THORNYCROFT'S TORPEDO BOATS.Plate XLVII
THORNYCROFT'S TORPEDO BOATS.
French Boats.—The next size of boats is the 87 feet type, as shown atFig. 154. Of this type of torpedo launch several have been built and are now under construction for the French government.
These vessels are 10 feet 6 inches beam; draught of water about 5 feet. They are built of heavier plating than theLightning, and are guaranteed to maintain a speed of 18 knots. The propellers in these boats are placed in front of the rudder, so as to give increased readiness in steering. In order to prevent oxidation as far as possible, the plates and frames below the water line are galvanised. A spark-catching apparatus is fitted to the base of the funnel, so as to prevent the position of the boat being betrayed to the enemy at night.
The armament of these vessels consist of an outrigger arrangement similar to that described atpage 167. They are also well adapted for the Whitehead torpedo. They are also provided with a strong buffer in the bows for deadening the shock, in the event of their coming into contact with an enemy's vessel at too high a rate of speed.
"Second Class" Boats and Mode of Manipulating the Fish Torpedoes from them.—Another type of Thornycroft torpedo boats, several of which have been built for continental governments, and which is termed "Second class," is shown atFig. 155. These boats are 60 feet long, 7 feet 6 inches beam, and draw some 3 feet of water; their guaranteed speed being 16 knots per hour. The mode of carrying the Whitehead fish torpedo, and manipulating it from such a boat by means of Mr. J. I. Thornycroft's invention, which has been fully described atpage 140, is shown atFig. 155and156, where Fig. 155 represents both torpedoes housed, andFig. 156one torpedo in the firing position, the other one being housed.
Four of this type of Thornycroft torpedo boats were attached to H.M.S.Hecladuring her recent cruise in the Mediterranean, and have been very favourably reported on as follows:—They do not suffer from the blows of the sea, nor from the strains incident upon hoisting in and out; nor yet when they are suspended ready for lowering, in which latter position they have frequently remained for twenty-four hours; that under careful management they are perfectly safe in a heavy sea, and they possess good manœuvring powers.
The Thornycroft torpedo frames were found to perform well the services for which they are intended. When proceeding at ordinaryspeed they are nearly noiseless, and cannot be seen on a dark night at a distance of 100 yards.
The Thornycroft Propeller.—All the torpedo boats built by this firm are fitted with the propeller invented by Mr. Thornycroft, and which bears his name. It is a modification of what is known as the Dundonald propeller, the principal difference being that in the Dundonald propeller the blades are inclined backward in straight lines, while in the Thornycroft propeller they are curved.
Experiment at Cherbourg.—The following account of an experiment which took place at Cherbourg in March 1877, whereby to test the efficiency of a Thornycroft torpedo boat in exploding a spar torpedo under the bottom of a vessel proceeding ahead at the time, is taken from theTimes, under date the 13th of March, 1877.
THORNYCROFT'S TORPEDO BOATS.Plate XLVIII
THORNYCROFT'S TORPEDO BOATS.
"Admiral Jaurez, who commands the squadron, ordered a disabled ship, theBayonnaise, during a rather rough sea, to be towed out by a steamer belonging to the navy. A second lieutenant, M. Lemoinne, was sent for, and informed that he had been selected to make the experiment of launching the Thornycroft against theBayonnaisewhile both were in full sail. He accepted the mission without hesitation, picked out two engine men and a pilot, and went down with them into the interior of the Thornycroft, of which only a small part was above water; this visible portion being painted of a greyish colour, so as to be easily confused with the sea. The torpedo was placed so as to project from the bow of the vessel, at the extremity of which were two lateen sailyards about three metres in length. The towing steamer then took up its position in front of the squadron, and the Thornycroft also assumed the position assigned for it; an interval of three or four marine miles separating the torpedo boat and theBayonnaise. On a signal being given, both were set in motion, the steamer advancing in a straight line, and the Thornycroft obliquely, so as to take theBayonnaisein flank. The steam tug went at 14 knots an hour, going at full speed in order to escape the Thornycroft. The latter went at 19 knots an hour, a rate not attained by any vessel in the squadron. The chase lasted about an hour, the squadron keeping in the rear, so as to witness the operations. At the end of that time the distance between the Thornycroft and theBayonnaisehad sensibly diminished, and at a given moment the former, in order to come up with the latter at the requisite distance, had to slackenspeed to 8 knots an hour. The whole squadron watched this last phase of the struggle with breathless interest, and people asked themselves whether the shock of the torpedo would not infallibly destroy the little vessel which bore it. It was feared that the lives of the second lieutenant, Lemoinne, and his three companions were absolutely sacrificed. However, the two vessels got visibly nearer. All at once the Thornycroft put on a last spurt, and struck theBayonnaisewith its whole force on the starboard bow. The sea was terribly agitated, a deafening report was heard, and theBayonnaise, with a rent as big as a house, sank with wonderful rapidity. As for the Thornycroft, rebounding by the shock about fifteen metres off, even before the explosion occurred, it went round and round for a few moments, and quietly resumed the direction of the squadron. No trace remained of theBayonnaise; it was literally swallowed up by the sea."
The experiment was a most complete success, the torpedo boat not being in the least degree injured.
The Power of Flotation of a Thornycroft Boat after being pierced by a Rifle Shot.—On the 5th of July, 1877, Messrs. Thornycroft and Co. made an experiment with one of their torpedo boats to ascertain under what conditions flotation is still retained after the boat has been pierced by a rifle shot.
The torpedo boat experimented on was similar to the one which has been described atpage 169. A Martini-Henry was fired through her side, about a foot under water in the stoke hole. Whilst at anchor the water entered in sufficient quantity to fill an ordinary size bucket in twenty-five seconds, but when she was driven ahead less water entered, and on the speed of 10 knots being reached, little or no water entered. The hole was a little more than three quarters of an inch in diameter.
The engagement on the Danube between the torpedo boatSchootkaand some Turkish vessels, in which the former vessel was pierced by bullets, but yet did not sink, led to the above experiment being carried out.
Efficiency of Thornycroft's Engines.—As a practical proof of the efficiency of the engines supplied by Messrs. Thornycroft and Co. to their torpedo boats, a similar engine has been used for over two years to work the various machines in connection with their works at Chiswick.
Torpedo Boats built by Messrs. Yarrow and Co.—Messrs. Yarrow and Co., of the Isle of Dogs, London, are also very well-known torpedo boat builders, and have during the last four years constructed a considerable number of such vessels for the English and different continental governments, and, as has been before stated, they are the constructors of the fastest vessel in the world.
Dutch Torpedo Launch.—In 1875 this firm built a torpedo launch for the Dutch government, specially designed for ocean purposes. It was 66 feet long, 10 feet beam, and 5-1/2 feet deep. She was driven by a pair of inverted direct acting engines. The boiler was of the locomotive type, with a working pressure of 140 lbs. per square inch, and capable of exerting a force of some 200 indicated horses.
Russian Torpedo Boat.—This firm also constructed for the Russian government two torpedo steamers 85 feet in length. The guaranteed speed of these vessels being 20 knots per hour. In 1878 the Russian government ordered one hundred exactly similar boats to be constructed, mostly at St. Petersburg, thus proving the high estimation held by that government of Messrs. Yarrow and Co.'s torpedo boats.
Description of a Yarrow Torpedo Launch.—Figs. 157,158, and159show an elevation, section, and plan of a torpedo boat, Yarrow type, a large number of which have been built for the Russian and other continental governments.
The length of this boat is 75 feet, its beam 10 feet, and draught of water 3 feet. She is built of steel of the best quality, no other metal possessing the requisite strength and stiffness for scantling, and plates of such lightness. It is divided into eight compartments by seven transverse bulkheads, the forward and after compartments being used for stores, the two central ones enclosing the machinery, while the steersman and operator are placed in the compartment immediately abaft the engines.
The steersman's head projects above the deck, and is protected by a rifle proof steel truncated cone, the top part of which is movable like the visor of a helmet. The hull is decked over from end to end with a curved shield, the midship plating of which is capable of resisting rifle shots, even at close quarters; its curved form being well adapted for giving the maximum strength to the structure, and quickly frees itself from any large body of water.
YARROW'S TORPEDO BOATS.Plate XLIX
YARROW'S TORPEDO BOATS.
The propelling machinery consists of a pair of inverted compoundcondensing engines. The revolutions per minute at full speed are about 470, and the indicated horse power about 280. The propeller is of steel. The funnel is fixed at one side of the centre line, to be out of the way of the bow torpedo pole and gear.
This type of torpedo boat attains a speed of from 17-1/2 to 18-1/2 knots per hour.
The armament of some of these boats consists of three spar torpedoes, a bow, and two quarter ones. The bow pole, which is strong and heavy, is hauled out and in by means of a small auxiliary engine.
Boats similar to these, but of larger dimensions, viz. 84 feet long and 11 feet beam, have also been constructed by this firm. Speed from 19 to 20 knots per hour.
English Torpedo Boats.—The following account of two torpedo boats which had been originally built by this firm for the Russian government, but, owing to the proclamation issued by the English government at this time prohibiting torpedo boats leaving England, were seized by the Customs authorities when on the point of completion, and were ultimately purchased by the English government, is an extract from theTimesunder date the 4th of July, 1878.
"These vessels are each 85 feet long with 11 feet beam, and draw, when fully equipped for service, an average of 3 feet of water. They are strongly constructed of steel, and are fitted with compound surface condensing engines capable of indicating 420 horse power. The high pressure steam cylinder of these engines is 12-1/2 inches in diameter, and the low pressure 21-1/2 inches, both having a 12 inch stroke. These boats are at present known by their builders' numbers, one being No. 419 and the other No. 420. The former is propelled by a three-bladed screw, 5 feet 6 inches diameter and 5 feet pitch; and the latter by a two-bladed screw of similar proportions. Messrs. Yarrow adopt supplementary engines for driving the air pump, circulating pump, and feed pumps; they consider this plan preferable to that of working these pumps direct off the main engine, as is sometimes done. One advantage in having separate pumping engines is that, whether the vessel is in motion or stationary, a powerful means is available for pumping her out, should the necessity arise. It is estimated by her builders that if the air pump and circulating pump were both utilised for this purpose, the water could be pumped out as fast as it could enter either of these vessels through one hundred holes made in the skin by Martini-Henryrifle bullets. If this is the case, these craft may be deemed safe from sinking so long as their machinery is working efficiently. The boiler is of the locomotive type, placed in the forward part of each vessel, and has a closed stoke hole. In connection with the boiler a very important improvement has been introduced by Messrs. Yarrow. This consists in a means of rendering the closed stoke hole safe for the men in the event of the collapse of a boiler tube—a contingency which cannot be absolutely guarded against. Its efficiency was proved beyond all question upon a previous trial of one of these boats. This was No. 419, which was tried on the 24th of May last under the supervision of the Admiralty officials. Upon that occasion an accidental rupture of one of the boiler tubes occurred nearly at the close of the runs over the measured mile, which so far had been very successful. When the boiler tube gave way the steam rushed out of the foremost hatchway from the compartment in which the smoke box end of the boiler is situated, and soon after from the two funnels. The men in the stoke hole, however, being shut off from the boiler, were uninjured, and remained at their post several minutes after the first outburst of steam. The accident, although an untoward event, was considered by the Admiralty officials as affording a highly satisfactory proof of the efficiency of Mr. Yarrow's invention.
"The engines are placed amidships, and each vessel has spacious cabin accommodation aft, as it is intended that they may be used either as despatch or torpedo boats. For the latter purpose the cabin framings above deck are removed and replaced by steel plating. They are steered from the cabin, there being a look-out for the steersman just above deck level. The deck is clear of all obstructions, the two funnels being placed one on either side. They are fitted with balanced rudders and steer well, answering their helms very quickly."
The trials of these two torpedo boats are taken from theEngineerunder date the 19th of July, 1878. At that time these boats completely eclipsed in speed everything that had hitherto been done. AtFig. 160is shown in elevation this type of torpedo launch.
"The trials were personally conducted by Mr. Yarrow, under the superintendence of the authorities from Whitehall, and consisted in a two hours' run without stopping, during which time the boats were tested at the measured mile at Long Reach. Each boat was run six times over the mile, three runs with the tide and three runs against it.The boats and machinery are similar in every respect, excepting that No. 419 is fitted with a three-bladed propeller, and No. 420 a two-bladed one, their diameters and pitch being the same in both cases. The weights on board were accurately weighed, and amounted to 6 tons in each boat, including coals, water, crew, and ballast.
"Trial of No. 419.
Min.Sec.Knots per hour.1st run downoccupied23623·0761st run up"32018·0002nd run down"23523·2262nd run up"31618·3673rd run down"23223·6843rd run up"31418·557
Mean of the six runs, 20·818 knots per hour.Mean steam pressure, 115 lbs. per square inch.Vacuum, 23½ inches.Mean revolutions of main engines per minute, 456.
"Trial of No. 420.
Min.Sec.Knots per hour.1st run downoccupied233½23·4521st run up"325½17·5182nd run down"232½23·6062nd run up"32117·9103rd run down"23223·6843rd run up"32417·647
Mean of the six runs, 20·636 knots per hour.Mean steam pressure, 115 lbs. per square inch.Vacuum, 24 inches.Mean revolutions per minute, 466.
"The highest speeds were obtained by No. 419, during the third runs up and down, the mean of which give 21·12 knots, which is equal to 24-1/3 statute miles per hour, during which time the engines were making 470 revolutions per minute. At the close of the runs, the bearings were found to be in first-class condition, and there was not the least sign of anything getting warm during any part of the trials."
Spanish Torpedo Boat.—The following description of a torpedo boat built by this firm for the Spanish government, enumerating all the improvements that have of late been effected in the construction of such vessels by members of this firm, is taken from theEngineeringunder date the 21st of February, 1879.
"The alterations have a twofold character, and have reference to the arrangements for discharging the products of combustion from thefurnaces and to those for steering the vessel. In brief, the boat is funnelless and is fitted with two rudders, one at each end. The main object in dispensing with the funnel is to enable the torpedo boat to approach as closely as possible to an enemy without being seen, a secondary, although still an important, consideration, being the absence of any obstruction to the steersman's view, such as a funnel on deck. The outlets for the smoke in the present instance are two ports, one on either side of the vessel, and placed about 15 feet in from the bow. Each of these smoke ports is fitted with a damper, and the smoke can be turned through either or both of the passages as desired. The control of these dampers is given to the steersman, who, on approaching an enemy, can direct the products of combustion through the port on the unexposed side of the vessel. The emission of smoke by day and of the glare and sparks by night are thus to a very large extent hidden from view, thus enabling the torpedo boat to approach very closely to the point of attack without being observed. The outlets are fitted with valves which are kept open by the blast, but which close on being struck by a passing wave. Should the vessel have to be out when a heavy sea is running the ports are closed, and a spare funnel is rigged up on deck, on one side. Although the smoke ports are placed forward in this boat, it is intended to place them aft in the next that Messrs. Yarrow build, as that arrangement will obviate the inconvenience at present experienced by those on deck from the heated gases of the furnace being carried along it at times by the wind, when on a certain course.
YARROW'S TORPEDO BOATS.Plate L
YARROW'S TORPEDO BOATS.
"The steering powers of the boat have next had attention from Messrs. Yarrow, and they have sought to remedy the defective steering common to these large quick-speed torpedo craft. To do this they have fitted the vessel under notice with two balanced rudders, one of which is placed forward about 10 feet from the bow, and the other in its usual position at the stern with the screw abaft it. Both rudders are connected with the same steering gear, and are operated simultaneously by one steersman. The forward rudder can be raised out of the water into a casing inside the boat if desired by means of a screw cut on the upper part of its spindle. By the same means, by unscrewing the collar on the spindle, the rudder can be released and dropped into the water should the necessity arise for so doing, by reason of its becoming fouled or damaged. In trials which have been made with this double-steeringsystem, it has been found that when steaming at high speeds the forward rudder has a much greater control over the motion of the boat than the stern one. The reason assigned for this is that at high speeds the forward part of the boat is lifted out of the water, and consequently offers a diminished side resistance to any turning motion brought to bear upon it.
"The boat in which these improvements have been introduced is 86 feet long by 11 feet beam and 5 feet 6 inches deep. She is fitted with compound engines having 22 inch and 12-1/2 inch cylinders, with a 12 inch stroke, and making 520 revolutions per minute when running at full speed. She is propelled by a three-bladed screw 5 feet 6 inches in diameter and 5 feet pitch. Put through some evolutions with the view of testing her steering powers, the double rudder arrangement was found to answer exceedingly well, and she turned a circle of a diameter equal to about three times her own length in 1 minute 15 seconds. She turned equally well either going ahead or astern, and in fact her steering capabilities were satisfactorily demonstrated. The new arrangement for carrying off the smoke also answered very well, with the exception that the heated gases occasionally swept the deck, which objectionable result will be avoided in future boats."
These boats are to be armed with spar torpedoes, and with the Whitehead fish torpedo, the cradles and fittings for which are shown atFig. 161.
The Fastest Vessel in the World.—Another type of torpedo boat, of which one of the same dimensions has been built by this firm for the English government, is shown atFig. 162. This vessel is as yet the fastest vessel in the world. The trials with this boat were made in March of this year, and were as follows:—
Runs.Time,Knotsper hour.Knotsper hour.Min.sec.First237=22·93Mean of first pair=21·35Second32=19·78Third233=23·53Mean of second pair=22·05Fourth255=20·57Fifth230=24·00Mean of third pair=22·23Sixth256=20·45
giving as a mean 21·93 knots per hour, or 25-1/4 statute miles. The boat was fully equipped for active service, i.e. with a load of 6-3/4 tons on board. It was found during the trial that at speeds of 17 and 19 knots thevibration of the boat was considerable, but when running over 20 knots it was hardly perceptible; the excessive vibration taking place when the revolutions of the engines became a multiple of the natural vibration of the boat.
Torpedo boats are at the present time being built by this firm for the English, French, Spanish, Austrian, and Italian governments.
Russian Torpedo Boats, built by Mr. S. Schibau, Prussia.—Mr. S. Schibau, of Elbing, Eastern Prussia, in 1878 constructed ten torpedo boats for the Russian government, similar to the one shown at Fig 163.
These boats are each 66 feet long, and 11 feet 3 inches beam. They are built of steel plates about an eighth of an inch thick. Their engines consist of three cylinder compounds, with surface condensers; and they run at 380 revolutions per minute, at full speed, driving a screw 4 feet in diameter. They have been variously armed, some with the spar, some with the Whitehead fish, and some with the Harvey towing torpedo. Their speed is about 18 knots per hour.
Messrs. Herreshoff's Torpedo.—Messrs. Herreshoff, of Rhode Island, U.S.A., have also constructed several torpedo boats. One of these, built for the English government, is shown in section atFig. 164. This boat is 59 feet 6 inches long, 7 feet 6 inches beam, and 5 feet 6 inches deep; she draws about 1 foot 3 inches of water.
RUSSIAN TORPEDO BOAT, HERRESHOFF'S TORPEDO BOAT.Plate LI
RUSSIAN TORPEDO BOAT, HERRESHOFF'S TORPEDO BOAT.
"The vessel is constructed with five water-tight bulkheads, and her hull is of composite construction below the water line, having a steel framing covered with wood planking. The upper part of the hull is wholly of steel, the plates being 1/16 inch thick, the top sides sloping inwards and the upper work forming a protective superstructure for the crew and machinery. She is propelled by a screw which is placed beneath the vessel in a central position, and which is driven by a direct acting condensing engine placed in the forward part of the boat. The diameters of the steam cylinders are 10-1/2 inches and 6 inches respectively, with 10 inch stroke, and they are of 100 horse power estimated. There is an independent feed pump and air pump. The stoke hold is enclosed and is supplied with air by a Sturtevant blower, which is driven by an independent engine of 2-1/2 horse power. The propeller is a two-bladed screw 38 inches in diameter and 5 feet pitch, the screw shaft being 23 feet in length. The vessel is steered by means of a balanced rudder placed a short distance from the stern and under the ship, the helmsman being located in a stern cabin with a protected look-out raised just above thedeck. The hull and machinery together weigh 6 tons, but with the working crew of four men and fuel, stores, and two torpedoes on board, boat weighs about 7-1/2 tons.
"Steam is supplied by a Herreshoff coil boiler, which constitutes another novelty in this boat. This boiler consists of a circular combustion chamber, which in the present instance is 4 feet in diameter internally, and within which is a coil of about 300 feet of 2 inch pipe coiled to nearly the diameter of the chamber. This coil is continued at the top so as to form a kind of dome under the cover of the combustion chamber. By the side of the boiler is a separator, into which the steam passes before it goes to the engine. The water from the feed pump is admitted at the top of the coil, and during its course to the bottom the greater portion of it becomes converted into steam. Having passed through the entire length of the coil, the steam and water are discharged together into the separator in such a manner that the water is entirely separated from the steam, and can be blown off as required. The steam is taken from the top of the separator, and returns through a short coil placed inside the combustion chamber, where it becomes superheated, and is led thence to the engines. It is claimed for this boiler that it cannot explode destructively, inasmuch as there is but a very small quantity of water in it at any time, and that it is distributed along the entire length of the coil. A rupture at any point would only be attended by a moderate blowing off of steam. The rapid circulation of the water is found to prevent the deposit of salts, the surplus water not converted into steam carrying with it all impurities. A good working pressure can be obtained within a few minutes of lighting the fire, and the boiler can be blown off in a few seconds. The large combustion chamber enables the full economy of the fuel to be realised."[P]
This vessel is guaranteed for a speed of 16 knots per hour. She can be propelled ahead or astern with equal speed, and can be brought to a dead stop when going full speed within a distance equal to her own length. Her turning powers are equally good. Her armament will probably be the fish torpedo.
Ordinary Torpedo Boat.—The most efficient and simple method of fitting and working a spar torpedo from an ordinary steam launch orpinnace is shown atFig. 165. This method will be readily understood from the figure; the dotted lines show the position of the spar and upright, when rigged in. The speed of this type of torpedo boat ranges from 6 to 9 knots. Occasions would no doubt occur in time of war when a torpedo attack by such boats would be a feasible matter, and therefore everything should be done to render these boats fit for that special service.
Defects.—The most important defects of such craft are:—
1.—The noise created by their engines, thus rendering an undetected approach to a hostile vessel impracticable.
2.—Their liability to be swamped by the explosion of the torpedo.
Of course there are many minor defects, but above are the principal ones, both of which might, to a considerable extent, be modified.
Torpedo Boat Attacks.—It is impossible to attempt more than a very general idea of how to conduct a torpedo boat attack, as so much depends upon the circumstances, ever changing, under which each particular attack would have to operate.
The spar and the fish torpedo are the submarine weapons that can best be manipulated from boats, the towing torpedo requiring a more roomy craft than the torpedo boat generally is to operate it from with any chance of success.
Methods of Protecting Ships from Boat Torpedo Attacks.—The principal methods that exist at the present time of protecting a ship from a boat torpedo attack are as follows:—
1.—Booms by themselves, or supporting nets hung vertically, surrounding the ship at a distance of 10 or 15 feet from the side of the vessel.
2.—A crinoline of wire, or chain, fixed by stays to the vessel's side, but capable of being lifted out of the water if required.
3.—The above methods supplemented by guard boats, and a cordon of boats.
4.—A cordon of boats, that is, boats connected at certain distances by means of hawsers, or chain cables, and at a distance of some 200 or 300 yards from the vessel, supplemented by guard boats, but without other protection.
5.—Electric lights and torpedo guns. These latter are small guns capable of penetrating the side of a torpedo boat and of being depressed at a very small angle.
As it is against these defences that torpedo boats would have to contend, therefore they have been described previous to explaining the mode of conducting a torpedo boat attack.
The first two methods of defence are of course quite impracticable when the attacked vessel is one of a blockading squadron, and it is against such vessels that a torpedo boat attack will generally be used and oftenest be successful.
In the case of a vessel forced to anchor in a harbour which is accessible to the torpedo boats of the enemy, by the application of either of the first two methods, supplemented by guard boats and electric lights, she would undoubtedly be almost impregnable against a torpedo boat attack, even were the boats armed with the fish torpedo, though she would of course not be in that state of readiness which is essential to a man-of-war's efficiency. As a general rule, no man-of-war should anchor unless absolutely necessary in the vicinity of an enemy's ports, and then should retain the power of moving in any direction in the quickest space of time possible, using the electric light and guard boats as a means of protection.
An attack by boats armed with the spar torpedo must always partake of the nature of a forlorn hope, this especially applying to the boats themselves, the crews of which, provided they are supplied with good life belts, would seem to run a far greater risk of a wetting and a prison than of being shot.
Not less than four torpedo boats should compose the attacking force. The crews of the boats, consisting of only those actually required, should fully understand "that the hostile vessel is to be torpedoed," i.e. they are not to give up the attack on the vessel opening fire, nor in the case of one or more of the torpedo boats being sunk, but to remember that one boat is sufficient to effectually carry out the object of the attack, viz. the sinking of the ship.
In making the attack, one boat should be directed on each bow, and one on each quarter, the final rush being as combined as possible. There must not be theslightest hesitation, and each boat must makedirectfor her point of attack.
The cause of the Russians failing so often in their torpedo boat attacks during the war of '77 may be traced to the absence of anything like a system, and to their giving up the attack directly they supposed themselves discovered.
When using the towing torpedo, two boats only could be used, and they should make the attack, either coming down from ahead, one on each side of the vessel, or coming up from the stern, one on each side of the vessel, or by the boats crossing the bow and stern of the vessel in different directions.
In the case of the fish torpedo the attack must be conducted in a different manner, the object in this case being to get within a certain distance only of the vessel undetected, and from thence send the missile on its deadly course. The distance should not be more than 500 yards; the closer up to 200 yards the better. In connection with such an attack, the torpedo boats might be supported by guard boats, whose particular duty it would be to engage the enemy's guard boats and so leave the torpedo boats free to do their particular work.
It has been suggested to use the electric light from the bows of torpedo boats, but this would do away with one of the chief characteristics of such boats, viz. their invisible and unknown approach, on which the whole success of the attack in a great measure depends.
Fosberry's Patent Torpedo Boat Protective.—To enable torpedo vessels and boats to remain afloat after being struck by shot from mitrailleuses, rifles, and other arms usually employed against such craft, and at the same time to retain their structural lightness, Colonel G. V. Fosberry, of the English army, has designed the following method, which is based upon the discovery that when india-rubber or the like is placed and secured on a metal plate, and is penetrated or punctured by a rifle bullet or similar projectile, which also passes through the metal plate, the hole or orifice so formed in the india-rubber will, after the projectile has passed through it and the metal plate, immediately be closed by the elasticity of the surrounding portions, so that no water can follow the projectile through the said hole or orifice. India-rubber or other elastic material, or a combination of such materials, in the form of sheets, belts, or coats, is placed upon or around those portions of the hull of the boat which are to be protected. Vulcanised or mineralised india-rubber is the material usually employed by Colonel Fosberry. Between the metal plates and the india-rubber covering an intermediate substance, generally kamptulicon, is interposed, which is cemented or riveted to the said metal plates, and to which the india-rubber is attached. This intermediate substance, which is the feature of the invention, must be of such anature that it may be caused to adhere closely and tightly to all parts of the metal, and also to the india-rubber covering, while the same are unperforated, but when the said india-rubber covering and the metal plate under the same are perforated by a bullet, the portion of the said intermediate substance adjacent to the perforation must be detached from the elastic covering and metal plate, and leave the former free to act like a valve, and close up over the hole so that no water may enter; and this intermediate substance, as applied by the inventor in the immediate vicinity of the perforation, will by the effect of the shot be so broken up and detached from the india-rubber covering as to allow the same to recover its original position independently of the new shape or position of the injured and deformed metal plate.
Should the india-rubber be placed upon the metal plates and be so attached to the said plates as to adhere and conform to them in or after their deformation, a hole made in the india-rubber would remain open; on the other hand, should the india-rubber without any intermediate substance be attached to the metal plate in such a manner that it will recover its position after perforation, water would penetrate between the metal and the india-rubber, and by the pressure of this water the india-rubber would be liable to be detached from a large area of the metal plate, and so become ineffective or even dangerous to the boat. Moreover, if the india-rubber is fixed directly upon the metal plates, in the case of a shot passing completely through the boat, that is to say, passing into the boat at one side and out at the other side, a large portion of the india-rubber adjacent to the hole made by the shot in leaving the boat will be torn or destroyed, but this will not be the case in boats constructed according to Colonel Fosberry's patent.
The French government have recently applied this invention to one of their torpedo boats with very successful results, thereby proving that it is not merely a theoretical idea.
Submarine Boats.—Submarine boats, if they could be constructed to fulfil the conditions hereinafter enumerated which are essential to a perfect boat of that nature, would for many reasons be a very important point solved in connection with torpedo operations, and therefore it is most extraordinary that a practicable submarine boat has not yet been designed and built.
Bushnell's Submarine Boat.—The first submarine vessel built for torpedo purposes was designed and constructed by David Bushnell in 1775. This vessel, operated by a Sergeant Esra Lee, was employed in an attempt in 1776 or thereabouts on theEagle, an English man-of-war, which proved unsuccessful, owing to the sergeant not being thoroughly versed in the management of his curious craft. She was soon afterwards sunk in the Hudson river, but was subsequently recovered by the inventor, though never used again. This vessel was capable of holding one person, and air sufficient to support him thirty minutes without receiving fresh air, and is fully described in 'Barnes's Submarine Warfare.'
Qualifications essential to a Submarine Boat.—A submarine boat should possess the following qualifications:—
1.—It should be of sufficient displacement to carry the machinery necessary for propulsion, and the men and materials for performing the various operations.
2.—It should be of such a form that it may be easily propelled and steered.
3.—It should have sufficient interior space for the crew to work in.
4.—It should be capable of carrying sufficient pure air to support its crew for a specified time, or of having the means of purifying the air within the boat, and exhausting the foul air.
5.—It should be able to rise and sink at will to the required depth, either when stationary or in motion.
6.—It should be so fitted that the crew possess the means of leaving the boat without requiring external assistance.
7.—It should carry a light sufficient to steer by, and to carry on the various operations.