With the publication of the first edition of _The Great Ice Age_ in 1874, Prof. Geikie’s reputation as a glacial geologist of the first rank was at once established. The book had a cordial reception and a ready sale. Prof. Green wrote a long and very sympathetic review of it for _Nature_, and, whether its teachings were generally accepted or not, the author had the satisfactory proof that it had not been neglected by the rapid exhaustion of the first edition. Within a few months he had to set seriously about the production of a new and enlarged edition. Much of its popularity was no doubt due to the clear and graceful style in which it was written. The more abstruse parts of the subject were not discussed with too much detail; great insistence was placed on the field evidence, and the discussion was such as could be followed by the general reader who had no special training in geological work. A studied moderation marked the conclusions arrived at, and no attempt was made to force a revolutionary interpretation of glacial phenomena into prominence. A great deal also was due to the fact that the book embodied not only its author’s work and the hypotheses he favoured, but also the results of the observations of many of his colleagues on the Survey who had a very wide acquaintance with field geology, and were, on the whole, very well agreed regarding the interpretation of the facts. The author fully acknowledged his obligations to colleagues on the Survey staff, but at the same time it was clear that on this subject he was the leader and not merely a compiler of other people’s results. The dedication to Sir Andrew Ramsay is especially significant, for from Ramsay more than from any other geologist had inspiration been received. Probably the effect of the book was greater in foreign countries than in Britain. In Germany, Switzerland, Sweden, and the United States many geologists were actively prosecuting the study of glacial deposits, and so clear and authoritative a statement of the observations and conclusions of the Scottish glacialists had much interest to workers in other lands. This appreciation the author valued greatly, and it was the cause of a great enlargement in the circle of his correspondents. He followed keenly the advance of glacial investigation in foreign countries, and especially the new evidence brought forward regarding changes of climate during and subsequent to the glacial period, and the early chapters in the history of man in Europe.