Part 11 (2/2)
The maximum speed at which the _Argonaut_ travels submerged is five knots an hour, and when she has arrived at her destination--say a sunken coal steamer--the working party pa.s.s into the ”intermediate”
chamber, whose air-tight doors are then closed. A current of compressed air is then turned on until the air is equal in pressure to that in the divers' room. The doors of this close over india rubber to be air and water-tight; one communicates with the ”intermediate,” the other is a trap which opens downwards into the sea. Through three windows in the prow those remaining in the room can watch operations outside within a radius varying according to the clearness of the water. The divers a.s.sume their suits, to the helmets of which a telephone is attached, so arranged that they are able to talk to each other as well as to those in the boat. They are also provided with electric lamps, and a brilliant flood of light streams upon them from the bows of the vessel. The derrick can be used with ease under water, and the powerful suction-pump will ”retrieve” coal from a submerged vessel into a barge above at the rate of sixty tons per hour.
It will thus be seen how valuable a boat of this kind may be for salvage operations, as well as for surveying the bottom of harbours, river mouths, sea coasts, and so on. In war time it can lay or examine submarine mines for harbour defence, or, if employed offensively, can enter the enemy's harbour with no chance of detection, and there destroy his mines or blow up his s.h.i.+ps with perfect impunity.
To return the _Argonaut_ to the surface it is only necessary to force compressed air into the s.p.a.ce below the deck and the four tanks in the hold. Her buoyancy being thus gradually restored she rises slowly and steadily till she is again afloat upon the water, and steams for land.
We have now glanced briefly at some of the most interesting attempts--out of many dozens--to produce a practicable submarine vessel in bygone days; and have inquired more closely into the construction of several modern designs; among these the _Holland_ has received especial attention, as that is the model adopted by our Admiralty, and our own new boats only differ in detail from their American prototype. But before quitting this subject it will be well to consider what is required from the navigating engineer, and how far present invention has supplied the demand.
[Ill.u.s.tration: _The ”Holland” Submarine in the last stages of submersion._]
The perfect submarine of fiction was introduced by Jules Verne, whose _Nautilus_ remains a masterpiece of scientific imagination. This marvellous vessel ploughed the seas with equal power and safety, whether on the surface or deeply sunk beneath the waves, bearing the pressure of many atmospheres. It would rest upon the ocean floor while its inmates, clad in diving suits, issued forth to stroll amid aquatic forests and scale marine mountains. It gathered fabulous treasures from pearl beds and sunken galleons; and could ram and sink an offending s.h.i.+p a thousand times its size without dinting or loosening a plate on its own hull. No weather deflected its compa.s.s, no movement disturbed its equilibrium. Its crew followed peacefully and cheerfully in their s.p.a.cious cabins a daily round of duties which electric power and automatic gear reduced to a minimum. Save for the misadventure of a shortened air-supply when exploring the Polar pack, and the clash of human pa.s.sions, Captain Nemo's guests would have voyaged in a floating paradise.
Compare with this entrancing creation the most practical vessels of actual experiment. They are small, blind craft, groping their way perilously when below the surface, the steel and electrical machinery sadly interfering with any trustworthy working of their compa.s.s, and the best form of periscope hitherto introduced forming a very imperfect subst.i.tute for ordinary vision.
Their speed, never very fast upon the surface, is reduced by submersion to that of the oldest and slowest gunboats. Their radius of action is also circ.u.mscribed--that is, they cannot carry supplies sufficient to go a long distance, deal with a hostile fleet, and then return to headquarters without replenishment.
Furthermore, there arise the nice questions of buoyancy combined with stability when afloat, of sinking quickly out of sight, and of keeping a correct balance under water. The equilibrium of such small vessels navigating between the surface and the bottom is extremely sensitive; even the movements to and fro of the crew are enough to imperil them.
To meet this difficulty the big water-ballast tanks, engines and acc.u.mulators are necessarily arranged at the bottom of the hull, and a pendulum working a helm automatically is introduced to keep it longitudinally stable.
To sink the boat, which is done by changing the angle of the propeller in the _Goubet_ and some others, and by means of horizontal rudders and vanes in the _Nordenfelt_ and _Holland_, it must first be most accurately balanced, bow and stern exactly in trim. Then the boat must be put into precise equilibrium with the water--_i.e._ must weigh just the amount of water displaced. For this its specific gravity must be nearly the same as that of the water (whether salt or fresh), and a small accident might upset all calculations. Collision, even with a large fish, could destroy the steering-gear, and a dent in the side would also tend to plunge it at once to destruction.
Did it escape these dangers and succeed in steering an accurate course to its goal, we have up to now little practical proof that the mere act of discharging its torpedo--though the weight of the missile is intended to be automatically replaced immediately it drops from the tube--may not suffice to send the vessel either to bottom or top of the sea. In the latter case it would be within the danger zone of its alarmed enemy and at his mercy, its slow speed (even if uninjured) leaving it little chance of successful flight.
But whatever the final result, one thing is certain, that--untried as it is--the possible contingency of a submarine attack is likely to shake the _morale_ of an aggressive fleet.
”When the first submarine torpedo-boat goes into action,” says Mr.
Holland, ”she will bring us face to face with the most perplexing problem ever met in warfare. She will present the unique spectacle, when used in attack, of a weapon against which there is no defence....
You can send nothing against the submarine boat, not even itself....
You cannot see under water, hence you cannot fight under water. Hence you cannot defend yourself against an attack under water except by running away.”
This inventor is, however, an enthusiast about the future awaiting the submarine as a social factor. His boat has been tested by long voyages on and below water with complete success. The _Argonaut_ also upon one occasion travelled a thousand miles with five persons, and proved herself ”habitable, seaworthy, and under perfect control.”
Mr. Holland confidently antic.i.p.ates in the near future a Channel service of submerged boats run by automatic steering-gear upon cables stretched from coast to coast, and eloquently sums up its advantages.
The pa.s.sage would be always practicable, for ordinary interruptions such as fog and storms cannot affect the sea depths.
An even temperature would prevail summer and winter, the well-warmed and lighted boats being also free from smoke and spray.
No nauseating smells would proceed from the evenly-working electric engines. No motion cause sea-sickness, no collision be apprehended--as each line would run on its own cable, and at its own specified depth, a telephone keeping it in communication with sh.o.r.e.
In like manner a service might be plied over lake bottoms, or across the bed of wide rivers whose surface is bound in ice. Such is the submarine boat as. .h.i.therto conceived for peace or war--a daring project for the coming generation to justify.
ANIMATED PICTURES.
Has it ever occurred to the reader to ask himself why rain appears to fall in streaks though it arrives at earth in drops? Or why the glowing end of a charred stick produces fiery lines if waved about in the darkness? Common sense tells us the drop and the burning point cannot _be_ in two places at one and the same time. And yet apparently we are able to see both in many positions simultaneously.
<script>