The average speed of the Bosphorus, during the whole time of being under way, going to and returning from the Cape of Good Hope was almost eight knots, (more than seven and three quarters,) a high average under the circumstances abovementioned.

She was thirty-nine days under way, going to the Cape, and thirty-four returning, including the very inconvenient delay caused by going so far out of the best winds, and into adverse currents, in order to touch, both going and returning at Sierra Leone, as well as the Cape Verd Islands; a service that might be less inconveniently executed by a small branch steamer.

At the return of the Bosphorus to Plymouth on the 12th of March, from which port she had departed on the 18th of December; her machinery and everything on board proved to be in such perfect condition that her commander (J. Vine Hall,) reported her ready to sail on another Cape vogage in four days.

Bosphorus, Hellespont, and Propontis.-These ships are remarkably easy at sea, their screws cause no annoyance, they can be shifted from one position to another in three minutes, at any time, and that of the Bosphorus is now in perfect condition.

When these ships are under sail only, shifting or feathering the screw makes a difference of nearly two knots in their speed.

March 20th, 1841.

G. S. S. C.

SCREW STEAMERS.

We have more than once directed attention to the great revolution screwsteamers are destined to effect in our mercantile marine, and every week gives strength to our convictions. The disaster which befell the Great Britain, though her only fault was she overran her commander, gave screwsteamers a check for a time, but they are now rapidly augmenting, and performing their voyages with great regularity. The Arno, one of this class of vessels, arrived last evening in five days and sixteen hours from Gibraltar. Before the year closes we shall have one, if not more, between this port and Chagres, and, as the railroad thence to Panama will be completed by that time, for the contractors are proceeding energetically with their work, with a view to opening it before the 31st of December, this route will materially facilitate the transmission of our textile fabrics from this country to the West Coast of America. In a few years we expect to find not only every ocean and sea traversed by English screw-steamers, but every estuary and river in which there is a port of any extent of trade entered by those from Liverpool. America is proverbial for her clipper sailing ships, owing to the peculiarity of her California and China trades, for the nature of the credit system under which they are carried on gives clipper ships an especial advantage; but, believing that screw-steamers will become best adapted to all trades that can afford to pay a fair remuneration for outward freights, they will ultimately displace the clipper sailing vessel. Every year diminishes the expenses of screw-steamers, from the greater certainty of coaling at intermediate ports at a reduced cost; for, let screw-steamers be but once established on any route, and the coaling depots will be created, as a matter of course, by other interests. Our feeling would be more zealously enlisted were Liverpool, whose position is peculiarly favourable for the building of iron steamers, making efforts to secure for herself her fair portion of their construction, instead of allowing the Clyde to have nearly the entire building to itself. Even a Joint Stock Company would be preferable to inactivity.-Liverpool Albion.

NAUTICAL NOTICES.

THE ISLAND OF RUAD, JUNE, 1850.-By Commander N. Vansittart, of H.M.S. Frolic.

Ruad Island the ancient Arad us is situated in nearly lat. 34° 49′ N., long. 35° 53′ E., is from the main land at nearest part about 1 miles, and from Tortosa S.S.W. 2 miles. It is the Aradus or Arad of scripture, whence Tyre is said to have drawn her mariners. It is about half a mile in length, and rather more than a quarter of a mile in breadth, and is surrounded by the remains of ancient walls: the castle or citadel being still nearly perfect without guns.

The island is nothing more than a barren rock, not even having a spring of water, for which they are entirely dependant on the artificial reservoirs containing rain water, and from supplies that are fetched from the river on the main land.

The anchorage, although it cannot be called a good anchorage, is for three or four brigs, corvettes, or small frigates to be preferred to most ports in Syria to the southward of it, being equal to Tripoli and Beyrout, and superior to Sidon, Tyre, Kiaffa, or Jaffa. It is sheltered from the south-west winds which appear to be the prevailing winds on the Syrian Coast; and which, in the winter time, blow with the greatest violence, consequently the ones mostly to be guarded against.

From W.b.S. to S.b.W., the anchorage is sheltered by the Island of Ruad.

From S.E. to N.N.E., by the main land, leaving the anchorage apparently exposed to winds, any point to the northward of west, and likewise to S.S.E. gales.

From a small island 13 miles south from the anchorage, and the many 2 and 3 fathoms patches to the southward, as they cause the sea in a gale to break violently over them, making the anchorage comparatively safe, although no doubt subject to a disagreeable swell. To the northward although not so well protected, there are several patches of 3 fathoms.

To enter the anchorage it is necessary to enter from the north point of the island, which is bold, having 10 fathoms close to it. At 200 yards is a small patch of 4 fathoms rock on it, so that it is necessary to keep the island of Ruad close on board; pass at a distance of 300 or 400 yards, where you have 5 fathoms least water. Good anchorage off the centre of the town in 5 fathoms sand and mud, 500 or 600 yards off, increasing 8 fathoms at half a mile. It would be most dangerous for a vessel to attempt coming in or going out to the south of the island from the many 24 fathoms patches there.

Water to be had from a stream on the main land bearing from the centre of the Island of Ruad, N.E.b.E. 1 miles; vessels may anchor off the watering place at 700 yards distance in 5 fathoms. At the entrance of the stream is a bar of sand with only a foot of water upon it. Boats would have to anchor 50 or 60 yards off. Watering at Tripoli from the river above Ali, which is distant from Ruad 25 miles, is better water and easier for the boats employed.

The island of Ruad as seen from seaward has the appearance of a fortified town, and shows out light from the main land, upon which the ruins of the christian church built by the Crusaders is very conspicuous, to the northeast of which is the town of Tortosa.

On nearing Ruad the mast-heads of the country vessels may be seen over

the town. The inhabitants give a very favourable account of the anchorage, and none of them ever recollect a vessel having been wrecked there. They have themselves eight brigs belonging to the island. Cattle to any quantity may be procured from the main land by giving timely notice.

The population of the island is 960 men, exclusive of women and children, the inhabitants all Mahometans, mostly seamen, carrying on a slight trade in native boats and small vessels, by exporting grain and fruit from the main land at Tortosa to other places, sponge fishery, and a party going over daily in fine weather to work on the main land.

SAILING DIRECTIONS FOR ALGOA BAY.-Extract from the Remarks of H.M.S. Hermes, Com. Fishbourne.

In approaching Algoa Bay from the southward in clear weather, the first land that will be visible are the mountains in the interior, sketches of the most remarkable of them are given on the chart made by the officers of the Hermes, viz., Winterberging land and of a mountain somewhat similar, also having a serrated top, the bearings from Cape St. Francis (which is sometimes taken for Recife,) and Recife are as follows:

The Coxcomb bears by compass from Cape St. Francis N.E. N. thirty miles, and from Cape Recife N.N.W. W. thirty-seven miles, and the mountain with the serrated top to the eastward of it bears N. 18° W. of Cape Recife, distant twenty-nine miles.

These bearings will be sufficient guide in steering for the Capes referred to, when they themselves are not seen. Continuing to steer for Recife the the next land that will appear will be the high land in its immediate vicinity, on which is a horizontal line of sand that looks very much like a sandy beach, but which is not now so; afterwards Recife itself will appear a little further to the eastward, showing low but distinct as a Cape, with one hummock near the extreme point. Nor will the lighthouse appear till after a further approach of four or five miles; its latitude is 34° 1' S., and longitude 25° 41' 30" E. No vessel should approach the Cape four miles to the eastward of Recife, or Recife itself nearer than two miles, and then only with a commanding breeze. Since the reefs extend to one mile and a quarter from the land, and there is a very decided and dangerous indrift: neither should any be tempted by the absence of break to approach nearer on the east side since it often occurs that the sea does not break on a seven foot patch a mile from the lighthouse, and yet without a moment's warning it will break in seven fathoms.

It is seldom prudent to approach nearer than to 13 fathoms water. When rounding Recife, or before a white stone beacon will be seen to the northeastward of the lighthouse, which when on with it, or more accurately when its top is in one with a perpendicular line on the lighthouse, it points to the eight foot patch of the Roman Rock, and is the leading mark up to it on a course about N.N.EE. This patch bears from the lighthouse N.N.E. § E. two miles and a quarter.

After picking up this leading mark the eye should be carried along the side of the hill opposite to where the Roman Rock lies, and to about two miles from the lighthouse, where will be seen two wooden beacons, which when in one, point to the eight foot patch of the Roman, and from which when in one bear W.b.N.

When the lighthouse has been brought to bear N.W. W., and the soundings are from 10 to 13 fathoms, intending to go between the rock and the main, the course may be altered to north. After running about two miles from the time of bringing the lighthouse N.W. W., and yet some distance

before the wooden beacons come in one, or 'when Beacon Point, which is a low sandy beach terminating in dark brown ragged rocks is W.N.W., the white stone beacon must be brought and kept just open to the eastward of the lighthouse, this will take the vessel to the westward of the Roman in from 7 to 8 fathoms with one or two casts of 6 fathoms before coming up to the wooden beacons. After the wooden beacons have been brought in one, and again opened on the other side some distance, the anchorage off the town may be steered for, always giving Beacon Point a berth of a full quarter of a mile.

Intending to go to the eastward of the Roman after having brought the lighthouse to bear N.W. W., the course N.N.E. E. may be steered, or any course more to the northward, that will admit of the stone beacon being kept open to the westward of the lighthouse; then when the wooden beacons have been brought in one, and again opened some distance, or when the staff and point of the Diamond on Fort Frederick have been brought in one with the centre of the remarkable hill behind it (a sketch of which is given in the chart,) or if these are not seen when Beacon Point bears W.N.W., the anchorage off the town may be steered for.

The captain of the port will indicate where merchant vessels are to anchor, but sandy bottom and good holding ground is to be found any where in 7 fathoms. Ships will ride much safer with long scope of cable, say 60 fathoms of chain and 30 fathoms of coir (additional next the hawse) in 4 fathoms, and proportionably more in deeper water-less than the quantity indicated should never be tried in this bay, and indeed it is seldom judicious to use less.

The Roman is not, as supposed, a single rock, but a number of single rocks rising above a bed of rocks full 500 feet long.

There is a red buoy with a staff and beacon on it moored in 9 fathoms N.E., by compass, from the eight foot patch of the Roman, outside of which vessels going to the eastward of the rock should pass, but if going to the westward they should not approach the buoy on its W. or S.W. sides nearer than one cable's length.

Directions for entering Algoa Bay at night.

In coming from the westward no vessel should make the light on a bearing to the southward of east, and should she from any cause have fallen to the northward, so as to have brought the light more to the southward, she must without fail haul out till the light bear east, or if she is not aware of the error or deviation due to the iron, &c., in the ship to E. S. before she arrives within five miles of the light. After which she may steer E.S.E. till the light bears N.b.W., then E.N.E. till it bears N.W., after which she may alter course to N.N.E. until the light is brought on the latter bearing: she should not get less than 12 fathoms water, and she should go sufficiently slow to obtain soundings. The current sets in strong towards the reefs, so if she find herself dropping in, she must haul to the southward.

While steering the course indicated, viz. N.N.E., going outside the Roman she must not on any account bring the light to the southward of S.W. & S. or S.W., or get less than 10 fathoms water, and if so must haul to the eastward till she has run three miles at least from the time of having brought the light to bear N, W., she may then steer N.W.b.N. to the anchorage. The town and vessels will appear from under the shadow of the land, as the anchorage is approached, even though no lights appear.

It is better to adhere to these directions, though lights should be seen apparently in the town or amongst the shipping, as these might be in a part of the bay north of the town, and thus deceive.

I would strongly recommend that no vessel should attempt to go to the westward of the Roman Rock at night, as the soundings are irregular, and the winds there are more baffling, the currents also set in towards the main land.

The Redwing Rock has been most carefully sought after without success, coupling which with the fact that there is no break in the place where it is said to be, leaves no doubt in my mind but that what was taken for a rock has disappeared. In Algoa Bay, and at about ten miles N.E.b.E. from the anchorage off Port Elizabeth, are the St. Croix Islands, under which there is good anchorage for all winds. Indeed it is a question, whether the town should not be near them, and under them the anchorage, for that part of the colony, the open country and the adjacent River Swartzcops, would afford no mean advantages not possessed by Port Elizabeth.

The Bird Islands in the eastern extremity of this bay, lay off Woody Cape, which is as its name imports covered with wood, except a small patch of sand at its highest part, and is the only seabound land in its vicinity that is so, which gives it in contrast with that for miles on either side a dark appearance; the land on the west side from near St. Croix Islands, are numerous sandy hillocks quite bare of vegetation; and that to the eastward up to Padrone Point, is nearly similar. Woody Cape is high, rugged, and not prominent, scarcely determinable as a cape, except when very near it ; not so Padrone Point which runs out into a low point of sand, forming a determined cape without vegetation, from which breakers run out some distance. The water breaks still further off, owing to the meeting by currents this point, and after strong winds.

The innermost danger from these islands is full five miles from Woody Cape, and they afford a tolerable anchorage behind them from W. to S.S.E. in in 13 fathoms, which is rather better than half a mile from the northern breakers closer to them, these would afford more shelter, but the ground is foul.

These islands are very low and proportionably dangerous, and though the main land will generally be seen before them, and the distance from them estimated from it, yet this is not entirely to be relied on, and in shaping a course to go outside of them allowance should be made for the fact that the eddy or return current sets in towards them, and then to the eastward.

The Doddington and western reef should be considered as part of the Bird Island reefs, and no vessel should go between them, the water does not always break on them, but in bad weather the break extends the whole way from them to the islands: the Doddington lies about eleven from Woody Cape.

There are many statements current, about breakers being to be seen from time to time in this bay during south-east gales, yet I believe others than those laid down, to have no existance, and that which has been mistaken for them is no doubt the effect of mirage. I had seen the appearance alluded to extend nearly the length of the bay, but examination and patient attention shewed it all to be unreal, as it vanished by degrees as we passed along. It may be occasioned by the sudden change of temperature in the air, which altering its capacity for moisture, causes an evaporation from the sea to take place to the lower strata, and less to the upper, which are therefore of unequal densities, and refract light in different degrees, producing the alternate appearance of white or broken water, and sea green, and regularly as the particles are set in motion, intermingling by the passage of the sea, and whose surface at the same time being smooth but in motion, reflects the rays from different points to the eye, as it rolls along, giving the rolling over appearance of wave crest or roller. There may be a little sea at times, the effect of rain or over falls, where there are as here currents and irregular