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the absence of the proper means for effecting them, we were delayed there until the 6th of August. During this time and indeed throughout the whole of our cruize, the weather was very unsettled, occasioning a great loss of time.

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On the 8th of August we were enabled to sail from Cashell Bay, where, on leaving Galway, I had gone for shelter. Carrying out a line of soandings on the parallel of Slyne Head, at the distance of one hundred and twenty miles to the westward of it, we crossed the tail of a bank of 82 fathoms, coarse gravel. This being entirely new, have named it the Porcupine Bank. It will be of use to vessels bound to Galway from the westward as a means of ascertaining their position by the lead. The bottom both to the northward and southward is deeper, being composed of fine dark sand, while the bank is composed of gravel and coarse sand.

August 10th, in lat. 53° 30', long. 15°, found the current from a boat moored to the bottom S.E. & S. 0.5 knot, which agrees with that shown by our reckoning for the last two days. Numerous pipe fishi, some with ova attached, were swimming on the surface; some of these were preserved.

Aug. 11th.-Our soundings this day taught us that in the parallel of 54° 10', the Irish Bank does not extend so far to the westward, and that Rockal is probably a separate bank.

Aug. 12th.-Weather again unsettled, with a heavy sea. Having determined the N.W. limit of the Irish Bank, bore away towards the tail of the Rockal Bank, sounding at intervals in from 1,500 to 1,200 fathoms, shoaling as we approached the Rockal Bank.

Aug. 14th.-At noon observed Rockal with several fishing vessels near it. There being too much sea to do anything in the vicinity of the rocks, hove to for the night.

Aug, 15th.-Got observations for latitude and longitude; found the current setting with flood tide N.b.E. 0.8 knot. The weather having become fine with only a moderate swell, sent a boat with a party to land on the rock; but the sea broke so heavily round it that the officer in command thought it would be imprudent for them to do One of the party, Mr. Johns, the boatswain, succeeded in getting a footing, but not at the part where the summit is accessible.

so.

The fishery is in the vicinity of the rock; but this very remarkable peak of a submarine mountain standing as it does in solitary grandeur above the ocean surface, is not unworthy of some attention in this report.

Rockal is in lat. 57° 35′ 53′′ N. by meridian altitude of sun; long. 13° 42′ 21′′ W., mean of a.m. and p.m. sights, four chronometers, sea horizon. The rock has an elevation of 70 feet above the sea, is about 250 feet in circumference at its base, and is composed of a coarse granite.*

The summit of the rock, sharp pointed and whitened by birds, can

Specimens have been sent to various museums in Ireland.

only be gained from its N.E. side, and landing is at all times difficult, for it is steep on all sides. On the N.E. side, however, is a small detached rock, called Haslewood Rock, uncovered at half tide, with 30 fathoms of water between it and Rockal, from which it bears N.E.b.N. a cable and a half distant.

Helen Reef, bearing S. 79° E. two miles from Rockal, has about 6 feet water over it at low water. It is so called from a vessel of that name that was wrecked on it, and is very dangerous. The situation of it is generally shown by its breakers, but towards high water and in very fine weather, it only breaks at long intervals. From being small and steep to, there is then nothing to indicate the approach to it. To avoid it keep Rockal clear of a W.b.N. bearing. There is a safe passage between it and the rock.

The lowest estimate that was formed of the range of the tide, (judging from the appearance of the rock,) was 6 feet; but this seems large for a tide wave in mid ocean. Purdy's Atlantic Memoir presumes to discredit the existence of any danger near Rockal, but is mistaken.

From Rockal we steered for the Irish coast, when nearly midway between it and the Irish Bank, we obtained one sounding of 1,660 fathoms, and found the current here from a boat moored to the bottom S.E.b.E. E., one knot.

From the edge of the Irish Bank I carried a line of soundings into Enis Head, and then proceeded to Valentia for coals. On receiving which, having carried out my instructions and effected the object of our cruize, I returned to Cork for further orders, getting a few soundings by the way.

In the course of our operations we found the donkey steam engine and the light iron reels for running the line off very serviceable, indeed indispensably necessary to our success. The Bulldog machine fully answered the purpose of bringing up a large quantity of the bottom, but we could not always get the weight to detach. On one occasion, too much line having been paid out, the bight got between the jaws of the nipper and prevented its closing; this lost us our specimen, but it affords another illustration of the line going straight down on the weight, and the consequent absence of any under current.

In carrying out this service I received every assistance from the officers on board, who all united their best endeavours to bring our cruize to a successful termination.

With reference to the principal object of our inquiry, that of finding a more gradual slope into the bed of the ocean, I consider that our soundings, shown in the accompanying chart, clearly prove that the general dip of the bank presents no difficulty whatever to laying a cable either from Valentia or Loop Head, or any other part of the West coast of Ireland between Bantry and Blacksod Bays, that may offer facilities for securely landing and working it.

Much pains were taken by sounding at short intervals to discover if anything like a precipice existed. Our steepest incline shows a

difference of level of 3,060 feet in 2-7 miles, or about 19 feet in 100 feet.* On the parallel of 51° 20′ we have a dip of 7,680 feet in a distance of fourteen miles. The intermediate soundings give no evidence of a precipice; but a mountain of this height on the land would present an imposing appearance, with perhaps some steep escarpments.

On the adjacent coast of Ireland we have precipices of 2,000 feet in height within half a mile of the shore. However these may have been caused, whether by the coutinued action of the Atlantic waves at their base, or by the erosive power of glacial or atmospheric agencies operating on their slopes, it is certain that the submarine mountains are not exposed to this action, or to any denuding process whatever. But it is more probable that any inequalities in them arising from original formation have been filled up by the gentle depositions of the soft clay that we found everywhere covering their slopes.

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On examining the soundings the slope will be found to vary 6 to 19 feet dip in 100 feet horizontal, a dip that cannot possibly strain or injure the cable. The knowledge of this fact will, I trust, remove one of the supposed difficulties in the way of laying it, and help to forward the successful realization of this great national undertaking.

I am. &c.,

R. HOSKYN, Master and Surveyor.

Rear-Admiral Washington, F.R. S., &c.,

Hydrographer.

Abstract of the Experiments made with the Pressure Gauges and Deep Sea Thermometers from the Sounding Log.

June 25th.-In 1,000 fathoms water.

Board of Trade min. ther., No. 49, registered 44°.
Johnson's metallic ther., No. 8 37°.

Johnson's pressure gauge, did not act, the stopper had not

moved.

Hearder's pressure gauge, all the mercury ran out of the legs into the tube, probably from its having capsized on the bottom.

June 27th.-In 2,350 fathoms.

Board of Trade min. ther., lost by line carried away.
Johnson's metallic ther., lost by line carrying away.

July 22nd.-In 200 fathoms.

Johnson's pressure gauge, did not act.

Board of Trade min. ther., registered 54°.

* Those depths to which we have added an asterisk (*) indicate, with others on the bank inside of them, the places where this gradual slope of the bank is found; the incline being about one half of that of the usual shingle beach.-ED.

Johnson's metallic ther., No. 9, 49°.
Board of Trade min. ther., 50.5°.

Johnson's metallic ther., No. 9, 48.5°.

August 10th.-In 540 fathoms.

Hearder's pressure gauge, the mercury was all disjointed, some in outer tube, no result.

In 820 fathoms.

Hearder's pressure gauge, lost by line parting.
In 1,500 fathoms.

Board of Trade ther., No. 18, registered 59°.
In 1,550 fathoms.

Johnson's metallic ther., No. 9, 31°.

August 11th.-In 1,540 fathoms.

Hearder's pressure gauge, No. 2, on coming up the short leg registered 750 fathoms; the long leg was full; in a few minutes after coming up the short leg fell to 1,000 fathoms. August 12th.-In 690 fathoms.

Hearder's pressure gauge, No. 2, on coming up the short leg registered 1,200 fathoms; the long leg was full: shortly afterwards the short leg registered 1,425 fathoms.

August 16th.-In 1,660 fathoms.

Board of Trade ther., No. 18, 51°.

August 29th.-In 400 fathoms.

Johnson's pressure gauges, Nos. 1 and 2, did not act.
Repeated the experiment, they did not act.

Hearder's pressure gauge, short leg registered 950 fathoms,
long leg, 300 fathoms.

Every injunction of the inventors for using these instruments was strictly complied with by Mr. Davis, who took great pains to secure their efficient working.

Johnson's metallic thermometer appears to give good results.

I think the reading of the Board of Trade thermometer is sometimes vitiated by the index not retaining its position.

Johnson's pressure guage never seemed to be in the slightest degree affected by pressure. Is it not possible that the water may pass freely round the cork without moving it? If the plug is forced into the tube with thn finger, instead of compressing the water passes it.

Hearder's pressure gauge is of no practical use in its present form. The liability to fall on its side on the bottom, will always interfere with its results.

R. HOSKYN.

In all cases in the following soundings the bottom was found and the depth fairly measured, but where the line parted in coming up, the sounding being lost the character of the bottom could not be ascertained.

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