometry," given by Des Cartes to the treatise in which he shews how the geometrician may as sist his invention by such kind of computations. In the year 1711, our author's "Analysis per Quantitatum Series, Fluxiones et Differentias, cum Enumeratione Linearum tertii Ordinis," was published at London, in quarto, by William Jones, esq. F.R.S. who met with a copy of the first of these pieces among the papers of Mr. John Collins, to whom, as we have already seen, it had been communicated by Dr. Barrow. It was published in consequence of the dispute relating to the invention of fluxions; which also occasioned the printing, in 1712, by the consent of sir Isaac, à collection of letters by him and others in that controversy, under the title of "Commercium Epistolicum D. Johannis Collins, et aliorum, de Analysi promota, jussu Societatis Regiæ in Lucem editum."

In the year 1714, Mr. Ditton and Mr. Whis ton having petitioned parliament for encouragement to a new method, by which they proposed to discover the longitude at sea by signals, the House of Commons appointed a committee to take it into consideration; who, after applying to our author, and obtaining his written opinion upon the subject, thought proper to reject the prayer of the petitioners. During the following year, Mr. Leibnitz, with the view of gaining credit to the pretension that the "Method of Fluxions" had been borrowed from his "Differential Method," attempted to baffle sir Isaac's mathematical skill by his famous problem of the Trajectories, which he proposed to the English by way of challenge; but, though it was the most difficult proposition which his ingenuity, after much study, was able to devise, the solution of it proved scarce

ly more than an amusement to our author. The problem was received by him at four o'clock in the afternoon, as he was returning from the Mint; and, though he was extremely fatigued with business, yet he finished the solution of it before he retired to bed. Upon the accession of king George I. to the British throne, sir Isaac was particularly noticed at court; and it was for the immediate satisfaction of that prince, to whom Leibnitz was a privy-counsellor at Hanover, that he was prevailed upon to put the last hand to the dispute about the invention of fluxions. In this court he was introduced to the princess of Wales, afterwards queen Caroline, who took great delight in literary and philosophical enquiries, and the conversation of men distinguished by their talents and knowledge. With that of our author she was always peculiarly gratified, deriving from it that full satisfaction in every difficulty, which she had in vain sought for elsewhere, and she was frequently heard to declare publicly, that she "thought herself happy in coming into the world at a juncture of time, which put it in her power to converse with sir Isaac Newton." It was at the solicitation of this princess that he drew up an abstract of his "Chronology," and communicated a copy of it to the abbé Conti, a Venetian nobleman then in England, upon a promise to keep it secret. But the abbé, who, when in this country, professed a particular friendship for sir Isaac, while he was privately doing him all the injury in his power in the dispute with Leibnitz, was so dishonourable when he returned to the continent, as to disperse several copies of it, and to procure a person to translate it into French, as well as to attempt a confutation of it. This version was printed at Paris, in 1725, and a copy of it, without the remarks, under the title of "Abrégé de Chronologie de M. le Chevalier Newton, fait par lui-même et traduit sur le manuscript Anglois," was sent to our author by the bookseller who printed it, under the pretence of asking his consent to the publication; but though he gave a direct denial, the whole of the work was sent into the world in the same year. Upon this he found it necessary to enter. into a defence of himself, which was inserted in the thirty-fourth volume of the "Philosophical Transactions," under the title of "Remarks upon the Observations made upon a Chronological Index of Sir Isaac Newton, translated into French by the Observator, and published at Paris." Of this paper, a French

translation appeared at Paris, in 1726, with a letter of the abbé Conti in answer to it. In the same year, likewise, some dissertations were published at Paris by father Souciet, against sir Isaac's Chronological Index;" a reply to which, by Dr. Halley, was given in the 397th number of the " Philos. Transactions."

Our incomparable philosopher enjoyed a regular and pretty equal state of health, until he attained his eightieth year, when he became subject to an incontinence of urine, which was thought to be occasioned by a stone in his bladder, and was considered to be incurable. However, by observing a strict regimen, and using other precautions, he procured consider able intervals of ease during the remaining years of his life; but not without enduring some severe paroxysms, which occasioned large drops of sweat to roll down his face. During these attacks, he was never heard to utter the least complaint, nor to express any impatience; and, as soon as he has had a moment's ease, he would smile and converse with his usual cheerfulness. Till this time, he had always read and written for several hours in a day; but he was now rendered incapable of this application, and was also obliged to rely upon Mr. Conduit, who had married one of his nieces, for the discharge of his duties at the Mint. On the morning of the eighteenth of March, 1726-7, he read the newspapers, and conversed for a considerable time with Dr. Mead, his physician, having then the perfect use of all his faculties; but he was finally deprived of them in the course of the succeeding night, and he breathed his last on the twentieth of the same month, when he was in the eighty-fifth year of his age. The last honours were paid to his remains in a manner suitable to his extraordinary merit, and that high estimation in which he was deservedly held in every part of Europe. His body lay in state in the Jerusalem chamber, adjoining the House of Lords, and on the twenty-eighth of March was conveyed to Westminster-abbey, the lord-chancellor, the dukes of Montrose and Roxburgh, and the carls of Pembroke, Sussex, and Macclesfield, supporting the pall. He was interred at He was interred at the entrance into the choir, at the left hand, where a stately monument, with a most elegant inscription upon it, was erected to his me

and venerable at the same time, especially when he took off his peruke, and shewed his white hair, which was pretty thick. He had never occasion to make use of spectacles; and he lost but one tooth during the whole of his life. Fontenelle says, that he had a lively and piercing eye but on this point he appears to have been misinformed; for bishop Atterbury, who personally knew him, assures us, that, "this did not belong to him, at least not for twenty years past," says the bishop, "about which time I became acquainted with him. Indeed, in the whole air of his face and make, there was nothing of that penetrating sagacity which appears in his compositions; he had something rather languid in his look and manner, which did not raise any great expectation in those who did not know him." His character has been drawn by Dr. Pemberton, Fontenelle, and others, from whose writings we shall select various particulars, necessary to complete the memoirs of this illustrious man. In contemplating his genius, it is not easy to determine which of these endowments had the greatest share in his composition; sagacity, pcnetration, strength, or diligence. He entertained, however, a very modest opinion of his own abilities; and in answer to one of his friends who said some handsome things of his extraordinary talents, he assured him, in an easy and unaffected way, that if he had done any thing worth notice, and of service to the world, it was owing more to his industry and patience of thought, than to any extraordinary sagacity. "I keep the subject constantly before me," said he, " and wait till the first dawnings open slowly, by little and little, into a full and clear light." It is said of him, that whenever he had any mathematical problems or solutions in his mind, he would never quit the subject on any account. When he has been getting up in a morning, he has sometimes begun to dress, and with one leg in his breeches sat down again on the bed, where he has remained for hours before he has got his clothes on. ner has been often three hours ready for him, before he could be brought to table. Among the other anecdotes which are told of him on this head, it is related that one day, his intimate friend Dr. Stukely happening to call at his house, was shewn into the room where sir Isaac usually dined, and where a boiled chicken had been some time waiting for him under a cover; but he was then too busily engaged in his study to attend to such matters. At length the doctor, not having dined himself, and find

Din

ing that sir Isaac did not make his appearance, sat down to table and completely finished the chicken; after which he put the bones in the dish, and replaced the cover. In a little while our philosopher came out of his study, and telling his friend that he was both weary and hungry, took up the cover; but, finding only the bones of the fowl left, observed to his friend, with a smile, "I thought I had not dined, but I now find that I was mistaken."

However, careful as sir Isaac was to preclude all interruption when engaged in intense application, he was not so far absorbed in philosophical pursuits as to be incapable of attending to any other object. On the contrary, he could arrest his thoughts in the midst of his most intricate researches, when his other affairs demanded his attention; and, as soon as he had leisure, resume the subject at the point where he had left off. This he seems to have done, not so much by any extraordinary strength of memory, as by the force of his inventive faculty, to which every thing opened itself again with ease, if nothing intervened to ruffle him. The readiness of his invention made him not think of putting his memory much to the trial; but this was the offspring of a vigorous intenseness of thought, out of which he was but a common man. He spent, therefore, the prime of his age in these abstruse researches, when his situation in a college gave him leisure, and while study was his proper profession: but as soon as he was removed to the Mint, he applied himself chiefly to the business of that office; and so far quitted mathematics and philosophy, as not to engage in any pursuits of either kind afterwards. Dr. Pemberton tells us, that he found sir Isaac had read fewer of the modern mathematicians than one could have expected; but his own prodigious invention supplied him with what he might have occasion for in any subject which he undertook. He often censured the handling of geometrical subjects by algebraic calculations, and frequently praised Slusius, Barrow, and Huygens, for not being influenced by that bad taste which then began to prevail. He used to commend the laudable attempt of Hugo de Omerique, to restore the ancient analysis, and very much esteemed Apollonius's book, "De Sectione Rationis," for giving us a clearer notion of that analysis than we had before. Dr. Barrow he esteemed, as having shewn a compass of invention, equal, if not superior, to any of the moderns; we add, our author himself excepted. But he

particularly recommended Huygens's style and manner, and thought him the most elegant of any mathematical writer in modern times, and the most just imitator of the ancients; of whose taste and form of demonstration sir Isaac always professed himself a great admirer. Dr. Pemberton likewise observes, that his memory was much decayed in the last years of his life; though there was no foundation for an opinion which was propagated, that he did not then understand his own writings. This opinion might perhaps arise, from his not being always ready to speak on the subjects of them, when it might be expected that he should; which the doctor attributes to an occasional absence of mind, not uncommon to men of genius. Add to this, that the behaviour which he had met with from Mr. Leibnitz, the abbé Conti, and others, had led him to the exercise of much caution when conversing before strangers, which had increased into a habit of reserve as he advanced in life.

Our author's temper is said to have been so mild and equal, that scarcely any accident could disturb it. One instance in particular, is mentioned of this disposition. He had a favourite little dog, called Diamond, which was one day left behind in his study when he was called out into the adjoining room. Upon his return, he had the mortification to find that the animal had overthrown alighted candle among some papers, containing the almost finished labours of many years, by which means they were set on fire and almost entirely consumed. This loss, as it took place when sir Isaac was far advanced in life, was irretrievable; yet instead of venting his resentment on the author of the mischief, he only rebuked him with this exclamation, "O Diamond! Diamond! thou little knowest the mischief thou hast done!" We have already mentioned, that this great man entertained a very modest opinion of his own abilities; and as a consequence of it we may observe, that he never talked either of himself or others, nor ever behaved in such a manner, as to give the most malicious censurers the least occasion even to suspect him of vanity. He was candid and affable, and always put himself upon a level with his company. He never thought either his merit or reputation sufficient to excuse him from any of the common offices of social life; and yo singularities, either natural or affected, distinguished him from other men. With respect to his religious sentiments, he was a firm believer in the truth of divine revelation, and a

serious rational Christian. His discoveries concerning the frame and system of the universe, he employed to demonstrate against atheism of all kinds the being of a God, and to illustrate his power and wisdom in the creation of the world; and he applied himself with the utmost attention to the study of the sacred writings, and considered the several parts of them with uncommon exactness. He adhered to the communion of the church of England, but was an utter enemy to intolerance towards non-conformists. He judged of men by their manners; and the true schismatics, in his opinion, were the vicious and immoral. On doctrinal topics he took the liberty of judging for himself, and differed widely in some points from the established creed. He did so, particularly, on the question concerning the person of Christ, having adopted, as we learn from the testimony of Hopton Haynes, esq. who was for many years connected with him in the office of the Mint, the unitarian sentiment. He did not neglect the opportunities of doing good, which the revenues of his patrimony and a profitable employment, improved by a prudent economy, put in his power. When decency upon any occasion required expence and shew, he was magnificent without grudging it, and with a good grace; but at all other times, that pomp which seems great to low minds only, was utterly retrenched, and the expence reserved for better uses. He never married; "and, perhaps," says Fontenelle, "never had leisure to think of it, taken up as he was at first in profound and continual study, and afterwards employed in an important and considerable post, which left no vacancy in his life, nor any occasion for domestic society." At his death, his personal estate amounted to thirty-two thousand pounds, which came among his heirs-at-law, he having died intestate, thinking, as Fontenelle tells us, that a legacy was no gift.

To give the reader a perfect idea of the philosophy of Newton, would be to conduct him through every part of his philosophical works. We must therefore content ourselves with a brief account of the design and plan of his "Principia," and a few miscellaneous observations chiefly extracted from the queries subjoined to his "Optics;" in which we shall follow Enfield's abridgement of Brucker.

"Dissatisfied with the hypothetical grounds on which former philosophers, particularly Des Cartes, had raised the structure of natural philosophy, Newton adopted the manner of philo

sophizing introduced by lord Bacon, and determined to raise a system of natural philosophy on the basis of experiment. He laid it down as a fundamental rule, that nothing is to be assumed as a principle, which is not established by observation and experience, and that no hypothesis is to be admitted into physics, except as a question, the truth of which is to be examined by its agreement with appearances. Whatever,' says he, 'is not deduced from phænomena, is to be called an hypothesis: and hypotheses, whether physical or metaphysical, whether of occult qualities or mechanical, have no place in experimental philosophy.' In this philosophy, propositions are drawn from phænomena, and are rendered general by induction. This plan of philosophizing he pursued in two different methods, the analytic and synthetic; collecting from certain phẩnɔmena the forces of nature, and the more simple laws of the forces, and then proceeding, on the foundation of these, to establish the rest. In explaining, for example, the system of the world, he first proves from experience that the power of gravitation belongs to all bodies: then, assuming this as an established principle, he demonstrates by mathematical reasoning, that the earth and sun, and all the planets, mutually attract each other, and that the smallest parts of matter in each have their several attractive forces, which are as their quantities of matter, and which, at different distances, are inversely as the squares of their distances. In investigating the theorems of the "Principia," Newton made use of his own analytical method of fluxions; but, in explaining his system, he has followed the synthetic method of the ancients, and demonstrated the theorems geometrically. The leading design of the "Principia" is, from certain phanomena of motion to investigate the forces of nature, and then, from these forces to demonstrate the manner in which other phænomena are produced. The former is the end towards which the general propositions in the first and second books are directed; the third book affords an example of the latter, in the explanation of the system of the world. The laws of motion, which are the foundation of the Newtonian system, are these three: 1.Every body perseveres in its state of rest, or of uniform motion in a right line, unless compelled, by some force impressed upon it, to change its state. 2. The change of motion is proportional to the force impressed, and is made in the direction of the right line in which that force is