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confidently urged which indicates such a misapprehension of the point at issue, is truly singular, and shows that however eminent they may be in their peculiar sphere, it is not the part of prudence to acquiesce in their deductions and hypotheses, without an examination of the grounds on which they rest.
But in the third place, the objection, if legitimate, is applicable in a large degree to geologists themselves, and invalidates their speculations as effectually as it can the views and reasonings respecting them, of those who are not of their profession. For what share of the facts on which geologists professedly found their theories, have they severally themselves observed? Not one probably in fifty, perhaps not in five hundred. It is physically impossible that such a writer, for example, as Sir Charles Lyell, should have personally inspected all the localities of which he treats, all the processes he describes, and all the facts which he alleges in support of his theories. Of the localities, those of South America, the islands of the Pacific and Indian Oceans, the seas, rivers, lakes, mountains, and plains of Eastern Asia, to say nothing of many others, he has never seen. Of the processes, many have extended through centuries, and could not have been inspected through their whole period by a single individual; and many of the facts had their dates ages ago, and are not now within the sphere of observation. And 60 of other writers. Instead of relying exclusively on their own personal investigation, they avail themselves of the observations and discoveries of others, and build their speculations with as much confidence on the facts of which they thus gain a knowledge, as on those which they derive directly from their own examination. And this is as legitimate, as safe, and as indispensable as it is in mineralogy, chemistry, geography, history, or any other branch of knowledge. It were to impeach geologists themselves of inaccuracy, and invalidate their reasonings, to suppose that the descriptions they give of the facts they have severally observed, are not intelligible and entitled to reliance. What claims can their systems have to be regarded as scientific deductions, if the facts on which they professedly found them are of a doubtful nature, or questionable reality? They are not, however, generally obnoxious in any measure to doubt. The number of practical geologists during the last thirty years has been very large; many of the most important localities have been explored by the most competent observers, and their descriptions are distinguished in a high degree, by minuteness, intelligibleness, and accuracy, and fully justify the use that is made of them by such authors as Lyell, La Beche, Murchison, Buckland, Conybeare, Sedgwick, Phillips, Macculloch; and together with theirs, and the works of other eminent writers, furnish the most ample means to such as are not professed geologists, of an accurate knowledge of all the great facts of the science, and just judgment of the validity of the inductions that are founded on them. Were it otherwise; were a practical acquaintance with all the facts that are made the basis of theoretical geology necessary, there is not a solitary treatise on the subject, that would not be in a large measure obnoxious to the objection, and as unworthy of consideration as the counter speculations are of the mere "divine and man of letters." This objection is thus in every relation ill-considered and unfortunate.*
* This is verified by the mode which is usually pursued by geological professors, in teaching the science to their classes. It is by verbal descriptions, specimens, and pictorial representations, such as are given in books, that they present the great facts of the system to their pupils, not by conducting them to the scenes where those facts can be ascertained by inspection. Thus Professor Phillips, of King's College, London, and one of the distinguished geologists of England, says:—
"Geology founded upon observations of the effects of terrestrial agencies upon a grand scale, admits of being taught, first, by actual demonstration of the phenomena as they are laid open by nature in mountains and valleys, cliffs and ravines; secondly, by the aid of specimens of natural products and representations and descriptions of the manner of their occurrence. As we cannot transport a pupil to the summit of the Alps, the glens of the Grampians, or the caverns of the Peak; as we cannot at pleasure show him the bold cliffs of Hastings, Whitby, or Charmouth, the wasting shores of Norfolk, or the extension of new land along the margin of the Adriatic, he must be taught to reason upon these characteristic phenomena by the aid of pictorial or verbal representation. With this view we QUESTIONS.
What is the first false notion that has been extensively spread respecting the nature of geology? Has geology any laws by which it can be demonstrated that the strata of the earth were formed in a particular way, and that a vast series of ages was occupied in their structure? What is it of which geology professedly treats, according to Dr. Buckland? What is the definition which Professor Phillips gives of its object? What is Sir C. Lyell's? What is Mr. Maccul
found museums of specimens, publish sections and maps and models, and endeavor by lectures on these examples and imitations of geological occurrences, to lead the student to the contemplation of the magnificent objects themselves. Could we dispense with these artificial aids, were it possible to compress into a short geological tour an actual inspection of the most important facts, much of the technical language which is now found so convenient might be dispensed with; many explanations might be spared; the monuments yet remaining of the changes which the earth has undergone, would tell their own history, and never require the little aid of words. But the writer and the lecturer must have recourse to other methods, and by a studied arrangement of representations and reasoning, strive to impress the same truths, with equal force of conviction, which are directly gathered from the more vivid, though less regular lessons in the glorious theatre of nature."—Guide to Geology, pp. 1, 2.
And this, we may add, is the method also in which the professors of the science prepare themselves to give instruction respecting it. The usual course is to attend the lectures of some distinguished geologist, and study books and specimens. The information derived from the direct inspection of the strata, is slight, generally, compared with that which isdrawn from these sources. And this method is not only as justifiable, but as indispensable to success in this branch of knowledge as any other. It were as absurd in a geologist, as it were in a chemist or astronomer, to neglect the discoveries others have made, and attempt to build up a system exclusively on his own observations. The objection often put forth with a very imposing air, thus shrinks, when properly considered, into very moderate dimensions.
loch's? Has it then, according to the definitions of these writers, any laws peculiar to itself, by which it can be proved that the strata were formed by the slow processes, and that the earth is of the great age, which their theory asserts? If geology, then, has no laws, and deals only with mere facts, what are the great facts of which it takes cognizance? Do those facts furnish any means of demonstrating the immense age of the world? Is it a mistake then to regard it as a demonstrative science? Exemplify the fallacy of attempting to prove the vast age of the world by it. What sort of a science then is it, if it is not a demonstrative one? Name some other subject, the knowledge of which is of the same kind as that of geology.
What is the second false impression respecting it that needs to be corrected? Are geologists accustomed to sneer at criticisms on their theory by persons of other professions, and denounce them as unworthy of notice? What is the first objection to that course? Is not the interpretation of the sacred text, Genesis i. and ii., within the proper sphere of the theologian? Has not the theologian quite as good a right to maintain the truth of the inspired narrative against the speculations of the geologist, as the geologist has to endeavor to sustain his theory against the testimony of the sacred text?
What is the second objection to the claims of geologists that none but persons of their profession are competent to criticise their theory? What is the error in the reasoning by which geologists attempt to prove the great antiquity of the world, which shows that they themselves are not masters of their own logic? State the first premise from which they infer the great age of the world. Point out its fallacy. What then is it, in fact, on which their inference of the age of the world from this premise rests? Is it on the facts of the strata themselves, or a mere hypothesis respecting the forces by which they were formed? State their argument in a syllogistic form. What is it now, in that syllogism, from which the inference of the age of the world is drawn—from the strata themselves, or from an hypothesis respecting the processes by which they were constructed? Is that hypothesis, however, found graven on the strata? Is not the infe