SKETCH OF ROBERT BOYLE. 549 



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 im- 

 pressed 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 Philosoph- 

 ical 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 in- 

 corporated 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 inter- 

 est 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 im- 

 provements 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 vol- 

 ume 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 im- 

 agination 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 



