Born in Granard, Co Longford, and was educated at the Dundalk Institution, whence he passed on to Galway College in 1879, where he carried off all the available scholarships in mathematics and medicine, finally graduating with the highest honours and a 1st class exhibition in the Royal University of Ireland in 1883. Subsequently he was appointed a Demonstrator of Anatomy in Trinity College, Dublin, was engaged for four years in private teaching, and thought of practising surgery. Taking up the study of physiology, he held the chair of Dunville Professor of Physiology in Queen's College, Belfast, from 1893-1902, and was made a Member of the Physiological Society January 20th, 1894. In 1902 he was elected to the chair of the Institutes of Medicine in the School of Physic, Trinity College, Dublin, and continued to hold this position to the time of his death. His outlook had been widened by a long course of post-graduate study at Galway, Dublin, London, Leipzig, Paris, Marburg, Heidelberg, and under Pavlov at St Petersburg. His studies had been concerned with food metabolism and nutrition, and to these subjects he accordingly devoted himself at Trinity College. He was an honorary member of the Imperial Military Academy of Medicine, St Petersburg. Soon after the outbreak of the European War, having made provision for the discharge of his duties in Trinity College by the appointment of a substitute, he offered his services and took up asylum work in Scotland in order to set free a medical practitioner of military age. Later on he was brought to London as scientific adviser to the Ministry of Food. In this capacity his knowledge of food values and the experiments he carried out in connection therewith helped him to give advice of great national importance to the Food Controller in the drafting of schemes for rationing the food of the nation. In recognition of his services the King decorated him in January, 1918, a Knight Commander of the Civil Division of the Most Excellent Order of the British Empire. In 1902 he was appointed Examiner in Physiology at the Royal College of Surgeons, and held office for many years. In 1914 he resigned the Fellowship of the College, writing to the Council on October 20th to say that he resigned "in consequence of his having been elected a Fellow of the Royal College of Physicians in Ireland, and thereby having become subject to a by-law of that College forbidding him to be a Fellow of any College of Surgeons." At the same time he enclosed a cheque for ten guineas, the amount of the fee payable by a Fellow on resignation in accordance with Section XVIII of the by-laws. At their meeting on Thursday, November 12th, 1914, the Council resolved to accept the resignation, which, so far as we know, is unique in the annals of the Fellowship, and to deliver to him an "Instrument declaratory of his having ceased to be a Fellow of the College". Early in 1916 he read a paper before the Royal Academy of Medicine in Ireland, in which he gave a detailed survey of the food-supply of Great Britain on the lines of the Eltzbacher report brought out in Germany a year earlier. Sir William Thompson met with an unusual death. The news of the sinking of the *Leinster* by a submarine in the Irish Sea reached Dublin, on October 9th, 1918, and considerable anxiety was felt for the safety of Thompson, who was one of three medical men on board. He had dined at Commons in Trinity College on the evening preceding the disaster; and had stated that it was his intention to sleep on board the mail boat that night and cross to London on the following day. About a fortnight later it became known that he had gone down with the ship, and that at the time of the disaster he had probably not left his berth and had no means of escape. He was survived by Lady Thompson - who was the eldest daughter of Professor Peter Redfern (qv), whom he had married in 1894 - a son and four daughters. His Dublin addresses were at 14 Hatch Street, and Trinity College. Publications: Thompson contributed numerous papers on physiological subjects to the medical journals. Translation of Pavlov's *The Work of the Digestive Glands*, 8vo, illustrated, London, 1902; 2nd ed, with bibliography, 1910. "Descending Degenerations from Lesions of the Superior Temporal Convolution in a Monkey." - *Brit Med Jour*, 1892, i, 817. "Descending Degenerations from Lesions of the Occipital Lobe" (with Dr C Shaw). - *Ibid*, 1896, ii, 630. "Anaesthetic and Renal Activity." - *Ibid*, 1906, i, 608, etc. "Die Vaso-motorischen Nerven der Glieder Venen." - *His u du Bois-Reymonds Arch*, 1893, Phys Abth, 102. "Nature of the Work of the Kidney, as shown by the Influence of Atropine and Morphine upon the Secretion of Urine," First communication, 8vo, London; reprinted from *Jour of Physiol*, 1894, xv, 433. "Physiological Effects of Peptone when Injected into the Circulation." - *Jour of Physiol*, 1896, xx, 435; 1899, xxiv, 374; 1899-1900, xxv, 1; 1905, xxxii, 137. "Die physiologische Wirkung der Protamine and ihrer Spaltungsprodukte." - *Zeits f Physiol Chem*, 1900, xxix, 1. "Systematic Food Production: What could be done in Ireland." - *Irish Times*, 1915, Aug 30. *The Food Value of Great Britain's Food-supply*, 8vo, with bibliography, Dublin, 1916.