« السابقةمتابعة »
geographical range by certain peculiarities of soil and climate; and when planted in situations where it does not enjoy these, it inevitably becomes more or less unhealthy; but in suitable positions there are few trees which seem more likely to bring a profitable return to the planter. Mr Loudon las enumerated the many valuable purposes to which the larch may be put; and the following notice of its use in ship-building is not among the least important. It relates to an examination which was made of the frigate Athole, eight years after she had been built, her hull, masts, and yards being made entirely of larch timber.
• The larch becomes harder and more durable by age in a ship. It holds iron as firmly as oak; but, unlike oak, it does not corrode iron. Iron bolts may be driven out afterwards perfectly clean. It does not shrink : the Athole had been caulked but once in four years. It possesses the valuable property of resisting damp, inasmuch as the pumpwell was as dry as the cabin. The beams and knees in the gun deck were as well finished as the best joiner's work, and they had no appear. ance of shrinking or straining. The Larch, a brig, the Diana, a steamvessel, and other ships, were afterwards built of the larch, and all with favourable results.'-P. 2398.
We cannot admit the supposition which has been thrown out, that the cedar of the Scriptures might possibly have been the deodar. It may be perfectly true that the timber of the latter is incomparably superior to that of the former; but the evidence in favour of the cedar of Lebanon is too conclusive to allow of any doubt upon the subject. No one pretends to have seen the deodar growing in any part of the country near Mount Lebanon. Its native range is the mountains of Eastern India, Nepal, and Thibet. Comparatively worthless as the wood of the cedar of Lebanon may be, it always bore a high repute for its incorruptibility and fragrance; and in a country no way remarkable for fine timber, it might well enjoy the reputation it did. Probably, also, its quality, on its native mountains, may be much superior to any that is grown in our less genial climate.
In conclusion, we congratulate Mr Loudon on having produced a work which will, we trust, be the means of diffusing through our plantations and shrubberies many beautiful trees and shrubs, hitherto rarely seen but in nurseries or botanic gardens. After this desirable change has taken place, our woods will assume a new and varied colouring when the leaves are bursting forth in spring, and an intense hue in autumn, of which the untravelled Englishman can, at present, scarcely form an idea.
Art. V.-Elements of Geology. By CHARLES LYELL, Esq.,
F.R.S., Vice-President of the Geological Society of London,
Author of • Principles of Geology.' 12mo. London : 1838. Tu This volume contains a view of the Elements of Geology,
by the author of one of the most popular books ever published in England on the principles of that fascinating department of natural science ;--and certainly one of the most valuable that has appeared since Mr Play fair's well-known Illus• trations of the Huttonian Theory.' It is worthy of Mr Lyell's reputation, but very different from what we had expected; for, having been mentioned in the advertisements as intended for be'ginners,' we had looked for something of a very plain and rudimentary description-a treatise, in short, that would have rendered the subject inviting by simplicity of style and illustration, and could have been read with ease and satisfaction by a well-educated woman.
Instead of this, the author has given us a clear and condensed abstract of what he conceives to form the proper • Elements' of his subject; and has transfused into it not only the result of much reflection, but also a great number of facts—which to us were new ;—this compression, indeed, being one of its defects, so far as it is intended to be introductory; since there are pages of quite as much depth as any in the larger work above mentioned. When these difficulties are mastered, its sterling value will be appreciated; and we have no doubt it will gain upon the public.
To ourselves, both as Geologists and Reviewers, the volume is particularly acceptable; as it brings before us, in a more manageable form, some of the doctrines of the author's · Principles
of Geology,' of which we have not yet given any account; while the passages, relating to the igneous theory and the metamorphic rocks, revive impressions that have long existed in our minds, and convince us that the time has come, when it is necessary to attempt a rectification of some points in the history of geological theory, during the most eventful period of its progress.
Mr Lyell's attention appears to have been first devoted to Geology during his residence at Oxford, about twenty years ago, after he had become a proficient in some other departments of natural history. He became, in 1823, one of the Secretaries of the Geological Society of London, of which he has since been President; and was thus immediately connected with many of the best working geologists of the day; and had at his disposal
all the facilities which could be supplied by an association zealously engaged in the advancement of a branch of knowledge still possessing many of the attractions of youth. His first publication was a paper on the recent fresh-water marl and limestones of Forfarshire,* _in which we can perceive the germ of many of his subsequent speculations. The lakes in that country affording deposits which resemble ancient lacustrine strata, the views which they suggested to him were naturally extended to the general analogy between the effects of still existing agency and those of causes which it was, at that time, the fashion to consider as having long ceased to act; and his attention, fortunately, was soon afterwards directed to the study of a district, which exhibits deposits of the same kind on a much larger scale, and in connexion with phenomena of still higher interest to theory. Not
many of our readers, probably, are aware that there exists, in the midst of France, a region occupied by volcanoes, which, although they have not sent forth lava within the memory of man, exhibit other appearances as characteristic of their origin as those of Sicily and Naples. The chain near Clermont, in Auvergne, from which the subjoined sketch was taken, is not more than three days' journey from Paris, and can easily be reached within a week from London; and it is as certain that each of the craters sketched in this little view, was once an active volcano, as that Etna and Vesuvius now burn and send out eruptions.
Part of the chain called the Mont Dome, Auvergne.—(Scrope.) The descriptions of this celebrated tract called forth Mr Lyell's enthusiasm, and probably had a considerable_share in determining the course of his succeeding enquiries. Few
pass: ages of greater excellence can be found in any of his productions, than some of those in a review, which he published in 1827,7 of Mr Scrope's beautifully illustrated work on the volcanic district
• Geol. Trans., 2d Series, II.
† Quarterly Review, Vol. XXXVI., p. 437.-See · Principles,' 4th Edit., Preface, p. vii,
of central France; from which it is obvious that his mind was already impregnated with many of the views that characterise his · Principles ;' nor does the latter publication contain any thing more ingenious than the method exemplified in the review, of calculating backwards in geological chronology, from existing appearances, through a series of preceding changes.
Before 1828, the author had made excursions both in France and England, in company with M. Constant Prevost of Paris, with whose opinions, especially on the tertiary strata, some of Mr Lyell's doctrines nearly coincide. He had completed the manuscript of part of his first volume in 1827—but wisely suspended its publication, that he might 'acquire more information
concerning the tertiary deposits; and, leaving England in 1828, attentively examined Auvergne and other tracts in France, from whence he passed through Piedmont into Italy—where he became acquainted with the productions of the earlier geologists of that country, especially of Lazzaro Moro, and his illustrator Generelli-to whom he afterwards assigned a prominent place in the History of Geology.
• In the course of my tour,' he tells us, · I had been frequently led to reflect on the principle of Des Cartes, that a philosopher should, once in his life, doubt every thing he had been taught; but I still retained so much faith in my early geological creed, as to feel the most lively surprise on visiting Sortino, Pentalica, Syracuse, and other parts of the Val di Noto, at beholding a limestone of enormous thickness, filled with recent shells or sometimes with the mere casts of shells-resting on marl, in which shells of the Mediterranean species were imbedded in a high state of preservation. All idea of attaching a high antiquity to a regu. larly stratified limestone, in which the casts and impressions of recent shells alone were discernible, vanished at once from my mind. . . I occasionally amused myself with speculating on the different rate of progress which geology might have made, had it been first cul. tivated with success at Catania; where the phenomena above alluded to, the great elevation of the tertiary beds in the Val di Noto, and the changes produced within the historical era by the Calabrian earthquakes, would have been familiarly known.' *
From Etna and its environs, the author returned to England in the beginning of 1829—having now fully decided on attempting • to establish four great subdivisions of the tertiary epoch, and • being also convinced that he had seen in Auvergne, Tuscany, * and Sicily, volcanic rocks contemporaneous with the sedimentary • strata of all those periods.'+
In the mean time, M. Desnoyers had printed, and was about to
* Principles, 3d edition, Preface, p. vil.
+ Ibid. pp. ix. x.
publish a paper on marine formations, more recent than those of the environs of Paris ;* and having conversed with Mr Lyell, then returning from Italy, respecting his observations in that country, he subjoined to his Memoir a note, expressing the value of the concurrent testimony thus derived from regions so distant. At the same period, also, M. Des Hayes had convinced himself that the different tertiary formations might be arranged in a chronological series; and on communicating with that gentleman, it was resolved to combine the result of an examination of the shells collected by Mr Lyell in Italy, with the great body of information previously in M. Des Hayes' possession. This was done in the third volume of the Principles of
Geology,' first published in 1833; and the same results have since, we believe, been published in other forms by M. Des Hayes himself.
It would seem, therefore, as frequently happens in the progress of discovery, that the necessity of extending and subdividing the tertiary class of deposits, had occurred about the same time, and independently, to the naturalists above mentioned, as well as to the author. Mr Lyell has more recently informed us, that Professor Bronn of Heidelberg had likewise been led, by independent researches, to similar views. The success with which he himself followed out his enquiries in this department of geology, has produced one of the most remarkable portions of his own works.
The succeeding summers, from 1829 to 1838–of this, which may be truly called a course of geological education--were employed by the author in examining the • Crag' of the eastern counties of England, the south of France, the Pyrenees, Belgium, and the Eifel, Switzerland, several portions of Germany, Denmark, and Sweden :- that of 1835, in particular, enabled him to produce papers on the gradual rise of the land in the last mentioned country, and on the chalk of Seeland and Moen.
The series of labours above mentioned, nearly represents the life of every practical geologist of the modern school. It will convince our readers that it is not without effort that reputation can be gained in this department of enquiry; and will explain how the author was conducted to some of his views respecting the more recent groups of strata—to the comparative neglect,
* Annales des Sciences Naturelles : Fevrier, 1829.
† Vol. III., 5th Ed., p. 367. A Journey in Italy,' Heidelberg: Dec. 1837.
I Phil. Trans., 1835. f Geol. Trans. 2d Series Vol. V. VOL, LXIX. NO. CXL.