SUBMARINE PERILS OF WARFARE

Dominion, Volume 7, Issue 2254, 14 September 1914, Page 3

SUBMARINE PERILS OF WARFARE

HARBOUR MINEFIELDS RUSHING A DEATH ZONE , (By G.N.G.) 11. The deadly mino _ has captured its unprepared victims in. the North. Sea, , and now the British Admiralty reserves to itself tiie ufuiost liberty regarding action against this new form of warfare." Well-swept tracks are being kept for commercial vessels. Usually sweeping is a 'method adopted for attack on minefields,' but it applies to the mine-strewn sea as woll. Sweeping is carried on with a length of weighted .rope stretched botween two boats, usually launches or cutters. The rope is allowed to drop down near the bottom, and the boats drift down with the ticlo. Anytirng caught is raised. Cables or the lilw are cut, and mines are exploded—mines aud tho like This operation is very slow, and must be carried out in daylight. It is impossible' under, fire. Tlio British fishing fleets are possibly, being used with their nets to sweep a clear course. Dragging a grapnel or ''creep" along the bottom, so as to catch cables or ground mines,, is another, method of cleaning up. Anything caught is lifted, examined, and cut: if this is impracticable, tho "creeps can be fitted with au. explosive charge, which is iired when any object is' grappled. "Creeps" must be towed' at a, very slow rate, ( and the', work at an* enemy's harbour mine-field could only be done under ocver of. darkness. Another trouble is the uncertainty *as to what; has been cut, and whether any area covered by mines has- been thoroughly cleared. Counter-mining is the explosion of hostile charges in .the mine-fifcld with the object of sinking or damaging mines or cutting cables. Charges of 5001b. of guncotton would be placed 180 feet apart, a line of twelve mines : being; fire 3 together; To clear, a dhannel of sufficient width, two such lines would be laid side by' side., .ill 1 such;'attacks "on. the: minefields as describ6d'would fail'if;proper watch was. kept, .unless, of course,' the fort's pf the harbour' were silenced. Possibly some attempts' would be made to cut the,main of "tho. field at or near the''shore'ends: -That and the minefield would'be defended by gunfire, assisted I .at 1 '; night .by./searchlignts, covering the minefield its approaches. ' Long' lengths" of unserviceable cable, moored by old oinkers, round and over the position of: mines and'cables is a defence". '•'' 'The > strength > of • all minecases and apparatus has been carefully planned to resist' counter-mining, but all screws and fittings must be tightly screwed up, as loose parts are apt to fly off' under, the influence, of neighbouring'explosions. . Rushfng a Minefield. If an enemy's Dreadnought wished to attempt a' "rush," how long would she be under fire, ' say,; in rushing : Port Nicholson? .From the time the rushing monster was under fire until she was Touhd into -the harbour, not more than two minutes would elapse. The attack would more than likely be at dirty; one at that. Would two' minutes give' sufficient time to stop that rushing armoured mass ? With the' minefield; greater -security would be given. Even with;"a^"reckle'ss' ; irtvaderi : "the ,leiplosion of a single mino under her would'so'hamper th'e'b'est 'vessel afloat that the forts would have more time :to get hits in.-..%Why do without a minefield P Germany and Austria were keener over "submarine mines when other nations scrapped theirs, and thousands of pounds of valuable instruments connected with that service, in .preference for the submarine vessel. Submarine mines will play a ,big part in this war.

Watch a Dreadnought rushing 'a minefield. The scene-is the North Sea. J.ust before dawn, on a howling wintiy'day, a, grey mass slips out from the raincovered coast,';,'in the vicinity of the Kiel Canal. .;;She is ipreceded by two destroyers .; They partly - cross their ; own' minefield, which, by the way, is inot'-a "mechanical"' field, bit electrocontact. The .disadvantage of the latter class of mine, is seen by one of the destroyers being pulled jup : short,' having fouled a mooring line or cable of one of the i mines,- and has snapped a blade' from her propeller. She cuts the gear away, drops a buoy -with sinker attached, Co mark the spot, so that the repairing, party can-attend to it, and boats change direction, going out' by'• the "friendly channel," which .•is.-' guarded by .'ground mines. . They should have done so' in the first instance.

Then comes • the rush, all speed is crammed on —they are out to sink some of-the British vessels before being discovered. But they have to cross an unknown minefield, composed possibly of the perfect mechanical ,mino. The mines will be so laid—those first crossed deeper down than the succeeding ones —that the lighter draught destroyers will have advanced -well into the minefield.before the biggest boat has struck a mine. If the fields are composed of electro-contact minis', controlled from the test-room of a vessel or a fort, then there would be something more to tell. As the three 1 rush the minefield, no matter what their- speed, destruction awaits them. Fire Station in Aotion. The test-room ,or fire station is buried away out of sight, in a most secure position. One looking into it is puzzled at tho sight of many rows of leads- or insulated wires that. run to shutters, batteries, and instruments. Some are painted black (noii-dangerous), but tho red ones oarry the death-dealing current of electricity. The olficer in charge receives.information as to what is going on outside from the ' observation station. He may bo given instructions to make the field "active," which means that the mines will fire on being struck; dl - he may await orders as to firing. It is essential that tho tester should bo cool-headed. Suddenly, the enemy, coming at tho rate of thirty knots an hour, is discovered. Tho fire control officer or tester is 'anxious to get the lot, and possibly may, allow them to advance well over th© trap. They tell their story in the test-room as they speed over the first lino of mines. One of the ships strikes.a mine.in that line and immediately a shutter drops, rings a bell showing the group in which is the exploded mine. Tho tester allows them to advance further, but by pressing a key'sends a reversing current to tho struck mine, which puts tho apparatus in order again ready to repeat tho dose..

"Bumping" a Mine. When a vessel bumps a mine the jar disturbs an inertia ball, attached to a frame of tho apparatus by, a spiral wire. Through the ball runs a strong silken cord, 0110 end of which is attached to tho top of tho fixture, and the othor to the end of a flat piece of iron, called an armature. This armaturo_ runs through an induction coil, and is pivoted at tho centre, s o that when tho ball swings,, the cord is pulled, and 0110 end of tho armature rises, whilst tlio other falls upon a small metal stud, bridging tho gap, the vessel's bump completing the circuit. Tho tester presses his reversing key, and tho current leaves the battery at tho testroom, runs along through cables of fuses, taking the shortest route to tho apparatus of the mino struck. Whoii it reaches tho Rt.iifl it forces the arma-

tur-o up, passes along to the part that is in connection with the mine case, and back through the water to the earth-plato close in shore, that being in connection with the other polo of the ■ battery by cable.' Tlio induction coil that surrounds tho armature has a magnet that keeps tlio armature up, as it were, wheii the firing circuit is opori, but when the cord pulls the armature down from its normal position, a magnet at the bottom attracts it, and holds it in position 011 the stud. Then tho firing circuit is completed. It is well to know that only the firing battery is strong enough to fire the mine. Again a. shutter drops, a bell rings, and the tester sees that a mine in t'ho second lino "has been struck. Ho has been advised • that all the vessels are 111 the danger zone, so he immediately presses the firing-key, and instantaneously the mine explodes. The firing-current rushes forward ;as tho other one did, explodes the two detonators, and these detonate the dry discs of guncotton,' into' which they are inserted. This causes the whole ■ charge of wet gun-cotton to be fired. ' ,

The vessel receives the shock in her most tender spot—underneath. Tliero has been 110 warning.. She is disabled, and is at the mercy of .the guns of fleet or fort. .■ A Dreadnought worth from two to three millions of money is put out of action by a mine costing very little. ' Water-tight compartments havo been quoted as a safeguard, but with an explosion of gun-cotton, such is the shock that nuts and bolts are started in tho machinery of tho engine-room, and in the gear arrangements of the guns. The remaining boats continue their rush. The .searchlights are full upon them, and it is only a matter of a\fow_ moments of life, for them. The order is given for all mines to be made active, or possibly a section only. By inserting one plug the whole field becomes active, or firing-plugs can be inserted for any sections that .the boats come to.' The action 1 of bumping any mine causes their destruction, and the "tell-tale" records it. in the test-room.

The last boat flees in .desperation, parallel to the lines of mines, and by good luck strikes the "friendly" channel. Here ground mines are laid, say, four mines, each of 500 pounds of guncotton. Alignment, poles, or the finder, tells when a ship is; oyer a. line of' such mines, and then the whole line is fired at oiice ; from the test-room. Her destruction is certain'. Just such a mine was orice fired alongside a rock, at'a depth of thirty feet, in the Wellington Harbour, and a huge column of water was raised, over 500 feet in height, whilst a deep' ' hole was . loft where the rock had been. . . The Mine Men. The attack over, the arrangements of the royal engineers or submarine miners are such that new mineß can bp quickly l placed in tho position of those,exploded, The_ tester or electrician in a submarine mining corps has to bo something more than the ordinary electrician, as he is known in electric lighting quarters. He must' have a good knowledge of algebra and logarithms, as well as trigonometry, mensuration, and general surveying. He has to deal with most delicate and sensitive instruments in the testing of cables, detonators, and apparatus. Electric batteries of several kinds come under his caro, and he has to test the mine cases for water tightness by hydraulic pressure. Electrical and hydraulic tests have also to be taken of all 'apparatus to see that there are no faults, _ and that all washers make a water-tight joint. Besides, lie must know the ground work of the submarine miner as'his A.8.C., find must be an expert in searchlight, range-finder and dynamo'duties.