As early as the year 1190 a man is said to have constructed a diving boat of leather. Numerous suggestions were made to enable men to go under water in order to bore holes through the sides of an enemy’s ships, which, considering the thickness of the planks, must have been a somewhat laborious undertaking. The Barbary corsairs are stated to have used some sort of submarine explosive against the ships of their opponents, but this explosive or combustible was most likely Greek fire. William Bourne, who served in Queen Elizabeth’s navy, is said to have had a submarine boat which could have been made useful, but there are no records in existence to show that the experiment ever took place. An interesting feature of the suggestion was that he proposed to sink or raise the vessel by admitting and expelling water. About the middle of the seventeenth century, a Dutchman is said to have invented a boat which travelled under water from Westminster to Greenwich, and it is even asserted that it carried passengers, in addition to twelve men at the oars, and that the air in the interior of this vessel was purified by a “chymicall liquor.” A Royal Warrant, dated June 29th, 1626, ordered the delivery of “360 fforged iron cases with fireworkes, 50 water mynes, 290 water petards, and two boats to conduct them under water, for H.M. special service to goe with the fleete.” Two worthy friars of the Order of Minims turned from their spiritual contemplations to devise a submarine, and they appear to have been the first to suggest that it should be built with both ends alike, and pointed so that it could move either end foremost; it was to be given wheels to move along the sea floor, and to be propelled by oars. It was even to carry guns, to be fired through holes in the side. Another inventor in the seventeenth century waxed so enthusiastic over his submarine, that, besides pointing out its advantages in all manner of possible and impossible circumstances in time of war, he represented that it should be used for submarine hunting parties, who might have great sport shooting the fish as the boat went along. A Frenchman named De Son, built in 1663, at Rotterdam, a vessel about 72 feet in length, circular, and running to a cone at each end, by which he promised, but did not perform, great things. A few years later a boat was designed by the Abbé Borelli to travel under water, his idea being that the boat should rise or sink according to the amount of water admitted through holes in the hull to skins provided for the purpose. Bushnell, an American inventor, had a vessel he called the _Turtle_, which seems to have been shaped more like an egg. It floated at the surface of the water with the pointed end downward, and had a small screw propeller, jutting out at one side. On the opposite side of the body of the vessel was a magazine containing about 150 lb. of powder. This magazine was detachable from the inside of the ship, and was fastened by a rope to