all the facts of the science, and all the inferences deducible from them, and what is more, we may be qualified to institute active original research, and to enroll our names on the list of those who have added, by their discoveries, to the sum of human knowledge, for geology is a science of observation. It is, moreover, a young and advancing science, many of whose data remain to be collected, and in the collection of them there are few who cannot assist. When we know about a dozen of the most common, simple minerals,—when we can recognise their combinations in rocks, when we know the technical terms of the science, and can distinguish crystalline from sedimentary, stratified from unstratified rocks,— and when we know the order in which the strata composing the earth's crust succeed each other, we are qualified to examine nature for ourselves, and to study geology, where it is best studied, in the field. We require not the expensive observatory or laboratory of the astronomer or the chemist, -all we want is a good hammer, and a strong arm to use it, active legs, a quick eye, and sufficient common sense to enable us to reason upon what we see. For the rest we may trust to the assistance of our fellowlabourers, and to that community of feeling by which they are ever animated; for geology is eminently a social science, and the great and rapid advances which it has made within the last few years, are in a great measure to be attributed to that division of labour, and that mutual co-operation which can only be effected by numbers acting in concert. "These volumes," says Mr. Murchison, speaking of the Transactions of the Geological Society of London, "must ever be valuable as the true records of our scientific progress; but great as may have been the acquirements of their authors, few indeed are the memoirs which have been completed without the aid of other distinguished fellows of the society, who, each in the branch of natural knowledge for which he stands preeminent, comes to the assistance of his wandering associate, and enables him to clothe his memoir in an appropriate dress. For where is the working geologist who, unassisted, can unravel the delicate and obscure complications of fossil organic structure? Do his fossil shells require to be identified, has he not the assistance of a Sowerby? and if these types of a former state of nature call for a comparison with existing species, is not a Broderip ever prompt in affording him the result of experienced discernment, and in unfolding the riches of his unrivalled cabinets? If he meet with difficulties in the determination of Mammalia, are not a Mantell and a Clifft at hand, to explain their relations and define their characters? Or if bewildered in the obscurity of fossil vegetation, is he not assisted by a Lindley? Have not, in fine, a Turner, a Prout, a Faraday, and a Herschel been willing instruments in enabling him to explain those laws of chemical change, without which the recondite parts of the science might have remained in utter darkness? Surely every contributor to our Transactions will acknowledge with gratitude the aid he may have received from several of our most gifted members, who, unambitious of personal fame, have been contented with the delightful consciousness of being sure, though silent, instruments in urging on the advance of truth. It is this kindly principle of co-operation, this true latent heat of the Geological Society, so ready to manifest itself on every occasion fitted to call it forth, which, warming and vivifying our endea

vours, gives to our proceedings their consistency and their strength, and enabling us to grapple with our hundred-headed science, constitutes the mainspring of our prosperity*.

If geology yields to astronony in the sublimity of the objects of which it treats, and in being unable to bring its truths within the pale of mathematical demonstration, it possesses this advantage, as a science for popular study,—that it presents them to us in a more palpable shape. One of the first, and hardest lessons which we have to learn of the astronomer, is to discard impressions founded on what we deem the evidence of our senses. Misled by these, we have been accustomed to consider the earth as at rest, and the sun as making a daily circuit round it. The astronomer demonstrates the contrary, and corrects our notions as to the relative size of the celestial bodies. He determines the figure of the earth, and the form of the orbit in which it moves, and ascertains the velocity of its daily and annual motion. He determines the magnitude of the sun, and its distance from us, and shows us other planets revolving round it, with their attendant satellites, and obeying the same laws which regulate the motions of that which we inhabit. He pushes his discoveries to the utmost verge of the visible creation; and, by the aid of powerful optical instruments, resolves those twinkling points, which we call the fixed stars, into groups of suns moving round each other in "mystic dance;" and he demonstrates that those laws of gravitation, which regulate the fall of bodies on the earth, are universal laws, which are obeyed in the remotest system of worlds within the reach of mortal ken. He can calculate, not only the motions of the bodies composing the planetary system, and point out their relative positions for any period of past or future time, but he can predict, within a few hours, the return of those mysterious wanderers, whose course extends into the regions of space, far beyond the remotest planet of our system, and whose periodic times are measured, not by days, but by years. It may be well said that in all this there is an overwhelming sublimity. The distances treated of are so immense, and the time required to complete some of the celestial cycles so vast, that they elude the grasp of our comprehension;—we may talk about billions and trillions of miles, and myriads of years, but we have scarcely a less vague conception of them, than we have of infinity of space, and eternity of time. Geology, on the contrary, appeals directly to our senses. She lays open the ground on which we tread, and convinces us, that the vast secular periods of the astronomer, which, with him, are mere abstract arithmetical truths, which he cannot prove to have had an actual existence, may all have been required for the production of those changes on the surface of our globe of which we witness the monuments. She proves that our present continents, with the most elevated of their mountains, were formed at the bottom of the ocean; and that our hardest rocks were once sand, and gravel, and mud derived from the wearing down of land no longer in existence. She points to a bed of rock, a few feet in thickness, teeming with the remains of organic life; and, from the successive generations of individuals which it contains, and from other indications, into which we will not at present enter, proves that a very long period must have been * Murchison's Anniversary Address-Proceedings of the Geological Society.

required for its formation. She then conducts us through a vast series of similar sub-marine deposits five or six miles in depth (how exposed to our view will be explained hereafter) abounding with the remains of plants and animals, and containing, not only the relics of successive generations of individuals, but of successively created races, each group of strata having its peculiar group of organic remains. She unfolds, page after page of this great book, this wondrous record of the changes our earth has undergone, and of the tribes of beings by which it has been peopled during a series of periods, of long but unknown duration, before it was inhabited by man. She first leads us to those formations now in progress in which he and his works are imbedded, together with the remains of this contemporary species of plants and animals. This page of the world's history is soon read.

Man is found to be but a creature of yesterday, compared with the globe he inhabits, and with the other beings with which it has been peopled. The very species of plants and animals now existing are found to have been called into being before him, for their remains occur in older, that is in deeper strata. The remains of existing species are found to be gradually intermixed with those of species that have vanished from the face of the earth. The proportion of extinct species increases as we descend. We come to lower beds still, in which not only extinct species occur, but extinct genera. The forms of organic life recede more and more from existing types, and they diminish in number in the lower rocks, till, at last, we lose all traces of them entirely. During our progress through this vast series of rocks, evidently of submarine formation, we meet with others bursting through them, which are as clearly of igneous origin, and derived from below. The lowest rocks we meet with are of this igneous character, and contain no organic remains. It may be that we have reached the records of a period when the world was unfit for the support of animal and vegetable life. It may be that the earlier pages of its history have been torn out, and that the rocks in question once contained the remains of still older races, but that all traces of them have been obliterated, by the fusion to which the rocks have been exposed. At all events, we have reached the dark ages of the earth's history, and we close the book. With speculations on the creation of the world,- —on the mode in which it was reduced from a chaotic state, -and of the causes which gave it its present figure, we have nothing to do. They were favourite themes with the geologists of former days, whose wild reveries threw a discredit on the science, from which it was long in recovering, even after its votaries began to walk in a more sober path. The cosmogonists, as they are called, applied themselves to the invention of modes in which worlds might be created, with an industry, which, if applied to the observation of phænomena in the world around them, might have led to important knowledge. But that was too humble a task for them. They preferred the field of imagination, and all their labours in that field tended but to bring chaos back again. In contemplating their worlds, it would seem as if "nature's journeymen had made them," and had "not made them well." And yet they arrogated to themselves a command over all the powers of nature, and they were not sparing in their use of them. They made the globe solid or hollow,

they filled it with water or matter in a state of fusion, as it suited their purpose, they changed its axis of rotation at pleasure, and when they were in difficulties they called in the aid of a comet, sometimes to produce a deluge, sometimes a conflagration.

But the day for this mode of philosophising passed away, and geology, for the last half century, has been a science of observation and induction, not of invention. Geologists now wisely limit themselves to an investigation of the crust of the earth; and vast as a series of deposits five or six miles in thickness may appear to us, the proportion it bears to the diameter of the earth is only as 1 to 1600. The paper covering a globe sixteen inches in diameter, is nearly thick enough to represent it. The series of rocks containing organic remains is found to rest upon rocks which are destitute of them, and which bear evident marks of having been in a state of fusion. The lowest rocks we meet with are of this igneous character. We know that lower still subterranean fires are in full activity, giving rise to volcanoes and earthquakes, and, from the great areas over which the shocks of the latter are simultaneously felt, it is probable that the source of internal fire is deeply seated. The mean density of the earth has been ascertained to be twice as great as that of the rocks at the surface; and supposing the interior to be composed of materials equally compressible with those of which the crust consists, the pressure to which the central parts are subject would cause the mean density to be much higher than it is found to be. A large portion of the interior must, therefore, be occupied by cavities,—or must consist of less compressible materials than the rocks of the surface, or there must be some expansive force within, capable of counteracting the effect of pressure. Central fire may be this counteracting force. This is all we know of the interior of the earth, and perhaps all we ever shall know.

Astronomers have declared, that they can discover, in the planetary system, no evidence of a period when it differed materially from its present state. They do not deny that it had a beginning, but they tell us that they can discover no traces of that beginning, neither can they see any prospect of an end. He who made it can doubtless destroy it, but its destruction will arise from causes unknown to us. It contains not within itself, as far as our observations extend, the seeds of its own dissolution; for it has been demonstrated that all the perturbations which can be produced in the orbits of the planets by their mutual attractions are periodical, and range within certain limits, slowly increasing during a long lapse of ages; then, as slowly diminishing, and never deviating widely from a mean state. The machine, therefore, having been created and set in motion, and having been so constructed as to be capable of continuing its action through all eternity, may have been left to itself, without the further active interference of its Divine Author. The researches of geology lead to different conclusions. We find that our planet has been subject to great and repeated changes; that there have been changes in the condition of the earth, accompanied by corresponding changes in organic bodies, adapting them to those altered conditions. It is true, that in his investigation of the crust of the globe, the geologist is as little able as the astronomer to perceive evidence of the beginning of things. It is even doubtful whether he is able to carry

back his researches to the commencement of organic life; though the paucity of remains in the earlier fossiliferous strata appears to favour the conclusion, that the still older stratified rocks, which contain no organic remains, were deposited when the ocean was destitute of living beings. It is, however, certain that we repeatedly see the commencement of new races, and are obliged, again and again, to have recourse to a supreme Intelligence and a creative Power. If we examine the marine remains of the strata, we find that whole genera of shells, which in the present seas are most abundant in species, were not in existence till after the chalk was deposited. Other genera again originated about the middle of the series, and soon became extinct, being represented by no species in the tertiary strata, that is, the strata above the chalk. These new creations supplied the place of other races which perished; for some genera are peculiar to the lower groups of rocks, not a single species of them occurring higher in the series than the coal measures. There are a few, and but a few, genera which, commencing in the lowest fossiliferous strata, have endured through all the changes to which the earth has been subject, and have species existing in the present seas. The changes which occurred in the organization of fishes appear to have been greater and more rapid, and exhibit a wider difference between those found above and below the chalk than is observable in the case of molluscs. For fuller particulars on this head we refer our readers to the paper “On recent Researches in Geology,” in our second number.

The same proofs of organic changes are afforded by the study of fossil botany. The formations containing vegetable remains may be arranged, according to Professor Henslow, in four groups, representing epochs, during any one of which no very marked difference is observable in the general character of the vegetation; but between any two of these groups the change is striking and decided, most of the genera being different, and none of the species alike. The character of the fossil vegetation of the earlier epochs is also such as to warrant the conclusion, that the plants of that epoch grew under a climate both hotter and moister than that of any part of the earth at present; and, since even in Arctic regions, the fossil plants are analogous to those now growing under the tropics, it seems probable that light as well as heat were formerly more equably diffused."

We can scarcely be said, at present, to have sufficient data for determining what were the animals inhabiting the land while the earlier strata was being deposited at the bottom of the sea. It was at one time supposed that a gradual developement of organic life might be traced through the series of formations from inferior to higher tribes, from beings the most simple to those of the most complex structure. It was thought, for instance, that the lower strata contained only the remains of animals without a vertebral column, such as molluscs and crustaceans. Of the former, the oyster and the whelk may be adduced as familiar examples; of the latter, the lobster and the shrimp. It was supposed that marine vertebrated animals did not exist till after the coal-formation was deposited; nor oviparous reptiles, such as lizards, and turtles till a somewhat later epoch; and that warm-blooded animals and birds were not created till after the chalk was deposited. But these views have