Of course, there are no authentic plans of Debrell's boat in existence, but from the descriptions which were published in regard to it I am under the impression that probably he did succeed in submerging below the surface of the water and propelling her with the tide for some distances. The description tells of some very ingenious arrangements for submerging the boat, in which he used goatskins sewed together in the form of bags. The mouth of each bag was nailed over an orifice opening from the interior of the boat into the sea. These goatskins were placed between planks, with a sort of a Chinese windlass arrangement for squeezing the planks together. When he wished to submerge the boat he allowed the planks to open out, and the water, rushing into the goatskins, increased the vessel's displacement so that it sank. When he wished to come to the surface he simply drew the planks together and squeezed the water out of the goatskins, thus restoring the vessel's buoyancy. According to description, the boat was propelled by oars extending through ports opening into the sides of the boat. Goatskins sewed in the form of cones prevented the water from entering the vessel, the base of the cone being nailed to the sides of the boat, the apex of which was cut off and bound around the staff of the oar. This gave sufficient flexibility to feather the oars and row under water. Nearly one hundred years after Cornelius Debrell's experiments an Englishman by the name of Day built a small wooden submarine and descended in it under the water. This experiment gave him sufficient confidence to undertake the construction of a large vessel, and he proposed to make a profit from its use by making wagers that he could descend to a depth of one hundred yards and remain there for a period of twenty-four hours. He built the vessel, placed his wagers, and descended. He won his wagers but never returned to the surface to claim them. [Illustration: BUSHNELL'S SUBMARINE, THE "AMERICAN TURTLE"]