Orotava, we computed to be about fifteen English miles, travelling at the rate of three miles an hour: suppose then we deduct five of these for windings and turnings, the distance from the sea to the Estancia, in a straight line, will be about ten miles; which, if carefully compared with the ascent of the road,* I reckon will make the perpendicular height of the Estancia to be about four English miles; to which add a mile of perpendicular height from thence to the Pike, the whole will be about five English miles: I am very certain I cannot be mistaken in this calculation above a mile either way. There is no place in the world more proper for an observatory than the Estancia: if a commodious warm house or cottage was built upon it, to accommodate astronomers while the moderate weather continues, viz., all July, August, and September, they might make their observations, take an account of the wind and weather of the region above the clouds, and remark their nature and properties. But if any person intends to visit the Pike, I would advise him to wait for fine clear weather, carry a good tent, plenty of water, and some provisions along with him, that he may be enabled to remain at the Estancia four or five days, in which time he might go twice or thrice to the top of the Pike, and make his observations at leisure.

A SHOAL CAST IN THE CHANNEL.

The maxim with which we set out on this work, and which stands recorded in the first page of our earliest volumes commencing in 1832, was this:

"There are no charts of any part of the world so accurate and no directions so perfect, as not to furnish frequent occasion for revision and amendment.”

They are the words of the late Hydrographer to the Admiralty, Admiral Sir Francis Beaufort, and every day proves the correctness of his observation. That charts of foreign coasts and seas should be imperfect might occasion no great surprise when the vast extent of coast line and surperficies of sea surface presented throughout the world is considered. It would be extraordinary if it were not so. It would be wonderful if any chart should escape the charge of imperfection. Even where the surveyor's pains have been well bestowed on it, when the lead has searched the bottom closely, and more soundings obtained than can be laid down on it: even then dangerous pointed rocks have afterwards been found.

But we need not look abroad for imperfect charts. The surveys of our own shores, which have been in hand ever since the peace of 1815,

* I imagine that no one who has been at Orotava will think twenty-two or twenty-three degrees too great an ascent from thence to the summit of the island; for so many have I allowed in calculating the perpendicular height.

are not yet completed. On the West of Scotland and Ireland, and on the South of England, the naval surveyor is yet busy confirming the truth of the words of Sir Francis Beaufort which we adopted long ago.

On our eastern shore, the North Sea for the most part has been well surveyed, especially in its southern portion, where long tortuous. sandy ridges are concealed by a few feet of water, or shown in their full length by a crest of breakers, the channels between them being rendered more difficult to navigate by treacherous currents. This sea has been deprived of much of its danger by the admirable surveys of the late Captain Hewitt of respected memory; but the English Channel, after the Varne and Ridge are passed, presents a field for plain sailing, a gradually deepening bottom, or at least one supposed to be so, where the careful navigator has no sands to fear. Hence the difference between the two. While the North Sea chart has been covered with soundings, that of the less dangerous British Channel shows fewer casts of the lead; and these, when beyond a few miles from the land, appear to have been laid down by latitude and longitude, while those of the North Sea, it is well known, are carried out by trigonometrical operations from the shore, these being facilitated by its shoal character affording anchorage.

It was with no great surprise, in this state of things, that we found the following letter in that excellent daily journal, the Shipping and Mercantile Gazette, of the 14th of May.

May 12th.

Sir, I beg leave to acquaint you, for the information of the Lords Commissioners of the Admiralty, that when in command of the Royal Mail ship Tay, last from Lisbon, at 2h. p.m., on the 11th ultimo, I struck shoal soundings, at 29 fathoms, in the fairway of the British Channel, about twenty-eight miles S.S.W. W., by compass, from Plymouth Mewstone. The vessel's way was completely stopped for one quarter of an hour, and I and my officers are most positive that such soundings were obtained; though in the Admiralty chart, in that position, nothing less than 40 fathoms is marked, and in charts in ordinary use, 50 fathoms. The obtaining the above soundings caused me, in thick weather, to deviate from my course, and haul to the northward to make the land, and has, unfortunately led to circumstances which have caused my dismissal from the service of the Royal Mail Company, though no damage has occurred to the vessel, and the officer in charge of the deck stopped the engines, as he was ordered, as soon as land was made. The severe sentence I have thus unexpectedly had to submit to, has placed me, with a wife and a young family, in the greatest distress.

I have, &c.,

GEORGE BRIDGES.

To Thos. Phinn, Esq., M.P., Secretary to the Admiralty.

Now, referring to the chart, we find no such depth as 29 fathoms

twenty-eight miles S.S.W. W. from the Mewstone. Indeed, this would place it within a mile or two of 40 fathoms,-and the commander of the Tay says, that charts in ordinary use give 50 fathoms, but the depth of 29 fathoms is unheard of. Still, there stands the assertion, and, as we have observed on former occasions, a statement of this kind is easier to make than it is to prove it wrong, and until it be so it is entitled to confidence.

Now a discreet commander in such a case would have reduced his speed and kept his lead going while he recovered himself from the surprise occasioned by such a cast disagreeing with his supposed position, (especially if the weather was thick,) until he had satisfied himself where he was; not leaving his deck for one instant while a symptom of doubt remained. It appears by the letter that the Tay stood to the northward for the land, and we have heard that the commander considered himself then on the South side of the Channel!-a rather strange conclusion considering that it would be difficult to find 29 fathoms at any moderate distance from the coast of France in the direction from which the Tay was coming to make the land. The commander of the Tay, it appears, however, by standing to the northward, was not long in finding out his real position without the assistance of his chart,-that his reckoning had been really correct, and that his chart was at fault in not showing that he might have expected this shoal cast,—if his eyes have not deceived him as well as an officer of the Tay who was assisting.

But what is to be said of the charts? One shows about 40, another 50, and the commander of the Tay finds 29 fathoms-a depth which neither of them gives! In this state of things we understand that directions have been given to that experienced and excellent officer, Commander Edward Burstall, well accustomed to such work, to examine the place of the Tay's soundings, and we hope also the whole of the adjacent district between it and the Start, and for the result of this officer's examination, when published, we shall look with great interest, a result from which, if we anticipate rightly, the seaman will have something to learu.

But in reference to our Channel soundings we trust the time is not far distant, now that the surveys of our coasts are drawing towards their completion, that the antiquated system of laying down soundings in a comparatively narrow sea like the English Channel, by latitude and longitude, will give place to others determined in position by a trigonometrical process. In opportunities offered by the fine calm weather of summer, with anchorage varying from 30 to 50 fathoms, a series of small iron beacon buoys, of Mr. Herbert's principle, with good ground tackle, and light surveying steamers might ride long enough for trigonometrical fixings carried out from the shore, and thence the soundings might be thoroughly examined and laid down from them. We should then have a piece of work so closely done, and so perfectly committed to paper, as to produce a chart of the English Channel that would be worthy of a great maritime nation, and one

which might almost form an exception to the aphorism of Sir Francis Beaufort, that "there are no charts so perfect as not to afford frequent occasion for revision and amendment." And possibly in such a work our neighbours on the opposite side of the Channel, ever foremost in the pursuits of science, might take their share South of the fairway midchannel line.

NAUTICAL NOTICES.

ANCHORAGE IN TONGOY BAY-Coast of Chile.

Sunderland, May 14th, 1856. Sir,-Since the establishment of smelting works by the South Mexican Copper Company in Tongoy Bay, it is rising to a place of some importance; and as there is no pilot to take a ship in, nor yet a chart of the Bay, 1 think the following notice would be of service to masters who have never been at this port :

At about half a mile south from the high chimney on the hill there is a rock which is covered at high water, and at low just awash, there is nothing on it to mark its position; it is just the place where strangers would bring their ships up in a convenient birth for discharging.

There is a good passage inside of this rock. If I had not obtained some information from a Captain in Coquimbo, it might have proved very disastrous to me. As soon as I was inside of Point Lingua de Vaca, it fell calm, and it coming on dark, I was anxious to get to the anchorage; so I out boats to tow ship, when, thinking I was past danger, and just going to let go the anchor, a man in the first boat struck the rock with his oar. There was not the least swell to indicate its position; this is not mentioned in any of the Directories I ever saw of the coast of Chile, and by inserting this in your valuable work, it may be of benefit to brother shipmasters.

Yours, respectfully,

A WEST COAST TRADER,

[Our trader has our thanks for his communication. Is he aware that "the directions say that no vessel, however small, should go into less than 4 fathoms."---Sailing Directions for South America, p. 322.]

HYDROGRAPHICAL REMARKS ON THE ROCAS SHOAL.-Made during the Visit of H. M. Steam-Vessel " Sharpshooter" to that Place in the Month of March, 1856.

On the 5th of March, 1856, I sighted the Rocas from the mast-head at 4h. 15m. p.m., bearing W.N.W., about nine miles distant, at which time we had no bottom with 46 fathoms. I then bore up N.W. to close the group, and on sounding at 5h. p.m obtained coral bottom in 13 fathoms, the rocks not being even then in sight from the deck. I therefore determined on remaining in that position during the night, and consequently anchored in 12 fathoms, the highest rock being then first visible from the deck, bearing West, true.

NO. 6.-VOL. xxv.

2 U

At 6h. 40m. a.m. the next day I proceeded under steam to the N.W., giving the shore a berth of about five miles, until arriving on the N.W. side of the sand-banks; where I anchored in 20 fathoms, coral bottom, at about 2 miles from the shore, with the following bearings :

Whilst describing the semicircle, our soundings were 13, 14, and 15 fathoms until the group bore S.b.E., when there was no bottom with 70 fathoms From this it appears that the shoalest water exists on the eastern side. A careful attention to the deep sea lead would alone betray to a vessel in doubt the vicinity of the shoal on approaching in that direction; when, if practicable, anchoring is a course strongly to be recommended, until daylight or clearer weather enables the Master to ascertain his true position.

As the prevailing winds in that quarter will always enable a vessel bound North to choose a course either to the East or West of this shoal, I do not see that any Masters would be justified in endeavouring to sight the same, a proceeding which might be attended with considerable danger and the benefits to be derived from which I am at a loss to conceive.

Having landed on the eastern sandbank, I caused a number of cocoa nuts to be planted thereon, which were furnished me by H. M. Consul at Pernambuco, with the view of their forming, in time, distinct land marks which will enable the place to be discerned at a much farther distance than is now possible.

From the means of the sights taken on board the ship and on shore, the position, as follows, may be relied on:-Centre of southern sand island, lat. 3° 51′ 25" S., long. 33° 46′ 23′′ W. of Greenwich.

This position agrees as nearly as possible with that given by Baron Roussin, and as laid down on the English Government charts.

The highest part of the bank may be set down at about ten feet above high water mark. Rise and fall of tide seven feet. We found the current to set W.N.W., true, hetween one and two miles per hour.

There were many wrecks of vessels lying on various parts of the sandbanks, only one of which presented signs of having been recently cast on shore,probably the remains of the English barque Countess of Zetland, lost during the month of October, 1855.

Between two and three hundred bales of cotton, with some anchors, were also observed, and two large casks of fresh water were found high up on the beach out of the reach of the tides. This fact, combined with the place abounding with birds, which may be taken with ease, and the ground being almost covered with eggs, would enable a shipwrecked crew to exist on this group for a lengthened period.

J. E. PARISH, Lieut.-Commander.

From a plan of the shoal that accompanies the foregoing remarks transmitted by H. M. Consul abroad, it appears that the Rocas consist of three distinct patches of coral rock lying in a W.b.S. and .b.N. direction. The easternmost is about a mile East and West, and half a mile broad. The middle one is scarcely a mile long, lying N.W, and S.E., having a good large patch of coarse grass. The westernmost is about the same size, lying East and West; and the edge of the coral bank which surrounds them is about three miles in length, about W.b.S. and F.b.N.; the whole being about eight miles in circumference. A remarkable rock, ten or twelve feet high, stands on the outer edge of the reef about half a mile due East (true) of the eastern bank. A wreck lies on the eastern edge of the eastern bank and a hut stands on the western edge of it-the surface between them being covered with cotton bales.