been completed. Having learned what to look for and how to interpret it when seen, we are as it were gifted with a new sense. Every landscape comes to possess a fresh interest and charm, for we carry about with us everywhere an added power of enjoyment, whether the scenery has been long familiar or presents itself for the first time. I would therefore seek at the outset to impress upon those who propose to read the following pages that one of the main objects with which this book is written is to foster a habit of observation and to serve as a guide to what they are themselves to look for, rather than merely to relate what has been seen and determined by others." At the very outset in this work, geology is regarded, "not as an amusement for the collector and a means of learning where he will get pretty and curious objects for his cabinet; not as a field where the ingenuity or perversity of the classifying mind may delight itself with grouping natural products as reason prompts; not in any other of those limited aspects beyond which it is feared the wisdom of some geologists never reaches; but as a history—the history of the earth in ages long gone by."
Believing that no branch of the study should be overlooked, we find him lamenting, in 1871, that while in all that relates to stratigraphic geology the British had kept ahead of other nations, they had allowed petrography, or the study of rock species, to fall into disuse. Matters had improved, partly perhaps under his own influence, in 1880, when, writing of the Mineralogical Society of Great Britain, he remarked upon a revival of interest in mineralogy, which had before been neglected for fossil-hunting.
In one of the reviews of Prof. Geikie's Science Primer of Geology, in 1874, a curious omission is remarked, in that the author had not referred to Darwin's theory of coral islands as a "proof that a part of the crust of the earth has sunk down"—the reviewer suggesting that to lead pupils up to this theory, and then test it as Darwin had tested it, was "an excellent exercise in that peculiar kind of reasoning about past causation which is of the essence of geology." Prof. Geikie appears to have built, as the saying is, better than he knew; for in 1884 he confessed himself reluctantly compelled, in view of Mr. Murray's observations in the Challenger Expedition, to admit that Mr. Darwin's theory could no longer be accepted as a complete solution of the problem of coral reefs.
Prof. Geikie has long taken an intense interest in the American geological surveys, and has followed them up with the closest attention for many years; and his notices of their reports and summaries of their results constitute a very considerable part of his frequent contributions to Nature. He was fully impressed with the magnitude and extent of the geological phe-
