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Show • PRINCIPLES OF GEOLOGY. CHAPTER I. Connexion between the Hubjects treated of in the former parts of this work and those to be discussed in the present volume-Erroneous assumption of the earlier geologists respecting the discordance of the former and actual causes of change-Opposite system of inquiry adopted in this work-Illustrations from the history of the progress of Geology of the respective me1·its of the two systems-Habit of indulging conjectures respecting irregular and extraordinary agents not yet abaudoned-N ecessity iu the present state of science of prefixing to a work on Geology treatises respecting the _changes now in progress in the animate and inanimate world. HAVING considered, in the preceding volumes_, the actual opera4 tion of the causes of change which affect the earth's surface and its inhabitants_, we are now about to enter upon a new division of our inquiry, and shall therefore offer a few preliminary observations_, to fix in the reader's mind the connexion between two distinct parts of our work_, and to explain in what manner the plan pursued by us differs from that more usually followed by preceding writers on Geology. All naturalists, who have carefully examined the arrangement of the mineral masses composing the earth's crust .. and who have studied theit· internal structure and fossil contents, have recognized therein the signs of a great succession of former changes; and the causes of these changes have been the object of anxious inquiry. As the first theorists possessed but a scanty acquaintance with the present economy of the animate and inanimate world_, and the vicissitudes to which these are subject, we find them in the situation of novices_, who attempt to read a history written in a foreign language_, doubting about the meaning of the most ordinary terms; disputing, for VoL, III. B |