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COURT-MARTIAL ON MR. GORDON.-The following was BrigadierGeneral Nelson's note on the finding of the court-martial in Mr. Gordon's case: Approved and confirmed. Moreover, I fully concur in the sentence awarded; such being fully borne out by the evidence. The prisoner to be hung on Monday next, the 23rd of October, 1865; to-morrow, the 22nd, being Sunday, and the state of this part of the country not rendering it necessary to inflict the punishment on the Sabbath-day.-A. A. NELSON, Brigadier-General, Commanding Field Forces.-Morant Bay, Oct. 21, 1865, 8 p.m." Gordon was tried on Saturday, the 21st of October. The court closed their proceedings the same evening. The evidence was early the next day forwarded to the general, together with the finding of the court, which had been approved and confirmed by Brigadier-General Nelson, the officer in command of the district. On Sunday, about one o'clock, the same was received by the general at head-quarters, who read it to the members of the executive cemmittee. Immediately afterwards it was forwarded by express to his excellency the governor in Spanish Town.

EXTRAORDINARY VOYAGE. Every yachtsman (says the Dublin Express) will share in the pride with which a correspondent relates a brilliant, and, we believe, unexampled exploit which has been per. formed by a small yacht of only 25 tons, which is not a stranger to the waters of Dublin Bay. The gallant little craft set out from Liverpool for the antipodes, and arrived safely in Sydney after a splendid run, performing the entire distance, 16,000 miles, in 130 days. Such an achievement affords grounds for reasonable exultation, not more as a proof of the nautical skill of our amateurs than of their adventurous spirit, which quite casts in the shade the most daring feats of Alpine climbers.

New Books.

CAST AWAY ON THE AUCKLAND ISLES, &c. From the Private Journal of Captain Thomas Musgrave. London: Lockwood & Co., Stationers Hall Court.

Such is the title of a little pocket volume, carefully and neatly got up, and edited by a gentleman, Mr. John Shillinglaw, not unknown to the pages of our work, and who has produced a most interesting and, to a certain extent, useful little book. We should characterise it as one of adventure, suffering, hairbreadth escapes, and amusing as well as instructive observation-one that has certainly rendered those miserable, solitary spots on the stormy ocean to which they belong as less unknown than they were, along with the periods when seals are available to the shipwrecked mariner as food, and the curious migratory habits of those animals. Had Capt. Musgrave been a solitaire in his troubles, we should have compared him with Robinson Crusoe, to whose strange adventures Capt. Musgrave's experience had a remarkable affinity. It will prove a fund of amusement to any juvenile aspirant for the sea, who will pore over it with delight.

CHARTS AND BOOKS PUBLISHED BY THE HYDROGRAPHIC_OFFICE, ADMIRALTY, in March, 1866.-Sold by the Agent, J. D. Potter, 31, Poultry, and 11, King Street, Tower Hill, London.

44.-Ireland, East Coast, Drogheda to Carlingford, R. Hoskyn, Master, R.N., 1858, (2s. 6d.)

189.-Sicily, West Coast, Trapani to Marsala, Lieutenant Wilkinson, R.N., 1864, (28.)

251.-Africa, North Coast, Cape Carbon to Fratelli Rocks, Lieutenant M. A Bérard, F.Í.N., 1836, (1s. 6d.)

637.-Newfoundland, West Coast, Little Port and York Harbour, French survey, 1851-63, (2s.)

2,545.-America, West Coast, Monterey Harbour, &c., Anchorages, United States survey, 1857, (1s. 6d.)

961 DE m = = 10.-Basilan Channel, Captain Sir E. Belcher, R.N., C.B., 1847, (2s. 6d.)

2,413.-East Indies, Rhio Strait, Dutch survey, 1863, (2s. 6d.)

2,577.-Philippine Islands, St. Bernardino Strait, and parts adjacent, Spanish charts, 1863, (2s. 6d.)

911.-Banda Sea, Cajeli, Saparvea, and Amboina Bay, Captain Sir E. Belcher, R.N., and Dutch surveys, 1840-47, (1s. 6d.)

2,407.-Russian Tartary, Tumen-ula River, Gaidamak Harbour, Eastern Bosphorus and Novik Bay, Russian survey, (2s. 6d.)

741.-Fiji Islands, Nairai and Mbatiki Islands, Captain Denham, R.N., F.R.S. 1856, (2s.)

Jersey Island Pilot, 2nd edition, Staff-Commander Richards, R.N., 1865, (1s. 6d.)

Hydrographic Office Notice, No. 1, Rocks off the S.E. Coast of Tanega

Sima.

EDWARD DUNSTERVILLE, Commander, R.N. Admiralty, Hydrographic Office, 21st March, 1866.

FRESH WATER FOR SHIPS.-Our readers are aware that some time last year a new pier was opened at Deal. It is constructed entirely of iron, and is 1,100 feet long, 25 feet wide, having a T shape; the head being 120 feet long and 50 feet wide, and affords every facility for communication with ships in the Downs. It appears that ships are now supplied with pure fresh water from this pier into the ships' casks, at any state of the tide, and at a very moderate cost.

TO CORRESPONDENTS.

We have received the letter from our old subscriber R. L. H.-not so useful a communication as those to which we were accustomed. Referring to the Duncan Dunbar's wreck, he will see our opinion of that wreck in our January number, pages 20 and 21, long before that of the Admiralty Hydrographer was given, and which seems to affront him sadly. Our remarks in the February number, to which he alludes, had reference to those of the Hydrographer, confirming what we had already said,-so that we, too, must endeavour to survive his disapprobation. As he alludes to our opinions on marine insurance, he will find a letter in this number, page 220, on the London which exactly confirms those opinions.

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REMARKS ON MR. HOPKINS' LECTURE ON THE COMPASSES OF IRON SHIPS.

According to the lecture of Evan Hopkins, C.E., F.G.S., &c., the long-sought problem of the Deviation of the Compass has been solved. What the most sanguine had almost despaired of seeing accomplished appears to be already realised. The announcement will be received with delight and thankfulness by all maritime nations; many a shipmaster will acknowledge the boon when he recalls to mind the anxious nights of watchfulness he has spent with doubtful compasses on the foggy shores of North America, in the neighbourhood of the coral reefs of the vast Pacific, or the partially surveyed groups of the China Sea. Until the fact is, however, positively established, I shall take the liberty to examine some of the premises advanced, both theoretically and practically, as I plainly perceive difficulties which Mr. Hopkins appears wholly to have disregarded.

1.-I doubt the power of the strongest battery to permanently destroy the polarity of such a complicated mass of iron as that which composes an iron ship; and when it is proposed to screw two powerful magnets on the bow and stern, it is simply upholding the theory which the lecturer wishes to annihilate.

2. The efficacy of elevated compasses has long been questioned by many; and there is a growing prejudice against their use on board steamships. Any one may remark this who visits one of our great maritime ports. Mr. Hopkins says that an elevation of 10 to 20 feet raises a compass beyond the disturbing influence of the iron hull. I can assure him that at 17 feet above the deck beams, in a steamer NO. 5.-VOL. XXXV. 2 G

without bulwarks, I have known a tripod compass 6o in error. Again: in a wet dock, I have remarked a compass card stealing slowly round under the influence of the attraction of a passing iron ship. If 20 feet is the extreme distance at which a mass of iron will attract the needle, why is so much care used in removing the ship to a considerable distance from any object which is built of iron? The man who would swing a ship for deviation when surrounded by such would be looked on with suspicion by competent judges.

I think it was the late Capt. Johnson who related an anecdote about a dockyard craft which, on her passage to Milford with water-tanks, found her compasses perfectly useless. The hold of this vessel must have been more than 20 feet from the binnacles.

Another grave objection to the use of elevated compasses is the increased wear of the pivots and caps; and when running in a heavy sea, their vibration becomes excessive, frequently swinging through an arc of several points.

3.

The lecturer must have been misinformed when he states that the steering compass is relied on to such a dangerous extent. In all ships of note the course is given from a standard, and referred to the steering by comparison. Doubtless, in coasting steamers, where men are constantly plying between the same ports, the steering compass may be frequently used to give the course, after those in charge have assured themselves by frequent runs of the exact bearing of their port.

Sluggishness is a defect in compensated and uncompensated compasses, depending on more causes than want of elevation. I have also frequently observed it in light weather on board of ships built of wood in the ordinary binnacles. Many of us have seen an old quartermaster attaching a twigging line to the bowl. After many years of voyaging in all classes of ships, I can safely assert that I never saw the "watch" employed in "hammering the binnacle."

4. The dumb card has long been in use, and for ships on distant voyages, when strictly attended to, is of occasional service; but on nearing land the course is so frequently altered, sometimes by hand, that it fails to be of service when most required. Mr. Hopkins attaches undue and exaggerated importance to the man at the wheel: that useful and necessary individual has really nothing whatever to do but to keep the ship on the course indicated, and if officers did not pay proper attention in ascertaining that the correct course was given to each "relief," mistakes would occur as easily with a card as large as the dial of St. Paul's as they do now with the ordinary one.

5 and 6 have long been acknowledged as highly advantageous.

I shall now make a few quotations from the lecture, and endeavour to answer some portions of it.

Page 182.-"Mariners are well aware of the difficulty in applying to the deviation either mechanical or tabular corrections; the most careful and experienced navigators place no reliance whatever on either of the methods now practised."

This remark casts a slur on the great astronomer who founded the science, by whose aid our ships have for a quarter of a century been

carrying English commerce over overy sea, increasing the national wealth and maritime power in an enormous degree. By one or the other of the above-named means of correction (nearly always the former) our iron mail boats dash over the stormy Atlantic through fog and dangerous currents with all but the regularity of a mail train. If they are a few hours after time, men anxiously speculate on the cause of delay; a day or two sends the premium of insurance up. With these facts before us, no one can assert that, when properly applied, these corrections admit of no confidence being placed in them. The error lies more at the door of those who, although armed with full powers, allow ships to proceed to sea with inferior compasses, badly adjusted or incorrectly tabulated.

Page 182." There are two modes now practised for correcting the deviation, each of which is considered to have its advantages and disadvantages; but, excepting for ships making short voyages in the same parallel of latitude, both methods are regarded as mere temporary corrections; and, even when confined to the same latitude, they can only be depended upon for a very short time, owing to the rapid changes taking place in the polarity of iron vessels."

After carefully watching the changes of magnetism which take place in iron ships, I have come to the conclusion that after a few voyages it never varies suddenly to a dangerous amount in an uncompensated compass; on the contrary, I now hold a register of deviations for several successive voyages of a steamship, which differ very little from each other when running down the same track.

The heeling error is the most dangerous, as it is the most difficult, to guard against. With a varying force of wind, or much rolling motion, no reliance can be placed on a deviation table, even when the upright error is small. In a ship built with her head N.W., on the N. and N.E. points, with the compass 30 feet from the stern and elevated 10 feet above the poop beams, I found the alteration 11° to 13° for each degree of list on the starboard tack. No opportunity occurred of trying the same points on the port. On the S.E. points on the starboard tack the errors were equally large.

Page 183.-"If a compass be surrounded by fixed magnets, or even by ordinary iron, it becomes absolutely useless as a guide."

This paragraph is rather ambiguous. If the lecturer means that a compass hedged in with magnets, or placed in the centre of an iron turret for experiment, becomes useless as a guide, I agree with him; but no man would attempt such a course in practice.

A little further down in the same page are charges of inconstancy of purpose against Messrs. Evans and Smith, of the Compass Department of the Navy. When these lines were penned, turret and plated ships were probably not in existence, for I have not read the article; its date is therefore unknown to me. Circumstances alter cases, and with new elements of difficulty to contend with, these gentlemen found what others had found before them,-viz., In some cases compensation is absolutely necessary; a compass ten or twelve points in error is quite useless for all purposes of navigation.

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