don, where he studied awhile at John Hunter's school of medicine in Leicester Square.
In London Thomson made many valuable friendships, and on his return to Edinburgh early in 1793 he became a fellow of the College of Surgeons of Edinburgh, the necessary funds being provided by Hogg, the manager of the Paisley bank. Until the autumn of 1798 he lived with an Edinburgh surgeon, named Arrott, and attended the Royal Infirmary as a surgeon. During this period he was much engaged in the study of chemistry. He conducted a chemical class during the winter of 1799–1800 which met at Thomson's private house, under the auspices of the Earl of Lauderdale, and consisted chiefly of gentlemen connected with the parliament house. In 1800 he was nominated one of the six surgeons to the Royal Infirmary under an amended scheme for the better management of the charity, and he almost immediately entered upon the teaching of surgery. He also gave a course of lectures on the nature and treatment of those injuries and diseases which come under the care of the military surgeon, and he visited London in the autumn of 1803 to be appointed a hospital mate in the army in order to qualify himself technically to take charge of a military hospital should it be found necessary to establish one in Edinburgh in case of an invasion.
The College of Surgeons of Edinburgh established a professorship of surgery in 1805, and, in spite of extraordinary opposition—mainly on political grounds—Thomson was appointed to the post. In 1806, at the suggestion of Earl Spencer, the home secretary, the king appointed him professor of military surgery in the university of Edinburgh. On 11 Jan. 1808 Thomson obtained the degree of M.D. from the university and King's College of Aberdeen. In 1810 he resigned his post at the Royal Infirmary in consequence of the refusal of the managers to investigate some criticisms on his surgery by John Bell (1763–1820) [q. v.] He continued to lecture, however, and in the summer of 1814 he visited the various medical schools in Europe to examine into the different methods followed in the hospitals of France, Italy, Austria, Saxony Prussia, Hanover, and Holland. He was admitted a licentiate of the Royal College of Physicians of Edinburgh on 7 Feb. 1815, since he was now acting as a consulting physician as well as a consulting surgeon. In the ensuing summer he again returned to the continent to watch the treatment of the men wounded at Waterloo, and in September 1815 he was mainly instrumental in founding the Edinburgh New Town dispensary. The smallpox epidemic of 1817–18 showed that vaccination was not so absolutely protective as had been supposed, and Thomson published his views upon the subject in two pamphlets, issued respectively in 1820 and in 1822. He delivered a course of lectures on diseases of the eye in the summer of 1819, thereby paving the way for the establishment of the first eye infirmary in Edinburgh in 1824. He was much engaged during 1822–6 in the study of general pathology, and in 1821 he was an unsuccessful candidate for the chair of the practice of physic in the university, rendered vacant by the death of James Gregory (1753–1821) [q. v.] In 1828–9 and again in 1829–30 he delivered a course of lectures on the practice of physic, both courses being given in conjunction with his son, William Thomson (1802–1852) [q. v.] In 1831 he addressed to Lord Melbourne, then secretary of state for the home department, a memorial representing the advantages likely to flow from the establishment of a separate chair of general pathology. A commission was issued in his favour, and he was appointed professor of general pathology in the university, giving his first course of lectures upon this subject in the winter session of 1832–3.
Repeated attacks of illness compelled him to discontinue his visits to patients after the summer of 1835, but he still continued to see those who chose to call upon him. He resigned his professorship in 1841. The duties had long been performed by deputy. He died at Morland Cottage, near the foot of Blackford Hill, on the south side of Edinburgh, on 11 Oct. 1846.
Thomson was twice married: first, in 1793, to Margaret Crawford, second daughter of John Gordon of Caroll in Sutherlandshire; she died early in 1804. Secondly, in 1806, to Margaret, third daughter of John Millar (1735–1801) [q. v.], professor of jurisprudence in the university of Glasgow. There were three children by the first marriage, the only survivor being Professor William Thomson, while of the second marriage a daughter and Professor Allen Thomson [q. v.] alone outlived childhood.
Thomson died with the reputation of being in his time the most learned physician in Scotland. ‘To almost the last week of his life he was a hard student,’ says Henry Cockburn in his journal, ‘and not even fourscore years could quench his ardour in discoursing upon science, morals, or politics. … He never knew apathy, and, medicine being his first field, he was for forty years the most exciting of all our practitioners and of all our teachers.’
