Born at Langford, Co Tyrone, in 1866, the third son of the Rev Canon Stack, and was educated at Haileybury School, at Pembroke College, Cambridge, and then at St Bartholomew's Hospital, where he was Brackenbury Medical Scholar. He was known as a hard-working student, with a mechanical bent, and good at sports. He was then House Physician to Dr Samuel J Gee; next Ophthalmic House Surgeon to Henry Power (qv) and Bowater J Vernon (qv), and afterwards Midwifery Assistant under Sir Francis H Champneys and Dr W S A Griffith. In 1897 he was appointed House Physician to the Bristol Royal Infirmary, and in 1902 House Surgeon. In these posts he showed to his tutorial classes his all-round knowledge of clinical medicine: he was as remarkable a coach in midwifery as in internal medicine, whilst his mechanical skill in carpentry and wood-carving gave him an artistic trend as well as the hand of a craftsman. In his 'grinds' he had at hand a fund of apt anecdotes. Stack organized social gatherings of students and junior medical practitioners, and was instrumental in starting *The Stethoscope* (1898), the journal of the Bristol Medical School, by undertaking the department of clinical pathology. He launched the movement which amalgamated the Medical Athletic Clubs, was the organizer of the Annual Bristol Medical Dinner, and in the Medical Dramatic Club served in various capacities as actor, stage carpenter, and scene-painter. In 1906 he was elected Assistant Surgeon to the Bristol Royal Infirmary, gave clinical lectures, and was also Surgeon to the Bristol Eye Dispensary, the Bristol Orthopedic Hospital and Home for Cripple Children, and the Cossham Hospital. In 1914, on the resignation of Alexander Ogilvy, he succeeded him as Ophthalmic Surgeon to the Bristol Royal Infirmary, and henceforth concentrated his energies upon ophthalmology In the war of 1914-1918 he served as Captain RAMC (T), doing excellent work as Ophthalmic Specialist at the 2nd Southern General Hospital in Bristol and at the 56th General Hospital in France. In 1920 he founded the South-Western Ophthalmological Society. He proved a neat operator, a gifted refractionist, and above all displayed a singular grasp of the medical aspects of eye diseases. Stack was a warm-hearted, impulsive Ulsterman, a staunch Irish Loyalist, and a Churchman - he was Churchwarden at St Paul's, Clifton, at the time of his death. For many months he suffered pain from a hypernephroma and was undergoing treatment in London, when he died on August 3rd, 1922. He had practised at Arvalee, Clifton Down Road, Bristol, and was survived by a widow and young children - three sons and a daughter. Stack was a brilliant clinician in any branch of medicine he touched. He had learnt from Dr Gee the mental habit of brushing aside non-essentials, and too, like Gee, he was quick to observe unusual features of disease in his patients and appraise their importance. Widely informed, Stack was not worried by the fact that individual cases did not conform to type. It was perhaps this characteristic in his teaching that students appreciated and carried away with them into their practices. In fact, he always aimed at teaching men to practise medicine rather than to pass examinations, and he did not allow them to forget that when they left hospital they would be treating sick people, not disease. He was very fond of children, and his ingenuity in devising 'test types' for children too young to read gave his consulting-room the quaintest appearance. It was full of toys and humorous pictures drawn to Snellen's scale. Publications:- "Notes on Hepatic Cirrhosis in Children." - *Practitioner*, 1892, xlviii, 185. "A Case of Diffuse Leontiasis Ossea." - *Bristol Med-Chir Jour*, 1900, xviii, 316. "Six Cases of Cerebrospinal Meningitis." - *Ibid*, 1901, xix, 44. "Gunshot Injuries to the Eyes." - *Ibid*, 1915, xxxiii, 198. "Poisoning by Mustard Gas: Ocular Effects" (with Carey Coombs and R Rolfe). - *Ibid*, 1920, xxxvii, 151.