“Having purchased a sloop of 50 tons it was prepared by building an air-tight chamber in the middle 12 feet long, 9 feet broad, and 8 feet deep, and capable of containing 75 hogsheads of air. Considerable pains were taken to make this as strong and as secure as possible. In the middle of the top of this chamber was a square hole, a scuttle just sufficiently large to admit a man; it was bevelled outwards, in order that the valve which was to close the chamber might be driven in more tightly. Screws were applied to this valve, in order to screw it home, and it, as well as the scuttle, was lined with flannel. On the decks of the vessel three buoys of different colours, white, red and black, were fixed by plugs in such a manner that they were to be disengaged by driving another plug from the inside of the chamber. These were designed as signals to indicate the state of health of the adventurer during his stay under water. The white was to denote his being very well, the red indifferent, and the black his being very ill. The ballast of 20 tons, by which the vessel was to be sunk and by disengaging of which it was to be raised again, was fixed to four iron rods passing through tubes into the chamber. The vessel was ballasted internally with 10 tons, which with the twenty suspended from her would, it was imagined, cause her to sink when full of water. Thus perished a man whose intrepidity resulted from his ignorance of the dangers he encountered, and who fell a victim to his obstinate confidence in the success of a plan concerning which his knowledge was totally insufficient to enable him to judge. The depth of water in which the vessel sank was 22 fathoms; the pressure of more than four atmospheres thus produced, in all probability crushed in the sides of the chamber soon after it reached the bottom.” [Illustration: ALVARY TEMPLO “AQUAPEDE.” (1826.) ] CHAPTER XI DAVID BUSHNELL The originator of the modern method of submarine warfare was David Bushnell, a native of Saybrook (now Westbrook) in the State of Maine, U.S.A., who in the latter part of the eighteenth century conceived the idea of destroying the British ships of war which were employed upon the coasts of North America by exploding gunpowder, contained in a magazine, beneath their bottoms. In order the better to fix the charge to the ships, Bushnell built in 1775 the first practical submarine boat, and the first of which any detailed account is extant. In a letter written in October, 1789, to Thomas Jefferson, the Minister Plenipotentiary of the United States at Paris, David Bushnell gives a very interesting description of his vessel and its achievements. This deserves to be printed here in full in view of the many quite remarkable devices (considering the period) which the inventor originated.