Now, Newton's experiments had shown him seven colours with distinct properties; but so convinced was Hooke of the truth of his own mere fancy, that he could not be made to admit the force of any evidence in refutation of it. Another of Newton's opponents on this occasion was a Father Pardies, a French Jesuit, and a person of very considerable learning and ability. The unequal refrangibility, as it is called, of the different rays of light, or that property by which the component parts of a ray of the sun's light, on passing through a prism, spread themselves out into an elongated image or spectrum, exhibiting a succession of seven distinct colours, forms the fundamental proposition of a most important branch of the science of optics, and one of the most curious truths which Newton's experiments established. But it was one which this Father Pardies would by no means admit, he having previously adopted the notion that rays of all colours were equally refrangible. So he set to work very laboriously, but we need not add, most unsuccessfully, to show that the elongation of Newton's spectrum was the effect, not of any change operated upon the direction of the rays in their passage through the prism at all, but merely of the different angles at which they must, he contended, have originally fallen upon the one side of the prism forcing them to issue still more widely diffused from the other, a hypothesis which not only admitted of being mathematically disproved, but which, even if it had been received as sufficient to account for the elongation of the image, would have left other equally undeniable and perhaps still more striking results of Newton's experiments altogether unexplained and unintelligible. But the most extraordinary attempt at a refutation of the new doctrines that appeared is contained in a paper, which may be found in the Philosophical Transactions,' by a philosopher of the name of Linus, a physician at Liege, who actually asserts that Newton's story of the elongated image produced by the prism is a pure fiction, that he himself on repeating the experiment never had been able to see any thing more than a luminous spot perfectly round, and perfectly colourless,-and that Newton must have been merely deceived by some coloured cloud accidentally passing along the heavens, which might perhaps, by tinging and scattering the light admitted into the chamber, have given rise to something like the lengthened and variegated image he imagined he had observed. We may very reasonably suppose that this worthy gentleman must, in performing his experiment, have made the slight mistake of omitting to introduce the prism altogether; and indeed why should he have taken the trouble of going through a part of the process which he had evidently convinced himself before-hand was so perfectly immaterial? The absurd attention which the Society showed to these objectors by printing their lucubrations involved Newton in a protracted and most teazing controversy, which seems to have given him great disturbance and uneasiness. On the urgent persuasion of his friends he was induced, though very much contrary to his own feelings, to answer some of his opponents; and his gentle spirit, formed for contemplation, was much more sorely ruffled by this unusual exercise, than to minds of the ordinary cast it will seem necessary or natural that it should. We find him at last requesting Oldenburg, the secretary of the Royal society, to prevent the appearance, as far as he conveniently could, of any objections or philosophical letters that might

concern him. And, again, in a letter referring to this subject, dated the 9th of December, 1675, he states in a strain of bitter regret that he blamed his own imprudence for parting with so substantial a blessing as his quiet to run after a shadow.

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In 1675 Newton obtained a dispensation from the king, Charles II. to continue in his fellowship without taking orders. The state of his pecuniary resources at this time may be understood from an order of the council of the Royal society passed on the 28th of January, by which he is excused from the weekly contribution of a shilling, account of his low circumstances, as he represented." For some years after this his attention appears to have been occupied partly in prosecuting his discoveries on the subject of light, and partly in perfecting his invention of the fluxionary calculus. So early as in the month of June, 1669, he had communicated to Barrow his treatise on that subject, entitled Analysis per equationes numero terminorum infinitas ;' and the manuscript had been soon after given by Barrow to the wellknown mathematician John Collins, who subsequently made known its contents to many of his scientific friends. It was not printed till 1711, after the death of Collins, among whose papers it was found. In 1672 Newton had also prepared another work, entitled A Method of Fluxions,' which, however, he declined at the time to publish, afraid of its involving him in a controversy similar to that which the announcement of his optical discoveries had occasioned, and from which he was then suffering so much distress. This work was, like the former, also written in Latin, and was not given to the world till 1736, long after the death of its author, when it at length appeared translated into English by Colson. It was in 1682, as we have already mentioned, that Newton, having accidentally heard of Picard's new measurement of the circumference of the earth, resumed his calculations on the theory of universal gravitation, and had at last the exquisite satisfaction of find. ing his original conjectures completely verified. Halley, the astronomer, in a visit which he paid to him at Cambridge in August, 1684, saw in his hands the demonstration of some of the fundamental propositions of the Principia;' and the manuscript of that work was laid before the Royal society in the course of the following April. As in the case of his optical discoveries, Newton found himself on this occasion again clamorously assailed by Hooke, who had, some years before, been appointed secretary to the Society on the death of Oldenburg, and who now actually claimed the honour of having previously found out nearly every thing that the Principia' contained. The Society, however, did not pay much attention to his passionately urged complaints; and under this treatment he seems himself to have in a short time become considerably less violent. Still Newton, deterred by the apprehension of a contest with new antagonists, objected strongly to the publication of the work. The third book in particular he was extremely anxious to suppress. "Philosophy," he writes in a letter to Halley, intimating this wish, "is such an impertinently litigious lady, that a man had as good be engaged in lawsuits as have to do with her." His objections, however, were at last overcome by the representations of his friends-and the work was published entire, at the expense of the Society, in May, 1687. The truths demonstrated in this immortal treatise, which may be said to have laid the founda

tion of all that has been achieved in physical science since the era of its appearance, were at first either violently opposed, or received with surprise and incredulity by the great majority of the mathematicians and astronomers of the day. The philosophy of Descartes, who had pretended to explain the celestial phenomena by the supposition of a multitude of airy vortices or whirpools, was then universally taught in the schools, and formed the common faith of the scientific world. Dr Brewster, however, in his late life of Newton, seems to have shown that the new philosophy was introduced, at least into the different universities of Great Britain, much earlier than has been generally supposed. It is certain also that even on the continent it soon had to boast of several distinguished disciples. Among these we may particularly mention the marquis of l'Hopital, one of the greatest mathematicians of the age. This gentleman, as Dr Pemberton informs us, after becoming acquainted with the 'Principia,' used eagerly to ask his visitors from England, "Does Mr Newton eat, or drink, or sleep, like other men? I represent him to myself as a celestial genius, entirely disengaged from matter." As for Newton himself, all that he had done never seems to have inspired him with any sentiment except that of a deeper sense of the narrow and insignificant range of his discoveries as compared with the whole mighty realm of nature. A little before his death, Dr Pemberton tells us, he observed: "I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me." "If I have done the public any service in this way," he writes also to Dr Bentley, in 1602, referring to his astronomical speculations, "it is due to nothing but industry and patient thought." This, indeed, seems to have been a frequent and favourite remark with him. "One day," says Dr Pemberton, "when some of his friends had said some handsome things of his extraordinary talents, Sir Isaac in an easy and unaffected way assured them that for his own part he was sensible that whatever he had done worth notice, was owing to a patience of thought rather than any extraordinary sagacity he was endowed with above other men." "I keep, said he, "the subject constantly before me, and wait till the first dawnings open slowly by little and little, into a full and clear light." An ordinary man, however, has no conception of that state of mind which Newton called "keeping his subject constantly before him," so earnest and unswerving was the attention he used to give to it, and so entirely did it occupy his faculties and withdraw them from every other object. During the two years," says Biot, "that he employed in composing his immortal Principia,' in which are developed so many admirable discoveries, he existed only to calculate and to meditate; and if the life of a being subjected to the necessities of humanity can furnish any idea of the pure existence of a celestial intelligence, we may say that his offered such a representation. Often lost in the contemplation of those sublime truths, he went through the ordinary duties of life without perceiving that he did so, and without his thinking principle seeming to preserve any connexion with his body.

See his cleventh chapter.

It is said that oftener than once, after he had begun to dress himself in the morning, he suddenly sat down again on his bed, arrested by some thought, and remained in this situation half naked for hours, pursuing the idea which occupied him. He would have even forgotten to take his food if they had not reminded him of it; nay, even sometimes when he felt himself hungry before any of his meals, it would not have been impossible to persuade him that he had already finished it. One day his particular friend Dr Stukeley, having come to dine with him, had to wait a long time before Newton came out of his study, in which he was shut up. At last, feeling rather hungry, the Doctor resolved to help himself to a chicken which had been set on the table; after eating which he returned the fragments to the dish, and replaced the cover Some hours after, Newton at last made his appearance, and seating himself at the table, remarked that he was very hungry. But when upon lifting the cover he saw nothing but the picked bones of the chicken, "Ah," said he, "I thought I had not dined, but I perceive I am mistaken."

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The same year in which the Principia' was published, Newton's quiet retreat at Cambridge was disturbed by a circumstance which eventually introduced the philosopher to a new scene. Among the other arbitrary attempts by which the infatuated sovereign who now enjoyed the crown signalized his short tenure of power, was a mandamus which he sent down to this university to admit Father Francis, a Benedictine monk, as master of arts, without exacting from him the oaths of allegiance and supremacy. With this illegal order the university refused to comply, and they forthwith elected nine of their members as delegates, to maintain their rights before the high court of ecclesiastical commission. Of these Newton was one, he having distinguished himself, it would appear, by his strenuous and determined opposition to the royal mandate. The king at last thought proper to yield the point; and the delegates of course obtained considerable credit by the success of their mission. Next year brought the abdication of James and the convention-parliament; and such was now the estimation in which Newton was held at Cambridge, that he was chosen by the university one of their representatives in that assembly. The state of the poll was, for Sir Robert Sawyer, 125, for Mr Newton, 122, and for Mr Finch, 117. The following year he returned to Cambridge, where he resided almost constantly till 1695. It was during this interval that he appears to have been affected with that attack of low spirits which has been by some of his biographers described as a fit of temporary insanity, while other writers have gone so far as to speak of it as a derangement of intellect from which he never entirely recovered. The public attention was first called to this occurrence in the life of Newton by an article published some years ago by M. Biot in the 'Biographie Universelle;' but the reader who wishes to find the question fully discussed, and illustrated by some documents which had not been previously published, is referred to Dr Brewster's Memoir in the 'Family Library.' The truth appears to be, that Newton was in fact in a bad state of health during the years 1692 and 1693, and it is not impossible that, suffering as he was at the time under a pressure of bodily

'Biographie Universelle.

illness, his mind may have received a greater shock than it otherwise would have done, from an accident which is said to have befallen some calculations on which he had bestowed a great deal of labour, their being burned, namely, by a candle which had been thrown down among them by his dog Diamond. "Ah Diamond! Diamond !" he is said to have exclaimed, on perceiving the destruction the creature had occasioned, "thou little knowest the mischief thou hast done." While labouring under this despondency, he wrote some strange letters to Locke and others of his friends, indicating the apprehensive and enfeebled condition of his mind; and from the curious notice printed by Biot from the papers of Huygens, it would seem that a rumour had found its way abroad that he had been seized with something like insanity. But that he was not really affected by any disorder to which this term could properly be applied, is sufficiently evidenced by the fact, that it was during this very period that he wrote his five profound and elaborate letters to his friend Dr Bentley, on the existence of a Deity,-the first of these compositions being dated the 10th of December, 1692, and the last the 25th of February, 1693. The conflagration of his papers is pretty satisfactorily ascertained by an extract which Dr Brewster has printed from the manuscript journal of Mr Abraham de la Pryme, now in the possession of George Pryme, Esq. Professor of Political Economy at Cambridge, to have happened about the beginning of the year 1692, and his letter to Locke, (published by Lord King in his life of that writer,) which has been supposed to demonstrate his insanity, as well as another of a somewhat similar tenor to Secretary Pepys, first given to the world by Dr Brewster, are dated in September, 1693. Soon after this he seems to have recovered his usual state of health.

In 1695 Newton's circumstances were materially improved by his being appointed, through the interest of his friend Mr Charles Montague, afterwards Lord Halifax, to the office of warden of the mint, a place of the value of £500 or £600 a year. On receiving this appointment he removed to London, and four years after, having been promoted to the mastership of the mint, the profits of which varied from £1200 to £1500 a year, he resigned the entire emoluments of his professorship to Whiston, who acted as his deputy, and who was a few years after, on his recommendation, appointed his successor in the chair. In 1699 also, he was elected a foreign associate of the Royal academy of sciences of France. In 1701 he was a second time returned to parliament as one of the representatives for the university of Cambridge, and in 1703 he was chosen for the first time president of the Royal society, a dignity to which he was annually re-elected for the succeeding twenty-five years. In 1704, his old antagonist, Hooke, being now two years dead, he at last published his complete work on optics; and two years after it was translated into Latin by his friend Dr Clarke; with whose performance Newton was so well pleased, that he presented him with the sum of £500 for his trouble. On the 16th of April, 1705, he was knighted by Queen Anne at Cambridge. This year, however, he lost his election in a contest for the representation of the university, and we believe he never again sat in parliament.

Some of the succeeding years of Newton's life were embittered by another unhappy controversy in which he became entangled with his celebrated contemporary, Leibnitz, on the subject of their respective