Sir Archibald Geikie was elected a Fellow of the Society in 1865, at the age of 29 years, and at the time of his death, in 1924, he was the senior Fellow, and hence the “father” of the Society. Throughout this long series of years he was devotedly attached to the Society and most anxious to promote its welfare and further its activities in all possible directions, and the Royal Society is much indebted to him for the services he rendered to it during the periods he acted as one of its officers. He served on the Council first from 1885 to 1887, and was Foreign Secretary from 1889 to 1893. In 1903 he was elected Secretary on the biological side in succession to Sir Michael Foster, and had as colleague on the physical side his friend Sir Joseph Larmor, the presidents during his term of office as Secretary being, Sir William Huggins and Lord Rayleigh. During the later years of the nineteenth century the work of the Society had undergone considerable expansion both on the physical and on the biological side. Thus, the part played by the Society in such undertakings as the International Catalogue of Scientific Literature, the Association of Academies, the National Physical Laboratory, and the investigations into certain tropical diseases, considerably increased not only the range of the activities of the Society, but also added considerably to the work of the Officers, Fellows, and staff. Geikie, throughout his tenure of office, took the greatest interest in the work of the Society as a whole, and his outlook was always a wide one, although as Secretary his activities were mainly concentrated on the biological side. One of the most characteristic features of his work was the interest he took in all biological questions, botanical, zoological, and physiological. He never confined his interest to the more special branches of knowledge that he had made his own.