lands, again to undergo the same process of waste from without, and of reconstruction from within.

Indeed, without this belief in the uniformity of nature's operations there could be no geological history. If nature were not uniform in her methods, this rock might have been formed by precipitation, that by sediment; this by water, and that by fire; this in a day, and that in a thousand years. The belief that similar results are produced by similar means lies at the foundation of geological science, and the moment departure from this belief is introduced, geology becomes a mass of uncertainties, and the phenomena of the rocky crust a series of isolated results, having no reliable cause, and unconnected by any continuity of method or design. The causes now productive of geological change must have been productive of similar changes in former ages. They may have acted at certain periods over wider or over narrower areas, and they may have acted with greater or less intensity according to the conditions by which they were accompanied, just as we see them operate in different areas in the current epoch, but we have no real evidence in the rocky crust that they ever acted by fits and turns, either with spasmodic violence or by general convulsion.

But while interpreting the earth's crust by this principle of uniformity, it must ever be remembered that we are living in a world of progress, and that ideas of uniformity and continuity must be held in connection with, if not in subordination to, this higher notion of universal progression. Geographically, the world is ever passing from one phase to another; vitally (so far as geology has interpreted), it has been peopled at each successive stage by higher and higher forms of existence. Though rain will ever act in the same way, the rainfall of any region may be less or greater now than it was in former ages; and though the earth

quake and volcano will ever be followed by similar results, the district that was formerly convulsed may be now quiescent. Physically and vitally, the same phenomena may never be, and indeed are never likely to be, enacted again in the same region, and thus it is that the doctrine of uniformity must be held in connection with that of progression and advancement. More than this: while to the mere geologist this world of ours "shows no traces of a beginning nor symptoms of an end," it may yet be established by the physicist and astronomer that there are causes beyond this earth, and to which this earth must be subject, which have ever been slowly affecting its individual condition as well as its planetary relationships; and that what we now consider uniform is only apparently so-nothing in nature repeating itself, but everything steadily though slowly passing on to other and other phases. But though these higher views were established to-morrow, and would necessarily affect our speculations as to the past and future of our planet, for all practical purposes in geology the doctrine of uniformity might still be retained, as giving consistency to our reasonings and leading to intelligible results.

Astronomical speculations, for example, relating to the gradual cooling of our globe from a state of igneous fusion -to its consequent contraction and greater rapidity of rotation to the secular diminution of the sun's heat, and its ultimate effect on the relations of the whole solar system— these and kindred speculations, which, under the advancement of physical science, are beginning to assume something like the consistency of theory, do not materially affect this idea of "uniformity with progression" as held by geologists. Indeed, the physicist may prove, contrary to the dictum of Hutton, that we can perceive "traces of a beginning and symptoms of an end" to this world of ours; but in doing so the means he calls into play are so slow and gradual

that no perceptible deviation in their mode of action can be perceived since the deposition of the oldest rock-systems, or the period to which the labours of the geologist are legitimately restricted. Within this range-and the time is inconceivably vast-the doctrine of "uniformity with progression" is the only one that gives consistency and stability to geological research, a safer guide to observation, and a surer key to the interpretation of the phenomena observed. Since its adoption, geology has taken, perhaps, the highest place among the natural sciences; before its reception, geology, as reliable world-history, can scarcely be said to have existed.

PRESENT ASPECTS OF GEOLOGICAL INQUIRY.

To the cultivator of any department of science it is of special importance that he should now and then take a review of its progress, noting the strength and weakness of its several points, and, in particular, of such innovations as have a tendency to affect the general conclusions already arrived at. This "stock-taking," if we may so speak, which is necessary to all knowledge, is more especially needful in geology-a science whose progress during the current century has been more rapid than that of any other branch of natural history, and whose conclusions are not unfrequently received as fanciful and uncertain. On the present occasion we attempt such a review, noting some of the leading moot points, and the grounds upon which they may be opposed or defended.

And here at the outset, and notwithstanding these differences, it may be safely remarked that the study of geology was never in a more equable and well-balanced condition. No one branch seems to be in the ascendant, or cultivated exclusively to the detriment of others. Mineralogy and the discrimination of rock-species are not now, as at the beginning of the century, regarded as constituting the science of geology; nor is it the fashion to allow pala

ontology to absorb the whole of our interest and attention. Mineralogy and chemical geology, palæontology and physical geology, have each their students and cultivators; and though occasionally some novelty like the 'Origin of Species,' the Antiquity of Man,' or the 'Potency of IceAction,' may temporarily arrest the attention, yet, on the whole, the students of our many-sided science seem convinced that its general progress can be best promoted by every one labouring in that department to which he has been led by his natural predilections, and for the cultivation of which he has the greatest facilities. It is thus that the chemistry of our science is promoted by such researches as those of Bischoff, Delesse, Deville, Hunt, and Forbes ; its physics by those of De Beaumont, Hopkins, Thomson, Mallet, and Sorby; its palæontology by Agassiz, Owen, Hall, Huxley, Pictet, De Köninck, Milne Edwards, Heer, Davidson, and others too numerous for detail; its stratigraphical successions by Murchison, Logan, Ramsay, Jukes, Rogers, Barrande, Hochstetter, Oldham, Hector, Selwyn, and others intrusted with government and colonial surveys; its systemal connections and higher generalisations advanced by such writings as those of Lyell, Phillips, Darwin, Dana, and Sedgwick; while in every county and provincial district a host of local observers are each contributing his mite of observation and discovery to the general fund of geological progress. No other branch of natural science, indeed, has of recent years made such rapid and substantial progress as geology; and though many problems yet remain to be solved and old errors to be exploded, still, on the whole, we may well congratulate ourselves on the nearer and hopeful attainment of something like an intelligible world-history. The increase of local observers, the augmented facilities for travel, the institution of government surveys by the different nations of Europe, the