Born on 2 April 1875 at Bannatyne, Barbados, only child of Henry Eudolphus Boyle, sugar-planter, and his wife, *née* Law. He was educated at Harrison College, Barbados, and at St Bartholomew's Hospital. As a student he was president of the Abernethian Society. After a short time as casualty officer at the Bristol Royal Infirmary he was appointed junior resident assistant anaesthetist, with W Foster Cross, at St Bartholomew's Hospital in 1902. He continued to serve the hospital throughout his career, being eventually (1913) senior anaesthetist, and lecturer on anaesthetics in the medical college from 1905. He retired as consulting anaesthetist in 1939. He was also anaesthetist to the St Andrew's Hospital, Dollis Hill; Lady Carnarvon's Hospital; Queen Alexandra Hospital for Officers, Highgate, and Paddington Green Children's Hospital. During the four years' war he was commissioned captain, RAMC(T) on 5 September 1914, and served in various London hospitals, being created OBE in 1920 for his services. Boyle did much for the practical development of anaesthetic administration. About 1912 the gas - oxygen - ether method began to be popular, largely through his example. He brought the first Gwathmey apparatus from America, and Boyle's own nitrous-oxide/oxygen/ether apparatus became well known. During the war of 1914-18 it was usefully employed in casualty clearing stations in France, and he successfully impressed the authorities with the importance of this form of anaesthesia in shock cases. Later he introduced the Davis gag for dissection tonsillectomy from America, and was a pioneer in endotracheal anaesthesia, and also improved the anaesthesia of midwifery. He was on the editorial board of the *British Journal of Anaesthesia* from its foundation in 1923, and was president of the section of anaesthetics at the Royal Society of Medicine in 1924. He was an original member of the Association of Anaesthetists of Great Britain and Ireland and influenced the Royal Colleges in the establishment of the Diploma in Anaesthetics, to which he was himself admitted in the first group in 1935. The same year he was appointed the first examiner for this Diploma, and was elected a Fellow of the Royal College of Surgeons as a Member of twenty years' standing. He was an excellent practical teacher. Boyle was a man of rotund figure and genial nature, popular with his colleagues and students as "Cocky" Boyle. He was a keen cricketer and a supporter of the Bart's rugby football club, and as a member of the senior staff had been president of the Students' Union. He married in 1910 Mildred Ethel, daughter of J W Widdy and widow of Leslie Greene, FRI, BA, who survived him but without children. Boyle died after a long illness at 4 Cliffe Road, Godalming, Surrey on 15 October 1941. Publications:- *Practical anaesthetics*. London, 1907; 2nd ed, 1911; 3rd ed, with C Langton Hewer, 1923. Nitrous-oxide: history and development. *Brit med J*. 1934, 1, 153.