waters) must the eruption of the lavas numbered 7 and 8 be supposed to have taken place; and that this third eruption occurred since the ejection of the second and intermediate lava seems evident from the specimen No. 4, which has one side blackened and vitrified, and converted into sponge-form lava; some fire at least, therefore, must certainly have acted upon it subsequent to its eruption. But this supposition seems confirmed and placed beyond a doubt by the great cellularity of these lavas, which as it is the natural result of the free and unrestrained extrication of the various gases during the fluidity of the rocks, proves their ejection to have happened under no greater pressure than that of the atmosphere; and, therefore, the third class of lavas might be termed, in contradistinction to the two kinds before referred to, aerial lava.

The ejection, however, of this last highly cellular and scoriaceous lava is no less general; it was confined to particular parts of St. Helena, in some places destroying the former character of the island, after the Neptunian deposit; and in others leaving it untouched and unaltered. Hence the formation of the "Great Plains," and hence would arise that "striking dissimilarity between the exterior and interior parts, from which principally "others contend that it is the remnant of a large island, the greater part of which has been sunk under water, by the force of earthquakes or volcanoes."* › With such views, then, of the subject, there does not seem to be such cogent reason for arriving at the conclusion, that,"upon the whole there appears to be strong grounds for supposing that the finest parts of the interior are the remnants of primitive land." †

is But I would also remark, that the face of this island has been made to present still more "striking dissimilarities" in its different parts, owing to the convulsions which have taken place even since the last lava burst forth.

St. James's Valley itself has been the result of one of these convulsions. The lava appears to have flowed" from a crater

See Beatson's Introductory chapter.

+ Beatson, p. 9.

somewhere about the site of the Water-fall,"* in a northwesterly direction, forming a high hill as far as the sea-shore. At some subsequent period a tremendous explosion has rent the hill from the top to its base, forming Ladder Hill, which lies west of the town, and Rupert's Hill, which lies to the east. This is most plainly and satisfactorily evidenced by the relative situations of the hills, and the exact correspondence and inclination of the strata.

I was happy to find, on perusing Governor Beatson's "Tracts," that his opinion, founded on a more extensive and careful survey of this spot, perfectly coincided with my own.

This, perhaps, is not the only instance of these (geologically speaking) modern earthquakes.

Mr. A. Blaxam of H. M. S. Blonde, in describing another part of this island, writes thus: † "The ridge termed Diana's Peak forms one edge of the crater: it is entirely composed of lava, the greater part of which is in a high state of decomposition. The ridge as it approaches the sea inclines towards it; so that we may suppose the remaining ridge, which is wanting to form the edge of a complete crater, lies buried in the sea."

If this crater (as from this account seems the probable conclusion) was formed by the eruption of lava, the burying of one side in the sea must have occurred subsequent to the

event.

Another source of scepticism, respecting the entire formation of this island by volcanic means, appears to arise from the consideration of the unbroken ridge of hills which runs east and west.

66

"In no part of this ridge," remarks Governor Beatson, (which is elevated 2,000 feet above the level of the sea,) is there a single chasm or opening. It seems therefore wholly unaccountable that it should have escaped being broken or shattered, if earthquakes or subterranean fires had occasioned the overturnings."

So far, however, from considering this unbroken elevation as militating against the theory before advanced, I think it may be See Philosophical Magazine, No, 342.

* Beatson, p. 2.

adduced as a corroborative proof in its favour. I will endeavour to explain.

The singular manner in which all the vallies converge from the circumference of the island to the Peak of Diana, as to a common centre, seems to point out this spot as the part upon which the disruptive force of the elastic fluids from below at first chiefly and more directly acted.

The insulated hill before referred to is, indeed, on a small scale, a good exemplification of this kind of formation; for the direction of the strata, dipping "on either side to the contiguous vallies,"† could only have been given by the expansive force of elastic vapours acting upon, and heaving up, a portion of the earth. The peculiarity of the vallies of this island, it may be also remarked, seems somewhat analogous to the effects which Von Buch describes as always resulting from elevations of land, unaccompanied by any ejection of lava, ‡

But while the centre of Saint Helena was chiefly acted upon, the grand course of the subterranean fires seems clearly to have been east and west, because the submarine base of this island (upon which by-and-bye I shall make some observations) extends at least twenty-five miles in this same direction. The soundings also which were made under the orders of Captains Cowan and Beville shew us, that the ground westward consists of "hollow ridges, apparently resembling the surface of the island." The natural consequence of such an extended line of subterranean agency lifting up the earth would be to form a lengthened elevation, which, if in any degree gradually and equally raised, would present one unbroken ridge," without chasm or opening."

The extended base of the island seems to have become, with some, another argument against its volcanic origin.

Saint Helena" is not a rock rising abruptly" out of the water, but extends under the sea, "at least twenty-five miles from east to west." §

* See Beatson's Geological Plan and Elevation of St. Helena.

+ Vide supra.

Although the last lava appears to have flowed from many parts, it was not thrown out en masse from its centre.

§ Beatson, p. 12.

But while this circumstance proves to us, that the volcanic action below was much more general than the bare inspection of the emerged part of St. Helena would, perhaps, have allowed us to have calculated; it most forcibly reminds us of the great similarity which exists between this portion of the world and others where volcanic eruptions have taken place—I mean the very extended action of subterranean fires. Etna, with its Lipari, Vulcano, and Stromboli; Hecla with its submarine eruptions at eight miles distance, and at even seventy; and the isles of France and of Bourbon, immediately present themselves as good illustrations of this fact.

That any one should be influenced in his decision respecting the volcanic origin of St. Helena by the supposed former existence of the "Atlantis" is somewhat singular. Geological arguments, and not literary, are alone to be made use of in the question now under consideration; and literary shall I indeed esteem them until the real existence and true geographical situation of this great island of Plato be clearly demonstrated and indisputably pointed out,-whether it may be in Sweden and Norway, according to Rudbeck; in the frozen ocean, according to M. Bailli, or in the Utopian land of fable, according to the more reasonable opinion of Sir William Jones.

But it is fit that these few, and perhaps too general, remarks should be brought to a close, and I would do so without asserting dogmatically the necessary tendency of the evidence resulting from them; for whether this hypothesis, respecting the formation of St. Helena, carries with it any plausibility, or the observations which a perusal of the ideas of others have elicited possess any value, I leave entirely to the reader's decision. I offer them diffidently, desirous rather of leading others to make this singular island an object of philosophic investigation, than anxious to make converts to any peculiar views I may be thought to have entertained upon the subject.

Refutation of the Charges contained in Mr. Ivory's "Remarks," &c. in the Philosophical Magazine and Annals for February lust.

FROM looking into Mr. Ivory's remarks, I find they have assumed that form which all his controversial discussions do when he has the wrong side of the question; which, in the present instance, he has in a superlative degree-for the doctrines which he compels himself to maintain are of the most untenable and contradictory description: but no matter for that, he must still keep up the farce and repeat the old chorus. In such circumstances, as is well known, Mr. Ivory labours hard, by a variety of ways, to obscure the subject, to divert the reader's attention from the real merits of the question, and to excite the indignation of the public against his opponent, by alleging no matter on how ridiculous, frivolous, or unfounded grounds that some advantage has been taken of himself—that some fraud has been committed; such as, in my case, "giving to Mr. Ivory's formula any shape I please,"-using the black art of" legerdemain,"-" playing tricks with the algebraic expressions," &c.

Charges like these, when true, call for exemplary visitation, especially playing off legerdemain with such a grave gentleman as Mr. Ivory; but as I am not aware of having practised any thing of the sort, and as no intelligible evidence is offered of my having played any tricks, I neither see cause for apology, nor need for reform. On the contrary, it is easy to show the futility of all these accusations, and that they may, with far greater justice, be charged upon their author. Indeed, in this case there is no need for playing tricks, or resorting to any unfair means whatever; for let Mr. Ivory take up any position he pleases, provided he retain, as he still obstinately does, his favourite but incompatible assumptions, and it is easy to prove the extravagant inconsistency of his doctrines, whether among themselves or with the best known facts.