discovered that astronomers had been mistaken in ascribing circular orbits and uniform motions to the planets, since each of them moves in an ellipse, having one of its foci in the sun; and after a variety of fruitless efforts, he, on the 15th of May 1618, made his splendid discovery, that the squares of the periodic times of the planets are always in the same portion as the cubes of their mean distances from the sun. The sagacity of this wonderful man, and his incessant application to the study of the planetary motions, pointed out to him some of the genuine principles from which these motions originate. He considered gravity as a power that is mutual between bodies; that the earth and moon tend toward each other, and would meet in a point so many times nearer to the earth than to the moon as the earth is greater than the moon, if their motions did not prevent it. His opinion of the tides was, that they arise from the gravitation of the waters towards the moon; but his notions of the laws of motion not being accurate, he could not turn his conceptions to the best advantage. The prediction he uttered at the end of his epitome of astronomy, has been long since verified by the discoveries of Sir Isaac Newton; namely, that the determinanation of the true laws of gravity was reserved for the succeeding age, when the Author of Nature would be pleased to reveal these mysteries.
NEWTON.
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
