independent of all disputed theoretical questions; and are now admitted by rational geologists of all schools.

The evidence of facts is undeniable as to all the main features of the process by which the surface of our planet was gradually brought into its present condition. The business of inductive geology is to compare the monuments of early changes in the earth's surface with those now in the course of progress: and that this is a sound principle to proceed upon is assured to us by the circumstance, that in the succession of these changes we meet with no interruption: we witness such effects locally and gradually going on at the present day: we trace by diligent observation the evidences of their having gone on in the same manner (whether or not upon a larger scale) in ages earlier than the records of history: in the deposits characterized by the remains of organized beings of the same species as those now inhabiting the earth: in the earlier beds, where existing species are mixed with extinct: until we arrive in succession at those containing none of the former and all of the latter class. The continuance of the same set of appearances is unbroken from the present time, through those comparatively recent deposits, up to those of older formation. And though the authority of Cuvier was once appealed to as having inferred from the alternations in the tertiary formations of the Paris basin, that here there were interruptions of order, from causes not apparent,

and that "the thread of induction was broken," yet the later researches of Lyell and others have explained those apparent breaches of continuity in the series, and the investigation of those tertiary beds, in all their varieties of organic characteristics, has now become the principal source of evidence by which geologists have fully established the unbroken series, the uninterrupted continuity of these formations, in relation with the existing organized products of the neighbouring seas, and the operations of now existing laws. And whatever may have been the magnitude of some of the operations in remote epochs, yet we find no deviation from the continuance of action of the same kind; no real suspension of regular laws, no simultaneous universal destruction and reconstruction of the globe; but through the whole range of those periods of which we can decipher the monuments, we have continued evidence of the same system of gradual changes by which the existing state of things was, by slow degrees, evolved out of previous orders of existence.

Such must be the general view of the matter (whatever difference may subsist on minor points,) which will be upheld by the inductive geologist in contradistinction to the dogmatical assertions of the cosmogonist. The chimerical, yet favourite notion, of a sudden total change, of a catastrophe by which one world was suddenly reduced to chaos, and another as suddenly called forth out of its ruins, during any

of the periods the records of which we read in their

existing organic remains, is not only wholly inadmissible, inasmuch as it must be derived altogether from considerations alien to those of physical analogy, but is absolutely contradicted by all inductive testimony.

We find no period since the very commencement of all those depositions which contain organic remains, at which some portion of the earth's surface was not abundantly peopled with an animal and vegetable creation, more or less different indeed from that now existing, but in all respects preserving an exact uniformity of plan and design, and precisely and admirably fitted for the kind of existence which accorded with the then condition of the globe; but destined gradually to disappear as those conditions were changed, and as other and varied forms of existence were in succession introduced. The total absence of all marks of any universal sudden overwhelming convulsion, supplies positive proof that nothing of the kind took place within any of those periods, the monuments of whose duration we find in the accumulated remains of successive formations; especially during any of the later epochs, and least of all subsequently to the latest tertiary deposits, that is, within those times which can alone possibly accord with the received chronology of the human species, and with the era of those changes which brought the globe into a state suited to the residence of man.

The adoption, then, of any such theory on which

to raise geological speculations must, on every ground, be utterly at variance with sound inductive principles.

Inductive Character of Geology.

In the illustrations above given, I have enlarged on those selected from geology in particular, with reference to objections often brought against that branch, as if it were of a less strictly inductive character than others. This, I conceive, is an idea which must totally vanish before the slightest real examination of the nature of the reasoning employed by any sound geologists; though it may be freely admitted that most extravagant speculations have occasionally been obtruded on the world under the name of geological theories. Yet these, the moment they are critically examined, are found to be defective, not merely in their details, but in the assumption of their first principles, and the very method by which the investigations are conducted. Among sound and rational geologists, whatever difference may exist as to certain theoretical views, none whatever can subsist as to the sole recognition of strict inductive reasoning, and the utter rejection of all other authority, on which to rest their conclusions.

Some persons have indeed been urgent in denying to geology the claim to be ranked among the exact sciences, and have appealed to the authority of great names in support of their assertion, having all

the while a very confused idea of the meaning of an "exact" science; and imagining that when it has been refused this title, it was meant to withhold from it the character of substantial physical truth and inductive certainty. Whereas it is evident to those who are but moderately conversant with the current scientific language of the day, that the phrase "exact science" has been used solely as designating those branches of physical inquiry which could be brought under the dominion of mathematical laws, and whose results could be exhibited in a numerical form, and compared with theory by arithmetical computation. In this sense undoubtedly geology has not yet become one of the "exact" sciences; though from the nature of some recent researches on the effects of mechanical forces such as may be supposed to have acted in the elevations of the various parts of the earth's crust, it would seem to be fast approaching to the condition even of this class of investigations. But, at any rate, this is quite independent of its claim to be received as among the most incontrovertible of those systems of inductive truth which have not as yet been of a nature to receive the aid of mathematical demonstration.

*

* See the papers of Mr. Hopkins in the Cambridge Transac tions.