In 1791, when twenty-five, he thought he should succeed better by practising at Knaresborough in the winter and at Harrogate in the summer. He analysed the waters at Harrogate, and in 1794 he built a house there and determined to practise only at Harrogate. An engagement to be married made him form a new plan for success. He persuaded his intended wife reluctantly to agree to emigrate to America after their marriage, which took place in the following year. Then he sold his house in Harrogate and purchased apparatus for lectures on natural philosophy and chemistry. On their way to America they went to Liverpool. There, whilst waiting for a ship, he was persuaded to give a course of lectures. This was successful, and he was invited to give the same course on chemistry and experimental philosophy at Manchester. He was still more successful, and invitations came to him from Warrington, Lancaster, Birmingham, and Dublin. He did not give up his intention of emigrating until he was offered the professorship in Anderson’s Institution at Glasgow. His wife had borne him a daughter, and she earnestly urged him to settle in Glasgow. In November 1796, when thirty, he published the ‘Outlines of a Course of Lectures on Natural and Experimental Philosophy.’ His subjects were the properties of matter, astronomy, electricity, magnetism, pneumatics, hydrostatics and hydraulics, optics and mechanics. When the session at Glasgow was over he went to Liverpool to repeat his course of lectures. In the autumn he returned to Glasgow and made known his intention of practising as a physician there. Fortune continued to favour him; his reputation increased and he soon had the best prospect of the leading practice in Glasgow. In 1797, when thirty-one, he published his ‘Outlines of a Course of Lectures on Chemistry.’ His twenty-seventh lecture was on Agriculture; his twenty-eighth on Bleaching; his twenty-ninth on Dyeing and on Calico Printing; and his last on the Analysis of Mineral Waters. On Christmas Day, 1798, his wife died in childbirth, and on New Year’s Day he wrote this feeling letter: Oh! my dear cousin, little did I expect that I should begin the new year with telling you that I am now deprived of all earthly comforts; yes, the dear companion of my studies, the friend of my heart, the partner of my bosom, is now a piece of cold clay. The senseless earth is closed on that form which was so lately animated by every virtue, and whose only wish was to make me happy.