A more recent form of the Lay torpedo boat is shown at [Figs. 139], [140], and [141], where [Fig. 139] is a plan or top view of such a boat, [Fig. 140] is a side elevation of the same, and [Fig. 141] is a midship section on the line x x. A is the hull of the boat, a is the main or central portion of the said hull, b, b are side or auxiliary portions of the same. These parts a and b may be oval or circular in transverse section; they are constructed of thin steel or other suitable sheet metal, and secured together by riveting or bolting. The side or auxiliary portion b form the reservoirs or chambers for the gas; they also serve to contain the propelling engines. c is the magazine, d the chamber or compartment for containing the coiled cable, e is the compartment containing the electrical steering and other apparatus, f is the firing rod or pin, g is the water ballast chamber, h is the cable, i the paying-out tube, j, j are the screws or propellers which rotate in opposite directions, and k, k are the sight or guiding rods.
The parts of the apparatus or mechanism whereby the various operations of the torpedo boat are effected are connected to the cable and controlled by electric currents transmitted from the station through the cable, as previously described. The Lay torpedo boat weighs about 1 ton, its length is 23 feet, and speed 12 knots per hour.
Spar or Outrigger Torpedo.—By a spar or outrigger torpedo is meant a torpedo which is carried at the end of a pole or spar projecting from a boat or vessel, and which may be fired either by contact or at will.
This system of submarine offence has up to the present time been the only one that has successfully stood the crucial test of actual warfare.
During the civil war in America the spar torpedo attack was resorted to by the Confederates and Federals, principally by the former, the result being the loss of two large men of war and severe injury to several other ships composing the Federal fleet, and the loss of one vessel of war belonging to the Southerners.
The spar torpedo was also used on several occasions by the Russians in their attacks on the Turkish ships in the war of 1877-8, but in only one attempt was it the means of sinking a Turkish vessel.
Description of McEvoy's Duplex Spar Torpedo.—At [Fig. 142] is shown a sketch of Captain McEvoy's improved patent duplex spar torpedo, which is the form most generally used at the present time, and which seems to fulfil all the requirements of such a submarine weapon, viz.:—
1.—Handiness, at the same time capable of containing a charge of gun-cotton sufficient in contact to destroy the most powerful vessel afloat.
2.—Certainty of action.
3.—Capable of being fired either on contact or at will.