EXPERIMENTAL CARGO-RECOVERING SUBMARINE
This vessel was built in 1899 and experimented with in 1900, to demonstrate the practicability of transferring cargoes from sunken vessels to submarine freight carriers. (See text.)
The crucial feature of diving operations lies in the time required in decompression, which, if held within the limits given by Fleet Surgeon Mourilyan, would practically limit diving operations to half the present depth of submergence and greatly increase the cost and the time demanded for such undertakings. Strange as it may seem, the human body will stand an immense amount of compression, but the greatest care must be taken to make the recovery to normal a very slow and deliberate process. Doctors Leonard Hill and Greenwood, of the London Hospital Medicine College, have conducted a series of scientific investigations regarding the physical limits of a normal man to compression without risk of strain or ultimate injury. Remarkable as it seems, they have shown that it is possible to submit to a pressure of seven atmospheres—the equivalent of a submergence to a depth of two hundred and ten feet, a depth considerably in excess of the best diving records up to the time of their experiments. These gentlemen proved conclusively that immunity from serious consequences could be assured, provided the period of decompression was sufficiently long. The experiments were not made under water, but were made in an experimental air-chamber especially fitted up for them by one of the big English submarine engineering companies.
SKETCH DRAWING ILLUSTRATING A METHOD OF TRANSFERRING CARGOES FROM SUNKEN VESSELS TO SUBMERGED FREIGHT CARGO-CARRYING SUBMARINES
Demonstrated as practical in 1900 by the combined use of the "Argonaut" and the demonstrating freight-carrying submarine shown above.
Under the conditions usually prevailing in the fields wherein divers are employed, it is not possible, with the systems of working generally adopted, to provide this period of decompression nor to work with this studied deliberation when descending from or when ascending to the ordinary surface vessel. The suit of a diver weighs over two hundred pounds, and when inflated the bulk is considerable. A diver being lowered from a vessel is swung to and fro like a pendulum, and if there is any sea on—the open sea is never entirely still—the surge naturally affects the diver so that it is beyond human possibility to limit his descent to a nicety or to take the time either in going down or coming up that science has proved necessary to his physical well-being in the most generous sense. The greater the depth the greater the difficulties, and to reach a submergence of one hundred and fifty feet is now practically prohibitive except under ideal conditions. The semi-submergible boat has, however, met the problem squarely and has overcome many of the difficulties heretofore deemed insuperable. The simplicity and the practicability of the working principle involved are graphically shown by the accompanying drawings.
This combination consists of a tube which may be built of any desired length or so constructed that this may be increased by the insertion of additional sections. This tube is provided with an operating compartment or working chamber at the free end, and water-ballast tanks are distributed throughout the length of the tube so that the structure can be placed in equilibrium with the water when ready for submergence. In the working chamber there are also water-ballast tanks by which that end of the tube can be sunk and caused to rest upon the bottom with any desired pressure or dead weight. This operating chamber has a hatch and door located in its bottom. This bottom door can be opened when needed—the whole compartment becoming then a virtual diving bell, so that divers can be sent out if so wished, or operations through this open passage to the water-bed can be pursued by means of tools and appliances controlled from within the compartment. There is also an air-lock or equalizing chamber. Its purpose is to enable the operators to become gradually accustomed to change of pressure when entering or when leaving the working chamber when the latter is being used with the bottom door open; the air pressure within the compartment would be maintained in constant accord with the water pressure corresponding to the particular depth at which this tube would be in use. The tube itself may have its upper end attached to the side of a surface craft, but preferably it floats in the well of a craft especially designed to work in combination with it, as shown.
