It was not until a year later that the _Narval_, a large double-hulled submarine with a ship-shaped outer shell of light, perforated plating, was launched in France. She was propelled by steam on the surface and by storage batteries when submerged. To distinguish this sea-going torpedo-boat, that could be submerged, from the earlier and simpler submarines designed and engined for underwater work only, her designer, M. Labeuf, called the _Narval_ a “submersible.” As the old type of boat soon became extinct, the distinction was not necessary and the old name “submarine” is still applied to all underwater craft. That Simon Lake and not M. Labeuf first gave the modern sea-going submarine its characteristic and essential superstructure is easily proved by dates. The _Narval_ was launched in October, 1899, the _Argonaut_ was remodeled in December, 1898, and on April 2, 1897, Mr. Lake applied for and was presently granted the pioneer patent on a “combined surface and submarine vessel,” the space between its cylindrical hull and the superstructure “being adapted to be filled with water when the vessel is submerged and thus rendered capable of resisting the pressure of the water.” But though in her remodeled form she became the forerunner of the long grim submarine cruisers of to-day, the _Argonaut_ herself had been built to serve not as a warship but as a commercial vessel. Like her namesakes who followed Jason in the _Argo_ to far-off Colchis for the Golden Fleece, she was to go forth in search of hidden treasure. She was to have been the first of a fleet of wheeled bottom-workers, salvaging the cargoes of wrecked ships; from the mail-bags of the latest lost liner to ingots and pieces-of-eight from the sand-clogged hulks of long-sunk Spanish galleons, or bringing up sponges, coral, and pearls from the depths of the tropic seas. But though he investigated a few wrecks and ingeniously transferred a few tons of coal from one into a submarine lighter by means of a pipe-line and a powerful force-pump, Mr. Lake has done nothing more to develop the fascinating commercial possibilities of the submarine since 1901, because he has been kept too busy building undersea warships for the United States and other naval powers. [Illustration: Courtesy of International Marine Engineering. The Rebuilt _Argonaut_, Showing Pipe-masts and Ship-shaped Superstructure.]