"This light is intended to lead between the Barnard and Newcome Sands into Lowestoft South Roads, and when vessels are in the Fairway of the Channel, the light will bear N.W.-Vessels working, and standing either towards the Barnard or Newcome, must immediately tack on losing sight of the light.

"Having arrived in Lowestoft South Roads, and intending to proceed to the northward, vessels should bring the low light at Lowestoft to bear N.E. by N. and then steer for it; keeping it a little on the larboard bow; and on approaching Lowestoft Ness, they must haul out towards the Stanford floatinglight, and thence proceed for Yarmouth Roads.

"And in pursuance of the further intention expressed in the said notice of the 11th July, 1831, the low light at Lowestoft will be exhibited on the evening of the said 15th inst. from a new Light-House, and will, when in a line with the upper light, bearing N. by E. lead vessels into the south entrance of the Stanford Channel, after which a bearing of the Stanford floating-light must be used as heretofore in navigating through that Channel.

44. TEMPERATURE OF THE OCEAN.

We are indebted to the kindness of Captain Prescott, of the Royal Navy, for the following interesting communication:

"To the Editor of the Nautical Magazine.

"My dear Sir,

"On my passage from England to Rio Janeiro, in His Majesty's Ship Aurora, on the 21st August, 1821, by means of a sea-gauge, constructed on Dr. Brewster's principle, we took up water from the depth of 117 fathoms, of the temperature of 58° Fahr.; the temperature of the surface being at the same time 820, and that of the air 83°. This was at noon, and as the weather remained calm, in the afternoon we ascertained the temperature at various depths, as stated below, that of the air, and of the water at the surface, remajning as before.

At 30 fathoms 710.

You will observe, that the minimum of temperature was at 90 fathoms, and the water at that depth 26° cooler than the air. We used it to cool our wine for dinner, which it did effectually, producing on the glass the refreshing appearance of ice. I subjoin the result of various subsequent trials, in which you will perceive that we never again found so great a difference of temperature.

"Should you deem the above extract, from my private journal, of sufficient importance to merit insertion in your instructive and useful work, you will oblige me by placing it there; and, wishing you every success, I remain,

Farnham, Surrey,
May 2, 1832.

My dear Sir,
"Very sincerely yours,

"J. PRESCOTT."

45. ANCHORAGE OFF ASCENSION.

We are indebted to the kindness of John Bennet, Esq. Secretary to Lloyd's, for the following extract of a Letter from Captain Hunt, of the Ship Atlas, dated 19th March, 1832, off the Isle of Wight.

"The Island of Ascension being both convenient and safe for ships homeward bound, to approach, when in want of provisions, water, or repairs, and Captain Bate and the officers of that establishment most attentive and ready to relieve the wants of ships of any nation resorting thither, and their means to do so, and to render assistance, being superior to any other place between the Cape of Good Hope and the Ports in Europe, it is to be regretted that accidents so frequently happen to vessels touching there. In most cases I am persuaded they have occurred through a want of knowledge as to the position of the Rock and Reef, lying N. W. of the anchorage. The following notice, therefore, may prove useful to strangers who have occasion to call there, should your Committee consider it worth posting for general information :

"The anchorage off Ascension is in Sandy Bay, a prominent Rock, on which is a Fort, forming its western boundary. Ships may anchor in any part of this bay, in moderate depths of water, as the bottom is clear, and free from danger.

"Commanders of ships coming from the eastern side of the Island, intending to anchor or cruise off the settlement until they have obtained supplies, must observe, that no safe anchorage can be found to the westward of the Fort, (above named,) neither is the shore safe to approach within a mile and a half of it, to the westward of that Fort.

"The best guide to clear the Reef and Rock lying to the N. W. of the anchorage, (and on which so many vessels have grounded,) is to keep the Houses and Barracks open to the eastward of the Fort, and never to shut them all in with, nor open them to, the westward of the Fort, unless the distance from the land be at least a mile and a half. In the latter case they would be in great danger of striking on the Reef above-mentioned, the Spit, or Rocks of which, lie nearly a mile from the nearest point of the shore.

"A buoy, checquered black and white, is to be laid on the Spit. When this buoy can be seen, a vessel should never pass to the westward of it, unless her distance from the land be at least one and half mile. The sea does not always break upon this rock, but there is always a considerable swell passing over it.

"Ships approaching Sandy Bay from the western side of the Island, must be careful not to get nearer to the land than a mile and a half, until the Houses and Barracks be opened to the eastward of the Fort. They may then stand into Sandy Bay to their own depths, free from all danger.

"By attention to the above observations, it will be impossible for ships to meet with accidents, for on all other parts of the Island the coast is bold, and may be approached to within a cable's length."

46. DEPTH OF THE OCEAN.

"To the Editor of the Nautical Magazine.

"SIR,-The depth of the ocean is a subject on which many opposite opinions have been advanced; and, with the hopes of determining so interesting a problem, a few years ago I constructed a machine, somewhat resembling that by Mr. Massey, but differing from his, in not requiring the assistance of a line.

"The principal obstacles with which I considered that it would have to contend were sea-weed, tides, and under-currents, which latter might sweep it away from the place where it was sent down. However, regardless of these, I set to work, and completed the machine. My first experiments with it were made in shallow water; and, to ascertain its correctness, I attached it to a line that was marked. The results were most successful; and I was delighted to find it answer so well in my operations between Spithead and Cowes, for I invariably found the depth of water given by the machine, precisely the same as that by the measured line.

"After being satisfied that my plan was likely to succeed, I submitted it to the Admiralty, and to my friend Captain Mudge, who communicated it to a scientific friend of his at Woolwich. This gentleman soon after enclosed me an etched plan of the apparatus, with his remarks on it, informing me, at the same time, that the celebrated Dr. Desaguliers had made an attempt something similar to that which I had proposed, with a glass globe-but that, after various essays, he could never recover the machine. This he attributed to drift, or to the bursting of the globe from excessive pressure; but, as the trials had been made under many unfavourable circumstances, no positive inference could be drawn from them.

"The object I had in view could in no way benefit navigation, but was merely to ascertain the depth of the ocean. As some of your numerous readers might have time and opportunity for making the experiments, I beg to forward my plan, for insertion in your useful little work. The expense attending the construction of the machine is very trifling, and the loss of lead, which is used as a weight to sink it, is also of no consideration, when a question of so much interest is to be solved.

"The following is an explanation of the parts of the machine. See drawing at commencement of the Number.

A The vane and flys

B Two connecting swivels

C Perpetual screw

ID Plate for the wheelwork

ab Wheels of different diame.
cdters, similar to Massey's.
E Suspension ring

F Float glass globe

G Catch with shoulders

H Clasps disengaged by arms at
I Connected with the rod III

K Lead to sink the whole
L Foot to rod, in case of oozy
bottom.

"It will be readily seen, that when the weight is disengaged from the rest of the machine, by the opening of the clasps, caused by the rod striking the bottom, it will remain there, and the globe will carry the other part to the surface. "I am, Sir, your obedient servant,

"JOE SOUNDINGS."

We are much indebted to our ingenious friend for his communication, and have inserted his plan, not with the hopes of its being extensively useful, as that is physically impossible; but with the idea that it may lead to experiment and discovery.

175

MARITIME PAPERS, REVIEWS OF VOYAGES, &c.

I.-Sargasso Weed.

It is well known to seamen, and others who have crossed the Atlantic ocean, that a certain part of that sea is generally covered more or less with a particular species of weed, called gulf-weed, but the reason of its accumulating there, and its origin, have given rise to much difference of opinion. The gulf-weed, or Fucus natans, (which may be translated floating weed,) of botanists, is said to have been first met with by the early Portuguese navigators, when they extended their voyages to the south, in quest of discovery. It is related, that they found a part of the ocean, to the north and north-west of the Cape Verd Islands, profusely covered with it; and from the peculiar resemblance which the little nodules on it bear to a small species of grape, they gave it the name of Sargaçao, from their word sarga, the name of this fruit. From thence our term Sargasso is derived, and the part of the ocean in which it is found is usually called the Sargasso sea. The Sargasso weed is also familiarly called tropical grapes, from being found in the vicinity of the northern tropic, but it is most generally known by the name of Sargasso or gulf-weed. The Portuguese likewise complained that the progress of their ships was impeded by it, and that it was with difficulty they made their way through it.

Among the early navigators who mention the Sargasso weed, is the celebrated Columbus, as we find it particularly noted in his journal, lately published by Senor Navarrete. It appears

also, that the vast quantities of it which he met with, afforded his superstitious and terrified crew another cause of complaint, among the many which they urged against his continuing on his first voyage; for it is related by the son of this great man, that they were so much frightened by it, that they imagined they were among rocks, and endeavoured, without success, to obtain soundings. Their apprehensions of danger were still further increased, by the progress of the ship through it being impeded, and by their finding a living crab among the weed. It is also related, that Thevet and De Lery, in their voyage from Brazil, were fifteen days in passing through some extensive fields of it, which they met with near the northern tropic, and that they were obliged to cut their way through it.

These accounts of the early navigators are by no means exaggerated, being fully confirmed by modern observation. The difficulty, however, is, to assign the particular place of its growth, and to account for its appearance in such quantities, to the north

west of the Cape Verd Islands. On this subject, Sir Hans Sloane, in his History of Jamaica, affords us some information. This learned writer quotes several authorities for its being seen on the coast of Guinea, and near the Cape Verd and Canary Islands, as well as on the island of St. Domingo, in the West Indies; in addition to which, he met with it on the coast of Jamaica. He also asserts, that it is carried with the currents through the Gulf of Florida, along the coast of North America, in great abundance, where he has gathered it, and found it to contain small crabs, &c. This opinion is general among sailors, who also consider that it is carried out into the Atlantic ocean by the effects of the gulf-stream. The conclusion at which the above author arrives, respecting its origin, is simply, that it is very likely to grow as well at the Cape Verd and Canary Islands as among those of the West Indies, and that it is carried to sea by means of the winds and currents in several parts. This appears to be a very rational conclusion, and at once relieves us from the supposition that it grows at the bottom of the sea in which it is found, according to one writer; although it is by no means unreasonable to suppose that it may grow on one side of the Atlantic ocean as well as on the other. Mr. Purdy, in his valuable memoir and directions for the Atlantic ocean, defines the limits of the Sargasso sea, as an eddy situated in point of latitude between the regular equinoctial current, setting to the westward, and those easterly currents put in motion by the westerly winds, commencing a little to the northward of the parallel in which the trade-wind begins to blow,' which at once accounts for its accumulating there. The limits, however, within which it has been met with, extend from the parallel of 20° to about 40° of north latitude, but varying much in position, according to particular winds and currents.

Mr. Turner, in his British Fuci,' gives the following definition of the Sargasso weed. "Root an expanded, callous disk; frond from one to two feet long, composed of a slightly-compressed stem, not thicker than small twine; pinnated throughout its whole length with short, simple, subalternate branches, also filiform, and covered with a profusion of oblong or oblongo-lanceolate, midribbed leaves, their margins irregularly serrato-dentate, and their surfaces dotted with dark-coloured, mucifluous perforations, similar to those observable in F. serratus, vesiculosus, &c. whence what Reaumur considered the male parts of fructification exude. The length, breadth, and form of these leaves, is very variable; they are found, from almost oval to oblong and lanceolate; from

An assumption which is quite at variance with the known decrease of temperature at certain depths. But Mr. Purdy furnishes us with an instance of a bottle being found near the Azores, that had been thrown overboard in about the latitude of 39° north, and longitude of 65°, the very middle of the gulf-stream. Other instances of the same nature are, no doubt, on record, but the above is sufficient to justify the opinion of seamen, that it may be carried still further to the south-east, till it reaches the Sargasso sea.