Launching the Lay Torpedo Boat.—For facilitating the launching and controlling of the Lay torpedo boats, a structure or submarine fort is used. This structure may be square, or oblong, and may be made to carry any number of the torpedo boats. The body is constructed of plate or sheet iron of suitable strength and stiffened with angle iron, or otherwise, and divided longitudinally or transversely into watertight compartments, into which the water is admitted to sink the said structure. At the top or upper side, cylinders or tubes are placed, each of which is capable of containing and launching one of the torpedo boats. At the forward end of each tube is a door, or cover secured to a rod or shaft fitted to turn in suitable bearings; this rod or shaft is provided with an arm which is connected to the piston rod of an engine worked by gas contained in a reservoir, or by other suitable means. The slide or other valve which controls the admission of the gas, &c., to this engine is arranged in connection with electro magnets, connected by a suitable cable with a keyboard on shore, or wherever the operator's station may be. By sending an electric current through this cable in one direction through the electro magnets, the door is closed; and by sending such a current in the opposite direction it is opened. The cables carried in the torpedo boats, and through which the mechanism on board each torpedo boat is operated and controlled, are also in this case connected with the keyboard, which must be provided with a number of sets of pole changers and switches, or equivalent devices, corresponding with the number of boats to be controlled by means of the said keyboard.
This apparatus will form a very convenient adjunct to fortifications or stations liable to be attacked by sea. The said fort may be prepared for use by placing torpedo boats in the said tubes, and may be kept floating until the enemy's ships have arrived closely enough to permit the determination of the point where the said fort can be most advantageously located for operating against the said ships. The fort is then towed to this point, or taken as near as possible thereto on rails, and towed the remainder of the distance. It is then submerged, and will be ready for immediate operation. The said fort is provided with suitable valves for the admission of water to sink the same, and with means for forcing in air through the pipe P* to expel the water when the fort is to be raised.
When it is desired to launch either of the said torpedo boats, the door of its tube or cylinder is first opened by sending a current through the cable that controls the door, as above described. Then the current is sent through the boat's cable to start her propelling engines. The said boat will then emerge from the cylinder or tube and will rise to the surface, or as near the surface as may be desired, and may then be directed and controlled by the operator at the keyboard, as previously described. And one after another of the said torpedo boats may be thus launched and exploded, without giving to the enemy any clue to the point or position from which they are being sent.
Launching the Torpedo from a Ship.—The method of launching the Lay torpedo boat from an ironclad or other large ship is shown at Fig. 130. The tubes or cylinders S in which the torpedo boats A are held are, in the apparatus shown at Fig. 130, closed at their inner ends by plates, or covers S1, which are provided with suitable water-tight and insulating packing boxes S2 for the passage of the electric cables of the said torpedo boats, each cable being connected with the keyboard, which is placed in any convenient part of the ship, and at their outer ends the said tubes are furnished with strong and well-fitted slide valves, or sluice gates S3, which are opened by screws, connected by gearing with a hand wheel, and shaft S4, S5, for the admission and exit of the said torpedo boats. Also these cylinders are provided with packing pieces at their sides, arranged to be pressed by screws or otherwise up to the sides of the torpedo boats in these cylinders, and thereby hold them firmly and immovably in rough weather.
The Method of Sinking and Raising a Lay Torpedo Boat.—The apparatus by which this is effected is shown at Fig. 131, which is a longitudinal section of a portion of a torpedo boat. The hull A of the torpedo boat is provided with a water chamber l, which has holes or apertures l1 in the bottom of the same, and is also provided with an air cock at l2. In connection with this chamber is arranged a small cylinder m, provided with a piston m1, whose rod m2 is attached to the lever of the said cock. A spiral spring m3 is provided to resist the inward movement of the said piston. The said small cylinder m is connected by a pipe m4 with a valve chest, in which is arranged a slide valve m5. The said slide valve is connected by a rod or rods to the lever or levers m6, whose fulcrum is at m*, and the said levers are connected by the links or rods m7 with the armatures of electro magnets n, which are included in the circuit of the cable, whereby the boat is controlled from the keyboard at the station; o is a pipe extending from the said valve chest to the aforesaid water chamber l; p is a feed pipe by which gas is conducted from the reservoir or generator to the valve chamber.
When it is desired to sink the torpedo boat an electric current is sent in one direction through the said magnets, and thereby operates the slide valve to admit gas to the cylinder m in front of the piston m1, which is thus forced inward and opens the air cock l2. The opening of this cock permits the escape of the air from the water chamber l, and consequently the entrance of water through the apertures l1, and the boat then immediately sinks.
When it is desired to raise the boat a current is sent in the opposite direction through the said electro magnets, thereby operating the said valve and piston in such a manner as to close the cock l2 and open the port o1 and the pipe o, thereby allowing the gas to pass from the valve chamber into the compartment l; this gas by its pressure expels the water from the said compartment, and the boat then having its normal buoyancy restored immediately rises to the surface.
The Lay Torpedo Boat used as a Tug to take out a Number of Small Torpedoes.—This arrangement is shown at Fig. 132 and 133. The small vessels or torpedoes are designed to be first sunk and then exploded, chiefly for clearing harbour or the like of mines or other obstructions. These results are accomplished by means of the following devices and arrangements, that is to say, each of the small vessels or torpedoes F is provided with apparatus which is included in an electrical circuit formed by a suitable insulated cable G, extending throughout the train of small vessels or torpedoes F. One vessel of this train, preferably the rear one, is connected with the station by an electrical cable H, which is payed out from a coil or coils, or a reel or reels, in the said vessel as the same travels through the water. This cable H connects with the cable G, which is connected with the towing boat A, and passes through the series of boats F to the said cable H. One wire of the said cable is arranged in combination with sealed or covered apertures in the bottom of a compartment or compartments of these small vessels F, as shown at I, the covers of these apertures being so formed as to be ruptured or destroyed by the explosion of a cartridge or cartridges placed in the said compartment or compartments. When a current of electricity is sent through the aforesaid wire of the cable it will explode the said cartridges and open the apertures, thereby admitting water into the said compartments so that the vessel F will sink.
The cable G that passes through the train of torpedoes or vessels F is so arranged that when a current passes through the other wire of the said cable it will fire cartridges placed in the charge chambers or magazines of the said small vessels, as shown at J. The part of the cable or towing line G, which connects the towing boat A with the train of small boats or torpedoes F, is attached to a hook or other device, which can be disengaged by sending a current through the cable K, connecting the boat A with the shore or other station. It will be understood that when being used for this purpose the said boat A is not or need not be charged with explosive material.
The aforesaid towing boat A takes the train of torpedoes F to any required position. It is then disengaged from the train, leaving the said small vessels or torpedoes F floating in such position. Then by sending a current first through one wire of the cable H the boats F are first sunk by the explosion of the cartridges and opening of the apertures, as above described. They may then be discharged immediately by sending a current through the other wire of said cable H and firing the cartridges in their magazines, or they may be left submerged to form mines which may be exploded at any desired moment.
The said small vessels or torpedoes may be provided with vertical rods to indicate their position to the operator at the station; these rods are shown at L, and they should be made hollow to allow the air in the water compartments or chambers to escape to permit the water to enter the same when the vessels F are to be sunk; or other suitable provision may be made for the escape of the air from these compartments.
The said vessels F are preferably made cylindrical with conical ends, and are provided with suitable insulating and water-tight packing boxes, as shown at F1 for the cable G to pass through at the stem and stern of each vessel.
The Lay Torpedo in Clearing Obstructions.—For this purpose the torpedo boat is provided with an apparatus, shown at Fig. 134 and 135, in combination with the electric cable, whereby the said boat is controlled and guided, and there is arranged in the boat A a compartment A3, from which extends down into the water a line or rod U, provided at its outer end with a hook or claw U1, properly formed to take hold of any chain or bar with which it may come in contact. In the said compartment A3, and upon the upper end of the said line or rod U, is placed a small case or cylinder U2 containing a charge of dynamite or other explosive material and a cartridge or fulminating cap, or a bottle of sulphuric acid, surrounded with a certain quantity of chlorate of potash and sugar. This case or cylinder U2 is shown detached and drawn to an enlarged scale at Fig. 135, and it will be seen that the said case is provided with a tube 1 containing a cartridge, or a phial filled with explosive substance at 2, and a ball or weight at 3. The said case is fitted to slide upon the said line or rod U, and when placed at the upper end thereof and not held or retained will slide to the lower end of the same. In the said compartment A3 is arranged at U4 an electro-magnetic apparatus, included in the circuit of the said cable, and connected with a bolt or catch which in its normal position holds the said explosive case and prevents its running down on the grappling line or rod U. This explosive case is also provided at its lower end with a grappling hook U5.
When the grappling hook U1, on the lower or outer end of the line or rod U, engages with any obstruction the boat will be stopped, and this stoppage will be indicated on the keyboard. The operator by this indication is apprised of the stoppage of the boat by an obstruction, and by sending a current through the cable by means of a switch provided for this purpose on the keyboard he can immediately release the explosive case U2, which runs down the line or rod U, and engages by its grappling hook U5 with the hook U1. The line or rod U is then disengaged from the boat A, and the explosive case U2 turns or falls over. As it turns over the ball or weight 3 contained in the tube 1 drops on the said phial 2, fractures it, and thereby allows the acid to mix with the explosive or fulminating charge and explode the case U2. This explosion will rupture or destroy the obstructing chain or bar, so that the ironclad ships or other vessels can pass freely and safely into the harbour or beyond the point where it was intended to stop them.
Used to clear away Mines and Electric Cables.—For this purpose there is an implement V provided, Fig. 136, somewhat of an anchor form, but with four or any desired number of arms V2 extending outward at a suitable angle from its shank V1. In the neck of each of these arms are fitted two small plain or toothed discs V3, which are so arranged as to present their teeth to any object lying in the angle or corner formed by and between the arms V2 and shank V1 of the said implement, as shown at W.
In using this implement it may be attached to a line or cable coiled in the torpedo boat, which, in this case, is used without being charged with explosive material, and is sent in advance of any ship that has to enter or pass through the suspected water. This line must be arranged in combination with a detaching apparatus controlled by electro-magnetic apparatus included in the circuit of the cable which connects the torpedo boat with the keyboard at the operating station.
By sending a current from the station the operator releases the said implement or its line from the detaching hook or holding device. The said implement then sinks to the bottom; then the said boat returns to the ship, paying out the said line as she so returns. The end of this line is then taken by a steam tug or other vessel, and the said grappling implement is thereby dragged along through the water over which the ships are to advance, thus breaking any wires or cables that may be in its course. This operation is shown at Fig. 137, in which A is the towing boat, K the controlling cable, V the said implement, V* the line attached to the implement V, X X submerged mines, and X1 X1 are the mine cables.
In some instances it may not be practicable to reach the enemy's ship or other object of attack directly from the station to which the torpedo boat is connected, and from which it is controlled. In this case a small boat, &c., is used in addition, which should be so arranged as to present to the enemy's view as slight a surface as possible. This mode of attack is shown at Fig. 138, where A is the torpedo boat, and N is the small auxiliary boat. This boat N is provided with a keyboard and battery like that described at page 144, and the electric cable L, carried on and payed out from the torpedo boat A, is connected with the keyboard. The boat N is also attached to and towed by the torpedo boat A by the tow line O; and the torpedo boat is steered and guided by means of the said keyboard in the boat N. The auxiliary boat is designed to contain two men, who lie down, one at the bow, the other in any convenient position abaft him; the latter has control of the keyboard, while the former by the aid of a telescope keeps the torpedo boat in view, and transmits his orders to the man at the keyboard. On arriving at such a distance from the enemy as to render an attack practicable, the tow line O is disengaged, and the torpedo boat A, guided and controlled, and fired from the boat N. The torpedo boat being exploded, the auxiliary boat can be rowed back to the station or ship to which it belongs. By this means the range of action of the torpedo boat is greatly extended, and with comparatively slight danger to those employed in making the attack.
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.:—
In Fig. 142, a is the case, capable of containing some 33 lbs. of gun-cotton; b is the tube through which the three wires w, w1, and w2 are led; c is the socket in which the wooden or steel spar is introduced and secured, d is the striker, which is attached to a brass contact plate within the head of the case a in such a manner that any pressure either on the head or side of the striker d will force the aforesaid plate in contact with the two studs to which the battery wires are attached; e is a cradle affixed to the striker d to ensure its action on contact being made by the torpedo with the attacked vessel; the explosive is inserted at f, the socket c being made to screw on and off.
When a hollow steel spar is used, the battery wires are sometimes led through the interior of the torpedo and the spar, by which means they are well protected; the only objection to this method of leading the wires being the probability of injury to them, should the spar be broken on contact, or by a shot.
McEvoy's Arrangement of Torpedo Wires.—At Fig. 143 is shown the arrangement of wires as devised by Captain McEvoy, whereby the spar torpedo may be exploded at will or on contact. c and z are the poles of the firing battery, to which are attached respectively the wires d and d2; f is the fuze, which is placed in the centre of the charge, and to the poles of which the wire d2 is attached, the other end of this wire being connected with the stud s; to the stud s1 is attached the other end of the wire d, and at the point c in the same wire is inserted a contact breaker; another wire d1 is connected to the wires d and d2 at the points r and r2 respectively, and at the point k in this same wire is inserted a firing key, which latter is shown in section at Fig. 144, from which the mode of connecting the two ends of the wires and of using the key will be at once apparent. The contact breaker is somewhat similar to the firing key, but there is no spring in it, contact being made or broken by screwing the two parts together or apart. The object of the contact breaker is to prevent the torpedo being exploded by contact, and so to place the control of the weapon entirely in the hands of the operator. As will be seen from Fig. 143, if contact is broken at c, it is impossible to fire the torpedo unless the firing key k be pressed in; but should contact be made at c, then either by means of the firing key k, or by the torpedo striking the hostile vessel, its ignition will be effected.
The foregoing method of arranging the spar torpedo wires is certainly very neat and effective, and is at the present time in extensive use. As yet it has not been adopted by the English government, they still preferring to fire the spar torpedo at will alone.
The different methods of manipulating the spar torpedo from boats will be described in the following chapter.
General Remarks on Offensive Torpedoes.—The torpedoes that have been described in this chapter are the only ones that at the present time can be considered as having been proved to be practically useful, and which in future wars may be employed against ships with some chance of success.
The spar, the Whitehead fish, and the Harvey towing torpedo have each been subjected to the test of actual service, the former weapon being the only one that has under those conditions been successfully used. Taking this fact into consideration, also the high pitch of excellence that has been attained in the construction of steam torpedo boats, and also the results of the numerous exhaustive experiments that have been from time to time carried out in England, America, and Europe, with various modifications of the locomotive, towing, and spar torpedoes, there can be no two opinions as to which of the numerous species of offensive submarine weapons is the most practicable and effective, and that is the spar or outrigger torpedo.
To manipulate successfully locomotive and towing torpedoes in an attack against hostile vessels, the operators must be not only unusually fearless and self-possessed, but also must possess a thorough practical knowledge of the complicated method of working and manœuvring those weapons—in fact, they must be specialists; whilst in the case of the spar torpedo, which may be fired by contact, it is only necessary to employ men capable of handling a boat well, and possessed of dash and pluck, to ensure an attack by such means being generally successful. Of course under some circumstances, such as in a general action, when the locomotive and towing torpedoes are manipulated from specially constructed torpedo vessels, they will prove of great value, and the fish torpedo fired from a boat, in close proximity to the attacked vessel, in smooth water, and unmolested, would sink a vessel which under the same circumstances, owing to her being protected by booms, might prove impregnable to a spar torpedo attack; but such favourable conditions will not often occur in war time.
As an offensive submarine weapon of defence, the Lay torpedo boat should prove of real value; and also manœuvred from specially constructed vessels, it seems capable of being used in a variety of ways. As yet little is known of this weapon, all the experiments carried out with it having been confined to America; but now that Russia has adopted it, and one or two have also been secured by the Peruvians, its practical value will become more generally known.
The German Torpedo Vessel Uhlan.—This torpedo vessel was built in Germany by the Stettin Engine Company, and launched in 1876.
She is armed with a contact torpedo charged with dynamite carried on a 10-foot ram, lying deeply under the water line. To protect the vessel from the effects of the discharge of the torpedo, she is built with two complete parts, sliding one within the other, and having a considerable extent of intermediate space between them. This space is filled with a tough and elastic material (cork and marine glue), which even in the case of the bows being carried away, would afford a second line of resistance. The Uhlan carries an engine of one thousand indicated horse power. The steam is supplied by Belleville's tubular generator. These engines occupy by far the greater space of the vessel, only a very small portion being left for her crew and coal. This great power of the engines is necessitated by the fact that she has to be driven at a very high speed, at the same time she has a very great draught, also the greatest facility of steering has to be attained; hence the proportion of width to length, 25 to 70 feet. In order to save the crew at the worst, a raft is constructed, which is also filled with a mixture of cork and marine glue, and is placed near the helm. The mode of operating with the Uhlan is as follows:—
The dynamite torpedo is affixed to the point of the ram by the aid of divers. The rudder is then fixed, and the crew opening a wide port on the vessel's side, jump on the aforesaid raft. The steamer then rushes forward, and explodes its torpedo in contact with the hostile vessel. The crew hold on to the torpedo ship, and in case she is not injured board her again and repeat the manœuvre, if necessary.[M]
This is a novel form of torpedo boat, but does not seem to be a very practicable method of torpedo attack.
Admiral Porter's Torpedo Ship Alarm.—The Alarm torpedo ship was built from plans designed by Admiral David D. Porter, U.S.N. Her total length, which includes a ram 32 feet long, is 172 feet; her beam is 27 feet 6 inches, and her draught of water is 11 feet. She is built of iron on the bracket plate system, that is to say, she has a double hull, one shell being constructed inside the other. Her double bottom is divided into a number of water-tight compartments. The whole interior of the vessel is also built in compartments, which may be hermetically closed, so that in case of both the shells being ruptured, it would still be impossible to fill the entire ship with water. She is steered by the same apparatus which propels her, viz. the Fowler wheel, which is illustrated at Fig. 145.
This wheel turns on a vertical shaft, and its paddles are feathered by an eccentric cam in such a manner that at one part of their revolution they have a pushing and drawing action on the water, while at another part they present only their edges. In fact it is simply a feathering paddle wheel, turned horizontally instead of vertically. By suitably turning the cam wheel, which is done from the helm, the feathering of the paddles is caused to occur at different points; and in this way the vessel may be turned, or rather her stern twisted around, as if on a pivot. At the same time, by suitably adjusting the paddles, the ship goes ahead, or astern, the engine meanwhile running in the same direction.
By the apparatus above described it is considered that the Alarm is afforded not only a means of speed, but of being handled with the utmost readiness, which latter is absolutely essential in such a vessel, as she must always meet her antagonist bows on.
The steering is accomplished from the wheel house located aft on the deck, or below deck, as all the appliances in the wheel house for steering, &c., are duplicated below. By means of a hand lever beneath the wheel, steam is admitted to a small auxiliary engine which works the cam that adjusts the paddles. Then by turning the horizontal hand wheel in either direction, the helmsman controls the movement of the cam, as desired. Just above the wheel is a dial with a pointer, which enables him to note the position of the paddles, and so adjust them as ordered. Inside the wheel house there are also devices for communicating with the men working the bow gun, and with those managing the torpedoes.
Her Armament—Engines.—At Fig. 146 is shown the spar and mode of working it. It consists of a long hollow iron cylinder lying on its supports between decks. Its outboard end rests in a kind of trough, and to this extremity the torpedo is fixed. The spar is controlled by means of tackles and a steam winch. The side spars are 18 feet, and the bow spar 32 feet in length. If the hostile vessel is defended by torpedo guards, by means of a mechanical contrivance the torpedo signals the fact, and is not exploded until the vessel has forced the obstructions. The engines of the Alarm are compound, with four cylinders, the condenser being placed between them. There are four cylindrical tubular boilers with an aggregate heating surface of 4,600 square feet. Her speed is about 16 knots. Her upper deck is only 3 feet above the water. She is fitted with an electric light, and also with machine guns on her broadside.[N]
This is undoubtedly a most formidable vessel, both as a ram and a torpedo ship, and if capable of performing all that is expected of her, will prove a valuable addition to the United States Navy.
Captain Ericsson's Torpedo Vessel "Destroyer."—This torpedo vessel was devised and built by Captain John Ericsson. The Destroyer is 130 feet long, 11 feet deep, and 12 feet beam, extreme; both ends of her hull are precisely alike, and terminate with very fine wedges. The rudder is attached to a vertical wrought iron post welded to a prolongation of the keel, just abaft the propeller, as shown at Fig. 147. The tillers consist of thin plates of iron riveted on opposite sides of the rudder, a few inches from its bottom. These tillers are operated by straight rods connected to the pistons of horizontal hydraulic cylinders of 5 inches diameter, which are attached to the sides of the keel. The steering gear by the above arrangement is placed 10 feet below the water line, while the top of the rudder is 6 feet below the same, and thus perfect security is afforded to this most important feature of a torpedo vessel. The intention of the designer in constructing this vessel is to render her so far impregnable, that in attacking bow on she can defy the opponent's fire, at the same time offering absolute protection to her commander and steersman, and also protecting the base of her funnel. The leading feature of the construction of the hull of the Destroyer is its being provided with an intermediate curved deck, which extends from stem to stern, and which is composed of plate iron strongly ribbed, and perfectly water-tight. This intermediate deck supports a heavy solid armour plate, fixed transversely to the line of keel, and 32 feet from the bow, inclined at an angle of 45°, and supported on its after side by a wood backing 4 feet 6 inches in thickness. Behind this formidable shield the steering wheel is manipulated, a wire rope extending from its barrel to a four-way cock placed near the stern, by means of which water pressure is admitted alternately to the hydraulic cylinders, previously mentioned, the motion of whose pistons actuate the rudder. The lower division of the vessel is ventilated by powerful blowers, and contains the machinery; it also affords a safe retreat for the crew during the attack. The upper division is filled with blocks of cork, excepting a small part near the bow, occupied by the aforesaid armour plate and wood backing.
The deck house is 70 feet long, and composed of plate iron, riveted water-tight to the upper part of the hull. As there are no openings in the sides of this deck house, the vessel may be run with her upper deck under water.
Armament of the "Destroyer."—The Destroyer is to be armed with torpedoes somewhat similar to the projectile torpedo, drawings of which were submitted by Captain Ericsson, the inventor, to Emperor Napoleon III. in 1854. The present weapon is composed of a solid block of light wood, the explosive charge being contained in a metallic vessel inserted at its forward end. Instead of being circular, as was the case with the original torpedo, its transverse section is square, with parallel top and bottom and vertical sides, forming very sharp wedges at both ends, cased with steel plates. The extreme length of the Destroyer torpedo is 23 feet. Ignition is effected by means of a percussion fuze placed in the head of the weapon.
Operating the Torpedo.—The method of operating the torpedo is that of inserting it into a horizontal tube near the bottom of the vessel, provided with valves for keeping out the sea during the process of insertion, as shown at Fig. 148. When near the hostile vessel, this valve is opened, and the torpedo expelled by a piston actuated by steam power, the expulsion being effected without recourse to gunpowder or other explosive agent. The area of the actuating piston of the Destroyer is 314 square inches, while the sectional area of the projectile is only 196 square inches; this difference in size of the two areas is a special and important feature of the invention, as will be understood from the following: the tension of the acting medium in the Destroyer exceeds 200 lbs. per square inch, therefore the torpedo will be pushed out by a force of (314 × 200) / 196 = 320 lbs. per square inch, and as the distance passed by the piston while impelling the torpedo is 30 feet, an energy of nearly 2,000,000 foot-pounds will be imparted to the projectile.
When making an attack, it is intended that the vessel should at the instant of firing her torpedo reverse her engines, this retrograde motion being greatly assisted by the recoil, which must attend the discharge of a body weighing some 1,400 lbs. impelled by the aforesaid enormous force, and moving through a distance of 30 feet before reaching the water.[O]
Certainly this new system of submarine attack seems feasible, but it has yet to prove, in common with all other new inventions, whether its theoretical capabilities are also practical ones. At Fig. 149 is shown a general view of this novel torpedo vessel under weigh.
Torpedo Boats.—In offensive torpedo warfare, whether using the spar, locomotive, or towing torpedo, especially in the case of the former class of submarine weapons, to ensure a successful attack it is absolutely essential to operate those weapons from steam boats, which are capable of fulfilling as near as possible the conditions herein enumerated:—
In addition to the foregoing, for the purpose of rendering these craft capable of defending themselves against the attack of guard boats, and also of being employed as such, and on river expeditions, &c., they should be built sufficiently strong to enable them to carry a small gun either in the bows or stern; this would apply more especially to those torpedo boats which are part of a ship's stores.
During the last four years a very large number of torpedo boats have been built, which more or less fulfil the aforesaid conditions, nearly the whole of which have been constructed by the two English firms, viz. Messrs. Thornycroft and Co. and Messrs. Yarrow and Co., and to the latter firm is due the honour of constructing the fastest vessel as yet in the world.
Up to the present time, a specially built torpedo boat has on only one occasion been used on active service, viz. at the attack on a Turkish monitor on the 20th of June, 1877, which is detailed at length in the following chapter. This boat was one of Messrs. Thornycroft and Co.'s launches, and from all accounts she behaved wonderfully well under the most untoward circumstances.
Thornycroft Torpedo Launches.—Messrs. Thornycroft and Co., of Chiswick, London, have during the last six years built a large number of torpedo launches for the English government and for several of the principal European governments.
Norwegian Launch.—The first torpedo boat ever built by this firm was the one shown at Fig. 150, for the Norwegian government. This boat was 57 feet in length by 7 feet 6 inches beam, drew 3 feet of water, and the stipulated speed was 16 English statute miles, or nearly 14 knots per hour; which speed was not to be ascertained by a mere measured mile trial, but was to be 16 miles through the water in a run of one hour's duration.
The hull of the vessel was constructed entirely of steel plates and angle bars, and, as may be seen from the diagram, was divided into six water-tight compartments, A, B, C, D, E, F.
The compartments marked A and F in the stem and stern were for stores; those marked B and E were fitted with seats for the crew, and were provided with movable steel covers, so that on going into action, or during rough weather, they might be completely covered.
The compartments C and D are for the steersman and the machinery respectively, and were covered completely by steel plating 3/16 of an inch in thickness—a thickness sufficient to withstand Snider or Martini-Henry bullets, fired from a distance of twenty paces.
The compartment D was furnished with a hood, having slits 1/4 of an inch wide, all round, through which the steersman could see with sufficient distinctness to direct his course easily. Motion was communicated from the wheel to the tiller by means of steel wire ropes, which it was originally intended should be encased in wrought iron tubes.
The possibility however of these tubes being bent by a shot, and so jamming the wire ropes, led to this arrangement being abandoned, and the ropes were simply run through eyes at intervals along the side.
The armament consisted of a cylindro-conical shaped torpedo towed from the top of the funnel, round which a ring was fitted with two pulleys for the towing rope, the strain being taken off by means of two stays attached forward.
The length of this torpedo was 13 feet and the diameter 9 inches, and with a speed of 11 knots it has diverged to about 40 degrees from the direction of the boat's motion when running in smooth water.
The torpedo is worked by means of a small winch and brake fixed on the after part of the engine room skylight; davits are provided for dropping the torpedo overboard.
The engines were compound, of the usual inverted double cylinder direct acting type, capable of developing about 90 indicated horse power, and were fitted with a surface condenser, so that the vessel could run in salt water, without danger of injuring her boiler.
A small tank contained a supply of fresh water, to make good deficiencies arising through leakage, and from steam escaping at the safety valves, &c.
The circulating, air, and feed pumps were driven by a separate engine.
The boiler was of the locomotive type, the shell being made of Bessemer steel; the fire box and its stays of copper, and the tubes of solid drawn brass.
On the official trial, which took place on the Thames on the 17th of October, 1873, the number of revolutions done in the hour was found to be 27,177, and the number required to do a mile in still water was 1578. The distance run in the hour was then, 27,177/1578 = 17·22, or very nearly 17-1/4 miles.
The steam pressure during the trial averaged 85 lbs. per square inch, and the vacuum 25-1/2 inches.
Swedish and Danish Boats.—Boats of the same size and similar in all particulars to the foregoing one—excepting the engines, which are improved by driving the air pump, feed pump, and circulating pumps off the main engines, and abolishing the auxiliary engine, which performed these duties in the case of the Norwegian boat—were made for the Swedish and Danish governments. The result was an increase of speed to 17·27 miles in the case of the Swedish boat, and to 18·06 miles, or 15-5/8 knots, in the case of the Danish boat.
There is no information regarding the armament of the Swedish boat, but the Danish boat was armed with two spindle-shaped torpedoes 12 feet long and 11-1/2 inches diameter, somewhat like the Whitehead torpedo. They were placed on deck longitudinally near the funnel, so as to facilitate launching, and were arranged to be towed from an upright pole 8 feet high, placed about 6 feet from the stem.
A small winch was fixed on either side aft, to pay out the towing line, and to bring back the torpedo. By these arrangements the torpedo could be projected at a large angle from the direction of the boat's motion, and at considerable velocity. The speed of the boat when towing one of these torpedoes is about 10 knots.
Austrian and French Boats.—The next size of torpedo vessel is that supplied to the Austrian and French governments, which is shown at Fig. 151. The dimensions are:—length, 67 feet; beam, 8 feet 6 inches; draught of water, 4 feet 3 inches. The guaranteed speed in the case of the Austrian boat was 15 knots in a run of one hour's duration, and in the case of the French boats 18 knots, in a run of two hours' duration. These boats were built of somewhat thicker plating than the 57 feet type, and the armour was extended.
They were divided into six water-tight compartments, and they differed from the Scandinavian boats in having the spaces forward and aft of the machinery permanently decked, instead of being covered with movable steel covers only.
The machinery was somewhat similar to that in the Scandinavian boats, excepting that the engines were capable of developing 200 indicated horse power, and that the air was supplied to the furnace by being forced into an air-tight stoke hole, instead of being forced directly under the fire grate.
The armament of these vessels consisted of two torpedoes attached to the end of wooden poles, 4-1/2 inches diameter and about 43 feet long, connected to the battery by insulated wires, and arranged to be fired either by coming in contact with the enemy's vessel or at any distance from it, at the will of the operator.
The torpedoes themselves were simply copper cases, of sufficient size, in the case of the Austrian boat, to contain 11,000 cubic centimetres of explosive, and in the case of the French boats, to contain 25 kilogrammes of dynamite.
The mode of arranging the wires is similar to that explained at page 155. The method of manipulating the torpedo poles consists of two tubes riveted together at right angles, so as to form something like the letter T. The torpedo pole is put through the horizontal tube, which is free to move round the centre of the vertical tube, and the vertical tube is free to move through a quarter circle at right angles to the centre line of the vessel.
In attacking in front, the vertical tube is laid over till it is parallel to the water surface, and the horizontal tube is allowed to incline sufficiently far to allow of the end of the pole, when run out, to be depressed from 8 to 10 feet below the water-line. It is held in this position by a pair of blocks attached to the top of a short mast.
In attacking on the broadside, the vertical tube is laid over till it assumes a position such as to allow of the pole, when swung round, to touch an enemy's vessel at about 8 or 10 feet below the water line.
The speed trials of the Austrian boat took place on the 11th of September, 1875, when she did 24,700 revolutions on her hour's run on the Thames, and the number of revolutions required to do a knot in still water was found to be 1357. This gives the distance run in the hour as 18·202 knots, or 3·202 knots over the contract speed. The steam pressure averaged 105 lbs. per square inch, and the vacuum 25-1/2 inches during the run.
In the case of the French boats, the total number of revolutions done in the two hours' run in the roadstead off Cherbourg was 49,818, and the number required to do a knot in still water was found to be 1382, so that the distance run in the two hours was 36·05 knots, or just over the contract speed. During the two hours, the average steam pressure was 108 lbs. per square inch, and the vacuum 25 inches.
The Austrian boat was sent to her destination on board a steamer, but the French boats, under the command of an experienced captain, steamed by themselves from Chiswick to Cherbourg, not crossing at the nearest points and running along the shore, but going boldly from Dover direct to Cherbourg.
Shortly after the arrival of the French boats in Cherbourg, they were altered so as to attack in front only, as the French authorities found that these small vessels were better adapted for resisting the effects of an explosion at the bow than at any other part.
The arrangement adopted is shown at Fig. 152, and consisted of a steel pole about 40 feet in length, having one end about 6 inches diameter, and solid, and the other about 1-1/2 inches diameter, and hollow; this pole was mounted at its solid end on small pulleys, which ran upon two ropes stretched fore and aft of the vessel; the other end, to which the torpedo was attached, was led over a pulley fixed on the bow. Ropes passing over pulleys to a windlass in the after compartment were attached to the inboard end, and by turning the windlass the pole was drawn backwards or forwards as required.
It will be observed that as the pole is drawn forward, the inboard end being constrained to move in a line parallel to the deck, the outer end is depressed in the water, and is so adjusted that when the pole is run out to its full extremity, the torpedo is depressed to about 8-1/2 feet below the water level.
Dutch and Italian Boats.—The third size of boat built by this firm for the Dutch and Italian governments are 76 feet long and 10 feet beam, and are guaranteed to do a speed of 18 knots. These boats are similar in design to the Austrian and French boats previously described, but differ from them in having engines of 250 indicated horse power, and in having more free board forward, so as to make them better sea boats.
The Dutch type are armed with the outrigger torpedo, as fitted to the French boats, and the Italian type with the Whitehead fish torpedo.
The "Lightning" Type of Boat.—Now comes the Lightning type of vessel, which is shown at Fig. 153. This vessel, built for the English government, is 84 feet long over all, 10 feet 10 inches beam, and draws about 5 feet of water. The machinery on board the Lightning is similar in design to that already described, and is capable of indicating 350 horse power. The hull of the Lightning is made of heavier plating than usually employed, and her lines are fuller, as she is intended for use in a tolerably rough sea if necessary; and in order that she may be able to remain at sea for some time, cabin accommodation on a scale larger than in any of the other boats is provided for the officers and crew. The steering gear is arranged so that the vessel may be steered from the deck, or from the conning tower, and the usual telegraph gear is fitted to communicate from the deck, or from the conning tower, to the engine room.
The top of the conning tower is supported on three screws, so arranged that it may be raised or lowered, and the space for sight adjusted according to the range of vision required, or the risk to be run from the enemy's missiles.
The Lightning is armed with fish torpedoes, which are discharged from her deck forward by means of a discharging apparatus.
The torpedoes are charged with air, by means of one of Mr. Brotherhood's air-compressing pumps.
The Lightning on her preliminary runs attained a speed on the measured mile of 19·4 knots per hour, a speed which will be somewhat reduced when she has her torpedoes, &c., on board, but which will then be over 18 knots per hour.
Several torpedo boats have been built and are in process of construction by this firm for the English government.