The definite establishment of the Royal Society in 1662 marks the opening of a great age of scientific discovery in England. Almost every year of the half-century which followed saw some step made to a wider and truer knowledge of physical fact. Our first national observatory rose at Greenwich, and modern astronomy began with the long series of observations which immortalized the name of Flamsteed. His successor, Halley, undertook the investigation of the tides, of comets, and of terrestrial magnetism. Hooke improved the microscope and gave a fresh impulse to microscopical research. Boyle made the air-pump a means of advancing the science of pneumatics, and became the founder of experimental chymistry. Wilkins pointed forward to the science of philology in his scheme of a universal language. Sydenham introduced a careful observation of nature and facts which changed the whole face of medicine. The physiological researches of Willis first threw light upon the structure of the brain. Woodward was the founder of mineralogy. In his edition of Willoughby's "Ornithology," and in his own "History of Fishes," John Ray was the first to raise zoology to the rank of a science; and the first scientific classification of animals was attempted in his "Synopsis of Quadrupeds." Modern botany began with Ray's "History of Plants," and the researches of an Oxford professor, Robert Morrison; while Grew divided with Malpighi the credit of founding the study of vegetable physiology. But great as some of these names undoubtedly are they are lost in the lustre of Isaac Newton. Newton was born at Woolsthorpe in Lincolnshire on Christmas Day, 1642, the memorable year which saw the outbreak of the Civil War. In the year of the Restoration he entered Cambridge, where the teaching of Isaac Barrow quickened his genius for mathematics, and where the method of Descartes had superseded the older modes of study. From the close of his Cambridge career his life became a series of great physical discoveries. At twenty-three he facilitated the calculation of planetary movements by his theory of Fluxions. The optical discoveries to which he was led by his experiments with the prism, and which he partly disclosed in the lectures which he delivered as Mathematical Professor at Cambridge, were embodied in the theory of light which he laid before the Royal Society on becoming a Fellow of it. His discovery of the law of gravitation had been made as early as 1666; but the erroneous estimate which was then generally received of the earth's diameter prevented him from disclosing it for sixteen years; and it was not till 1687, on the eve of the Revolution, that the "Principia" revealed to the world his new theory of the Universe. [Sidenote: The Latitudinarian Theology.]