ISAAC NEWTON was born on Christmas-day, 1642 (O. S.), at Woolsthorpe, a hamlet in the parish of Colsterworth, in Lincolnshire. In that spot his family had possessed a small estate for more than a hundred years; and his father died there a few months after his marriage to Harriet Ayscough, and before the birth of his son. The widow soon married again, and removed to North Witham, the rectory of her second husband, Mr. Smith, leaving her son, a weakly child who had not been expected to live through the earliest infancy, under the charge

of her mother.

Newton's education was commenced at the parish school, and at the age of twelve he was sent to Grantham for classical instruction. At first he was idle, but soon rose to the head of the school. The peculiar bent of his mind soon showed itself in

his recreations. He was fond of drawing, and sometimes wrote verses; but he chiefly amused himself with fechanical contrivances. Among these was a model of a wind-mill, turned either by the wind, or by a mouse enclosed in it, which he called the miller; a mechanical carriage moved by the person who sat in it; and a water-clock, which was long used in the family of Mr. Clarke, an apothecary, with whom he boarded at Grantham. This was not his only method of measuring time: the house at Woolsthorpe, whither he returned at the age of fifteen, still contains dials made by him during his residence there.

Mr. Smith died in 1656, and his widow then returned to Woolsthorpe with her three children by her second marriage. She brought Newton himself also thither, in the hope that he might be useful in the management of the farm. This expectation was fortunately disappointed. When sent to Grantham on business, he used to leave its execution to the servant who accompanied him, and passed his time in reading, sometimes by the way-side, sometimes at the house of Mr. Clarke. His mother no longer opposed the evident tendency of his disposition. He returned to school at Grantham, and was removed thence in his eighteenth year to Trinity College, Cambridge.

The 5th of June, 1660, was the day of his admission as a sizer into that distinguished society. He applied himself eagerly to the study of mathematics, and mastered its difficulties with an ease and rapidity which he was afterwards inclined almost to regret, from an opinion that a closer attention to its elementary parts would have improved the elegance of his own methods of demonstration. In 1664 he became a scholar of his college, and in 1667 was elected to a fellowship, which he retained

beyond the regular time of its expiration in 1675, by a special dispensation authorising him to hold it without taking orders.

It is necessary to return to an earlier date, to trace the series of Newton's discoveries. This is not the occasion for a minute enumeration of them, or for any elaborate discussion of their value or explanation of their principles; but their history and succession require some notice. The earliest appear to have related to pure mathematics. The study of Dr. Wallis's works led him to investigate certain properties of series, and this course of research soon conducted him to the celebrated Binomial Theorem. The exact date of his invention of the method of Fluxions is not known; but it was anterior to 1666, when the breaking out of the plague obliged him for a time to quit Cambridge, and consequently when he was only about twenty-three years old.

This change of residence interrupted his optical researches, in which he had already laid the foundation of his great discoveries. He had decomposed light into the coloured rays of which it is compounded, and having thus ascertained the principal cause of the confusion of the images formed by refraction, he had turned his attention to the construction of telescopes which should act by reflection, and be free from this evil. He had not, however, overcome the practical difficulties of his undertaking, when his retreat from Cambridge for a time stopped this train of experiment and invention.

On quitting Cambridge Newton retired to Woolsthorpe, where his mind was principally employed upon the system of the world. The theory of Copernicus and the discoveries of Galileo and Kepler had at length furnished the materials from which the true system was to be deduced. It was indeed all involved in Kepler's celebrated laws.

The

equable description of areas proved the existence of a central force; the elliptical form of the planetary orbits, and the relation between their magnitude and the time occupied in describing them, ascertained the law of its variation. But no one had arisen to demonstrate these necessary consequences, or even to conjecture the universal principle from which they were derived. The existence of a central force had been surmised, and the law of its action guessed at; but no proof had been given of either, and little attention had been awakened by the conjecture.

Newton's discovery appears to have been quite independent of any speculations of his predecessors. The circumstances attending it are well known: the very spot in which it first dawned upon him is ascertained. He was sitting in the garden at Woolsthorpe, when the fall of an apple called his attention to the force which caused its descent, to the probable limits of its action and law of its operation. Its power was not sensibly diminished at any distance at which experiments had been made: might it not then extend to the moon and guide that luminary in her orbit? It was certain that her motion was regulated in the same manner as that of the planets round the sun: if, therefore, the law of the sun's action could be ascertained, that by which the earth acted would also be found by analogy. Newton, therefore, proceeded to ascertain by calculation from the known elements of the planetary orbits, the law of the sun's action. The great experiment remained : the trial whether the moon's motions showed the force acting upon her to correspond with the theoretical amount of terrestrial gravity at her distance. The result was disappointment. The trial was to be made by ascertaining the exact space by which the earth's action turned the moon aside from her course in a given time. This depended on her actual

distance from the earth, which was only known by comparison with the earth's diameter. The received estimate of that quantity was very erroneous; it proceeded on the supposition that a degree of latitude was only sixty English miles, nearly a seventh part less than its actual length. The calculation of the moon's distance, and of the space described by her, gave results involved in the same proportion of error; and thus the space actually described appeared to be a seventh part less than that which corresponded to the theory. It was not Newton's habit to force the results of experiments into comformity with hypothesis. He could not, indeed, abandon his leading idea, which rested, in the case of the planetary motions, on something very nearly amounting to demonstration. But it seemed that some modification was required before it could be applied to the moon's motion, and no satisfactory solution of the difficulty occurred. The scheme therefore was incomplete, and in conformity with his constant habit of producing nothing till it was fully matured, Newton kept it undivulged for many years.

On his return to Cambridge Newton again applied himself to the construction of reflecting telescopes, and succeeded in effecting it in 1668. In the following year Dr. Barrow resigned in his favour the Lucasian professorship of mathematics, which Newton continued to hold till the year 1703, when Whiston, who had been his deputy from 1699, succeeded him in the chair. On January 11, 1672, Newton was elected a Fellow of the Royal Society. He was then best known by the invention of the reflecting telescope; but immediately on his election he communicated to the Society the particulars of his theory of light, on which he had already delivered three courses of lectures at Cambridge, and they were shortly afterwards published in the Philosophical Transactions.