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Professor James Thomson (1786 - 1849):
Mathematician and academician

James Thomson was a leading figure in the Belfast Academical Institution (later the Royal Belfast Academical Institution), being Headmaster of the School of Arithmetic, Bookkeeping and Geography as well as Professor of Mathematics in the Institution’s Collegiate Department; he was also an admired and popular pedagogue who published some of the leading teaching texts in his own day and beyond. 

He was born on the farm of his father, also James Thomson, at Annaghmore near Ballyhahinch in the centre of County Down; at the age of only 12 he witnessed the major battle there during the significant year of 1798, the uprising of the United Irishmen was defeated (rather brutally) by the Government forces. In 1825 he wrote this experience up in his article published in the Belfast Magazine with the title “Recollections of the Battle of Ballynahinch, by an Eyewitness”. The descriptions are quite comprehensive, with much detail of the actual battlefield conditions as wel as a description of the range of weaponry available to the rebel army of Lord Moira, from pitchforks to pikes to swords to guns.

He was also expected along with his five siblings to help out on the family farm, so that his schooling was sound in quality if limited in range, it being at  the local country seminary run by a Presbyterian minister, Rev Samuel Edgar DD, at Ballykine quite nearby.  When still young he was already showing an interest in science; at least one source has him designing and constructing sundials when not into his teens.

Thomson entered university in 1810; like many Ulster students it was in Scotland and as was also common then he walked there. The Belfast Academical Institution was founded in that year but was not in operation until 1814 by which time Thomson had graduated Master of Arts (AM) at Glasgow where he also took classes. Although he would become best known as a mathematician, he originally enrolled to study theology and medicine, his original intention to enter the Presbyterian ministry. He returned to Belfast in 1814 taking up his Headmaster post at the Academical Institution that year and his professorship in Mathematics the following year. He and took up residence directly opposite the Academical Institution; he purchased what was just a field, building two adjacent houses, one of which he lived in, the other one he let. He was one of the founders of the Presbyterian Church in Fisherwick Place, only yards from his house, and was a regular attender. In 1832 he returned to Glasgow to occupy the Chair of Mathematics at the University there; he would remain there until his death from cholera in 1849. He left the Academical Institution under something of a cloud as he felt that the Collegiate Department should be given equal recognition as compared to the other schools and departments and seemingly felt that the Institution had rather snubbed him by not inviting him to join a management committee. Jamieson (the author of the sesquicentennial volume on the Institution) writes, though, that a “dignified yet insistent” letter from Thomson to the Board of Governors reminded him that his “homely” and “deliberate” appearance and manner did not relegate his status to that of a simple usher. Furthermore, Thomson would later look back on his mature Belfast years very favourably, for all that he was rising most days to be at his papers by 4 am. Perhaps a better pointer to his institution (sic) loyalty was that in 1823, when the Institution was in some financial distress, Thomson forwent the Professorial; part of his salary – the sum in question being £50. 

Thomson was a prolific publisher of a number of acclaimed books: Thomson’s Arithmetic, published in 1819, was a popular textbook, as was  the fashion this title was a short form of the proper title, A treatise on arithmetic, in theory and practice: With an appendix, containing an introduction to mensuration. This eventually would appear in over 70 editions. Similarly, another textbook, Thomson’s Geography or properly An introduction to modern geography: with an appendix, containing an outline of astronomy and the use of the globes ran to nearly 30 editions. Other titles were Trigonometry, Plane and Spherical (1829); The Phenomena of the Heavens (1827): The Differential and Integral Calculus (1831); An Atlas of Modern Geography as well as an Algebra in 1834; and he also produced an edition of Euclid. These were only books; he published frequently in the Journal of the Edinburgh Royal Society and the equivalent Proceedings of the Royal Society (of London).

He was elected a Member of the Belfast Literary Society on 5 October 1818 and served as President for the 1821-1822 session (this position was based on a vote of all members and his held for one year). He read nine papers before the Society, whose titles show his wide interests: examples are “A View of the Progress of Mathematics among the Saracens”; “Essay on the opinions that have been formed respecting the nature and phenomena of the fixed stars”; “A sketch of the progress of mathematical science among the Greeks”; more simply, “On the tides” and “On rivers”.

Thomson had married in 1817 but his wife died quite young (in the early 1830s) leaving a young family (the eldest child, a daughter, was only 12 years old). Three of the seven children did not survive to adulthood. Two of sons made very success careers; his namesake son James became a highly distinguished engineer, while his son William became the internationally renowned physicist, a familiar Lord Kelvin to the citizenry of Belfast, his statue conspicuous at the entrance to the Botanic Gardens. James senior’s house in what is now College Square East features a commemorative blue plaque. He was awarded the degree of Doctor of Laws, honoris causa, by his Glasgow alma mater in 1829.

Born: 13 November 1786
Died: 12 January 1849
Richard Froggatt

John Jamieson: The History of the Royal Belfast Academical Institution 1810-1960, (Belfast, William Mullan, at 16); Dictionary of Irish Biography (Cambridge/ Royal Irish Academy, 2009, 9, 348; also online at; Belfast Literary Society: Historical Sketch, With Memoirs of some Distinguished Members (Commemorative Centenary volume, 1902); Brian J Todd: A Remarkable Belfast Institution: the Royal Belfast Academical Institution 1810-2010 (RBAI 2013)