TREASURE. LOST AND FOUND
Tram and again in Mr. Masters' book we are given exciting instances of human ingenuity, backed by vast mechanical resources, battling with natural difficulties. Could any- thing, for instance, be more thrilling than the repeated attempts to recover the million pounds' worth of precious metals sunk in the Lutine ' for over a hundred years ? The treasure has not yet been recovered, and still lies encased as in a safe by an enormous crust of corroded cannonballs under at least five feet of sand, at the bottom of the sea off the Dutch coast. At one time the divers got so near to the treasure as actually to bring up a lump of corroded iron with the impress of a gold ingot on it Or the attempts to find the even more romantic (but slightly doubtful) treasure sunk with the Spanish galleon in Tobermory Bay ?
But salvage operations are not always directed at the recovery of treasure in so concise a form as gold and silver ingots. Even wheat has been salved after immersion, and the water drained out of it through wire mattresses. Often, of course, it is simply the ship itself which is salved, and this was especially the case during the War, when so many ships were sunk or disabled by mines or torpedoes in weather which made immediate salvage possible ; and there are thrilling accounts of races against time to tow a sinking vessel to a beach where it could rest until it was patched and removed to dock.
But perhaps the most interesting chapter of all is that on the work of the deep-sea divers. For ingenuity and mechanical resources are not enough : the ultimate factor in salvage, as in nearly all aspects of the human struggle with Nature, is often the sheer physical endurance of one or two men. The physical strain of deep-sea diving is very great owing to the enormous pressure under which the diver has to work. As Mr. Masters puts it, to expect the human body to undergo strains three, four and five times greater than the body is built to stand is like expecting a motor- car designed for a load of 30 cwt. to carry a load of six tons. Of course, it would not be possible to withstand such pressure without counter-pressure, and divers breathe compressed air of a density sufficient to withstand the pressure from without. But the strain of breathing compressed air is itself very great ; and apart from the strain on the heart and lungs, it leads to a considerable excess of nitrogen in the body. The nitrogen is inclined to form bubbles in the blood, which, if they reach the heart, may cause death or. paralysis. While the pressure within and without the body is equal, of course, these bubbles do not form : it is when the diver is coming to the surface, and the external pressure is weakened, that they are apt to appear—just as bubbles appear in a soda- water syphon when the tap is opened. The only safeguard for this is to make the ascent from deep water extremely gradual, with continual rests, in order that the excessive nitrogen may be worked off from the lungs. At great depths, such as 400 feet, it is only safe to remain down for a period of twelve minutes. It will easily be seen why men of the necessary physique are extremely rare.
Only once, Mr. Masters points out, have all the celebrated submarine fights between divers of the cinema and novel originated in fact, and that was when two rival divers each claimed to have found first a cannon embedded in the sand. They fought furiously ; but being of very unequal physique, the smaller man endeavoured to escape. The other pursued him in a paroxysm of rage, and endeavoured to keep him down by the legs ; but finally they were both hauled to the surface, and history says that they became good friends ever after.
RICHARD HUGHES.
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