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346 SIR ISAAC NEWTON notice by his "Forsaken " and "Lovers' Quar- rel," from Moliere's Depit amoureux, which were engraved for the u Literary Souvenir " of 1826. Among his other works are " Shylock and Jessica," " Yorick and the Grisette," "The Abbot Boniface," " A Poet reading his Verses to an impatient Gallant," " Macheath," " Lear attended by Cordelia and the Physician," " The Vicar of Wakeneld restoring Olivia to her Mother," and "Abelard in his Study," most of which have been engraved. He was elected a member of the academy in 1833. In 1832 he revisited the United States. Shortly after his return in 1833 he exhibited symptoms of mental aberration, and the last two years of his life were passed in a lunatic asylum. NEWTON, Sir Isaac, an English philosopher, born at Woolsthorpe, Lincolnshire, Dec. 25, 1642, died in Kensington, a suburb of London, March 20, 1727. He was a posthumous and only child, like Kepler, and was born prema- turely. He was descended, according to his own account, from Sir John Newton of West- by in Lincolnshire, and according to another from a Scotch family in East Lothian. When he was three years of age, his mother, having married again, gave him to the charge of his maternal grandmother. He went to school at Skillington and Stoke till his 12th year, when he was sent to the free school at Gran- tham, six miles from his native hamlet, taught by a Mr. Stokes. He ranked low in his classes or some time, but being ill treated by the boy who stood next above him he determined to defeat his opponent in class work, and applied himself with such resolution to his books that he at length stood at the head of the whole school. He was usually less interested in the sports of his schoolmates than in construct- ing little mechanical contrivances, in which he showed marked facility of imitation and in- vention. He arranged a set of pins or gno- mons upon the adjacent houses so as to mark the time of day by their shadows ; the arrange- ment served as a* sort of town clock, and was known as " Isaac's dial." On the outside wall of his house at Woolsthorpe there is still a sun dial which he must have carved there. There were formerly two, but the stone on which the other was cut was removed in 1844 and presented to the royal society. In 1656 his mother, again a widow, took him to help in the management of the farm at Woolsthorpe ; but such was his passion for study that he found little time to look after the concerns of the farm. His mother sent him back to Gran- tham, where he was fitted to enter Trinity college, Cambridge, in 1661. It does not ap- pear that he showed a marked preeminence in the studies of the university, but he extended his acquirements beyond the prescribed routine in several directions. In the winter of the year in which he was elected scholar (1664), or earlier, he invented his binomial theorem, to which he had been led by investigations into the problem of the quadrature of the circle, and directed his attention to the subject of circles or halos around the moon, of which he gave the theory in his treatise on optics. In 1665 he took the degree of B. A., and proba- bly in the same year invented fluxions.: At this period the thoughts of philosophers were strongly directed to the telescope. Huygens had constructed instruments which revealed the rings and satellites of Saturn. Descartes had explained the theory of refraction, and had pointed out how glasses could be ground of such a shape as to unite parallel rays of light in a focus. Still these glasses had the great defect of giving a confused image, which was thought to be owing to imperfect manu- facture, and Newton applied himself to grind- ing them with more accuracy. But he also experimented with a ray of light, and soon came to the conclusion "that light was not homogeneous, but composed of rays, some of which were more refrangible than others." This showed him that the defect of the lens of the refracting telescope was inherent and not accidental. He accordingly abandoned his attempts to improve that instrument, and de- voted himself to the construction of a reflect- ing telescope, which James Gregory of Aber- deen, in view of the defects of the refracting medium, had already invented. While New- ton was engaged on this, the plague forced him to retire to Woolsthorpe (1666), and it was more than two years before he resumed his researches. During his retreat at Wools- thorpe (whether in this or the previous year is uncertain) he first conceived the identity of gravity with the force which holds the plan- ets to their orbits, and made his first test cal- culations; but, starting with the erroneous es- timate then entertained of the earth's mass, he failed to verify the happy conjecture (see ASTRONOMY) ; and it was not till about 1680 that he resumed work upon the problem. On the cessation of the plague he returned to Cambridge, was made junior fellow in Octo- ber, 1667, and senior fellow in March, 1668, and graduated M. A. in July of the same year. In the autumn of 1668 he completed a reflect- ing telescope 6 in. in length, magnifying 40 times, which enabled him to see Jupiter's sat- ellites and the phases of Venus. This was the first reflecting telescope ever directed to the heavens, for Gregory never completed the in- strument which he had invented. Compared with the much earlier refractors of Hevelius and Huygens, however, this was a small and ill-made instrument. In the autumn of 1671 Newton made another, which was sent up in December " for his majesty's perusal." It is carefully preserved in the library of the royal society of London. His mind appears to have been much occupied at this time and for many years afterward with " chemical studies and practices." His celebrated letter (1669) of ad- vice to Mr. Aston, who was about to set out for a tour of the continent, reveals a strong belief in the doctrines of alchemy ; and he cer-