THE HARBOURS OF NEW ZEALAND.

5

A.—No. 4

guns, but are riot equal to them in endurance. Of the old Armstrong breech-loading guns, I should prefer the 40-pounder to any of larger calibre, for the larger guns are not to be depended upon, owing to the breech piece not being sufficiently strong. Gun Carriage. — Moncrieff. —To insure the full benefit of these guns, they must be mounted on the Moncrieff carriages, or some other contrivance on the same principle. The advantages gained by this method are too obvious to require noticing; the principal one for our purpose being the great economy introduced in the construction of forts, owing to the very small risk the guns run of being dismounted by the enemy's fire. Mounting Battery Guns. —Mr. Menere, of Melbourne, appears to have invented a method of mounting battery guns which he says is superior to the Moncrieff in the following particulars :— 1. It does away with cog-wheel action. 2. The gun rises 6 feet, which is more than the Moncrieff. 3. The carriage can be manufactured in the Colony, and can be more readily repaired when disabled. 4. It is cheaper, more effective, and more easily managed. 5. The recoil is not so destructive to the platform. 6. It is capable of being rapidly removed from one pit to another. Prom the meagre account given in the Melbourne Herald it is impossible to form an opinion as to the merits of this invention, but I will make a few remarks on some of the points on which superiority is claimed: —■ 1. The only cog-wheel actions in the Moncrieff carriage are, I believe, that used for the pawl to drop into when the gun descends, and those used for training; and, according to the published accounts, they are not in the least liable to get out of order, having been subjected to the severest trials that the artillery officers could devise. 2. I am not, of course, personally acquainted with the Moncrieff carriage, but according to published accounts the gun rises from 12 to 15 feet above the ground, or from 8 to 10 feet above the loading position ; and I think that the statement of the Herald that it only rises its own diameter is quite incorrect. 3. I do not understand why the Monerieff carriage cannot be made in the Colony. 5. That the recoil of the gun destroys the platform Ido not believe. Experiments with small guns have been made upon ice, without any perceptible slipping of the carriage; and I think that any one who is acquainted with the great caution with which any new invention is introduced into the British Service wili not be inclined to credit a statement so wildly put forward. 6. I can hardly believe that a carriage sufficiently strong to stand the recoil of a heavy gun can be rapidly removed out of a pit 10 feet deep. I therefore do not feel at all confident that Mr Menere's invention is superior to that of Captain Moncrieff; nevertheless it might be worth while to obtain more precise information about it. Comparative advantages of Torpedoes and Guns. —The greatest advantage that can be claimed for torpedoes is, that they are capable of destroying, at one blow, the strongest ship yet built. That torpedoes are the cheapest and safest defence against a fleet of ironclads no one can doubt, and they also have the advantage of being much more easily extemporised than guns; but their great fault is that the expense is the same, whether the harbour is to be defended against one or a dozen ships. This does not apply to the Harvey torpedo, which is only used where required. Guns once in position entail no further expense ; but torpedoes would have to be placed long before they were wanted, and during this time sailing ships and steamers would be constantly passing over them, and would probably often damage them. My opinion therefore is, that against an attack by wooden ships, rifled guns would prove superior in defence to torpedoes ; but that when a port is closely blockaded, the addition of torpedoes would prove of great service, but not otherwise. We must also remember that moored torpedoes of whatever kind, but more especially self-acting ones, would bo of little use unless moored within range of guns, for if they were unprotected there would not be much difficulty in fishing for them with boats, cutting the wires, and raising them, so that in all cases guns would have to be used; and I think that, for tho object we have at present in view, a few rifled guns, combined with the Harvey torpedo, would protect the JN Tew Zealand harbours far more economically than any attempt to defend them by means of stationary torpedoes. The Harvey torpedo can, I believe, be obtained from Mr. W. Kunn, St. George's Street, London Docks, who is a part proprietor in the concern. Danger from Boat Attacks. —The greatest source of danger to land guns is from a land attack. Where guns are at some distance, and unprotected by a garrison, a sudden landing by boats could be easily effected and the guns captured before any resistance could be offered. This is particularly the case in this Colony, for we have no permanent force to garrison them, and volunteers could not be expected to be always on guard. I would therefore recommend that a small force of artillery be applied for from the Home Government; and as the defence of the Colony is now left entirely to the British fleet, I would suggest that this force should consist of Marine Artillery, under the command of the senior naval officer on the station. Pact II. — Defence of Auckland Harbour. The harbour of Auckland is approached by two channels, one between Eangitoto and the North Head, the other between Eangitoto and Brown Island. Close to the point where both these channels and the harbour meet, lie some low rocks, covered at high water, called the Bean Rocks. There can be no doubt but that these rocks form the most important position in the defence of the harbour. Not only would all ships approaching the harbour be exposed to a raking fire, from a battery placed on them, from the time they first came within range of its guns, but they would have to pass within 800 yards of it before they could enter the harbour ; and even if they succeeded in passing it without being sunk, there is no part of the harbour in which they could be sheltered from its fire. Its guns would also flank