Barrel Torpedo.

Barrels are frequently used as torpedoes, being thoroughly caulked and pitched and strengthened as much as possible. They are slung with rope or chain slings, moored in position, and exploded either by contact or electrical fuses. In the majority of cases with defensive torpedoes at present, they are so arranged as to be fired either by contact or at will.

TORPEDO-FUSES.

Torpedo-fuses may be classified under four different heads; viz., Percussion, Friction, Chemical, and Electric.

A percussion fuse is one in which the flame is produced by a blow on some fulminating compound. Of such a type is the fuse of the Whitehead torpedo, which in principle is precisely that of the firing arrangement of breech-loading small-arms. The shock on the nose of the torpedo starts it back, releasing the firing-pin spring, which driving against a cap or fuse of fulminate, explodes it. The fuse of Singer’s torpedo cannot depend directly on the shock of collision to explode it, as the shock might be very light. As an intermediary, therefore, the heavy cover of the torpedo is used, which falls off when the torpedo is tilted, and by its descending weight releases the lock mechanism. This consists of a firing-pin and spring secured vertically underneath the torpedo and held retracted by a small pin. This pin is withdrawn by the falling cover, permitting the firing-pin to drive forward against the bottom of the torpedo. Just over the spot where it strikes is a short rod travelling in guides, the upper end being in contact with a small capsule of fulminate, which is exploded by the shock of the outside pin.

The Torpedo Time-Fuse

is in principle a lock mechanism in which the firing-pin catch is in connection with a train of clockwork. This clockwork being set to run for a certain length of time, the torpedo is set adrift to float against the vessel or obstruction, and the torpedo explodes at the end of the time for which it is set. The original and most crude form of this type of fuse is a candle cut to a certain length, the bottom being connected to a quick-match. It is not in this case a percussion fuse, as the quick-match communicates directly with the charge.

McEvoy’s Fuse

consists of a percussion system in connection with a small propeller. As long as the torpedo drifts with the current the propeller does not revolve, but if it is brought up in any way the force of the current starts the propellers, which after a few turns release the firing-pin spring.

The torpedo by means of which the Albemarle was sunk (see cut, page 335) was exploded by a percussion fuse of still a different nature. The torpedo itself was attached to the end of a spar, but just before explosion it was intended to detach and capsize. A hollow tube passed through the axis of the torpedo, having at the nose-end an ordinary percussion-cap arrangement. The rear half of the torpedo formed an air-chamber, and at the rear end of the tube an iron ball, free to move along the tube, was held in place by a small pin to which a laniard was attached to be pulled by hand. The torpedo being thrust by the spar under a vessel was detached, and the air-chamber caused it to tumble bottom up immediately. The pin then being withdrawn by the laniard, the ball dropped on the percussion-cap and fired it.

Hill’s Fuse

consists of a brass body having a percussion anvil screwed into its lower end. A spiral spring surrounds this anvil, projecting slightly above it and forming a seat for a light case holding the fulminate, which is of a very sensitive composition. Covering the top of the fuse-case, and just clear of the fulminate-case, is a light copper dome. A slight blow on this dome presses it in and drives the fulminate down on the anvil.

McEvoy’s Improved Percussion-Fuse

consists of a fuse-case containing an ordinary spring gun-lock, nipple, and percussion-cap. The hammer of the lock is held back by a vertical rod free to travel in a guide. On top of the rod is a ball held in place lightly by the upward pressure of a spring. In case that the torpedo is struck and tilted over the ball falls from its seat on the rod, the latter is forced up by the spring, releasing the hammer and exploding the percussion-cap.

Friction-Fuses.

Friction-fuses as a rule consist of some arrangement by which an ordinary friction cannon-primer is exploded. This is done by attaching a firing laniard to the friction-bar of the primer and either leaving it free, so as to fire at the will of the operator, or attaching it in such a way that the momentum of a vessel catching it will pull it. McEvoy’s improvement on Singer’s percussion-fuse consists in attaching the laniard of a friction primer to the heavy cover.

Chemical Fuses

are those in which substances separated until required for action are then brought into contact and unite chemically with an explosive effect.

Sulphuric-acid Fuse.

This fuse consists of a brass fuse-case containing the magazine and crowned by a thin lead cylinder containing the chemicals, which consist of a small closely sealed glass phial of sulphuric acid placed in the tube and packed with a mixture of potassium chlorate and loaf-sugar. A slight blow on the lead cylinder breaks the bottle, thus permitting a contact between the explosive mixtures.

Harvey’s Torpedo-Fuse.

The principle of this fuse is precisely similar. The bottom of the firing-rod is in this case hollowed and partially packed with the potassic chlorate and loaf-sugar mixture. Over it a small bulb containing a few drops of sulphuric acid is placed and packed carefully with raw cotton. The mouth of the hole is then sealed with a lead capsule. The firing-rod is itself suspended over a firing-pin against which it is driven by the levers on the top of the torpedo.

Electrical Fuses

depend upon the heating powers of an electrical current to ignite certain explosive substances, preferably gun-cotton. Although there are many modifications of the electrical fuse, they almost without exception agree entirely in general make. Two current wires are necessary, called terminals, and having their inner ends separated, in order that some substance offering a high resistance to the passage of the current may be inserted between them. The terminals are of copper wire; the resistance material or bridge is generally of fine platinum wire, although other substances are used in different types. The terminals are as a rule separated by a small block of hard wood which forms an insulator and a support. Around the bridge a wisp of gun-cotton is generally wrapped, although here again other explosives are used in modified forms. This combination is called an exploder, and it is inserted in a fuse-case or magazine containing powder or gun-cotton. The exploder and magazine together form the fuse. One of the terminals is generally attached to the exterior of the torpedo, which forms an earth; the other one is connected with an insulated wire or cable leading to the electrical battery. These fuses are made to explode either at will or on contact. If they are to explode at will, the firing circuit as a rule is not completed until the moment desired for explosion. If they are to explode by contact, the general manner of use is to insert in the circuit at some part a resistance-coil of sufficient force to weaken the current below the firing point. At the moment of contact, the resistance coil is automatically cut out and the torpedo is fired. Another way is to use what is called a circuit-closer, which normally leaves the circuit broken, but on being touched the circuit is closed and the torpedo is fired.

One advantage of the electrical fuse is the facility with which the whole circuit may be examined at any time to test its condition. It is simply necessary to send a very weak current through the circuit, and, the resistance being known, the length of the circuit can be measured electrically and the position of flaws may at any time be located. The modifications of the different fuses depend in a great manner upon the type of generator of the current, as voltaic batteries, dynamo- and magneto-electric machines are used according to the position of the torpedo.

CLEARING CHANNELS OF TORPEDOES.

The greatest skill and care is necessary in attempting to clear a channel of mines and torpedoes. Light-draught boats, launches, gun-boats, drag-nets, grapnels, and materials for handling torpedoes at a distance of thirty or forty feet are indispensable. Torpedoes of the Brooks class may be dragged over many times and escape notice. The frame-torpedo requires the aid of counter-mines or large torpedoes extemporized and sunk on them to blow them to pieces. The shallow water both sides of the channel must be carefully and thoroughly dragged for leading wires. Boats on search must proceed with frames rigged from their bows to catch and explode torpedoes in advance. Deep-draught frames of timber must be dragged up or floated down a channel. Muddy bottoms must be thoroughly sounded, and after the search is complete deep-draught vessels cannot pass through suspected channels without torpedo-catchers rigged from their bows. Too close an examination of a torpedo after it is picked up must be avoided. It may almost invariably be easily and safely exploded, and no better disposition can be made of it.

EXAMPLES OF THE USE OF TORPEDOES
DURING THE PAST TWENTY YEARS.

Whitehead.

Sent from the British frigate Shah against the Peruvian iron-clad Huascar, May 29th, 1877. During the running fight between these vessels, the Shah discharged a Whitehead from a bow tube under water, which failed to reach the Huascar, the reason given being that at the moment of firing the latter changed her course. It is to be presumed that the torpedo in this case was carefully aimed, as there was no cause for great hurry. The Huascar could not be aware of the moment of firing, and the failure appears to demonstrate the great difficulty of using this type of torpedo between rapidly moving vessels at distances of eight hundred yards or over.

Sent from Russian steam-launches against Turkish iron-clads off Batoum, December 28th, 1877. The Turkish vessels in this instance were lying at anchor, surrounded by booms of logs and vertical timbers, and having guard-boats out. The Russian launches succeeded in passing the guard-boats and approaching to within less than a hundred yards of the Turks before they were discovered. Two Whiteheads were then launched at one iron-clad, missing their mark completely, both being found on the beach, unexploded, next morning. The attributed causes of the failure were non-familiarity with the complications of the torpedo itself, darkness, and a slight swell.

Sent from Russian torpedo-launches against a Turkish revenue vessel, January 26th, 1878. In this instance the torpedo-launches were entering Batoum harbor with the intention of attacking the iron-clad fleet, when they were met by a revenue steamer coming out. Whiteheads were discharged at a distance of less than one hundred yards, and the steamer was struck and sunk.

The Lay torpedo has never been used in war.

Towing-torpedoes were used on several occasions by the Russians against the Turks, but never successfully.

Spar-Torpedoes.

Attack by a steam-launch armed with a spar-torpedo on the Confederate iron-clad Albemarle, October 27th, 1864. The Albemarle in this instance was secured to a wharf and surrounded by a boom of logs at a distance of about thirty feet. The Federal steam-launch approached within one hundred yards of the boom without being discovered. Fire then being opened on her, she started ahead full speed, passed the ram, and made a complete turn in order to get speed and direction for striking the boom a fair blow. Hitting the boom, the launch breasted it in several feet and mounted it, evidently coming to a stand-still. At this moment, and whilst under a close fire, the torpedo-spar was pushed under the ram and the torpedo was exploded fairly, thus sinking her. In this case success was due entirely to a cool and deliberate execution of a thoroughly developed plan.

Attack by Russian launches armed with spar-torpedoes on the Turkish monitor Duba Saife, on the Danube, May 26th, 1877. In this attack the launches passed the guard-boats without being seen. The monitor was not protected by booms, and two launches, making a dash at her from opposite sides, planted their torpedoes fairly, exploded them, sank the monitor and escaped.

Attack by Russian spar-torpedo boats on the Turkish fleet at Sulina, June 10th, 1877. There were six torpedo-boats arranged in two divisions in this attack, the two fastest boats leading. These leaders reached to within thirty yards of the Turks before being discovered.

Fire was then opened on them. The first boat, coming down on the bow of one of the monitors, fouled her cable and swung alongside; her torpedo was exploded, but not being put in proper position no damage was done. The boat succeeded in getting clear, but was sunk by the Turks and the crew captured. The other boat succeeded in exploding her torpedo, but also failed to get it in position. The other division of boats did not follow up the attack.

Attack on a Turkish monitor off Rustchuk by a Russian Thornycroft boat. In this attack the Russians approached very closely before being discovered. Fire was opened on the boat and the circuit-wires of the torpedo were cut, rendering it harmless; the boat escaped.

Attack on Turkish monitors at Soukum Kaleh, August 24th, 1877. Four torpedo-boats, taking advantage of an eclipse of the moon, dashed into the Turkish fleet. They were discovered at a distance and a heavy fire was opened on them, driving them off. One boat exploded her torpedo, but it was not properly placed and did no harm.

Attack by a spar-torpedo boat on the United States frigate Minnesota, April 9th, 1864. In this attack the Minnesota was unprotected; the torpedo-boat was discovered about fifty yards away and fire was opened on her. Her torpedo was properly planted and exploded, damaging the frigate considerably, but the charge was not heavy enough to sink her.

Attack by a spar-torpedo boat on the United States corvette Housatonic, February 17th, 1864. The boat used in this attack was in reality a submarine boat, but there are good reasons for believing that on this occasion she was used as a spar-torpedo boat. She was discovered about fifty yards away, but there was no time to open fire on her. She planted her torpedo fairly and exploded it, sinking the vessel and herself at the same time.

Besides these attacks there were several during the American civil war, in which the boats were discovered at a distance and driven off.