Slowly the Deutschland rose to the surface, the tanks were blown out and the Diesel engines flung into the gearing. At our highest speed we now went rushing toward the free Atlantic.[6]
The homeward voyage was completed without untoward incident and long before the month had ended, the first—and probably last—merchant submarine was again safe and snug in her home port.
The cargo-carrying submarine, however, is by no means the only type of underwater vessel engaged in peaceful pursuits which has been suggested so far. Mr. Simon Lake, the American submarine engineer and inventor, has frequently pointed out the commercial possibilities of the submarine.
In the early part of 1916 a series of articles from his pen appeared in International Marine Engineering. They contained a number of apparently feasible suggestions looking towards the commercial development of the submarine.
First of all he tells of experiments made with submarines for navigation under ice. The proper development of this idea, of course, would be of immense commercial value. Many harbours in various parts of the world are inaccessible during the winter months for vessels navigating on the surface. Navigation on many important inland lakes likewise has to be stopped during that period. Submarines, built so that they can safely travel under the ice, would overcome these conditions and would make it possible to use most ice-bound ports throughout the entire year at least in Mr. Lake's view.
Ever since Mr. Lake began inventing and building submarines he has been interested in the possibilities which submarines offer for the exploration of the sea-bottom and for the discovery of wrecks and recovery of their valuable cargoes. His first boat, the Argonaut, as we have heard, possessed a diving chamber for just such purposes. He has continued his investigations and experiments along this line, and in these articles he shows illustrations of submarine boats and devices adapted for such work. Properly financed and directed, the recovery of cargoes from wrecks undoubtedly would not only bring large financial returns to the backers of such a venture, but also do away with the immense waste which the total loss of sunken vessels and cargoes inflicts now on the world. Submarines in peace may yet recover for the use of man much of the wealth which submarines in war have sent to the bottom of the sea. Marine insurance, too, would be favourably affected by such an undertaking.
Still one other commercial submarine boat is advocated by Mr. Lake. This is to be used for the location and collection of shellfish on a large scale. Of this vessel its inventor says:
The design of this 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 compartment. With only a few inches of water over them, headway is then given to the submarine and the oysters are automatically raked up, washed, and delivered through pipes into the cargo-carrying chambers. 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.
This boat 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 collection of oysters more nearly like the method of reaping a field of grain, where one "swathe" systematically joins on to another, and the whole field is "cleaned up" at one operation.
Man's greediness for profit has already driven the salmon from the rivers of New England where once they swarmed. Mechanical devices for taking them by the hundreds of thousands threaten a like result in the now teeming rivers of Washington and British Columbia. Mr. Lake's invention has the demerit of giving conscienceless profiteers the opportunity to obliterate the oyster from our national waters.