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insults by the enemy who, under the pretext of watching it, followed and harassed it in its retreat. Davout had become in fact a sort of plenipotentiary of that army of which the reconstituted Royal Government affected to no longer recognise the legal existence or rights. He had at the same time to protect the army against the Government and to protect it against disorganisation; he had to maintain it in obedience and discipline, and to negotiate its submission while preserving its pride and interests. Davout managed to combine these duties with the higher qualities of patriotism and honour.'

Eventually, under his orders, the army, which had been withdrawn behind the Loire, mounted again the white flag; and then, in obedience to the King's command, he made over the command of it to Marshal Macdonald preparatory to its being broken up. He stood up manfully for the generals who appeared at first to be marked out for vengeance for the part taken by them during the Hundred Days. His own hands were clean, at any rate; but although not brought to trial himself, he was for a long time interned at Louviers under police supervision. It was not till after some years that the Prince of Eckmühl, already restored to his rank of Marshal of France, was called up to the Chamber of Peers. The hardships of war had apparently left no mark on his strong frame, but a life of inaction proved more trying to his constitution than the fatigues of war, and he survived the fall of the Empire only eight years, dying in June 1823, having then, after twenty years of continued employment as a general, and eight of retirement, barely reached the age at which in ordinary times an able and fortunate soldier may hope to emerge from subordinate rank. Nations undergo tribulation when such a career is possible. Happy the country whose generals are old!

We may observe in conclusion that the task of editing these letters was entrusted to M. de Mazado by the Countess de Cambacérès, the daughter of the Marshal, and they could not have been placed in better hands. But, acting under the direction of the family, the editor has evidently glossed over some of the most questionable passages in the Marshal's career, in order to present as favourable a view as possible of his hero, and has made some statements which might be controverted. But we have no wish to enter upon debateable ground, and we accept the work as a valuable contribution to the history of the First Empire.


ART. VIII.-Geology, Chemical, Physical, and Stratigraphical. By JOSEPH PRESTWICH, M.A., F.R.S., F.G.S., Professor of Geology in the University of Oxford. 8vo. London: 1886.

WH THEN we consider for how many centuries history, politics, medicine, and even the study of animals and plants, have occupied men's minds, it may well be a matter of surprise that the science of their terrestrial dwelling place dates from but yesterday. It is true that ignorance of geography was long an insuperable bar to any really satisfactory geological progress, but the removal of that obstacle did not alone suffice to enable the study of the earth to develope as it should have developed. Its retardation was largely due to a generally received belief that we already 'knew all about it.' A narrow literalism in the interpretation of Hebrew poetry, guarded and maintained by the formidable powers of which ecclesiastical authority disposed, had led men to attribute the forms and dispositions of mountains and valleys, as well as their mineral composition, to the immediate action of divine creative power, only modified by subsequent diluvial action. Thus it came about that when the real existence of fossil marine shells far inland and on hills above the sea level became widely recognised, they were generally referred to the action of the one universal deluge. The publication of Buffon's 'Théorie de la Terre' (which so startled the ecclesiastical faculty of Paris that its censured author had to make a retractation) marks approximately the commencement of any wide diffusion of scientific geological speculations. This was just before the middle of the last century, though it was only towards its close that rock masses came to be more systematically studied and better understood. Then Werner, Hutton, Dolomieu, Saussure, and others, showed that the earth consisted partly of stratified sedimentary rocks and partly of others which were unstratified.

Though fossils had then come to be recognised as relics of past life of different kinds and in different degrees divergent from existing life, nevertheless little was understood of the order of succession of that life on the earth till 1799, when the researches of William Smith proved not only that the various strata held a definite and uniform relation one to the other, but also that each group had its own distinctive set of fossils-each past period of the world's history being

characterised by the possession of different forms of animal and vegetable life.

The earlier geologists were, as is well known, occupied with vigorous controversy about the respective shares which aquatic and igneous agencies had taken in the formation of the earth's crust, but a general disposition existed to account for geological phenomena by a liberal allowance of cataclysms and convulsions far exceeding anything which the modern world could be supposed anywhere to exhibit.

In opposition to this convulsionist and cataclysmal school, there arose one of the greatest of modern geologists, the late Sir Charles Lyell, who sought to prove that there was no evidence that the world had ever presented phenomena brought about by agencies different even in degree from those which act at the present time, and he triumphantly showed, in many instances, that a liberal, yet not unreasonable, allowance of time would account for several geological facts not previously thought to be so simply explicable. But Sir Charles Lyell's system, which is known as uniformitarianism,' is an example of one extreme begotten by an opposite exaggeration. After having been for a time widely accepted, it is now thought by many to be untenable. Even its author began in his later days to modify his own views very materially under the widereaching influence of Darwin and the theory of evolution.

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The work to a review of which this article is devoted will afford some aid to the reaction against extreme uniformitarianism. Mr. Prestwich, in his just published Geology,' himself points out that the fundamental question of the relation in this respect between time and force has given rise to two schools, one of which adopts uniformity of action in all time, while the other considers that the physical forces were more active and energetic during past geological periods than they are at present. One school considers that the causes at present in action on the surface of the globe are not only those which have ever been in action, but also maintains that at all former periods they have been equal in kind and in degree, and that the energy with which the forces of nature now operate are sufficient, with unlimited time, to account for all past phenomena. The other school, on the contrary, considers that, while identical in kind, the causes in operation in past times were affected by a more active and energetic action of those forces than obtains at present. The discussion of this question, he tells us, must be reserved until the reader is master of the facts


' of this science;' but he nevertheless declares his own view to be that while the laws of chemistry and physics are unchangeable and as permanent as the material universe ' itself, the exhibition of the consequences of those laws in 'their operation on the earth has been, as new conditions and new combinations successively arose in the course of its 'long geological history, one of constant variation in degree and intensity of action.' To this modified and, as we think, most rational uniformitarianism, we give in our cordial adhesion.

Not on this account alone, but for many other reasons besides, we welcome with great satisfaction the appearance of this work on Geology by the present professor of that science at Oxford. It is to consist of two volumes, of which only one is now published, though the other, we hope, will speedily follow. The work has been very long in preparation-so long that we have not been free from fear lest some untoward accident should deprive us of the advantage of its publication under its author's personal supervision. For more than half a century Professor Prestwich has been known as a worker and author in his favourite science-a science he loved so well that not all the distractions and anxieties attending a mercantile career perceptibly diminished either his ardour for or his eminence in it, while exclusive devotion to it was the eagerly adopted first consequence of merited commercial success. Occupied at the beginning of his scientific career with the oldest fossiliferous formations, he has come to be perhaps the greatest living authority on all which concerns the latest tertiary and post-tertiary strata.

His just published volume may be said to be complete in itself, and being devoted to preliminary studies, which are very clearly set forth, it is just the work required by any one who would begin the study of geology. The volume which is to follow will be occupied by descriptions of the earth's strata, with their contained fossils, concluding with those theoretical questions connected with cosmical and physical phenomena which relate to the history of the evolution of our planet.

The first object of the beginner in geological science should be to make himself acquainted with the materials of which the subject of his study-the earth-is composed, and the laws which govern them. On this account our author (whose first chapters are intended for those who approach the subject for the first time) has divided his present

volume into two parts: (1) A description of the minerals and rocks which form the crust of the earth, tracing the combination of elementary substances that enter into the minerals forming the rocks, together with the characters of the different rocks so formed; (2) An exposition of the various agencies which have acted on those materials both under existing and under past conditions. The second part begins with the fourth chapter, wherein are described those processes of change by which the older rocks, in consequence of alteration and decomposition, have come to furnish the materials out of which newer rocks have arisen. These latter, stratified, rocks consist of the insoluble residue of the primeval unstratified rocks, the soluble constituents of which have found their way into the ocean-their common receptacle-being carried there by surface waters. The stratified rocks thus formed consist of a very limited number of substances, comparatively indestructible save by wear and tear often resulting in stratigraphical reconstructions. In the next (fifth) chapter the past life of the earth is briefly reviewed, and to this succeeds a series of very interesting and admirably written treatises on the actions of rivers and tides, meteorological agencies, underground waters and springs, ice action, volcanoes and earthquakes, coral islands, faults and cleavage, mountain ranges, metalliferous deposits, igneous rocks, and metamorphism.

This book, therefore, contains in abundance all that is necessary for any one who would make a beginning in this science. Nevertheless, it is not by the reading, however attentively, of books, however excellent, but by the observation of Nature herself, that geology-like every natural science can alone be fruitfully investigated. As Professor Prestwich expressly tells us, the fundamental and indispensable qualification for the geological student is accurate and true observation in the field, the habit of carefully recording facts on the spot, and the power of discerning the bearing of all the various phenomena that come before him, and apportioning their relative value. Without this the abstract sciences are of no avail; and the student will often find himself launched in a wrong direction, and in fruitless inquiries. The real class rooms of a geologist are to be found in quarries, pits, railway sections, cliffs, mountain passes, and ravines. To these the student must resort, to obtain that mastery of the science which will enable him to interpret facts rightly and to draw conclusions justly. It is this direct study of nature, this exploration of ground ever

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