his curiosity and interest. There should be enough of detail to enable him to understand how conclusions are arrived at. All through its chapters he should see how observation, generalisation, and induction go hand in hand in the progress of scientific research. But it should not be overloaded with technical details which, though of the highest importance, cannot be adequately understood until considerable advance has been made in the study. It ought to present a broad, luminous picture of each branch of the subject, necessarily, of course, incomplete, but perfectly correct and intelligible as far as it goes. This picture should be amplified in detail by a skilful teacher. It may, however, so arrest the attention of the learner himself as to lead him to seek, of his own accord, in larger treatises, fuller sources of information. To this ideal standard of a class-book I have striven in some measure to approach. Originally, I purposed that this present volume should be uniform in size with the Class-Book of Physical Geography. But, as the illustrations were in progress, the advantage of adopting a larger page became evident, and with this greater scope and my own enthusiasm for the subject the book has gradually grown into what it now is. With few exceptions, the woodcuts have been drawn and engraved expressly for this volume. Mr. Sharman has kindly made for me most of the drawings of the fossils. The landscape sketches are chiefly from my own note-books. I have to thank Messrs. J. D. Cooper and M. Lacour for the skill with which they have given in wood-engraving the expression of the originals. In preparing the Second Edition, I have thoroughly revised this Class-book, so as to keep it abreast of the onward progress of Geology. The sale of a large impression, and the numerous communications received from teachers and others, have led to the belief that the book might be made still more useful if printed in such a form as to admit of its being sold at a greatly reduced price. This change has now been effected; but the volume, though diminished in bulk, contains rather more matter than the first edition. Care has been taken to make the Index full and accurate. 30th June 1890. |