them, with his hand upon the Gospels, what were called the 'sinful and detestable errors and heresies' which he had maintained. The firmness of Galileo gave way at this critical moment of his life: he pronounced the recantation. But at the moment he rose, indignant at having sworn in violation of his conviction, he exclaimed, stamping his foot: E pur si muove (It still moves!). Upon this relapse into heresy, he was sentenced to imprisonment in the Inquisition for life, and every week for three years he was to repeat the seven penitential psalms; his Dialogues were also prohibited, and his system utterly condemned. Although Galileo was in this manner sentenced to confinement, it appeared to those who judged him that he would not be able, from his age, to endure such a severe punishment, and they mercifully banished him to a particular spot near Florence.

Here Galileo lived for several years, employing his time in the study of mechanics and other branches of natural philosophy. He was at this time afflicted with a disease in his eyes, one of which was wholly blind, and the other almost useless, when in 1637 he discovered the libration of the moon. Blindness, deafness, want of sleep, and pain in his limbs, united to embitter his declining years; still his mind was active. In this condition he expired in January 1642, in the seventy-eighth year of his age. His remains were deposited in the church of Santa Croce, at Florence, where posterity did justice to his memory, by erecting a splendid monument, in 1737.

The year in which Galileo died, was that in which ISAAC NEWTON was born. This eminent individual, who was destined to establish the truth of the discoveries of his illustrious predecessors, Copernicus and Galileo,

was born on the 25th of December 1642, at Woolsthorpe, in Lincolnshire, where his father cultivated his own moderate paternal property. After receiving the rudiments of education, under the superintendence of his mother, he was sent, at the age of twelve, to the grammar-school at Grantham, where the bias of his early genius was shewn by a skill in mechanical contrivances, which excited no small admiration. Whilst other boys were at play, his leisure hours were employed in forming working-models of mills and machinery; he constructed a water-clock from an old box, which had an index moved by a piece of wood sinking as the drops fell from the bottom, and a regular dial-plate to indicate the hours.

On his removal from school, it was intended that he should follow the profession of a farmer, but his unfitness for the laborious toils of such a life was soon manifested. He was frequently found reading under a tree, when he should have been inspecting cattle, or superintending labourers; and when he was sent to dispose of farming produce at Grantham market, he was occupied in solving mathematical problems, in a garret or hay-loft, whilst the business was transacted by an old servant who had accompanied him to town. These indications of the bias of his disposition were not neglected by his anxious mother; she sent him again for a few months to school, and on the 5th of June 1661, he was admitted a student of Trinity College, Cambridge.

The combination of industry and talents, with an amiable disposition and unassuming manners, naturally attracted the notice of his tutors, and the friendship of his admiring companions; amongst these was Isaac

Barrow, afterwards justly celebrated as a preacher and mathematician. Saunderson's Logic, Kepler's Optics, and the Arithmetic of Infinites by Wallis, were the books first studied by Newton at Cambridge. He read the Geometry of Descartes diligently, and looked into the subject of judicial astrology, which then engaged some attention. He read little of Euclid, and is said to have regretted, in a subsequent part of his life, that he had not studied the old mathematicians more deeply.

The attention of Newton, while he was pursuing his studies at Cambridge, was attracted to a branch of natural philosophy hitherto little understood-namely, light. It was the opinion of the celebrated philosopher, Descartes, that light is caused by a certain motion or undulation of a very thin elastic medium, which he supposed pervaded space. Newton overturned this theory. Taking a piece of glass with angular sides, called a prism, he caused the sun to shine upon it through a small hole in the shutter of a darkened apartment. By this experiment he found that the light, in passing through the glass, was so refracted or broken as to exhibit on the wall an image of seven different tints or colours; and after varying his experiments in a most ingenious way, he established the very interesting facts-that light is composed of rays resoluble into particles; that every ray of white light consists of three primary and differently coloured rays (red, yellow, and blue), each of which three is more or less refrangible than the other. This remarkable discovery laid the foundation of the science of Optics.

In 1665, the students of the university of Cambridge were suddenly dispersed by the breaking out of a pestilential disorder in the place. Newton retired for safety

to his paternal estate; and though he lost for a time the advantages of public libraries and literary conversation, he rendered the years of his retreat a memorable era in his own existence, and in the history of science, by another of his great discoveries, that of the theory of Gravitation, or the tendency of bodies towards the centre of our globe. One day, while sitting in his garden, he happened to see an apple fall from a tree, and immediately began to consider the general laws which must regulate all falling bodies. Resuming the subject afterwards, he found that the same cause which made the apple fall to the ground, retained the moon and planets in their orbits, and regulated, with a simplicity and power truly wonderful, the motions of all the heavenly bodies. In this manner was discovered the principle of gravitation, by a knowledge of which the science of astronomy is rendered comparatively perfect.

On his return to Cambridge in 1667, he was elected Fellow of Trinity College; and two years afterwards he was appointed Professor of Mathematics, in the place of his friend, Dr Barrow, who resigned. His great discoveries in the science of optics formed for some time the principal subject of his lectures; and his new theory of light and colours was explained, with a clearness arising from perfect knowledge, to the satisfaction of a crowded and admiring audience. He was elected a Fellow of the Royal Society in 1671, and is reputed to have been compelled. to apply for a dispensation from the usual payment of one shilling weekly, which was contributed by each member towards the expenses. He had at this period of his life no income except what he derived from his college and his professorship, the produce of his estate being absorbed in supporting his mother and

her family. His personal wishes were so moderate, that he never regretted the want of money, except when it limited his purchases of books and scientific instruments, and restricted his power of relieving the distresses of others. About the year 1683, he composed his great work, the Principia, or Mathematical Principles of Natural Philosophy. In 1688, the memorable year of the Revolution, he was chosen to represent the university in parliament, and the honour thus conferred on him was repeated in 1701. His great merit at last attracted the notice of those who had it in their power to bestow substantial rewards, and he was appointed Warden of the Mint, an office for which his patient and accurate investigations singularly fitted him, and which he held with general approbation till his death. Honours and emoluments at last flowed upon him. In 1705, he received the honour of knighthood from Queen Anne.

Newton's benevolence of disposition led him to perform all the minor duties of social life with great exactness; he assumed no superiority in his conversation; he was candid, cheerful, and affable; his society was therefore much sought, and he submitted to intrusions on his valuable time without a murmur; but by early rising, and by a methodical distribution of his hours, he found leisure to study and compose, and every moment which he could command he passed with a pen in his hand and a book before him. He was generous and charitable. His wonderful faculties were very little impaired, even in extreme old age; and his cheerful disposition, combined with temperance and a constitution naturally sound, preserved him from the usual infirmities of life. He was of middle size, with a figure inclining to plumpness; his eyes were animated, piercing, and intelligent;