THE SUBMARINE.

Auckland Star, Volume XXXV, Issue 94, 20 April 1904, Page 4

THE SUBMARINE.

It seems now pretty certain that the Petropavlovsk was the victim of a submarine mine laid by the Japanese. The appalling power of this engine of war has been very fully demonstrated in this struggle at Russia's expense. ■ The submarine is a weapon ' dangerous to enemy and friend alike— r all the more so when used in the way adopted by the Japanese at the entrance to Port Arthur.. When we see the destruction

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wrought by an accidental contact with one of these mines we are able to realise in some measure their terrible dcadliness when used in defence works under modern, scientific methods. There are various kinds of submarine mines, suitable to the characteristics of different stretches of water. Some are caused to explode when in contact with

or close to a vessel; others act at a greater distance. Some, again, are under control, while others once they are laid down act automatically. What are called observation mines are fired by electricity from the observing station. Controlled electro-contact mine* are fired when a hostile vessel by striking them gives notice that it the mine. Uncontrolled, mechanical, electromechanical, or chemical mines explode when struck"* .* Dormant mines are those sunk and attached to the bottom, as seen in our I illustration. On the approach of a hostile fleet these mines can be caused to rise and obstruct the fairway by simply pulling at the cable to which they are attached. «■ * Less than 501b of gun-cotton or dynamite contained in a case without any air space will suffice to fatally damage the. double skin of any modern ironclad if exploded in actual or very close contact. At the same time it must be. noted that widely divergent conclusions" have been arrived at as to the pressure required to destroy a first-class battleship. It is computed that a mine charged with 1001b of dynamite would, blow up a vessel 16ft away, or, if directly over the mine, at a depth of 18ft. Our navy uses gun-cotton to charge mines, and according to a French authority 5501b of that explosive has an effective range horizontally of thirtynine feet and vertically of fifty feet. The air space necessary to render the mines buoyant does not, in the larger mines, lessen their destructive power. In all buoyant mines it is highly advisable, however, to use no larger charges than are absolutely necessary, the best being those containing a thoroughly effective minimum charge. Electro-contact mines are so spaced that there is not much danger of their fouling one another when acted on by eddies and contrary currents. They

must he so*spaced that when one is 1 exploded it will not cause adjacent mines to signal as if struck by a vessel, for that would cause them 'also to be exploded, and thus the whole electrocontact mines in one group might be fired all at once when only one of them ought to explode. Ground mines, with detached circuit closers, are possibly the most formidable forms of submarine defence. Their usual form is a cylindrical case, generally charged with 5001b of gun cotton or dynamite. In water of eighty feet in depth a ground mine requires 15401b of guncotton to be fatally effective. In several exploded mines, however, guncotton has been found only partially burned. Guncotton, by the way when teased out, may be lighted on the palm of the hand, but when compressed its effects are terrible. , When the water is too deep for ground mines large buoyant ones are used. These are securely anchored by dead-weight sinkers; and so cannot .shift their positons. They require to be very carefully laid down, for as an authority naively puts it, " it is a serious thing when mines walk about with their sinkers and take up new positions which they arc uot intended to occupy." . It is, in fact,Nrae of the most difficult of all problems of harbour defence to arrange a mine system that will absolutely stop an enemy's vessel at any,

time and in all weathers and yet not interfere with the passage of friendly vessels. Mines are really at their best in absolutely closing up narrow waterways to all traffic. Submarine mines are usually placed checker wise in rows and groups at varying depths. When a. channel is broad the mine area Is controlled partly from one side and partly from the other. •!••,-. The firing room of a mine station is an electrical maze of mystery. All the cables from the mines are brought in, and the end of each wire is separately connected with the firing key and separately labelled. In the hands of an [intelligent officer the keyboard is a vertiable death-dealer. The one essential to a successful mine defence is secrecy, and that is'-wEy the marine sappers and miners of various countries conduct bogus mining operations for the special benefit of spies who swarm in the neighbourhood of the ports and dockyards. In the case of war, the real mines would be secretly laid in very different " fields," and so complete is the system in Great Britain, and so perfectly trained are the men, that the boldest commander afloat would never dare to risk his vessel amid a network of such terribly destructive entanglements as a well-laid field of live mines,

controlled from a. properly protected station on shore. Most of our larger ports in New Zealand are so placed thatthe waterways leading to them are capable of being mined so as to render close approach of any hostile craft next to impossible. Auckland.is probably, the worst situated in. this particular. "A certain foreign Government'is credited with having adopted a system of submarine defence the- principle of which is illustrated herewith. An endless' chain is stretched around four posts,set in blocks of stone in the bottom of the threatened harbour. These stones form the four corners of a square. At regular intervals along this chain' are cables holding torpedoes/ These float below the surface of the water at exactly the depth at which they would strike the vulnerable bottom of a ship. About sixteen torpedoes would be used on one chain. English experts, however, think little of the scheme. The most approved method of an obr servation mine is where the officer has the assistance of a camera obscura, as shown in our illustration. At the top of this hidden hut arrangement is a lens which admits the only light in the place. Beside the lens is a mirror, which reflects the image of any vessel in the bay." At the table the officer is sitting watching a man on which the light is streaming from above. On this map the approaching vessel is reflected, and the officer whenever the vessel sails above a mine presses the key on the switchboard by his side and the vessel is blown to atoms. His chart, of course, is marked with crosses, each cross showing the exact loca-' tion of a mine, and "when the reflection of a vessel approaches a cross he knows it is time to act. , , -._,.., _- t j iw j' •-