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 Coltersworth, 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 shown 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 utter 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 laborers; 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 strong 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 1660, 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 a 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 mathematician 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 colors; 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 colored 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 center 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.