In the Track of the Troops by Robert Michael Ballantyne (big screen ebook reader TXT) 📕

it would blow the boat and men to atoms. To which my mother replied, "Horrible!" and asked how, in that case, the crew could fire it and escape. Whereupon he responded, "You shall see presently."

Another peculiarity in the launch was that it had a species of iron hood or shield, like a broad and low sentry-box, from behind which protection the few men who formed her crew could steer and work the outriggers and the galvanic battery, without being exposed.

This little boat seemed to me like a vicious wasp, as it left the side of the ship with a rapid throbbing of its engine and twirling of its miniature screw.

When at a sufficient distance from the ship, an order was given by the officer in charge. Immediately the outrigger on the right or starboard side was run out by invisible hands to its full extent--apparently fifteen feet beyond the bow of the launch; then the inner end of the outrigger was tilted violently into the air, so that the other end with its torpedo was thrust down ten feet below the surface of the water. This, I was told, is about the depth at which an enemy's ship ought to be struck. The launch, still going at full speed, was now supposed to have run so close to the enemy, that the submerged torpedo was about to strike her. Another order was given. The operator gave the needful touch to the galvanic battery, which, like the most faithful of servants, _instantly_ sent a spark to fire the torpedo.

The result was tremendous. A column of seething mud and water, twenty feet in diameter, shot full thirty feet into the air, overwhelming the launch in such a shower that many of the unprofessional spectators imagined she was lost. Thus an imaginary ironclad was sent, with a tremendous hole in her, to the bottom of the sea.

That this is no _imaginary_ result will be seen in the sequel of our tale.

"Why, the shock has made the _Nettle_ herself tremble!" I exclaimed, in surprise.

"Oh, the poor boat!" cried my mother.

"No fear of the boat," said young Firebrand, "and as to the _Nettle_-- why, my good fellow, I have felt our greatest ironclad, the mighty _Thunderer_, of which I have the honour to be an officer, quiver slightly from the explosion of a mere five-pounds torpedo discharged close alongside. Few people have an adequate conception of the power of explosives, and still fewer, I believe, understand the nature of the powers by which they are at all times surrounded. That 100-pounds torpedo, for instance, which has only caused us to quiver, would have blown a hole in our most powerful ship if fired in _contact_ with it, and yet the _cushion of water_ between it and the tiny launch that fired it is so tough as to be quite a sufficient protection to the boat, as you see."

We did indeed "see," for the waspish little boat emerged from the deluge she had raised and, steaming swiftly on, turned round and retraced her track. On reaching about the same position as to the _Nettle_, she repeated the experiment with her second torpedo.

"Splendid!" exclaimed young Naranovitsch, whose military ardour was aroused.

"It means, does it not," said Bella, "a splendid ship destroyed, and some hundreds of lives lost?"

"Well--yes--" said Nicholas, hesitatingly; "but of course it does not always follow, you know, that so _many_ lives--"

He paused, and smiled with a perplexed look. Bella smiled dubiously, and shook her head, for it did not appear to either of them that the exact number of lives lost had much to do with the question. A sudden movement of the visitors to the other side of the ship stopped the conversation.

They were now preparing to show the effect of a gun-cotton hand-grenade; in other words, a species of bomb-shell, meant to be thrown by the hand into an enemy's boat at close-quarters. This really tremendous weapon was an innocent-looking disc or circlet of gun-cotton, weighing not more than eight ounces. Innocent it would, in truth, have been but for the little detonator in its heart, without which it would only have burned, not exploded. Attached to this disc was an instantaneous fuse of some length, so that an operator could throw the disc into a passing boat, and then fire the fuse, which would _instantly_ explode the disc.

All this was carefully explained by Firebrand to my astonished mother, while the disc, for experimental purposes, was being placed in a cask floating in the water. On the fuse being fired, this cask was blown "into matchwood"--a wreck so complete that the most ignorant spectator could not fail to understand what would have been the fate of a boat and its crew in similar circumstances.

"How very awful!" said my mother. "Pray, Mr Firebrand, what _is_ gun-worsted--I mean cotton."

The young lieutenant smiled rather broadly as he explained, in a glib and slightly sing-song tone, which savoured of the Woolwich Military Academy, that, "gun-cotton is the name given to the explosive substance produced by the action of nitric acid mixed with sulphuric acid, on cotton fibre." He was going to add, "It contains carbon, hydrogen, nitrogen, and oxygen, corresponding to--" when my mother stopped him.

"Dear me, Mr Firebrand, is a _popular_ explanation impossible?"

"Not impossible, madam, but rather difficult. Let me see. Gun-cotton is a chemical compound of the elements which I have just named--a _chemical compound_, you will observe, not a mechanical _mixture_, like gunpowder. Hence it explodes more rapidly than the latter, and its power is from three to six times greater."

My mother looked perplexed. "What is the difference," she asked, "between a chemical compound and a mechanical mixture?"

Firebrand now in his turn looked perplexed. "Why, madam," he exclaimed, in modulated desperation, "the ultimate molecules of a mixture are only placed _beside_ each other, so that an atom of gunpowder may be saltpetre, charcoal, or sulphur, dependent on its fellow-atoms for power to act; whereas a chemical compound is such a perfect union of substances, that each ultimate molecule is complete in its definite proportions of the four elements, and therefore an _independent_ little atom."

"Now, the next experiment," continued Firebrand, glad to have an opportunity of changing the subject, "is meant to illustrate our method of countermining. You must know that our enemies may sometimes sink torpedoes at the entrance of their harbours, to prevent our ships of war entering. Such torpedoes consist usually of casks or cases of explosives, which are fired either by electric wires, like the telegraph, when ships are seen to be passing over them, or by _contact_. That is to say, an enemy's ship entering a harbour runs against something which sets something else in motion, which explodes the torpedo and blows it and the ship into what natives of the Green Isle call smithereens. This is very satisfactory when it happens to an enemy, but not when it happens to one's-self, therefore when _we_ have to enter an enemy's harbour we _countermine_. This operation is now about to be illustrated. The last experiments exhibited the power of offensive torpedoes. There are several different kinds, such as Mr Whitehead's fish-torpedo, the Harvey torpedo, and others."

"Dear me," said my mother, with a perplexed air, "I should have thought, Mr Firebrand, that all torpedoes were offensive."

"By no means; those which are placed at the entrance of harbours and navigable rivers are defensive. To protect ourselves from the offensive weapon, we use crinolines."

My mother looked quickly up at her polite young mentor. "You play with the ignorance of an old woman, sir," she said, with a half-jocular air.

"Indeed I do not, madam, I assure you," returned Firebrand, with much earnestness. "Every iron-clad is provided with a crinoline, which is a powerful iron network, hung all round the ship at some distance from her, like--pardon me--a lady's crinoline, and is intended to intercept any torpedo that may be discharged against her."

Attention was called, at this point, to the counter-mining experiments.

It may be said, in regard to these, that they can be conducted in various ways, but always with the same end in view, namely, to destroy an enemy's mines by exploding others in their midst.

For the sake of illustration, it was supposed that the surrounding sea-bottom was studded with invisible torpedoes, and that the _Nettle_ was a warship, determined to advance into the enemy's harbour. To effect this with safety, and in order to clear away the supposed sunken torpedoes, a counter-torpedo was floated between two empty casks, and sent off floating in the desired direction by means of the tide. This countermine consisted of an iron cylinder, containing 300 pounds of powder, and was electrically connected with the _Nettle_. A small charge of gun-cotton was fixed to the suspender that held the torpedo to its casks. When at a safe distance from the ship, this charge was fired. It cut the suspender and let the torpedo sink to the bottom. There it was exploded with terrific violence, as was quickly shown by the mighty fountain of mud, water, and smoke that instantly shot up into the air. It has been proved by experiment that 500 pounds of gun-cotton exploded below water, will destroy all the torpedoes that lie within a radius of 120 yards. It is obvious, therefore, that a warship could advance into the space thus cleared and then send a second countermine ahead of her in the same way. If neither tide, current, nor wind will serve to drift the casks, the operation might be accomplished by a small boat, which could back out of danger after laying each torpedo, and thus, step by step, or shot by shot, the advance could be made in safety through the enemy's defences.

After this, twelve small charges of gun-cotton were sunk in various directions, each representing a countermine of 500 pounds. These were discharged simultaneously, to demonstrate the possibility of extending the operations over a wide area. These miniature charges were sent down in small nets, and were quite unprotected from the water, so that the gun-cotton was wet when fired.

This fact caught the attention of my mother at once.

"How can it go off when _wet_?" she exclaimed, turning her bright little eyes in astonishment on her young companion.

"Ha, that is one of the strange peculiarities of gun-cotton," replied Firebrand, with an amused look; "you don't require to keep it dry like powder. It is only necessary that there should be one small lump of dry gun-cotton inside the wet stuff, with a detonator in its heart. A detonator, you must know--"

"Oh, I know what a detonator is," said my mother, quickly.

"Well then," continued Firebrand, "the exploding of the detonator and the dry disc causes the wet gun-cotton also to go off, as you have seen. Now they are going to exhibit one of the modes of defending harbours. They have sunk four mines, of 300 pounds of gunpowder each, not far from where you see yon black specks floating on the water. The black specks are buoys, called _circuit-closers_, because they contain a delicate contrivance--a compound of mechanism and galvanism--which, when the buoys are bumped, _close_ the electric circuit and cause the mine to explode. Thus when a ship-of-war sails against one of these circuit-closers, she is immediately blown up."

"Is not that