STEAM DOCKS AT DEPTFORD.-One of the greatest improvements of the present day, and the most important to the metropolis and its nobleTM river, is the projected magnificent docks for steamers at Deptford. There is no class of the whole community that will not feel the benefit of them, either in the avoidance of accident, the loss of life and property so common in the crowded pool, the saving of time and other inconveniences to merchants and travellers, and many other advantages which are too numerous to mention, but all of which render it most desirable that this important scheme should be carried into execution as early as possible.

ARIEL SHOAL.-New Zealand.-The following notice of a dangerous shoal off Poverty Bay, is important to seamen.

"A reef, even with the water's edge, and about twelve miles off the nearest point of land near Poverty Bay, has lately been discovered by the master of the Ariel, with the following bearings from the vessel :-middle of the reef, E. N. one and a half distance, Gable End Foreland, N1⁄2 W., Toto Muta, W. S. E. M. CHAFFERS, Harbour-master, Port Nicholas, New Zeeland.

Tasmanian Gazette.

SHOAL NEAR THE EQUATOR.-Captain Sprowle, of the Circassian, is stated to have seen a sand bank in the hollow of the sea, in lat. 1° S., long. 19° W., in the direct track of vessels to and from the South Atlantic. There are strong grounds in addition to this for concluding that there is some bank thereabouts. Our readers will no doubt remember the communicaton of Mr. Purdy in a former number of this work. (First Series, vol. for 1835, p. 641.) Some of the positions he alludes to come very near to that of the Circassian. We hope our seamen will be on the look out for this new danger, and transmit us any discoveries they may make concerning it.

PROCURING FRESH WATER FROM THE SEA.-We understand that this great object is at length in a fair way of being accomplished; viz. the supplying of ships with the entire quantity (of the purest kind,) of the daily consumption of water from the sea.

The process by which this end is to be obtained is so simple that there seems no reason to doubt its working on board ship equal to the full expectations of the projectors; and the produce of water in proportion to the consumption of fuel, has we learn been brought to one gallon for every half pound of coal, or twenty tons for one :-thus permitting the holds of our men-of-war to be disencumbered of water, and five per cent. of the weight thereof of coal carried in lieu.

We are informed that the process is founded upon an extremely beautiful idea, which it is most extraordinary should so long have escaped the notice of chemical and scientific men, being actually under the eyes of every body for many years; but certainly quite new, as extended and applied by the parties who have now brought the process to public notice, and who are Captain Sir J. Stirling, RN., and Mr. R. D. Middleton, lately a master in the merchant service.

We shall endeavour to obtain more particulars, and watch the progress of this most important measure, and communicate them to our readers.

CUMMINS'S MINERAL SYMPIESOMETER is an invaluable instrument to the mariner, as well as for mountain purposes. The fluid will retain its colour, cannot evaporate, neither will it congeal at a low temperature; the instrument is admirably adapted for carriage, it being very port. able is ready for use in a moment, without requiring any preparation; and is stated to be superior to any portable barometer yet invented. Another great advantage of it is, that the fluid is preserved without the assistance or inconvenience of a cork stopper, as in other instruments of the kind.

CHANNEL PACKET STATION.-Dartmouth and Falmouth.

SIR.-AS you have published the Report of the Commissioners appointed to decide on the comparative merits of the ports in the Channel, with reference to a Steam Packet Station, in your magazine, I am sure you will not object to call the attention of the authorities, and of the Commissioners themselves, to an error in their calculations, which may have materially influenced their decision.

As regards safety, they do not consider Dartmouth to be superior to Falmouth; they allow that Falmouth is provided with a lighthouse, buoys, &c., which must all be done at Dartmouth, at great expense, if the Packets are moved there; but they consider that a gain of two hours in time, warrants the change and the attendant expenses. The following is their statement of the relative distances of Falmouth and Dartmouth.

"If to Falmouth we subtract a difference in the sea distance of 47 miles, or in time six hours, and add 82 miles mail coach, or in time eight hours, leaves in favor of Dartmouth two hours."

Now that they have made a very great mistake in their mail coach distance a reference, to any road book will show. They calculate all their distances on the West of England to Exeter, through which city all the roads run. The old post-office distances are as follows:Exeter to Falmouth

101 miles

The Dartmouth distance can be reduced to thirty miles, if a new road is cut; but even then, the difference will be only sixty-seven miles, making an error of fifteen miles, or one hour and a half in time, in the calculation of the Commissioners, and leaving a difference of time in favor of Dartmouth of half an hour only, which half hour depends on the steamers always making eight miles an hour in all weathers, which is well-known they cannot do.

certainly is worth considering again, whether for a doubtful half

hour it is worth depriving a town of an old-established benefit, and going to the expense which must be incurred to make Dartmouth safe. I am, Sir, &c.,

Totness, 26th Nov.

AN OLD SUBScrieer.

Loss OF THE BUFFALO STORE SHIP-This ship was at anchor in Mercury Bay, New Zeeland, on the 28th of July, on which day it came on to blow a most powerful gale, and continued so for three days, Every preparation was made for encountering it by striking loweryards, topmasts, and letting go all the anchors; but, notwithstanding all these precautions, the ship parted from them, and by the coolness and good management of her commander, Mr. J. Wood, she was run ashore, and all her crew saved, with the exception of one poor unfortunate seaman, named Moore, and a boy by the name of Cornes, both belonging to Chatham. The ship is now high and dry at low water, on the beach, and is completely gone to pieces; and the crew were fully employed in saving what stores and provisions they could from the wreck. A great portion of the ship's company was at the time in the woods, cutting and trausporting timber; but on hearing of the loss of the ship, they went from Cooks Bay in an open boat, to the assistance of their shipmates, and in doing this they met with most severe weather, and were compelled to run into a creek to ride out a gale. At the date of the information, August the 6th, a ship was standing into Mercury Bay, to convey the officers and crew who had been encamped on the beach to Sydney, whence they would come to England. -Hampshire Telegraph.

LOSS OF THE SPEY PACKET.-Accounts have been received of the wreck of the Spey packet, Lieut. James, on her voyage to Havana, on the 24th of November last. The Spey, it appears, intended crossing the tail of the Great Bahama Bank, passing on it between Racoon Cay and Bonavista Cay, through an opening which had not fallen under the examination of our surveyors, instead of passing to the southward. Going at the rate of five knots, she was too fast on the reef to be got off with the utmost exertions of her crew. Happily no lives were lost, and, indeed, everthing of importance in the vessel was saved by the judicious and active measures of her commander.

NEW BOOKS.

POOR JACK.-By Captain Marryat.-Longman, London. 1840.

We can assure our readers that they will find Poor Jack a very pleasant Nautical companion, steering his course of duty through the sea of life beset with dangers and difficult navigation, starting from port in an obscure station, but by a careful attention to the helm and trimming his sails by the help of good advice and good example, he returns home to reap the fruits of honesty and good conduct.

PATCH-WORK-By Captain Basil Hall, R.-N.Moxon, London, 1841.

The high reputation of Captain Hall, which his peculiar style has long ago obtained for him as a Naval writer, is well sustained in the three very interesting volumes before us. There is indeed in them something of everything, every hue and colour of shreds and patches, but all forming a delightful and

and pleasing collection. We have not room to particularize, but shall snatch a leaf out of the Captain's book on some not distant occasion, and in the mean time recommend those who enjoy cheerful and animated pictures in narratives and descriptions to have immediate recourse to Patch-work.

SERMONS. By the Rev. W. Bennet, vol. 2.-Cleaver, London.

We do not sit in judgment on these matters, but having already recommended the first volume to our Naval friends, and finding the second no less to our own taste, we may say to them, "you may gain instruction from its pages, and rejoice over the 'message' it contains.”

PICTURESQUE VIEWS ON THE RIVER NIGER.-Sketched during Lander's last visit in 1832 and 1833.—By Commander W. Allen, R.N., F.R.G.S., &c. And sketched we may add with great taste.

There is a charm about these views imparted to them by the artist, and the subject which is particularly captivating. It is impossible to look them over but with feelings of deep interest, excited by reflections on the benighted condition of the African race, who, in the midst of the profuse luxuriance which Nature has bestowed on a large portion, (if she has been niggardly in other parts) of their country, are still the victims of blind superstition, ignorance, and barbarism. The views are done in the best style of the lithography of the present day, and form a be-fitting ornament to the drawing-room table.

THE FRIEND OF AFRICA.

This little periodical which appears to have been got up for the express purpose of announcing the progress of the civilization of Africa, gives a full account of the expedition about to sail for the Niger, and which we shall avail ourselves of in our next number. The opening address makes a strong appeal to its readers, and the small sum of one penny per week should carry it far and wide. There seems to be every probability of finding in it the latest intelligence of the expedition, as well as the most interesting accounts from central

Africa.

THE PRACTICE OF NAVIGATION AND NAUTICAL ASTRONOMY.-By H. Raper, Lieut. R.N., Secretary to the Royal Astronomical Society.-Bate, London. 1840.

(Continued from p. 895 of vol. for 1840.)

THE work before us commences with an introductory chapter, in which many elementary matters are explained, as are required by those who have only an acquaintance with the first rules of arithmetic. Passing over other matter, we would direct particular attention to the manner in which the raising of the trigonometrical canon is treated. The method used is simpler, easier, and will be better remembered, than what we find in the common books of navigation, where the student is directed to compare the side made radius to radius, an angle, to a side and vice versa. Here it is first shown under the head proportions,-how when four terms are proportional, three being given, the fourth may be found. The true nature of the trigonometrical canon being then demonstrated by referring to similar triangles, and the method of employing rightly the terms sine, co-sine, tangent, &c., being shown in a way that cannot well be misunderstood, it becomes almost impossible if the slightest attention has been paid, for the learner not to be now enabled to raise and solve the canons in the natural and legitimate manner, by comparing a side to a side, &c. We are not aware, that in all our reading we ever saw a subject better explained, and it is done too without any reference to pure mathematical knowledge. After having acquired this method, the common one which is generally given becomes very easy, and is likewise in a few words described to the reader. There now follows a passage in which the two methods are compared together, which we shall insert, not only as a specimen of the author's le, but to show what care is taken that nothing may be misunderstood, by se who have not the advantage of an instructor.

"Now, in the first place, the method proposed is more natural than the latter, because, when the two sides are taken together, their trigonometrical relation to each other is immediately perceived, which, when they are separate is not so apparent. Again, since the term sine or cosine is determined altogether by that side which we make radius, the term radius should, according to the natural progress of ideas, immediately precede the term sine, cosine, &c."Page 28.

After this introductory chapter, we come to what may be considered more peculiarly the object of this treatise. In general the cases into which the different sailings may be divided, are used merely as a vehicle for exercising the learner in plane trigonometry. That error has been avoided here, as every example which is given in the chapter which explains these matters, is a useful problem in navigation. We must not, however, thus hastily dismiss that part which treats of what is usually called great circle sailing. Most mariners are aware that this method alone gives the proper courses to be steered, in order to make most directly to any distant port to which the vessel may be bound; but it also shews something more. By this sailing, it may be ascertained how far a ship may deviate from her apparent direct course, in search of a wind, or from any other cause, without increasing the number of miles that she has to run, in order to reach her destination. Highly useful as this method of navigation appears, it has hardly ever been practiced, owing to the complicated form in which the rules have been laid down! Kerigan in his laborious work on navigation, published in 1826, has attempted to simplify the rules, but the directions which he gives are of too complicated a nature to be followed by the generality of seamen. In the work before us, all these difficulties are completely mastered, and great circle sailing is now rendered almost as easy as Mercator's. The plan which Lieutenant Raper adopts for solving the different cases by inspection is very short, and will be the method commonly used at sea. This is effected by a new and original table devised by himself, and will be hereafter of the utmost importance in the science of navigation. Without entering into any long account of this table, we shall only generally state, that by its aid spherical triangles can be solved much in the same manner, that plane right-angled triangles may be solved by the aid of what is commonly called the traverse table.

After the sailings, we have an excellent and original chapter on taking departures, in which the most accurate and useful methods of ascertaining distances from the land are clearly explained.

In that portion of the work which treats of nautical astronomy, no rule is omitted for any possible case that may occur, and the work concludes with a chapter explanatory of the proceedings that are necessary for the safe navigating of a ship; in short, pointing out the best manner of making a practical application of all the matters which have been previously treated.

Many of the tables are quite original. Table 3, which is entitled spherical traverse table, we have already alluded to as performing for spherical triangles all that the present common traverse table does for right angled triangles. This table will no doubt be very soon extensively used, more particularly if the author performs his promise of publishing it separately in a more extended form. After the logarithmic sines, &c., is given a table for interpolation, by which the seconds if required may be taken out at once. Table 61 is the log. sine square calculated to fifteen seconds of space, and six places of logarithms, and is used in all the rules given in nautical astronomy, the answer being always to be found in this table. All the tables used in clearing the lunar distance are so arranged, that allowance may either be made or omitted for the height of the barometer and thermometer. But it would be only trying the patience of the reader to proceed further, therefore, the last table to which we shall refer, is that containing maritime positions, although not placed last in this work, as it comes in its natural and legitimate order, immediately after the table of meridional parts. It has been too much the practice for authors to compile this. table, principally from such books of navigation as have preceeded their own, ENLARGED SERIES.-NO. 2.-VOL. FOR 1841.

T