ably prove advantageous; inasmuch as they would prevent trawling and line-fishing, as well as the anchoring of ships, where they prevail.

It is quite possible, in laying down the cable, to avoid the Porcupine Bank, which, as I have already stated, does not extend South of the parallel of Cashla Bay; but if it should be carried over the bank, no fears need be entertained of the effects of the heavy seas, which characterize an Atlantic storm; because, as shown in my "Preliminary Notice," the smallest stones, occurring on its surface, exhibit appearances of being as little disturbed, as if they were at the bottom of a lake. On the other hand, a buoy might be permanently placed on the bank in proximity to the cable to indicate where the latter could be found in case of accident: by this means, the repairing of injuries (which I cannot but conceive would be of very rare occurrence) sustained on this side of the Atlantic would be materially expedited.

I may, in passing, remark that the Porcupine Bank is an important feature in favour of making Galway an Atlantic packet station. In being the most westerly land-fall on the coast of Ireland, it will enable steamers during a fog, or cloudy weather, to obtain, by soundings, an early intimation of their approach to land :—while, both on the north, and on the south, no such advantage exists; because the outer edge of the hundred-fathoms terrace, of which the bank is an outlier, trends rapidly towards the land, approaching it to within only a distance of from twenty-five to fifty miles.

If now we refer to the Atlantic sea bed off the coast of Kerry, it will be found to present features of a different character. Beginning at the coast, say, near Valentia, the bottom slopes down somewhat suddenly to a depth of 525 fathoms: it next rises again, apparently at the same angle, till it reaches a level, varying from 195 to 230 fathoms below the surface of the ocean, and where it forms a submarine ridge about twenty-five miles in width, 140 miles from land, and terminating southward on the parallel of Cape Clear. This ridge, which is evidently a tongue or southern extension of the deepest portion of the terrace lying off Galway, declines rapidly, that is, on its western side, to a depth of from 1,500 to 1,700 fathoms. Further out, the bottom sinks to 2,040 fathoms. Now, if we refer to Maury's map, it will be seen that the last mentioned sounding, by proceeding to the South, makes that part of the sea bed, where it was obtained, a portion of the great three-miles-deep submarine valley, which runs down to the Cape Verd Islands on the coast of Africa, and which, according to the authority cited, actually attains nearly its maximum depth, viz., 2,675 fathoms, somewhere off the South coast of Kerry. Unfortunately the soundings on the North of the parallel of Valentia and near the meridian we are now in, are not sufficiently known; but, from the rise of the bottom, as indicated by the two last mentioned soundings, it is to be suspected that the three-mile-deep valley gradually rises up to the two-miles-deep "telegraph plateau," somewhere on the parallel of Loop Head in Clare. It may possibly ex

tend much further North; but, even in this case, it cannot but have lost its distinctive character, and become reduced to a mere trough in the telegraph plateau.

It will now be seen that a telegraph cable, running from any part of Kerry, must of necessity cross two valleys,-the easternmost one, upwards of half a mile in depth, and the westernmost, about three miles,-before it reaches the telegraph plateau. Nothing is known of the western side of the deepest valley; but its eastern side appears to be precipitous, and, it is to be feared, rocky. The specimen of Discina, a shell which lives fixed to stones, rocks, and other objects, mentioned in my "Preliminary Notice," as having been taken on the East side of the valley, at the depth of 1,240 fathoms, may be regarded as supporting this apprehension. The difficulties attending this route, however, may very possibly be overcome by carefully selecting the course where unfavourable circumstances least prevail, and allowing sufficient length of cable to be payed out, so that it may rest on every portion-not only elevations but depressions-of the inequalities of the sea-bed.

In conclusion, I may remark that it appears to me, that the conditions most favourable for a telegraph cable, between this country and Newfoundland, are a gentle, undulating in-shore bottom, extending far into the Atlantic before obtaining any great depth, and its outer edge passing down to the deep telegraph plateau by a not over rapid fall. These conditions can be found no where on the coast of Ireland except off Galway, where also occurs the Porcupine Bank, the advantages to be derived from which have already been stated. Belmont, near Galway, November 15th, 1862.

Supplementary Note.

Mr. Hoskyn preserved specimens of deep-sea soundings in bottles containing spirit, by which means they have been prevented from drying, and have retained their original consistency. Orbulo globigerinous mud, thus preserved, has quite the appearance of a thickish batter paste. To what depth below its surface the deposit continues in a pasty condition has not yet been ascertained. The "Bulldog machine," so successfully used on board H.M.S. Porcupine, brought up large quantities of it; we may therefore conclude that the deposit was penetrated to the depth of a few inches. Further, if we take into consideration the enormous vertical pressure of the ocean in deep places, it is difficult to conceive otherwise than that water should be forced to a considerable depth into the permeable mud forming the two-miles-deep "telegraph plateau." Under these conditions, we may fairly assume that, at least, its surface mass is highly charged with water, and consequently so soft and oozy that a body like a telegraph cable could not remain long on it without being covered up. The mud, consisting as it does of living and dead specimens of Foraminifera, and their comminuted debris, is clearly an organic deposit. The rate at which it is formed will therefore depend on the

rate of reproduction of these organisms,-all other circumstances being favorable. Although little is known regarding the subject just mentioned, still we may form some idea of the rate at which Foraminifera increase or multiply by a reference to facts supplied by other living objects. It is well known that many of the lower groups of animals are enormously reproductive. Numerous cases might be adduced; but it will be sufficient for my purpose simply to notice a group in which calcareous matter is an abundant constituent. Darwin, on the authority of Lieutenant Wellstead, R.N., cites the case of a ship stationed in the Persian Gulf, the bottom of which became encrusted with a layer of coral two feet thick in twenty months. He likewise notices some experiments made by Dr. Allan on the coast of Madagas car, from which it was ascertained that portions of coral, weighing ten pounds, increased four feet in height and several feet in length during the short space of six or seven months (Vide Darwin's Coral Reefs, pages 87 and 88). These cases may be accepted as good analogical proof in favour of the belief that Foraminifera-the lowest group of animals known-multiply to a surprising extent.

While investigating this subject, however, we must not overlook another of some importauce. Both corals and Foraminiferous shells are formed of lime derived from certain, if not all, the calcareous solutions occurring in the ocean-the principal being sulphate of lime (4.617 per cent.) and chloride of calcium (3.657 per cent.-that is, proportional to other associated mineral ingredients). How these two compounds are in the first place derived, as appears to be the case, from another calcareous compound-viz., bi-carbonate of limecommon to the water which rivers discharge into the ocean; or how they are afterwards decomposed by the vital agency of coral-forming Zoophytes and Foraminifera, and next converted into the carbonate of lime of their skeletons or coverings, are subjects beyond my present purpose. The question for consideration is-Are calcareous solutions as copiously supplied to the Atlantic for its Foraminifera as they are to tropical seas for the uses of coral-forming Zoophytes? I see no reason to doubt the affirmative, as the per centages above given are deduced from analyses made by Pibra of waters from the Pacific, Atlantic, and German Oceans.

It may also be observed that the balance of Nature requires us to believe that the Foraminiferous life of the deep Atlantic is quite equal to the supply of calcareous matter.

Thus, considering that rivers are every moment conveying enormous quantities of lime from the land into the sea, and that oceanic currents are widely diffusing it over the Atlantic, we may conclude that Foraminiferous organisms, every where occurring on its deep-sea bed, are appropriating this calcareous matter as rapidly as it is supplied. They evidently play the same important part in our seas as the coral-forming zoophytes in warmer latitudes; and, although the latter are labouring in shallower depths, and building up the more striking atolls and fringing reefs, the latter are nevertheless working quite as efficiently in the abysses of the Atlantic, and forming an enormously

wide-spread calcareous deposit. Ages on ages will be consumed before this deposit can attain the thickness of some of our masses of limestone; but assuredly it will be materially increased during the short span of a human life.

In conclusion, reflecting on all the considerations which have been noticed, I feel my convictions strongly supported that a telegraph cable, if laid down on the orbulo-globigerinous bottom of the Atlantic, will, after the lapse of a few years, become sufficiently covered up to be protected from any ordinary danger.

PRELIMINARY NOTICE OF THE ORGANIC AND INORGANIC OBJECTS OBTAINED FROM THE SOUNDINGS OF H.M.S. "PORCUPINE OFF THE WEST COAST OF IRELAND,-By Professor William King, Queen's College, Galway, and Queen's University in Ireland.* Sufficient time has not elapsed to enable me to make a detailed report on the various objects which the Lords Commissioners of the Admiralty have done me the honour to place in my hands for examination. I trust, however, to have the report prepared for the press in the course of this winter. On the present occasion I purpose giving a summary of the results of my investigations as far as they have been conducted.

The greatest depth at which specimens have been obtained is 1,750 fathoms. The soundings from this and less depths-up to 500 or 600 fathoms consist essentially of the same kinds of microscopic organisms already made known by Bailey, Huxley, Wallich, and others.

The marvellous profusion of Foraminifera and other minute structures, occurring on the bottom of the Atlantic, shows that over a vast portion of the submarine area (averaging about two miles in depth), known as the "telegraph plateau," which apparently stretches uninterruptedly from the mid-west coast of Ireland to Cape Race in Newfoundland, there are being formed calcareous deposits analagous to common limestones. While nearly all the particles of these deposits are either the testaceous coverings of dead Foraminifera or the finely levigated debris of their shells, it is evident that the surface of the deep Atlantic sea-bed is one vast sheet of the same organisms in a living state, whose office it is to clear the waters of the ocean of all the mineral and organic impurities which are ever flowing into them.

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Dried specimens of deep sea ooze procured from 1,500 to 1,750 fathoms off the west coast of Ireland bear a striking resemblance to the roe of a fish, owing to their containing myriads of Globigerine and Orbulinæ. This circumstance led me to suspect that roe-stone or oolitic limestone, instead of being, as is generally conceived, a concre

* [The important additions made to this notice since it appeared in our last, have induced us to repeat it here.-ED.]

tionary deposit, is a purely foraminiferous formation. In prosecuting my investigations on this point, although I have failed to detect any well defined specimens of Globigerina in oolite, I have been rewarded by discovering that it consists essentially of an allied monothalamous genus. Having carefully examined type specimens of Carboniferous, Permian, and Jurassic oolitic limestones, respectively from Edenderry in Kildare, Sunderland in Durham, and the Isle of Portland, I have no hesitation in stating that they consist for the most part of an organism identical with, or allied to, Orbulina universa.

It has long been the opinion of geologists that many limestones are of organic origin; but considering that travertine (Rome) and pisolite (Carlsbad) are purely chemical deposits, it is believed that a number of other calcareous rocks-oolites in particular-have been produced by chemical action. It is now evident, however, that the great bulk of our limestones is organic in its origin,-formed immediately by vital action, like orbulo-globigerinous mud and coral reefs, or derived from the disintegration of shells and other invertebrata. Beds of limestone are often spread over several hundred square miles in area, and one or two thousand feet in thickness. What lessons do they teach us when considered in connexion with the orbulo-globigerinous mud of the Atlantic! Animal life is ceaselessly abstracting lime from the ocean. This calcareous matter is derived, by mechanical and chemical processes, from limestone rocks, which, too, were formed by the vital action of successive generations of ancient invertebrata. The organic and inorganic changes, involved in these processes, have been repeated over and over again during the long lapse of time, forming the sum of geological periods: but, looking into the far past which geology discloses to our view, we must conceive a period when limestones did not exist,-when life was not created!

It has been seen how calcareous rocks have been formed;-the next question for solution is-from what have they originated? Shall we say-from primordial or azoic rocks formed previously to the Laurentian period? But no such rocks-is there any evidence for believingcould contain carbonate of lime, if they resembled our granites: they would contain silicate of lime averaging about eight per cent. In this case, may not the calcium of the carbonate of lime, forming limestones, have been originally the calcium of the silicate of lime of ante-Laurentian igneous rocks? In North Wales there occur argillaceous and siliceous aqueous deposits (nearly the oldest known to the geologist), collectively measuring from five to six or more miles in thickness. They have all the appearance of having been derived, by mechanical and chemical agencies, from the silica and silicate of alumina of previously existing quartzose, felspathic, and other rocks allied to granites. Now there is required for the elaboration of the enormously thick and ancient sedimentary deposits of North Wales, the abrasion and removal of vast masses of previously existing igneous or other rocks. Is it not a fair inference, then, that the silicate of lime (though fractional in quantity compared with its associated constituents) of the latter rock-masses, became converted into, and was sufficient to produce, the carbonate