counted for, and for which the only sufficient cause that has ever been proposed, is an universal and transient deluge.

Again, at page 328, Dr Fleming contends, that these bones found thus universally in fissures, and caverns connected with them, cannot have been drifted into their present position by the waters of a general flood, and there surrounded by them with mud; because, in the solitary instance of the large cavern of Wokely Hole, there is a river now running through it, and depositing mud and sand upon human bones or urns, or any thing else that may now, or at any modern period of time, have been deposited within the level of its winter floods. Surely it is at least incumbent on him to show that there is, or may have been, a river running through every cave, and every fissure in the world, in which bones and bony breccias are found imbedded in mud, before he can establish a conclusion like this. His present argument is stated thus: "A subterranean river runs through the cave at Wokey, which may have deposited mud during its highest floods. But why may not the mud in the Kirkdale cave have been deposited by a similar agent?" The answer is, because there is no river there to deposit it; and, because it is impossible that now, or at any past period of time, any river should flow, or ever have flowed there. The cave at Wokey is a connected series of large and lofty vaults, with two apertures near its floor, by which a subterranean river at this moment runs in and out continually; whilst that at Kirkdale is a small hole (seldom larger than a large gutter-hole), not five feet square at its mouth, and branching internally into smaller ramifications, which finally terminate in a close end, or cul de sac; so that by no possibility could any river now, or at any past time, have found a passage through it.

I fully agree with the observation quoted from Mr Young, that the cave at Kirkdale is not a fissure in the rock, and that it has a number of rounded hollows or depressions in the sides and roofs, (and possibly on the floor, though I have never seen them there), resembling such water-worn hollows as we see in rocks, in the beds of rivers, or on the shores of the ocean; but I must add, that the appearance of such hollows is a feature common to the cave of Kirkdale, with every other cave in limestone rocks that I have ever examined; and in every case there is decided evidence that the hollows have not been produced by friction from moving water, in the fact, that, though not unlike in shape, they are never smooth and polished like the holes worn in the beds of rivers, and on

the sea-shores, but are constantly rough and studded over internally, like a corroded preparation, with thousands of small and delicate points, projecting in high relief over these surfaces, and which would inevitably have been destroyed, had friction or any kind of violence been employed in producing the cavities in question.

In reply to the note at page 327, in which the authority of Professor Goldfuss is quoted by the editor to support an opinion, that the elk and hyæna are the animals intended by the terms schelch and halb-wolf in the romance of the Niebelungen, written in the thirteenth century, and enumerated among the beasts slain in a hunt a few hundred years before. that time, in Germany; I have only to observe, that the authority of the same romance would equally establish the actual existence of giants, dwarfs, and pigmies, of magic tarn caps, the using of which would make the wearer become invisible; and of fire-dragons, whose blood rendered the skin of him who bathed in it of a horny consistence, which no sword or other weapon could penetrate.*

Dr Fleming will, I am sure, excuse me, if I suggest to him, that the tone of levity in which he speaks of the facts established by the evidence of the den at Kirkdale, as a parallel case to the fables of travellers who have pretended to discover the decayed timbers of the Ark, is not the most appropriate to a discussion of the nature now before us.

Appendix.-Since this article was sent to the editor, Dr Fleming has published a second paper, in No. XXIII. of the Edin. Jour. in which he proposes to explain the universal dispersion of diluvial deposits by the bursting, at different periods, of an almost universal series of lakes. Had such lakes ever existed, it may fairly be asked, Where are the traces of their ancient locality? It is evident from the terraces, or parallel roads, in the valleys of Glen Roy, Glen Gloy, and Glen Spean, and some three or four more, which are all that have hitherto been noticed on the surface of the whole earth, that wherever such lakes have burst their ancient barriers, they have left behind them, in these terraces, evidence that shows the amount of their former extent and successive depressions. Even river-floods, of any magnitude, produce a similar effect, and form terraces in the adjacent gravel-beds that mark the line of their highest inundations, as I have stat

*Vide Weber's Northern Romances, p. 172.

ed, in a note at page 217, first edition, of my Reliquiæ Dilu-, viana. Is it not, then, utterly impossible that such an universal system of lakes as Dr Fleming's hypothesis assumes, could ever have existed, without leaving on their banks similar terraces to those of Glen Roy, Glen Gloy, and Glen Spean? Not one example, however, of such a terrace occurs in England, a country that is half covered with diluvial gravel. Neither, I believe, are there any other lacustrine terraces in Scotland, but those just mentioned, although river terraces are very common. Until, therefore, such lacustrine terraces are found to be of nearly universal occurrence on the sides of upland valleys, we remain without a particle of evidence that such lakes have either existed or become extinct, and must consider the assumption of Dr Fleming respecting them to be altogether gratuitous.

In this same second memoir, p. 294 and 295, I find Dr Fleming advances facts, in direct contradiction to the demonstration in his former paper, that a universal flood had no share in the formation of our diluvium, which, in part at least, he founded, on the asserted "absence of marine exuvia," in diluvial deposits, viz. those I have stated, that marine shells of existing species occur in the diluvium of the neighbourhood of Peterhead, and in the Paisley Canal, near Glasgow. He also quotes other cases of the same kind, e. g. that of recent marine shells, discovered by Mr Adamson on the banks of Loch Lomond, &c. ; but he makes no allusion to his denial, in his former paper, of the existence of such deposits, and I presume could not have been aware of facts which so materially affect his argument, at the time of his writing the paper in question. At any rate, it would have been more candid to acknowledge his error, than to leave to me the task of pointing it out, and applying it to my advantage in the matter at issue between us..

I forbear at present to offer any further remarks on Dr Fleming's second memoir, as I should be drawn to greater length than the patience of your readers would tolerate, or the limits of a Journal, destined to be the vehicle of original communications, rather than of controversial discussions, could with propriety admit.

Postscript. I have just been informed by Mr Weaver, that he has established, beyond all doubt, the fact of the elk having existed as a postdiluvial animal in Ireland. Its bones and horns, he says, occur in the Bog of Kilmegan near Dundrum, in the county of Down; they lie at the bottom of the peat

between it and a bed of shell-marl, resting upon, or being merely impressed in the marl, which is composed of a bed of fresh-water shells, from one to five feet thick, and must have been formed while the bog was a shallow lake. In this and other similar lakes and swamps, Mr Weaver imagines. these animals fled for refuge from their enemies, and were drowned in the waters, or swallowed up in the morass.

ART. LVIII.-Menstruum for Biting-in on Steel Plates. By MR EDMUND Turrell. From the Transactions of the Society for the Encouragement of Arts, Manufactures, and Commerce.*

THE demand that has taken place for engravings upon decarbonized steel plates, on account of their great durability when compared with copper-plates, has caused many eminent artists to employ their talents upon that peculiar preparation of metal; and many beautiful specimens of line engravings have been produced, capable of yielding proofs or prints to an extent unknown before the invention and application of that peculiar preparation of steel, which was first, I believe, made known to the world by Mr Perkins, who has made use of it very extensively in his bank-note manufactory in the United States of America, and more recently in London.

If the execution of a fine engraving upon such prepared or decarbonized steel had depended entirely upon the graving tool, the principal difficulty that presents itself would be the superior hardness of the metal, which of course would offer greater resistance to the action of the graver than copper; but as most or all the engravings of the present time are a mixture of etching and graving united, it was of course equally necessary for the artist to be able to etch and bite in upon decarbonized steel, as well as to cut with the graving tool.

In order to form a just idea of the difficulties that occur in etching and biting-in upon steel-plates, it will be necessary to state a few facts relative to etching upon copper.

The usual method is to cover the copper-plate with a coat of varnish, commonly called etching ground; and when the lines that are necessary to represent the subject are cut

The large gold Medal was presented to Mr Turrell for this communi

cation.

through the varnish with a point or needle, a border or rim of soft wax is raised round the sides of the plate, and nitrous acid, sufficiently diluted with water, is poured upon the whole surface, and immediately a corrosion of the copper takes place in those parts or lines where the varnish has been removed or cut through. The action of the acid is at the same time rendered obvious to sight by the continual formation and disengagement of bubbles of nitrous gas, on all the etched parts, thus indicating to the artist how the process is going on.

Various acids have been tried for this purpose, both singly and compounded in various proportions; but experience has proved that very pure nitrous acid is superior to any compound that has hitherto been produced, and I believe it is also superior to any other acid that can be used singly; for there is one requisite that is absolutely necessary and indispensable, namely, that whatever acid is used, it should not only have a powerful affinity for the copper, and by its chemical action corrode and deepen the etched lines, but it should also be capable of holding the oxyd formed in perfect chemical solution, otherwise the lines would soon be choked up by a deposition of the oxyd so formed; as the deposition increased, the oxyd would press upon the edges of the etching var nish and loosen it, by which means a partial corrosion would take place under it, and shallow lines would be the consequence. The lines produced under such circumstances are also generally rough and uneven on their edges. The process just described is technically called biting-in, and such a production would be called a bad biting. On the contrary, when the oxyd of copper formed during the process is immediately dissolved in the fluid that forms it, a fresh surface at the bottom of the line is continually offered to the acid to act upon, and then the corrosion produces the very best effect, that is to say, very deep lines, with beautiful, clear, and even edges.

When etching upon steel was first introduced, great difficulty was experienced in biting-in the etched plates, for whatever acid was used, it invariably happened that the lines when corroded were exceedingly shallow and rough upon the edges, many times so much so as to cause serious disappointments and great loss to those engaged. Such, indeed, was the risk of failure, that several artists have refused to execute any thing on steel, on account of the difficulty of bitingin their etchings.

I believe I am correct when I state, that Messrs Perkins