lines of a general theory. These defects are now materially corrected. In the summers of 1838 and 1839, I accordingly made excursions in England, in the Isle of Wight, and in France, not less than 2500 miles in extent; testing the general theory by personal observations on localities. The substance of which is now given in the Dissertation appended to the volume before me. I have here to acknowledge how much I owe to information obtained by attending the Geological Section, at the meeting of the British Association for the Advancement of Science, held in August last, at Birmingham. Such meetings certainly contribute to the advancement of Science. They not only enable the scientific student to become acquainted with what is known; but also to ascertain the exact direction in which he may extend the bounds of knowledge. If I there gained little from public discussion on Geology as a physical science, I learned much concerning the grounds of difference among Geologists. Their speculative opinions are certainly crude, unsatisfactory, and unsettled. It is folly to discuss trivial details, while the very outlines of the Science remain in perfect disorder; while the motions of the heavenly bodies, and their influence in deciding Geological phenomena, obtain no notice; while the 2 speed of Oceanic currents, primarily and now, have no place in Science; while those lines of tidal deposition, which are admitted, continue to be totally overlooked; while existing tidal currents, those true indexes to the past, are kept out of the way altogether; while the surface of the earth, so complete in sound Geological lessons, and multifarious in the best ascertained facts, are deemed unworthy of notice; and while the Mosaic Geology, so full of exactness and truth, shall be declared in discordance with Geological evidences, even by the high ones in Science, it is quite premature to go into finical, if not useless details. Witnessing defects so palpable, and differences. so truly lamentable, have nevertheless taught me how much I have to hope from dispassionate minds, and how little to dread from those whose ill-digested speculations are totally irreconcileable, in discordance and at issue with each other. Under these impressions, sustained by such hopes, and cheered by the approbation which my readers have bestowed on my humble work, I feel deeply grateful for the past, augmented confidence in the immutable truth of the Geological system I have published, and unqualified admiration of those Scriptural views in Geology, which abound so much in the Holy Bible. Akehead, Wigton, Cumberland, April 4th, 1840. Page On the Improvement of Navigation, the Construction of Assumed Outline Map of the Granite formation of the Earth 25 GEOLOGY. CHAPTER I. ON GEOLOGY AS A SCIENCE. TRUE Science is a classification of phenomena, conceptions, and ideas, concerning such matters of thought as become the subject of notice, reflection, and examination. It is indeed a prescribed form contrived in aid of the human understanding. Science is therefore a simplification of our ideas, for rendering abstruse and complicated questions familiar and plain; suited alike for general and comprehensive views in the application of our thoughts, or descending to particular and trivial details. Considered in such a light, it is an instrument by which information is readily gathered; we are thereby enabled to communicate what we know more distinctly, and order and exactness in investigation are preserved. Subjecting the various branches of our reflection and forethought to well constructed forms, rays of true light are separated from the confused elements in which they previ B ously lay concealed; and a power is thus framed by human invention, like unto infinite wisdom itself, which constantly works out extended designs according to easy and applicable rules. To distinguish sound science from that which may be fanciful and spurious, is therefore worthy of our careful solicitude and consideration. The elements of science, or the materials of which its frame-work is composed, should always be clearly defined, and easily separated from each other, so that grounds of wrangling about constituent parts should not remain a subject of dispute. In determining on various orders and classes, the scheme of any science should be exact and obvious. Pure science may be indeed well illustrated by referring to the alphabet of language,—and in the language of enumeration, to the cardinal signs by which quantities are expressed. Though these be composed of nothing but generalised fictions, yet by their conversion in use to particular objects, our conceptions assume definite and comprehensive forms of intelligence, whether extending even to infinitude, to minute and detached objects, or to a communication and recording of our ideas. Indeed, by a species of typical transfusion, the verb is rendered significant in language; we learn its right use, and its meaning becomes exact and known, when stripped of its abstract features in an applied sense. Such symbols even aid investigation, lead to the invention of fresh instruments of |