Submarine Warfare, Past, Present, and Future

It was originally designed to make the attack by passing under the keel of a ship towing a contact torpedo, having a small reserve buoyancy. Under favourable conditions the torpedo would be drawn under water when the vessel descended, strike the bottom of the ship, and explode on contact.

During her first cruise under the orders of Lieut. Payne (or Paine?) an enemy’s vessel passed close to her without noticing her; the swill raised by her paddles sunk the David, and Payne alone of all the crew saved himself. When the boat was recovered from the bottom, Lieut. Payne persuaded eight sailors to embark with him; a squall of wind caused the boat to fill with water, Lieut. Payne and two bluejackets alone escaping by leaping out of her as she went down. No sooner was the boat recovered from the bottom than her gallant commander offered to try again. A new crew volunteered, and all went well for a time. But one night, off Fort Sumter, she capsized, and only four (of whom Lieut. Payne was one) escaped.

A third time she was raised, and the next essay was made in the Cooper River, under the lead of Mr. Aunley, one of the men who had constructed the boat. Alas! She sank for the fourth time, having caught her nose in the bottom, and all hands were drowned. Once more she was recovered only to foul the cable of a schooner at anchor in the harbour, and to sink for a fifth time.

Up to this time five crews of eight each had volunteered for service in the ill-starred David, and of these forty men, no less than thirty-five had perished. The brave Southern sailors, instead of fighting shy of the submarine, were as ready as ever to face death again. The David was recovered, and Lieut. Dixon, with Captain Carlson, both officers in the Confederate army, volunteered with five others to take her out against the Northern fleet. The Federal corvette Housatonic lay outside the bar in Charleston harbour, and it was on this vessel that on the evening of February 17, 1864, the attack was made, an attack which is thus vividly described by Admiral David Porter, U.S. Navy, in his book, “The Naval History of the Civil War”:—

“At about 8.45 p.m. the officer of the deck on board the unfortunate vessel discovered something about 100 yards away, moving along the water. It came directly towards the ship, and within two minutes of the time it was first sighted was alongside. The cable was slipped, the engines backed, and all hands called to quarters. But it was too late—the torpedo struck the Housatonic just forward of the mainmast, on the starboard side, in a line with the magazine. The man who steered her knew where the vulnerable spots of the steamer were, and he did his work well. When the explosion took place the ship trembled all over as if by the shock of an earthquake, and seemed to be lifted out of the water, and then sunk stern foremost, heeling to port as she went down. Her captain, Pickering, was stunned and somewhat bruised by the concussion, and the order of the day was ‘Sauve qui peut.’ A boat was despatched to the Canandaigua, not far off, and that vessel at once responded to the request for help, and succeeded in rescuing the greater part of the crew. Strange to say, the David was not seen after the explosion, and was supposed to have slipped away in the confusion; but when the Housatonic was inspected by divers, the torpedo boat was found sticking in the hole she had made, and all her crew were dead in her. It was a reckless adventure these men had engaged in, and one in which they could scarcely have hoped to succeed. They had tried it once before inside the harbour, and some of the crew had been blown overboard. How could they hope to succeed on the outside, where the sea might be rough, when the speed of the David was not over five knots, and when they might be driven out to sea! Reckless as it might be, it was the most sublime patriotism, and showed the length to which men could be urged on behalf of a cause for which they were willing to give up their lives and all they held most dear.”

It was by deeds such as these that North and South are to-day united, as they never were before.

When Lieutenant Hobson, during the Spanish-American war, offered to sink the Merrimac at the entrance of Santiago harbour, half the American sailors were wild to join in the hazardous task, and if volunteers for submarines had been requested it is certain that men would have come forward in 1898 as they did so nobly in 1864.

The David, that finally succeeded in sinking the Housatonic, proved so costly an experiment in human lives, because she was not worked as a submarine, but as a low freeboard surface torpedo boat, a purpose for which she was never designed, and for which, as we have seen, she proved dangerous and inefficient. As some one has observed, she was intended for submerging at pleasure—her own pleasure, however, not that of her crew. During the attack on the Housatonic, on February 17th, the vessel did not run under water. The crew submerged it to the hatch coaming and left the cover open against the protest of Mr. Howgate, who despatched it on its mission. The attack was made by a spar torpedo, and the wave thrown up by its explosion, when it struck the Housatonic, entered the open hatchway and swamped the vessel. Most accounts of the feat of the David state that all the crew were drowned. From the following extract it would seem that the gallant captain survived the attack.

“I remember on one occasion during the war,” wrote Hobart Pacha in an article, “The Torpedo Scare,” appearing in Blackwood’s Magazine for June, 1885, “when I was at Charleston, meeting in a coffee-room at that place a young naval officer (a Southerner) with whom I got into conversation. He told me that that night he was going to sink a Northern man-of-war which was blockading the port, and invited me to see him off. I accompanied him down to his cigar-boat, as he called it, and found that she was a vessel about forty feet long, shaped like a cigar, on the bow of which was placed a torpedo. On his stepping on board with his crew of four men, his boat was immersed till nothing but a small piece of funnel was visible. He moved off into the darkness at no great speed—say at about five miles an hour. The next evening, on visiting the coffee-house, I found my friend sitting quietly smoking his pipe. He told me that he had succeeded in making a hole in the frigate which he had attacked, which vessel could, in fact, be seen lying in shallow water, some seven miles off, careened over to repair damages. But he said that, on the concussion made by firing the torpedo, the water had rushed in through the hatches of his boat, and she had sunk to the bottom. All his men were drowned. He said he didn’t know how he escaped himself, but he fancied that he came up through the hatches, as he found himself floating about, and swam on shore. This affair was officially reported by the American blockading squadron, corroborating the fact of the injury done to the frigate, and stating that the torpedo-boat was got up, with four dead bodies in her hold. Here is one system which might be utilised in naval warfare if perfected, and I am given to understand that a submarine torpedo-boat is already invented by Mr. Nordenfelt.”

After the sinking of the Housatonic the Federals again turned their attention to submarine warfare, and in October, 1864, some trials were made on the Hudson with a boat named the Stromboli, constructed at Fairhaven from the designs of an engineer, one Wood. It was not, properly speaking, either a submarine or a diving boat, but by letting in a certain quantity of water into the reservoirs it could be brought flush with the surface, leaving only the conning tower, the chimney and the ventilator above the waves. A steam engine propelled the Stromboli at a speed of ten miles an hour, while a spar torpedo formed the armament. On the 16th of November, 1864, the Stromboli was under the command of John Lay, and was ordered to proceed to Hampton Roads to attack the Confederate cruisers. It appears to have arrived on the 6th of December, but its subsequent doings are not to be discovered.

Another semi-submarine which figured in the American Civil War was the Sputyen Duyvil, built by Messrs. Mallory & Co., from the plans of Messrs. William Wood and John Lay. She was made of wood, and her dimensions were, length 74 feet, beam 20 feet, draught 7½ feet. On going into action she could be immersed to a depth of 9 feet in order to put her armoured side below water, she was to fight with her deck, which was placed with 3–in. armour, flush with the water. Amidships, and standing about 3 feet above the deck, was a pilot house from which the boat could be steered. The Sputyen Duyvil was attached to James River’s squadron during the year 1865, but there is no evidence that she was ever brought into use; her torpedoes were fired on contact, and were worked through a hollow iron boom projecting from the bow, and having inside it a rod to which the torpedo was to be attached.

“When you have been shown lovingly over a torpedo by an artificer skilled in the working of its tricky bowels, torpedoes have a meaning and a reality for you to the end of your days.”—Rudyard Kipling.

“The next great naval war will bestow upon the torpedo and its users a halo of romance which will eclipse entirely that surrounding the gun and the ram.”

“The arts of shipbuilders and steel-workers stand for nothing when a Whitehead torpedo succeeds in striking a ship’s bottom and tears and rends it with the explosion of 200 lbs. of gun-cotton. In the hands of ignorant or careless people the Whitehead is nearly as dangerous to its friends as to its foes, but in the hands of skilful and resolute men it is the most terrible engine of warfare which the world has ever seen.”—Lieut. G. E. Armstrong, in Torpedoes and Torpedo Vessels.

“The spar-torpedo is the dagger which a determined man plunges into the body of an enemy who does not protect himself with a coat of mail; the Whitehead torpedo is the bullet which, easy to discharge from afar, kills the enemy in its path.”—Lieut. C. Arnault.

Although twenty-five Federal vessels are known to have been sunk and destroyed, and nine others more or less injured by various kinds of torpedoes during the great war of secession, the many objections to the employment of the spar-torpedo were only too evident. The necessarily close proximity of the craft attacking and the ship attacked, resulted in some cases in the destruction of the former as well as the latter, and inventive minds therefore set to work to devise a submarine weapon which could be discharged at the enemy from a distance. The result was the automobile fish torpedo, an instrument of warfare which is to be found in every navy, and the sole armament of the modern submarine boat.

In a history of under-water warfare, a description of the Whitehead torpedo, which is in reality a crewless submarine boat, must find a place, but a word may be said beforehand respecting the difference between the “Mine” and the “Torpedo.”

The mine is a stationary charge of explosive contained in a case moored beneath the surface of the water. The torpedo is a case of explosive, which by some means or other is provided with the power of aggression, either on or below the surface. The mine awaits the enemy, in fine, whilst the torpedo goes to seek him. Into the details of Submarine Mining it is not proposed to enter here.

Torpedoes are divided into two classes—(1) Uncontrollable. (2) Controllable. Class I. comprises Projectile, Rocket, Drifting, and Automobile torpedoes; the last named are now practically the only kind of uncontrollable torpedo employed. In nearly all navies the “Whitehead” is the type adopted; the German uses the “Schwartzkopff,” which differs only from the former in that it is made of phosphor-bronze instead of steel. Controllable torpedoes comprise Spar, Towing, Dirigible, Locomotive and Automobile. Great Britain has adopted the Brennan locomotive torpedo for coast defence only, and she still retains the spar-torpedo, although it is doubtful if it would ever be used in a naval engagement.

Somewhere about the year 1860 an officer of the Austrian Marine Artillery devised plans for the construction of a surface screw boat or fire-ship, to be propelled either by a steam or hot-air engine, or by clockwork, to be steered from the shore by means of long tiller ropes, and to carry in its fore part a large charge of gun-cotton, the explosion of which was effected by means of a pistol in communication with a movable blade at the bow, and with one vertical and two horizontal spars, so that if any of these arrangements came into contact with the object aimed at the pistol was fired and the charge exploded.^[8] On the death of this officer, which took place before he had time to put his ideas into practice, the pen drawings came into the possession of Captain Lupuis, an officer of the Austrian navy. During the sixties Captain Lupuis carried out a series of experiments with a view of discovering a means of propelling a floating torpedo along the surface of the water and directing it by means of ropes and guiding lines. The forward end of the torpedo was to be charged with explosive, and on coming in contact with a vessel it would be exploded by the automatic firing of a pistol. The motive power was to be either steam or clockwork. The Austrian Government, before whom he laid his plans, told him that they could not consider them until he discovered some reliable form of motor and a better method of steering. In the year 1864 Captain Lupuis sought the advice and assistance of a Mr. Whitehead, at the time manager to an engine manufacturing company at Fiume, and the result was that the latter invented the famous locomotive torpedo that bears his name.

The first Whitehead fish torpedo was produced in 1866, but it was a very much less terrible engine of destruction than it is to-day. It was built of steel, was 14 inches in diameter, 16 inches at the fins, and weighed 300 lbs. Its explosive charge was 18 lbs. of dynamite. The motive power was compressed air charged to a pressure of about 700 lbs. to the square inch, and the air chamber was made of ordinary boiler plates. The speed was only six knots for a short distance. Mr. Whitehead’s design was a great improvement on Captain Lupuis’s. It ran beneath the waves, it was independent of outside aid when once started, and its motive power was superior both to steam and clockwork. Still it was by no means a perfectly reliable weapon, and its great fault was that it failed to keep a uniform depth in the water.

By 1868 Mr. Whitehead had invented the “Balance” Chamber, which has since proved a very effective means of controlling the depth of the torpedo. In 1868 a committee of Austrian naval officers experimented with two Whiteheads whose dimensions were as follows:—

The trials were carried out at Fiume; the Austrian gunboat Genese was handed over to Mr. Whitehead to fit with a bow ejecting tube, and the target consisted of the yacht Fantasie. The result was the adoption of the Whitehead by the Austrian Government in 1868.

Although the Austrian Government purchased the secret of the Whitehead torpedo, they were unable to secure the exclusive right of manufacture. On the invitation of the English Admiralty, Mr. Whitehead came to England in 1870, bringing with him two torpedoes and a submerged tube.

The first two English torpedoes were of two sizes and of the following dimensions:—

The trials were carried out on board the Oberon, an old paddle-wheel sloop. Over 100 runs were made and the average speed obtained was 8·5 knots for a distance of 200 yards, and 7·5 knots for 600 yards. The balance chamber proved capable of keeping the torpedo at the required depth, although at times it behaved in an erratic fashion. After the trials, the committee of investigation reported that in their opinion “any maritime nation failing to provide itself with submarine locomotive torpedoes, would be neglecting a great source of power both for offence and defence.” Acting on this verdict the English Government, in April, 1871, purchased the secret and right of manufacture of the Whitehead torpedo for £15,000.

Naturally certain conservative officers, incapable of recognising the possibility of improvement in the weapons of naval warfare, sneered at the torpedo, but their scorn had little effect, and in a short time all the great navies of the world had adopted the Whitehead or some similar form of fish torpedo. One instance will be sufficient to show that naval men failed in many cases to realise the potential value of this instrument of destruction.

Commander W. Dawson, R.N., in a paper read before the Royal United Service Institution, commenting on the drawbacks of the Whitehead, remarked that he did not attach much value to self-contained powers of locomotion in submarine projectiles, and said that he believed that progress must be looked for in modification of the outrigger and the towing torpedoes which were free from complicated mechanism, simple in their application, and above all safe to the operators and to friendly vessels.

In 1876 Mr. Whitehead produced an improved torpedo. It had a diameter of only 14 inches, a speed of 18 knots for a distance of 600 yards, and a charge of 26 lbs. of gun-cotton. It was fitted for the first time with the “servo-motor,” which, as Lieutenant Armstrong remarks, makes the steering almost as perfect as if a mannikin helmsman were steering the torpedo from the inside. In 1884 it was still further improved. The speed was raised to 24 knots and the explosive charge was increased. In 1889 the speed was again raised to 29 knots for 1,000 yards, and the charge was 200 lbs. of gun-cotton.

The Whitehead torpedoes carried in His Majesty’s ships to-day are of two dimensions:—

Several different patterns of Whitehead torpedoes are turned out at the various factories, but they all resemble each other in their main characteristics.

The “baby,” as the seaman calls it, is a cigar-shaped object made of steel or of phosphor-bronze. It is divided into compartments, and in the foremost of these is placed in war time the explosive charge. At the head is the end of a pointed rod penetrating the explosive, and when the torpedo comes into contact with a solid object, the point of the rod is driven in against a detonator which explodes the charge and tears a hole in the ship’s bottom. Abaft the explosive chamber comes the air chamber; herein is stored the compressed air which acts as the motive power of the torpedo. Behind this is the balance chamber, where all the automatic steering apparatus is fixed. Abaft this are the engines; these are worked by the compressed air from the air chamber and revolve a shaft, on to the end of which are two screw-propellers working in opposite directions. Furthest aft of all is another hollow air compartment termed the buoyancy chamber. There are four rudders, two horizontal for steering from right to left, and two vertical for maintaining the proper depth.

One might be forgiven for thinking that the narrower the fore part of the torpedo the faster would be its speed; a study of fishes shows, however, that this is not Nature’s principle, and the Whitehead is therefore thicker at the fore than at the tail; technically, it has “a full entrance with a very fine run.” The Whitehead is divided into eight sections, containing:—

1.

The firing arrangement.

2.

The explosive chamber.

3.

The air chamber.

4.

The “balance” chamber.

5.

The engine chamber.

6.

The buoyancy chamber.

7.

The bevel wheel chamber.

8.

The horizontal and vertical rudders and propellers.

1 and 2. The Firing Arrangement and Explosive Chamber.

At the head of the Whitehead is the end of a pointed steel rod which penetrates the chamber containing the explosive. When the torpedo’s nose comes into contact with a ship’s side, or in fact any rigid object, the point of this rod is driven in against a detonator cap inserted in the centre of the charge: the immediate result is an explosion sufficient to tear a large hole in the ship’s hull. The detonator is fulminate of mercury, which, when ignited by a sudden blow, expands to about 2,500 times its own size. The sudden expansion gives such a severe blow to the gun-cotton around it that it at once explodes. Special precautions have to be taken to prevent the torpedo from damaging the ship from which it is fired: it might happen through carelessness that a lieutenant would fire one with the port closed, and so three checks are provided. The rod is so arranged that it cannot go back until a small “collar” with propeller fans on it has revolved off. When the torpedo enters the water the fans begin to turn, and when it has run some 30 yards the collar is worked off. Even then the charge will not explode unless the blow to the rod is severe enough to shear off a little copper pin standing in the way. Lastly there is a third precaution in the shape of a safety pin which holds the collar fixed until it is withdrawn at the last moment as the torpedo is launched into the tube.

It happened in the Russo-Turkish war that a Russian lieutenant in command of a torpedo-boat forgot to haul out the “safety pin” and the consequence was that though the torpedo reached the target it failed to explode. From what has been said it will be understood that torpedo warfare is not quite so simple as it looks. In time of peace the torpedo is not fitted with its war head, and so for daily purposes a steel dummy head is used, while there is an arrangement that causes it to rise to the surface on completion of their run. To facilitate its recovery, a “Holme’s light” is carried on to the head. This consists of an arrow-headed tin canister pierced with tubes and full of phosphide of calcium, which on contact with the water gives out both a strong light and a strong smell.

3. The Air Chamber.

This contains the motive power of the torpedo and it comes just behind the explosive chamber. The air is compressed into the compartment by means of air-compressing pumps fitted on board ship, and the latest types are tested to a pressure of 1,700 lbs. to the square inch.

4. The Balance Chamber.

Next the air chamber comes the balance, or secret chamber, although the secret is now universally known. Here is contained the mechanism for automatically transmitting to the horizontal rudders the movements necessary for keeping the torpedo at a uniform and pre-arranged depth below the surface during its run. It consists of a hydrostatic valve and a pendulum whose combined movements are transmitted to an air cylinder called a “servo-motor,” placed in the engine room. The hydrostatic valve is kept in its place by a spring that is forced in by the pressure of the water when the torpedo goes below a certain depth to which the valve has previously been adjusted. If the pressure be less than that of the set depth the opposite action takes place. This valve is connected with the servo-motor, which in its turn acts on the horizontal rudders. The pendulum consists of a heavy iron weight curved to correspond with the circular section of the torpedo and suspended by the pivoted steel rods or arms. It swings in a fore and aft direction and is connected by rods to the rudder for a certain distance after the discharge of the torpedo. A controlling gear is provided which keeps the rudders fixed. It will thus be seen that by the combined actions of the hydrostatic valve and the pendulum the Whitehead, after leaving the tube, is brought to the proper depth very rapidly and is held at this depth throughout her run. Both these devices are necessary, as the torpedo has a great tendency to run down an inclined plane at great speed, and this requires to be checked. In addition the balance chamber contains various valves (the stop valve, the charging valve, the starting valve, the delay action valve and the reducing valve) through which the air passes on its way to the engines from the air chamber.

Inside the engine room are the propelling engines and the servo-motor. The engines are of the single-acting three-cylinder Brotherhood type. The compressed air, after leaving the air reservoir, passes through the main pipe to the pressure-reducing valve. In the latest pattern 18 inch Whitehead the indicated horse power is 56. The torpedo is started by means of a trigger which projects a little beyond the casing of the torpedo, and which automatically opens the starting valve when the torpedo is fired, the trigger just before leaving the tube is caught by a catch in the tube which draws it back when the catch releases itself.

The Servo-Motor.

This ingenious apparatus was called into existence owing to the fact that the mechanism of the balance chamber was unable, through its feeble power, to work the horizontal rudders of the faster Whiteheads direct. The servo-motor is, then, the air engine from which is derived the power to move the diving rudders. It is only about 4 inches long, but so great is its power that with only half-an-ounce pressure on the slide valve the piston is capable of lifting 180 lbs. It consists of a cylinder, a piston, and a cylindrical slide valve. Its balance mechanism acts on the slide valve of the servo-motor, and this acts on the piston, and the motion of the piston is transmitted to the diving rudders by means of a rod and a system of levers.

6. The Buoyancy Chamber.

Abaft the engine room is the buoyancy chamber which gives the necessary buoyancy to the torpedo: to guard against the collapse of the chamber flat steel rings are fitted into it for support. In the “Tail,” the rearmost compartments of the torpedo, are carried the bevel wheel mechanism, the vertical and horizontal rudders and the propellers, and the counter mechanism for adjusting the length of run.

The Gyroscope.

From the foregoing description of the many devices employed to enable the Whitehead to accomplish the tasks for which it is intended, it might be thought that everything that science could imagine has been done to ensure its efficiency. There still, however, remained one great drawback to the efficiency of the torpedo, and this was its deflection from right to left, which was often so serious as to prevent it from striking the object at which it was aimed. The hydrostatic valve and the pendulum were sufficient to keep the torpedo at the required depth without diverging from her true vertical course, but it was apt to swerve from its course in a right or left direction either by reason of the blow it received on striking the water, by dents on its shell, by air leakage, or other causes. An error of only one degree in its course means a lateral error of nearly 50 feet at 800 yards, and it was in order to prevent the deflection of the Whitehead out of the line of fire that the principle of the gyroscope has been applied to the torpedo. In addition to her pair of ordinary vertical rudders, which may be set to any angle up to 20 degrees by means of a clamping screw, the torpedo carries a pair of movable vertical rudders placed in recesses in the vertical fins and controlled by the gyroscope through a servo-motor. The ordinary vertical rudders are usually discarded if the latter are carried.

In a manifesto issued in July, 1901, the Navy League declared that owing to the lack of prevision no adequate provision for gyroscopes and other “essentials of efficient fighting” had been made. Soon afterwards, in the House of Commons, Mr. Arnold Forster, referring to the condition of the navy, remarked that the gyroscope was an exceedingly complicated and beautiful appliance, which from its nature and mechanism you could not get by sending round the corner. Its manufacture, he said, was a long process, involving considerable skilled labour, but still it had been carried out with unremitting zeal, and a great many vessels were supplied with them, He assured the House that there had been no relaxation in the effort to provide all torpedoes with this necessary and desirable accomplishment.

The working of the gyroscope as applied to the Whitehead torpedo may now be described. In the centre of the lower part of the buoyancy chamber is placed a small heavy-rimmed flywheel or gyroscope about 1¾ lbs. in weight, carefully suspended on gymbals (like a ship’s compass) in a vertical position and transverse to the axis of the torpedo. The apparatus is “set” by winding up a strong spring, and the action of firing the torpedo from the tube releases the spring and causes the gyroscope to spin round at a rate of about 2,200 revolutions a minute. The use of the gyroscope is based on the fact that if a wheel be set spinning on its axis with any considerable velocity, it will always tend to revolve in the same place to which it is set spinning. The gyroscope works a servo-motor, which in its turn works a pair of movable vertical rudders, and the slightest deviation from the direction in which the torpedo was originally fired causes the gyroscope to move the rudders and bring back the torpedo to its pre-determined course. Thanks to the hydrostatic valve, the pendulum, and the gyroscope, the Whitehead torpedo is almost certain to hit the object at which it is aimed. In peace manœuvres the Whitehead has often been run absolutely dead straight, with no divergence either up or down, or from right to left, to a distance of 2,000 yards. In 1890 the range of the Whitehead (Mark X R.L.) was officially placed at 800 yards, so the value of the gyroscope is quite evident.

Torpedoes are fired in four ways—

1.

By submerged tubes.

2.

By above-water tubes.

3.

By revolving tubes.

4.

By boat’s “dropping gear.”

The torpedo is blown out of the tube either by compressed air suddenly injected into the rear end, or by an impulse charge of a few ounces of powder, usually cordite. The air pressure varies from 300 to 600 lbs. to the square inch, and the powder charge from 4 oz. to 6½ oz. Submerged tubes are of course tubes below the water-line, and all the most recent ships are fitted with these, as their advantages over above-water tubes are universally recognised. After the Chino-Japanese war all governments, when demanding designs for new warships, made it almost a sine qua non that the torpedoes should be discharged from below water. In firing torpedoes from above-water tubes the torpedo is liable to be hit by the enemy, and it is generally considered that if the tube be hit by even a small projectile it must inevitably explode; the submerged tube affords protection both to the men and the weapon, while the torpedo is less deflected on entering the water. The weight of the submerged tube is some 7 tons, 2 tons more than an above-water one. In order to avoid any possibility of the Whitehead inflicting injury on the vessel firing it, and in order that it may be as little deflected as possible, a guiding bar is run out of the tube by means of pneumatic power when the torpedo has been placed in it. The guiding bar holds and guides the torpedo until quite clear of the ship, when by means of a secret apparatus it releases the torpedo at the end simultaneously; without this arrangement the torpedo would be enormously deflected towards the stern directly it began to leave the tube, and would probably strike the ship from which it had just been fired.

Revolving tubes are carried either singly or in pairs on board torpedo-boats and destroyers, and the torpedoes are fired from them by powder impulse only. “Dropping gear” is only used on second-class torpedo boats and picket boats. It consists of a pair of clip tongs suspended from pivoted davits; the tongs being opened, the torpedo falls into the water, the engines are set in motion, and it speeds off to do its deadly work. The torpedoes for the English Admiralty are made at the Royal Gun Factory, by Messrs. Greenwood and Batley, of Leeds, and by Mr. Whitehead’s factory at Portland.

Mr. Whitehead has another factory at Fiume, whence he supplies almost all the Great Powers with his torpedoes. In time of war the torpedo would be discharged by an officer in the conning tower; by the aid of a torpedo directory he would make the necessary adjustments and would fire the torpedo down below by pressing his hand on an electric key, thus completing a circuit connected with the firing apparatus in the tube.

About the year 1878 a gentleman in holy orders, Mr. Garrett by name, designed a submarine boat, which was built by Messrs. Cochrane, of Liverpool. It was 45 feet long, of the shape of two cones, with a central cylindrical portion. This vessel, to which the name of Resurgam was given, was tried in the Birkenhead Float in 1879. It descended by means of pistons which varied the displacement of the boat by being drawn in and pushed out, as well as by central rudders which steered it up and down. Compressed-air tanks were provided, and chemicals were stored to purify the air after use.

Soon after a larger boat was constructed in which steam replaced manual labour as the motive power; when about to sink the chimney was removed and an air-tight stopper fitted on the opening to the up-take; the furnace mouths were similarly closed by doors, like those of a gas retort, and the boat sank. Power was supplied on Lamm’s system by the hot water in the boiler. After a number of experiments she was finally lost off the Welsh coast.

The attention of Mr. Thorsten Nordenfelt (the inventor of the gun which bears his name) was directed to Mr. Garrett’s design, and the result was that he decided to build a submarine vessel himself. He acknowledged that the negative experience gained during the trials of the Garrett boat had been of advantage to him in avoiding the faults which made that boat unsuccessful.

Mr. Nordenfelt’s first submarine boat was built at Stockholm, and was tried in the Sound of Landskrova, in Sweden, in September, 1885, in the presence of delegates from most of the leading Governments.

Its dimensions and details were as follows: Length 64 feet, beam 9 feet (over sponsons 12 feet), draught 11 feet, displacement 60 tons; speed on measured mile 9 knots; distance travelled without re-coaling 150 miles; depth to which safe descent was possible, about 50 feet. Engines, surface condensing compound type, with two cylinders and cranks at 90°; at pressure of 100 lbs. to square inch, indicating 100 horse-power. Boiler of ordinary marine return tube type, having one furnace, and about 200 square feet of heating surface; two hot-water cisterns, rhomboidal in body with spherical ends. The boilers and cisterns contained about eight tons of water. Both boilers and cisterns were made for a working pressure of 150 lbs. to square inch. One fish torpedo, 14 feet long, was carried outside on the bow and discharged mechanically. The sinking apparatus consisted of two vertical propellers driven by a 6–h.p. double-cylinder engine, and placed in sponsons on each side of the boat. The revolution of these caused the boat to descend horizontally when its buoyancy had been sufficiently diminished. There was one cold-water tank in the centre of boat, holding about four tons of water, for regulating buoyancy. This tank was used as coal bunker when doing long surface runs. In the stern was a four-bladed propeller 5 feet in diameter, and the rudder for port and starboard steering was placed aft of this propeller.

In the bow on either side were balanced rudders on one and the same axle, always maintained in the horizontal position. The crew consisted of three men, and when the boat was closed up there was sufficient air to supply three men for six hours without causing discomfort, and this was not supplemented by any storage of compressed air or restorative chemicals. The depth below the surface at which the boat travelled could be varied in two ways; either by varying the speed of the vertical propellers, or by reducing the speed of the engines driving them by an automatic valve controlling the steam supply. On the surface the boat was driven by working the boiler in the usual manner, and the temperature of the water in the cisterns was kept up to a degree corresponding to a steam pressure of 150 lbs. When it was desired to descend, the ashpit and fire door were closed, as also the funnel inside the boat, and the vertical propellers were started. For sub-surface travelling there was available, as propelling power, the steam given off by the heated water (about eight tons), and this was found sufficient for a distance of 14 knots; on one occasion, when the boat was opened up, there was still over 20 lbs. pressure in the boiler.

Mr. Nordenfelt recognised that for the defence of open coasts and for operations where it might be necessary to keep the sea for days together without being able to seek the shelter of inlets or the mouths of rivers, other and larger proportions than those of his first 64 foot-boat would be desirable.

He accordingly constructed a boat on such larger lines, the details of which are as follows:—

Length 100 feet, beam 12 feet, displacement 160 tons, speed on measured mile 12 knots, distance travelled without re-coaling 900 miles, depth to which descent could safely be made, about 50 feet. Engines, surface condensing compound type, with two cylinders, and cranks at 90°, and at a pressure of 100 lbs. of steam indicating 250 h.p. Boiler, of the ordinary marine return tube type, having two furnaces; about 750 square feet of heating surface. Hot-water cistern, rhomboidal in body with spherical ends. Both boiler and cistern made for a working pressure of 150 lbs. per square inch. Armament, two fish torpedoes, 14 feet long, carried outside on the bow and discharged mechanically. Two Nordenfelt quick-firing machine guns consisting of 1–inch calibre. Sinking apparatus, two vertical propellers, driven by two engines, each indicating 6 h.p.; these propellers were placed in the fore and aft line. This was an improvement on the earlier boat whose screws were fitted in side sponsons. The mere arrest of these propellers sufficed to bring the boat to the surface, as it had a reserve buoyancy. Bow fins, whose action was both automatic and controllable, maintained the boat in the horizontal position. The main propeller was placed abaft the rudder. Two main cold-water cisterns placed at each end, and containing 15 tons of water each, also one in centre of boat for regulating buoyancy containing 7 tons; coal bunkers on the side of boiler; 8 tons of coal carried at the side of hot-water cistern and in middle of boat. Crew, three men in a watch: two watches carried. With coal in the bunkers only, this boat could keep the sea for five days or more. No attempt was made to purify the air when submerged. When descending, the boat was perfectly horizontal, and was invariably kept so when moving under water by means of the bow rudders operated by a plumb weight.

Nordenfelt II. had two distinct conditions of existence as a torpedo craft—that of a surface boat and a submarine one. The sinking operations were as follows: the furnaces were hermetically closed, upon which combustion was soon brought to an end. The piece of funnel connecting the boiler with the outward portion was then removed and the doors placed in position. Whilst these changes were being effected, water was allowed to run into the ballast tanks to reduce the buoyancy to its proper limit, and this arrived at, nothing remained but to close up the conning tower and to set in motion the vertically acting screws to place the boat quite out of sight.

In a paper which he read before the Royal United Service Institution, on February 5, 1886, Major-General Sir Andrew Clarke in the chair, Mr. Nordenfelt after mentioning previous under-water vessels, gave his views as to the reason of their failure.

First of all he said they were always built too small and too weak. The longest was 45 feet, and their small dimensions and weak plates made them useless in bad weather and dangerous for submersion; the small air space available forced the crew to use chemical means to obtain pure air. Secondly, they were never made for firing a fish torpedo; consequently they had to endeavour to fix a mine to the bottom of a vessel, a feat which Mr. Nordenfelt considered impracticable, owing to the risk of contact with the vessel, which, especially if it were pitching or moving, might easily destroy the boat. Thirdly, in all the early boats, the mines were charged with only black powder, the effect of which was less destructive than that of the gun-cotton or dynamite in the fish torpedoes. The effect of the explosion, again, against a wooden ship, was nothing like as serious as against the thin bottom plates of an ironclad. Fourthly, all the boats hitherto in use were propelled by hand power; this gave too much hard work to the crew, who could not take the boat any distance on the surface previous to the actual attack, and made it quite impossible for it to face any rough weather. In the Nordenfelt boat the use of steam diminished the number of men, and they had so little to do when below the surface that the temperature, lower than in modern stokeholes, was no detriment. Fifthly, all previous boats had most unreliable means of descending and ascending. The descent by steering downwards in the American boats of the Civil War period was quite as dangerous as the attempts before and after that time to lower and raise the boats and to keep them steady at any desired depth, by means of increasing and decreasing the weight of the boats by more or less water-ballast or by altering their displacement.

None of these boats used the principle which Mr. Nordenfelt applied to pull his boat down by mechanical means, while relying upon its always retained buoyancy for rising; so that if the mechanical apparatus failed the boat rose at once to the surface. Again, they did not have the tendency to steadiness given by the two forces of constant pulling down by the vertical screws, acting all the time, whether still or moving, against the pulling upwards caused by the buoyancy.

Mr. Nordenfelt considered it most dangerous to rely upon a detachable weight in case of emergency, as the apparatus for detaching it would be always liable to fail. He confessed that he could not imagine how the longitudinal instability of a submerged boat could possibly have been satisfactorily controlled by any of the means applied to the previous boats. Even Goubet’s system of moving water or weights fore and aft inside the boat must act more slowly and cause more diving and oscillation than his rudders which always remained in the horizontal, and thus controlled the slightest tendency of the boat to get out of the longitudinally horizontal position. He considered it absolutely essential to keep the boat horizontal when moving, as he believed that any inclination downwards with the impetus of a heavy boat would almost to a certainty carry the boat below its safe depth before it could be effectually counteracted by shifting weights.

The reason which led Mr. Nordenfelt to construct his submarine boats was the almost insuperable difficulty in carrying the Whitehead and Schwarzkopf fish torpedoes with any degree of certainty up to the short distance at which they could be considered infallibly effective. It seemed to him that a much greater chance would be given for carrying the torpedoes within striking distance, if, instead of trying to rush the distance by many boats, all the time exposed to the destructive fire from machine guns, he could carry the torpedo secretly up to this distance without the probability of being seen at all, and without any probability of being struck by the enemy’s shot even if seen.

The tactics to be adopted by his submarines in action were thus laid down by Mr. Nordenfelt. Out of sight of the enemy the vessel ran on the surface with its cupola and about three feet of its turtle back out of water, but by forced draught, blowing out its smoke under the surface. When she arrived within such distance of the enemy that she might be discovered, she descended into the water so far that the cupola alone appeared above the waves, this was done by taking in water into the cold-water tanks sufficient to reduce the floatability to what the horizontal screws were capable of overpowering. The “reduced floatability” was never done away with, but the descent from the “awash” position was effected by starting the vertical screws, thus overcoming mechanically the buoyancy of the boat, which was pulled down to a less or greater depth depending upon the speed given to the screws.

The three main points in Mr. Nordenfelt’s system on which he laid special stress were these:

1. That by using water as the means of storing up energy he was in possession of a reservoir which could never get out of order, and which could be replaced at any hour in any part of the world, and without any extraneous assistance from shore or other ships. The reason of all others which at once decided him to adopt the hot-water system was the enormous factor of safety obtained by his being able to blow out, by steam pressure without the use of machinery, large weights of water which would lighten the boat and counteract any leak likely to occur. Mr. Nordenfelt had little faith in electricity as a motive power, which is not surprising considering the accumulators then in use.

2. The submerging the boat by mechanical means: Mr. Nordenfelt was convinced that previous attempts had proved unsuccessful, mainly because either they depended upon varying the displacement of the boat by taking in water to submerge her and to regulate the depth at which they desired to operate, or they descended by steering downwards. His objection to the first-named method of descending, by taking in water and thus increasing the specific gravity of the boat, was that practically there was no difference in the specific gravity of water on the surface or at 50 feet depth; thus when the boat had lost its buoyancy at the surface it had also no buoyancy at any given depth, and the risk was thus very great of suddenly descending beyond a safe depth.

3. The horizontal position Mr. Nordenfelt found to be a sine qua non for a submarine boat.

When Mr. Nordenfelt built his boats electric accumulators were very much inferior to those of to-day; no designer of an under-water vessel would think nowadays of using the steam given off by heated water for under-water propulsion. As to his theory that a submarine boat must always descend on an even keel, this has since proved to be entirely erroneous; the modern diving torpedo boat goes down at an angle and is brought to the horizontal position at the required depth either automatically or by hand-worked mechanism.