SUBMARINE OYSTER-GATHERING VESSEL
By admitting water ballast into ballast tanks the vessel is allowed to sink to the bottom with sufficient weight to afford traction to the toothed driving wheels in the central operating compartment. This compartment is open at the bottom; water is prevented from entering it by the use of compressed air. As this apartment is well lighted the oysters may readily be seen lying on the bottom the full width and length of the compartment. When the boat is given headway the oysters are automatically transferred into the cargo holds by means of a system of pipes and suction pumps to induce a flow of water which carries the oysters from the dredges.
The design of a submarine oyster-dredging vessel is such that the vessel goes down to the bottom direct and the water is forced out of the centre raking compartment so that the oysters may be seen by the operator in the control department. With only a few inches of water over them, headway is then given to the submarine and the oysters are then automatically raked up, washed, and delivered through pipes into the cargo-carrying chambers, as shown. Centrifugal pumps are constantly delivering water from the cargo compartments, which induces a flow of water through the pipes leading from the "rake pans" with sufficient velocity to carry up the oysters and deposit them into the cargo holds. In this manner the bottom may be seen, and by "tracking" back and forth over the bottom the ground may be cleaned up at one operation.
The author's design of vessel illustrated has a capacity of gathering oysters from good ground at the rate of five thousand bushels per hour. The use of the submarine will make the recovery of oysters more nearly like the method of reaping a field of grain, where one "swath" systematically joins on to another, and the whole field is cleaned up at one operation.
In many other fields of industrial and commercial enterprise the submarine is qualified to render valuable services. In general submarine engineering work; in the construction of breakwaters, lighthouses, driving piles and building abutments, and in the deepening and improvement of waterways and harbors, the submarine will be utilized. In prospecting for, and the recovery and separation of, gold from river-beds and sea-coast bottoms submarine devices have been found to be very efficient and economical. A new method of laying tunnels under water has been proposed in which adaptations of the submarine boat will play a great part. However, these latter developments of the submarine are so highly specialized and a description of them would be so very technical that mere mention of these possibilities will be sufficient for the purposes of this book.
Thus it is evident that the submarine has a utility entirely apart from that of a military weapon. Its unique qualities fit it for the labors of peace as well as for those of war. Of course, in both cases, either as a naval weapon or as an industrial mechanism, it is the unique capacity of submergence possessed by the submarine which makes it of value, and in either case it is the question of accessibility which is all-important. In the war use the chief function of the submarine is to make itself inaccessible to the foe. It is immune from attack because it cannot be seen. It is able to strike at its foe with success because its presence is not detected by him. It is thus able to make use of its destructive energy in perfect safety. On the other hand, the chief value of the industrial submarine lies in the fact that it constitutes a means of access to places otherwise inaccessible to men. It is very desirable and very profitable for men to go down into the depths of the sea. There are things well worth doing on the bed of the ocean. Travel may be made safe, goods of great value may be brought up, foodstuffs of the first order may be obtained there; with submarines men may prosecute their labors beneath the sea with very little danger and at a minimum of cost. The diver's profession will become, through the use of this mechanism, an important factor in the economic affairs of the world.