in which Newton lived. Not only was Newton profoundly religious, but his whole life was spent, and all his affections were concentrated in a circle of men, who, holding the same doctrines, consisidered themselves bound by their station or profession to defend and propagate them. The English philosophers of that period took pleasure in combining the researches of science with theological discussion; to which they were the more inclined, because the cause of protestantism had identified itself with political liberty; and men studied the bible to find weapons against despotism. The choice of Newton by the University of Cambridge as one of the delegates sent to King James, shows clearly that he shared in such sentiments; nor is it a more surprising fact, that Newton wrote upon the Apocalypse, than that R. Boyle, one of the greatest natural philosophers of the same period, published a treatise, entitled "The Christian Virtuoso," of which the object is to show that experimental philosophy conduces to a man being a good Christian,than that Wallis, the celebrated mathe matician, composed a number of tracts on religious subjects,-than that Barrow who reckoned Newton himself among his pupils, and who resigned in his favour the mathematical chair, consecrated his latter years to theology, in order to take the degree of doctor in that faculty-that Hooke, whom we have so often mentioned, composed a work on the Tower of Babel-that Whiston, Newton's pupil and successor at Cambridge, also composed an essay "on the Revelation of St. John," and other treatises on pure theology-that Clarke, another still more illustrious pupil of Newton, the faithful translator of his Optics, the zealous promoter and ingenious defender of his philosophy, was at the same time the most profound theologian and sublime preacher in England; and finally, that Leibnitz himself, to take no other example, in the course of his literary life, voluntarily made numerous excursions into the provinces of natural theology, revelation, and biblical criticism; that he commented on the story of Balaam, treated in various ways the question of grace, and with the laudable intention of uniting Protestants and Catholics, discussed with Bossuet the principal doctrinal points which separate the two churches. This alliance of the exact sciences with religious controversy, at that time so

general, is the natural mode of accounting for the theological researches of Newton, however singular they might appear at the present day. There is another tract belonging to the same class of writings, which we must also mention, not only from the importance of the subject in a religious point of view, but also because it affords us a new opportunity of seeing the extensive knowledge which Newton possessed in these matters. The title is "An historical account of two notable corruptions of the Scriptures," in fifty pages 4to.; it contains a critical discussion of two passages in the Epistles of St. John and St. Paul, relating to the doctrine of the Trinity, which Newton supposes to have been altered by the copyists. From the nature of the subject, and from certain indications at the beginning of the pamphlet, it probably was composed when the works of Whiston and of Clarke on the same subject drew upon them the attacks of all the English theologians, that is, about 1712-13. It is certainly very remarkable that a man of the age of seventy-two or seventy-five should be able to compose rapidly, as he himself insinuates, so extensive a piece of sacred criticism, and of literary history, in which the logically connected arguments are always supported by the most varied erudition. At this period of Newton's life, the reading of religious works had become one of his most habitual occupations; and after he had performed the duties of his office, they formed, along with the conversation of his friends, his only amusement. He had now almost ceased to think of science, and as we have already remarked, since the fatal aberration of his intellect in 1693, he gave to the world only three really new scientific productions. One of these had probably been prepared some time previously, and the other must have occupied but little time: the first, published in the Philosophical Transactions, consists of only five, though very important, pages. It contains a comparative scale of temperatures, from the point of melting ice to that of the ignition of charcoal; the lower degrees are observed by means of a thermometer of linseed oil, the scale of which is divided into equal parts; the zero corresponds to the melting point of ice, and the 81st degree to the melting point of tin The higher degrees are calculated according to the law of cooling in a metallic mass, by supposing the instan

taneous decrease in temperature to be proportional to the temperature itself, and by observing the time of the arrival of the fluid at each degree of temperature intended to be marked. These two methods of observation are connected by applying them to the same temperature for instance, to the fusion of tin, which is the highest in the one series, and the lowest in the other.

We have thus in this paper three important discoveries-first, a method of comparing thermometers, by determining the extreme terms of their scale from phenomena taking place at constant temperatures-secondly, the determination of the laws of cooling in solid bodies at slightly elevated temperatures; and thirdly, the observation of the constancy of temperature in the phenomena of melting and boiling-a constancy which has since become one of the foundations of the modern theory of heat: this important fact is established in Newton's treatise, by numerous and various experiments, made not only on compound bodies, and the simple metals, but on various metallic alloys, which shows us that Newton clearly perceived their importance. There is reason to believe that this paper was one of those composed before the fire in his laboratory.

a

The second paper we must mention, also dated 1700, was communicated by Newton to Halley, and was plan for an instrument of reflection to observe with at sea, without the observer being disturbed by the motion of the ship. It has been pretended that this idea, since so generally and so usefully employed by navigators, had been in vented a long time previously by Hooke. It is true that in the history of the Royal Society for 1666, there is mentioned an instrument proposed by Hooke, to measure angles by means of the reflection of light; this announcement, however, is unaccompanied by any description to enable us to judge of the nature of the instrument; and if we endeavour to supply this defect by consulting the works of Hooke, written after this period, we shall find, that though he often makes use of reflection, it is always when applied to large fixed instruments; an idea which has no rela-. tion to that of employing reflection in moveable instruments, in order to render the angular distance of remote objects under observation independent of small changes of place in the centre of obser

vation from which they are viewed. There is no reason to believe that any one formed this happy and important idea before Newton, though the inexplicable silence of Halley, with regard to Newton's letter to him, left to another man, Hadley, the honour of again conceiving it (in 1731), and of so happily executing it, that mariners have given the name of Hadley's Quadrant to this ingenious and useful invention.

The last labour of Newton that remains to be mentioned, was of another sort, and composed on a totally different occasion. In 1696, J. Bernoulli proposed to the mathematicians of Europe, to discover a curve, down which a heavy body should descend in the quickest time pussible, between two given points at unequal heights. Newton having received this problem, presented on the next day a solution of it, but without any demonstration, merely saying that the required curve must be a cycloid, for the determination of which he gave a method. This solution appeared anonymously in the Philosophical Transactions, but J. Bernoulli immediately guessed the author; “tanquam," says he, ex ungue Leonem." This method of defiance, then in vogue, was again presented some years later to Newton, but by a more formidable adversary, and in a case where victory was of still more importance. In 1716, when the dispute about the invention of the infinitesimal analysis was at his height, Leibnitz wishing to show the superiority of his calculus over Newton's method of fluxions, sent, in a letter to the Abbé Conti, the enunciation of a certain problem, in which it was required to discover a curve such as should cut at right angles an infinity of curves of a given nature, but all expressible by the same equation; "he wished," he said, "to feel the pulse of the English analysts." Of course the question was a very difficult one. It is said that Newton received the problem at four in the afternoon as he was returning from the Mint, and, that though extremely fatigued with business, yet he finished the solution before retiring to rest. It has been, however, justly remarked, that Newton only gave the differential equation for the problem, and not its integral, in which the real difficulty consists. This was his last effort of the kind; and he soon entirely ceased to occupy himself with mathematics: so that during the last ten years of his life, when consulted

about any passage in his works, his reply was, "Address yourself to Mr. De Moivre, he knows that better than I do." And then, when his surrounding friends testified to him the just admiration his discoveries had universally excited, he said, "I know not what the world will think of my labours, but, to myself, it seems that I have been but as a child playing on the sea-shore; now finding some pebble rather more polished, and now some shell rather more agreeably variegated than another, while the immense ocean of truth extended itself unexplored before me."*

This profound conviction of the numerous discoveries that still remained to be made, did not, however, bring him again on that sea where he had advanced so much farther than any other man. His mind, fatigued by long and painful efforts, had need of complete and entire repose. At least we know, that thenceforward he only occupied his leisure with religious studies, or sought relief in literature or in business. Newton, the greatest of mankind in science, was, if we may dare to say so, but an ordinary man in other pursuits; he never distinguished himself in parliament, to which he was twice summoned; and in one instance he appears to have acted with inexplicable timidity. In 1713, a bill was brought in for encouraging the discovery of a method for finding the longitude at sea. Whiston, the author of the bill, and who himself tried to gain the reward proposed in it, obtained the appointment of a committee for discussing the measure; and four members of the Royal Society were invited to attend-Newton, Halley, Cotes, and Dr. Clarke: the three latter gave their opinions verbally, but Newton read his from a paper he had brought with him, without being understood by any one; he then sat down and obstinately kept silence, though much pressed to explain himself more distinctly. At last Whiston, seeing the bill was going to fail, took on himself to say, that Mr. Newton did not wish to explain more through fear of compromising himself, but that he really approved of the measure. Newton then repeated word for word what Whiston had said, and the report was brought up. This almost

puerile conduct, on such an occasion, tends to confirm the fact of the aberration of Newton's intellect in 1695, though it might have been merely the effect of excessive shyness, produced by the retired and meditative habits of his life. For, to judge from a letter of Newton," written some time before the disastrous epoch, in which he points out the conduct to be pursued by a young traveller, it would appear that he was very ignorant of the habits of society.

From the manner in which his life was spent, we may easily conceive that he was never married, and (as Fontenelle says) that he never had leisure to think about it; that being immersed in profound and continual studies during the prime of his life, and afterwards engaged in an employment of great importance, and ever quite taken up with the company which his merit drew to him, he was not sensible of any vacancy in life, nor of the want of domestic society. His niece, who with her husband lived in his house,. supplied the place of children, and attended to him with filial care. From the emoluments of his office-from a wise management of his patrimonyand from his simple manner of living, Newton became very rich, and employed his wealth in doing much good. He thought, says Fontenelle, that a legacy is no gift, and therefore left no will-it was always out of his present fortune that he proved his generosity to his relations, or to the friends whom he knew to be in want. His physiognomy might be called calm rather than expressive, and his manner languid rather than animated: his health remained good and uniform till his eightieth year; he never used spectacles. About that age he began to suffer from an incontinence of urine; but notwithstanding this infirmity, he still had, during his five remaining years, long intervals of health, or at least of freedom from pain, obtained by a strict regimen and other precautions, which till then he had never had occasion for. He was now obliged to rely upon Mr. Conduit, who had married his niece, for the discharge of his official duties at the Mint. Newton was useful to Conduit, even after death: for the honourable confidence that existed between them gave him a sort of claim to the office, which the king

Conduit. Vid. Turner.

+ This anecdote is mentioned by Whiston in his work, "Longitude Discovered,"-8vo. London, 1738.

Biographia Britannica, p. 3242,

"Newton," says Fontenelle, "did not suffer much, except in the last twenty days of his life: it was truly judged from the symptoms, that he was afflicted with the stone, and that he could not recover. In the paroxysms of pain, he uttered not a moan, nor gave any sign of impatience; and, as soon as he had a moment of relief, he smiled and spoke with his usual gaiety. Hitherto he had always employed some hours every day in either reading or writing. On Saturday the 18th of March, he read the papers in the morning, and conversed for some time with Dr. Mead, the physician who attended him, having then the perfect use of all his senses and his understanding; but in the evening, he entirely lost them without again recovering, as if the faculties of his mind were not destined to linger by degrees, but at once to vanish. He died the Monday following (March 20th, 1727,) at the age of eighty-five. His corpse lay in state in the Jerusalem Chamber, and was thence conveyed to Westminster Abbey; the funeral ceremony was numerously attended; the pall was supported by six peers; and every honour was paid to his remains."

The family of Newton, justly sensible of the distinction derived from their connexion with so great a genius, erected at a considerable expense a monument to his memory, on which is inscribed an epitaph, ending as follows:Sibi grotulentur mortales tale tantumque exstitisse humani generis decus." Let mortals congratulate themselves that so great an ornament of the human race has existed"-an eulogy which, though true in speaking of Newton, can be applied to no one else.

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Besides the works we have already mentioned, Newton published an edition of the "Geographia Generalis" of Varenius, 8vo, 1672, reprinted in 1681. There is no really complete edition of the works of Newton, though Bishop Horsley published one in five volumes, 4to, to which he has given this title; but he has

There

omitted a number of papers collected by Castillon (4 vols. 4to, Lausanne, 1744). By joining to these two books Newton's scientific letters inserted in the Biographia Britannica, we may make a tolerably complete collection of his works. Among the numerous translations that have appeared of the principal ones, we must not omit that of the Principia in French by Madame Duchâtelet, since it contains excellent notes supposed to be by Clairault. are also two books in English, viz. H. Pemberton's "View of Sir I. Newton's Philosophy," (London, 1728, 4to), and C. Maclaurin's "Account of Sir I. Newton's Philosophical Discoveries," both of which will well repay the trouble of perusing them. It is, however, in the writings of the modern continental mathematicians, that we find the more complete developement of those brilliant discoveries which have shed so much lustre on the name of Newton. It is with the works of LAPLACE, Lagrange, Biôt, Lacroix, Monge, Garnier, Poisson, DELAMBRE, Boucharlat, Carnot, Bailly, Bernouilli, Euler, Bossut, Montucla, De Zach, Lalande, Francœur, Legendre, Poisson, Gauss, Hauy, &c. &c., that the student must become acquainted, before he can hope to attain to a thorough knowledge of the system of the universe. In science, it is perhaps more necessary than in any other species of knowledge intimately to understand what has been done by our predecessors; and it therefore becomes our duty to express our earnest hope, that our readers will not merely content themselves with studying the works of that great man whose discoveries we have in this treatise recorded, but that, endeavouring themselves to enter on the same illustrious career, they will diligently peruse the writings of the distinguished individuals whose names we have just mentioned. in Hutton's Mathematical Dictionary of the principal MSS. now in existence, that were written by Newton.

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