PLATE III
Represents a clockwork Torpedo, as prepared for the attack of a vessel while at anchor or under sail, by harpooning her in the larboard and starboard bow.
B is a copper case to contain one hundred or more pounds of powder; C a cork cushion to give the whole Torpedo such a buoyancy, that it will be only from two to three pounds heavier than salt water. To ascertain such weight, when it is charged with powder and the lock screwed on, it is put into a large tub of sea water. C is to have fifteen or twenty inch-holes bored in its sides and top, to let the water rush in and the air out, otherwise, the air would prevent its immediately sinking. A is a cylindric brass box, about seven inches diameter and two inches deep, in which there is a gun-lock with a barrel two inches long, to receive a charge of powder and a wad, which charge is fired into the powder of the case B. In the brass box A there is also a piece of clockwork moved by a spring, which being wound up and set, will let the lock strike fire in any number of minutes which may be determined within one hour. K is a small line fixed to a pin, which pin holds the clockwork inactive; the instant the pin is withdrawn the clockwork begins to move, and the explosion will take place in one, two, three, or any number of minutes for which it has been set; the whole is so made as to be perfectly tight and keep out the water, although under a pressure of twenty-five or thirty perpendicular feet. D is a pine box two feet long, six or eight inches square, filled with cork; it is ten or fifteen pounds lighter than water, and floats on the surface; the line from it to the Torpedo is the suspending line, which must be of a length in proportion to the estimated draft of water of the vessel to be attacked; vessels of a certain number of guns usually draw within a few feet of the same draft of water; the suspending line should be from four to eight feet longer than the greatest draft of the vessel, that it may bend round the curve of her side, and lay the Torpedo near her keel. From the Torpedo and the float D, two lines, each twenty feet long, are united at E, from thence one line goes to the harpoon, the total length of the line from the Torpedo to the harpoon being about fifty feet, according to the length of the vessel to be attacked, will, when the ship is harpooned in the bow, bring the Torpedo under her bottom near midship. See the harpoon. It is a round piece of iron, half an inch diameter and two feet long, the butt one inch diameter, the exact calibre of the harpoon-gun; in the head of the harpoon there is an eye, the point six inches long is barbed, the line of the Torpedo is spliced into the eye of the harpoon, a small iron or tough copper link runs on the shaft of the harpoon, to the link the Torpedo-line is also tied, and at such a distance, that when the harpoon is in the gun it will form a loop as at H, but when fired, the link will slide along to the butt of the harpoon, and, holding the rope and harpoon parallel to each other, the rope will act like a tail or rod to a rocket, and guide it straight; without this precaution, the butt of the harpoon would turn foremost, and make a very uncertain shot. F is the harpoon-gun, made strong, and to work on a swivel in a stanchion fixed in the stern-sheets of a boat. My experience with this kind of harpoon and gun, is, that I have harpooned a target of six feet square fifteen or twenty times, at the distance of from thirty to fifty feet, never missing, and always driving the barbed point through three inch boards up to the eye, which practice was so satisfactory, that I did not consider it necessary to repeat it. The object of harpooning a vessel on the larboard and starboard bow, is, to fix one end of the Torpedo-line, then, if the ship be under sail, her action through the water will draw the Torpedo under her; if she be at anchor, the tide will drive it under her, where, at the expiration of the time for which the clockwork was set, the explosion will destroy her.
This being the kind of Torpedo and clockwork by which the Dorothea in Walmer roads, and the brig in New-York harbour were blown up, and the harpoon having succeeded to fix the line to the target, these two experiments shall be combined, and the mode of practice, with the prospect of success and risque to the assailants, examined.
PLATE IV, Fig. 1
Represents the stern of a row-boat; a platform about four feet long, three feet wide, is made on her stern on a level with the gunwale, and projecting over the stern fifteen or eighteen inches, so that the Torpedo, in falling into the water, may clear the rudder. On the platform, the Torpedo and its suspending line of cork are to be laid, and the harpoon-line carefully coiled as at F, so that when the harpoon is fired, the line may develope with ease: very pliable well greased, or white line would be best for this purpose. The harpoon and gun are so well engraved as require no explanation. B is the copper case to hold one hundred or one hundred and fifty pounds of powder. C, the box of cork to diminish its tendency to sink and bring it to a specific gravity of only two or three pounds more than sea-water. Its suspending box of cork explained in [Plate III] is not seen in this figure, lest the drawing should be confused; it can be imagined in its proper place. A, is the brass box with the clockwork lock; D, the pin which prevents the clockwork moving; the line from the pin is tied to a bolt, or otherwise fixed to the boat as at E. Thus fastened, when the Torpedo is pulled into the water, the pin D will remain in the boat, and the clockwork will begin to act. The man who shall be stationed at the gun, and who may be called the harpooner, is to steer the boat and fire when sufficiently near. If he fixes his harpoon in the bow of the enemy, it will then only be necessary to row away; the harpoon and line being fixed to the ship, will pull the Torpedo out of the boat, and at the same instant set the clockwork in motion. This reduces the attack of each boat to one simple operation, that only of firing with reasonable attention. Should the harpooner miss the ship, he can save his Torpedo and return to the attack. While I was with the British blockading fleet off the coast of Boulogne in 1804 and 1805, I acquired some experience on the kind of row-boat best calculated for active movements, and which I now believe well adapted to a harpooning and Torpedo attack; hence I propose clinker-built boats, each twenty-seven feet long, six feet extreme breadth of beam, single banked, and six long oars; one blunderbuss, on a swivel, on the larboard and one on the starboard bow; one ditto on the larboard and one on the starboard quarter, total four, for which cartridges should be prepared, each containing twelve half-ounce balls. To work the blunderbusses, in case of need, two mariners should be placed in the bow, two in the stern; each of those men to be provided with a horse-pistol and cutlass, and each oarsman a cutlass, in case of coming to close quarters with a boat of the enemy.