bility of that earth questioned, in which he had established his kingdom."
"At length," says Sir Henry W. Ackland, "Boyle arrived at Rome, where he passed as a Frenchman. He was shocked by much which he saw and heard of the life and immorality of even the clergy there." He studied unceasingly, reading much on all his journeys. At Marseilles, in 1642, he learned of the breaking out of the rebellion in Ireland, a fact that was more deeply impressed upon his mind by the consequent impossibility of getting any money from home, and he did not return to England till 1644. There he learned of the death of his father, and found himself heir of certain estates in Ireland and of the manor of Stalbridge. In London, the next year, he became a member of the Philosophical College, a society of scientific men, which, in consequence of the political agitation of the times, held its meetings as secretly as possible, first in London and then in Oxford, and was called the "Invisible College." After the Restoration this society was incorporated by Charles II as the Royal Society. "The course of Boyle's life," says Sir H. W. Ackland, "must be considered as now fully determined. He had gradually acquired a keen interest both in science and theology, an interest never to be abated, and henceforth interlaced with all his thoughts and writings." In 1646 he settled at Stalbridge, and devoted himself to study, scientific research and experiments, and authorship. Visiting Ireland in 1652, he made anatomical dissections with Sir William Petty, and verified by actual experiments the circulation of the blood. He removed to Oxford, where he lived fourteen years, enjoying the society of many learned men. Here he made improvements in Otto von Guericke's air pump, and by curious experiments made various discoveries on the properties of air, the propagation of sound, etc., the most important of which was the discovery of the law called Mariotte's in the text-books, but more properly Boyle's, of the intimate relation between the volume of a gas and the pressure. He constantly, say his French biographers, opposed the teaching of Aristotle, which was still current in the schools; and was, like Bacon, convinced that the truth could be discovered only by experiment. He would not even read the works of Descartes, lest, finding in them more imagination than observation, and hypotheses rather than facts, he should be tempted out of his chosen path. None of the scientific systems then in vogue were received by him. In particular he brought experimental demonstrations to bear against the theory that salt, sulphur, and mercury were the essential principles of bodies. He allowed matter no properties but mechanical ones. To him we owe the exact determination of the fact that air is absorbed in calcinations and combustions, and that metallic calces