that which embraces the history of the animal and vegetable king. doms by which that surface has, through the various stages of its existence, been tenanted. The latter, as may readily be conceived, offers the most prolific field of the two to the investigation of creative design. But the former is by no means barren in such speculations. Indeed, though wanting in those examples of nice and beautiful contrivance by which, in the animal and vegetable kingdoms, all the resources of the most consummate art, refined ingenuity, and profound science,-if such phrases are allowable,→→→ seem to have been employed for effecting the purpose in view, this department of natural history presents instances of the adaptation of means to an end of a peculiarly grand and striking character. We are not sure, indeed, that our author has quite done justice to this part of the subject, which offers views of the creative intelligence and design not a whit inferior in force of evidence to those afforded by the animated creation, on which, by preference, he has so ably and eloquently dwelt.

We assume the main object of the disposition of the earth's surface to have been the provision of a state of things most favourable to the utmost possible development of animated and sentient existence, and consequently to the largest aggregate amount of ENJOYMENT. For what other end can we imagine so worthy of the exercise of the wisdom and power which are the co-attributes of the Divine Benevolence? In this view the astronomer shows us the globe of our earth hung in space by invisible but all-powerful chains, and performing that double revolution upon its own axis, and around the solar centre of light and heat, which are alike essential to the maintenance and constant renewal of life upon its surface. Taking up the argument where he leaves it, the geologist exhibits the admirable contrivances by which the crust of this ball has been rendered, throughout innumerable ages, capable of supporting countless myriads of organic existences. Now how has this great end been accomplished? Looking at the question à priori, it might be supposed most consistent with the order, harmony, and regularity which is maintained, chiefly by the great principle of gravitation, throughout the planetary system of which our globe is a portion, that its surface should present one unvaried character, the nucleus perhaps being enveloped in concentric folds of its component materials, gaseous, liquid, and solid, disposed like the coats of an onion, in the order of their specific gravity, or some other more or less symmetrical arrangement. But the slightest consideration will convince us that any such disposition would have been fatal to the possible existence of the greater part-probably to the whole-of the organic creation, The multiplicity and amount of animal and vegetable

D 2

life

life with which the surface of the globe has ever teemed, are wholly dependent on the excessive irregularity with which its few and simple elements have been compounded into an endless variety of mixtures, and scattered up and down, hither and thither the great mass of liquids collected, it is true, into separate bodies, but at the same time circulating in an endless course through and over the whole-the solid parts aggregated into an universal crust, but which at the same time is broken up into the wildest confusion, so as on some points to pierce the clouds, on others to sink beneath the deepest oceans, while it exposes in turn upon its surface every variety of substance that enters into its composition, even those which could only have been formed originally in its inmost depths-the gaseous overspreading and penetrating all, but constantly undergoing the most irregular and complex changes. All this apparent confusion and disturbance, seemingly so opposite to the prevailing tranquillity, order, and almost symmetrical arrangements of the celestial universe, has been always indispensable to the existence of the animal and vegetable kingdoms on the surface of our planet, and can only be explained on the supposition that it was ordained for that end.

Geology points out by what contrivances these essential irregularities have been brought about, and the limits within which they are for the same useful purpose restrained. In the present state of the science all, it is true, are not agreed on the means which in the infancy of the planet were adopted to separate the atmosphere and ocean from the solid frame-work of the earth. But there is now no longer any difference of opinion among geologists as to the agency employed for elevating the latter as dry land above the liquid level of the ocean, and for giving to it that rudely varied surface and infinitely modified composition, which we have spoken of as of such paramount importance to organic nature. The agency employed is mainly of two very simple kinds, namely, first, the expansive and alterative power of heat proceeding from the interior of the globe; secondly, the action of the immense body of water which is constantly moving over its surface, and engaged in grinding down its prominent parts, and re-distributing their materials in stratified beds within its hollows. These antagonizing forces of fire and water have from the first produced and continually maintain that endless variety of form and composition in the mineral masses of the earth's surface, to which its animal and vegetable inhabitants are indebted for their varied existence. The one has originated that class of rocks which are unstratified and crystalline, having been protruded in a state of igneous fusion, or something like it, from the interior of the globe to the places they now occupy, the other has given rise to the immense aggregation

of

of stratified and alluvial rocks which compose the greater part of its dry surface, although, from the marine remains they contain, it is clear they have mostly been deposited below the ocean, and subsequently lifted up by the expansive force of subterranean heat.

In order to bring clearly before the mind's eye of his readers the dynamical changes which have been thus wrought upon the crust of the earth, Dr. Buckland has engraved a long and elaborate ideal section of a portion of this crust; an improved reduction of the magnificent sketch of the same subject with which Mr. Webster (so well-known for his observations in the Isle of Wight and elsewhere) used to illustrate his geological lectures. Nothing can be more instructive than this section: it teaches more at a glance of the ancient history of the globe, and the revolutions to which it has been subjected, than the perusal of many a laboured treatise on the matter. The eye is carried gradually forward from the formations, igneous and aqueous, which are going on at present, to the most ancient which have been shattered and displaced by the convulsions of ages; and to each period is annexed a minute but spirited representation of the principal characteristic races of animals and vegetables that belonged to it.

What may be the precise nature, cause, or seat of the igneous power, by which the crust of the earth has always been so powerfully affected, is a matter still involved in much obscurity. Its activity is witnessed daily in the volcano and the earthquake; and the geologist traces its past violence in the visible fracture, disturbance, and elevation of the sedimentary strata, as well as in the vast masses of crystalline rock which have burst their way upwards through these, in the state of lava or something analogous to it, on almost every part of its surface, and at every age of its history. Two theories contend for the explanation of this force, that of central heat,' which supposes the nucleus of the globe to have always been at an intense temperature, and probably fluid, the cooling of the surface having first formed the solid crust, and then in its inward progress broken up and convulsed it—and the chemical theory,' which supposes the nucleus to be composed of the metallic bases of the earths; the phenomena of heat, eruptions, and elevatory expansions being caused by the oxydation of these substances by water or air that penetrates to them through clefts in the superficial rocks.

Dr. Buckland, unwilling apparently to determine between these conflicting theories, assumes both to be true-an easy way of escaping a difficulty, and avoiding to commit himself to either alone -but not, perhaps, very philosophical, inasmuch as either is alleged by its advocates to be alone equal to the solution of the problem.

It is not for us to determine this litigated point: yet, as on former occasions, we have avowed a preference for the theory of central heat, we may repeat here that it has one great advantage at least over its rival, namely, that it explains all the phenomena from first to last, including even the generation of the atmosphere and ocean; whereas the chemical theory supposes the pre-existence of the earth, atmosphere, and ocean, in their separate states, and then brings them into contact to produce the results to be explained. Nor, in truth, could we ever well understand how it is imagined that the process of internal oxydation is kept up after the nucleus has been thoroughly coated with solid rock. A state of quiescence, it appears to us, must very shortly have been reached, in which all internal activity would cease; for the fissures, to which the advocates of this theory have recourse as the channels of communication between the external oxygen and subterranean metals, are thể results, and therefore cannot be admitted as the causes, of the development of subterranean energy which is to be accounted for.

Be this as it may, we have in this potent subterranean heat, whencesoever derived, the primary agent in the series of changes which the surface of the globe is continually undergoing. By this force new rocks have been from time to time thrust forth from the bowels of the earth, and beds of gravel, sand, clay, limestone, and other aqueous deposits heaved up from the bottom of the seas. These in their turn become subjected to the action of the other great power already spoken of, the abrasive force of moving waters. Violent commotions of a diluvial character no doubt must accompany many of the expansive throes of the igneous agent-and of these, indeed, we have recent examples in the agitation occasionally witnessed in the ocean during paroxysmal earthquakes. It is chiefly, however, by a series of minor and individually trifling, but ceaseless efforts, that the plastic agency of water operates to modify the surface of the globe. The fall of rain, the flow of brooks and rivers, the waves, currents, and tides of the sea, inconsiderable as their power would seem to be when contemplated in a single instance, and during the lapse of a short period, yet, from their almost universal and incessant influence, produce in the long run an amount of change fully equivalent to that effected by the more violent and striking, but less constant and general action of subterranean energy. Both combine, together with the minor but still very important action of the atmosphere, of changes of temperature, and of the chemical elements of the air, water, and rocks upon each other, to keep up that condition of the surface of our planet which fits it for the habitation of an almost infinite variety and multitude of sentient beings, whose enjoyment seems to have been the final cause of this portion of the divine creation.

And

And this leads us to the interesting consideration on which our author has both justly and forcibly touched, of the limited, but still demonstrable adaptation of the globe to man. With a view to human uses, the production of a soil fitted for agriculture, and the general dispersion of the minerals and metals used in the arts, were almost essential conditions of the earth's habitation by civilized man. Now this has been brought about solely by the disturbance and irregular arrangement of the earth's crust which we have already remarked upon as the common result of the igneous and aqueous forces to which it has been subjected. By their joint influence, those inestimably precious treasures, mineral salt, coal, and the metallic ores have been first formed, and subsequently brought to the surface and distributed on almost every point of it. Under any more simple and regular disposition of the solid matter of the globe, we should have been destitute of all these essential elements of industry and civilization. Under the existing disposition, all the various combinations of strata, with their valuable contents, whether produced by the agency of subterranean fire, or by mechanical or chemical deposition beneath the water, have been raised above the sea to form the mountains and the plains of the present earth; and have still further been laid open to our reach by the exposure of each stratum along the sides of valleys.

A striking example of this adaptation is afforded by the coal formation, in which the remains of plants of a former world have been preserved and converted into beds of this useful mineral, after being transported to the bottom of former seas and estuaries or lakes, and buried in beds of sand and mud, which have since been converted into sandstone and shale by pressure, desiccation, and the chemical action of their particles on each other operating during an immeasurable lapse of time.

'Besides the coal, many strata of the carboniferous order contain subordinate beds of a rich argillaceous iron ore, which the near position of the coal renders easy of reduction to a metallic state; and this reduction is further facilitated by the proximity of limestone, which is requisite as a flux to separate the metal from the ore, and usually abounds in the lower regions of the carboniferous strata.

A formation that is at once the vehicle of two such valuable mineral productions as coal and iron, assumes a place of the first importance among the sources of benefit to mankind; and this benefit is the direct result of physical changes which affected the earth at those remote periods of time, when the first forms of vegetable life appeared upon its surface.

The important uses of coal and iron in administering to the supply of our daily wants, give to every individual amongst us, in almost every moment of our lives, a personal concern, of which but few are

conscious,