English Projectiles. 3

 

IN the First and Second Numbers I have adverted to the inferiority of the rifle, compared with the smooth bore, in point of range ; and after the first article appeared, and whilst the second was in the hands of the Editor, the Times correspondent on the first of July corroborated my views in a remarkable manner, by stating that the experiments with some new kind of bullet used from a smooth-bored musket tried by Major Nessler, at
Vincennes, had given a result of 25 per cent. in point of accuracy, and 50 per cent. in point of range, as compared with the rifle.

My ideas on this are of some years’ standing, and it is possible that now the subject is beginning to be ventilated, a defective shot will ultimately cease to be compensated by a defective barrel, wherein the rifts or rifles very materially affect the strength of the
projectile weapon while diminishing the range.

Time was that great guns were made of castbrass or of wrought-iron, in the days when cast
iron was but little known. Cast brass, or gunmetal, had the advantage of being tough and little liable to burst; but it had the disadvantage of being costly, and of being so soft in texture, that the bore was rapidly worn by the shot, and the muzzle drooped, and the vent was melted away.

It is true that gun-metal could be mixed so as to become as hard as bell-metal, but in that case it became also as brittle. So serious was the destruction by wear, that the Barbary pirates, who always used brass guns, and bought their shot from the very Italians whom they victimised, always required the shot ere it cooled from the casting to be forged true by cup tools of the smith, so that the whole surface might be smooth.

The wrought-iron guns were a sort of iron cooperage, made with staves and hoops. The
famous Scottish gun, Mons Meg, was built by the smith on the spot where it was used,—
so says tradition,— and three lumps of granite were chipped into spheres by hand.

At the first shot the walls of the Douglass castle were pierced through. At the second shot the arm of the lady of the castle was cut off while in the act of lifting the wine-cup at the noontide meal. The third shot was not fired, the castle being surrendered under fear of what further devilment Mons Meg might achieve.

As time rolled on, the charcoal iron of Kent and Sussex was adapted to the purposes of the
moulder, and great guns were cast from the same quality of metal that furnished the far-famed railings round St. Paul’s to Sir Christopher Wren.

But the iron produced by baked wood became scarcer as the forests disappeared, and the iron produced by baked coal or coke was inferior in quality. Increase of substance was resorted to, to make up for decrease in quality. The weight was a positive advantage in throwing shot, but difficulty of transport was an objection. As powder improved in quality, the inferiority of cast-iron became more apparent; and for all guns of transport and military use brass obtained the preference as a material.

Still the cost of brass, and want of knowledge how to work wrought-iron, caused cast-iron to be retained for use in forts and vessels. The first wrought-iron gun of any magnitude was made at Liverpool for the American Commodore Stockton.

It was said that a second one was made in imitation of it in the United States. But, any how, a wrought-iron gun, either English or American, was burst in discharge on board the vessel, and killed three American officers. Still the perception that wrought-iron was the right material went on increasing. One, forged by an English firm on speculation, was tried at Woolwich Arsenal. It burst at the first discharge, and the fracture showed a granular texture of the coarsest kind in some parts. It had in fact become brittle by the process of continual hammering after the heat was reduced — a process known as “cold swaging.”In some portions rents of great size and length appeared, showing oxidised surfaces on which scale acted as a partition between layers much as a layer of flour serves to separate bakers’ rolls.

The memorable experiment of Mr. Nasmyth with his steam hammer, which ended, it was said, in burning away the external surface as fast as fresh layers could be applied, appeared to end the contest as to the power of oxygenating iron by welding, when, without Government assistance, the Mersey Forge took it up, and succeeded in making, on
their own account, a monster gun which did not burst.

What the cost was we do not know, but no others have been made, and we are still ignorant as to the internal condition of the metal. Until it shall be cut into strips longitudinally, and divided on many points transversely, we cannot finally pronounce what its condition is.

Of the ineligibility of cast-iron for our modern – charges of powder, the most remarkable example was given in the mortars used at Bomarsund. They were not mortars in the old sense of the term, i.e., they did not resemble the vessel in which the chemist pounds his drugs, and in which the chamber and length are about equal, and which may have taken their origin from the traditional experiment of Roger Bacon.

They more resembled carronades, being about six or seven diameters in length. In these guns the force of the powder acted to disintegrate, split, and honeycomb the internal metal of the breech, precisely as is done by the pressure of the water in an hydraulic ram. The ultimate result was bursting, splitting the gun longitudinally like a log of wood, the course of the fracture being determined by the line of the vent.

The force exerted by the mortars on their solid beds being found mischievous to the vessels, the plan was resorted to of bedding them on caoutchouc. This would doubtless relieve both the strain on the gun and the strain on the vessel,but, in such case, all the power absorbed would be abstracted from the propulsion of the shell or shot.

Four men have been conspicuous in working at the improvement of artillery — Lancaster, Whitworth, Mallet, and Armstrong. The three former with government money, the latter, as the Americans say, “on his own hook.” Lancaster stuck to cast-iron, and his object was to vary the mode of rifling, so as to obtain the same effect with a smooth bore without chinks or crevices.

In short, his gun was a one-grooved rifle, or spiral bore of an oval section. The shot or shell was of about two diameters in length, cast to fit the guns, but with too little length of parallel to keep it straight (in short, egg-shaped), and it was not altogether satisfactory. But it did good service at Sevastopol, where our chief sailor-hero, William Peel, had one in battery, and, probably from good management, found it effective.

An unlucky Russian shot damaged the muzzle, and its operations were over. But our hearty sailor himself peeped down the bore, and determined that the mischief was remediable if he could get workmen. Away he went on board the steamers in the harbour, found two engine-fitters willing to work under fire, carried them back with him, and, within twenty-four hours, the damaged part of the gun was amputated, and the blue jackets were again at work pitching “whistling Dicks ” into the Forts to the satisfaction of their commander.

Joseph Whitworth was set to work by the government, with ample funds, and his ruling passion — accuracy of workmanship — was brought into play. Wind was wholly excluded from a long shed, and rifle barrels were fixed up, resembling Lancaster‘s in the absence of grooves, but varying from them by the use of flat instead of rounded curves.

The barrel was polygonal, forming a very quick spiral, and the shot was planed by machine to an exact fit. It was a spiral polygonal piston of very quick pitch approaching to a screw. But it had not the quality of a steam piston — elasticity — to ensure an elastic fit without any tendency to jam. Mr. Whitworth wished to spin his top too rapidly, and when put into the best cast-iron guns that Woolwich Arsenal could procure, the tangential tendency of the shot induced such a quarrel with the polygonal spiral that the gun would not hold together. The shot became a practical wedge, and the gun burst.

Mr. Whitworth is now essaying to produce guns, at his own cost, of greater tenacity; but, even if wrought-iron be used, the enormous friction resulting from so quick a pitch must rapidly wear it out or induce great windage by a bad fit. Mr. Mallet began with an idea — a principle — to throw the largest possible amount of powder in a shell into the enemy’s fort, so that the explosion might act as a mine to destroy everything within reach.

A shell of three feet in diameter, and weighing a ton and a quarter, was proposed to be thrown three miles, and, breaking through bomb proof and all other defences by vertical fall, was to bury itself in the ground, and, in the act of bursting, scoop out a crater twenty-five feet in diameter, converting into destructive missiles every brick and stone erected on its surface, to the destruction of the defenders.

Very good war-work this, if only the moving mines could be efficiently projected. So Mr. Mallet proposed, first to himself, and afterwards to Lord Palmerston, to construct a mortar of wrought-iron, of some fifty tons in weight, and Lord Palmerston very wisely agreed to the proposition. In all new material things there must first be a theory propounded, and then a practice must be undertaken, for only by practice can such things be verified; and if no new theories are to be put into practice, for fear of possible or probable failure, we should simply become a nation of Chinese.

Even supposing Mr. Mallet’s plan to have been a failure, the knowledge gained by the
experiment far exceeds in value all the cost. In a war question, it is quite important to know beforehand what will not answer as well as what will answer, and so to make a new step from the failure.

So Lord Palmerston was right. Fifty tons of iron in one lump would be an awkward thing to move, except on board a vessel,and also a very difficult thing to forge, so Mr. Mallet bethought him of the “built” guns of old,and began to build after a new fashion. He did not make his gun in staves with all the strength in the hoops, but made it of all hoops joined together edgewise, building up the tube with a succession of short cylinders. This provided against lateral force.

The longitudinal connection of the cylinders was provided for by a series of bolts with heads at one end and screw nuts at the other, so that the whole strain between the shot and the breech in the act of propulsion came on the screw threads, and it is said that two shots could not be fired without straining the threads, and so loosening the cylinders. This might perhaps be remedied by increasing the number of the bolts, but there is another difliculty.

The proportion of weight between shot and barrel in an American hunting-rifle is about one to four hundred. In an English 64-pounder cast gun it is about one to one hundred and fifty. In Mr. Mallet’s gun the proportion is, shot one, gun forty. If therefore this gun were made perfect in other respects, the weight would have to be made up by the carriage, or the earth, and if placed on a vessel it would have to be placed on buffers of caontchouc, or it would probably damage the vessel.

It would be quite right to carry forward this experiment, increasing the numbers of thebolts, diminishing the diameter and using a cylindrical instead of a spherical shot, thus reducingthe diameter, with the same quantity of explosive matter and dead weight. The only reason formaking the gun in parts is to attain facility in transit. New discoveries, to which we shall presently allude, have settled the question as to
procuring malleable iron in any sized mass we may desire.

While these experiments were going on at the expense of Government, Mr. Armstrong of Newcastle, no regularly bred but a positively born engineer, was experimenting on his own account,possessing all the where withals, abundant means and a well-fitted engineering factory in prosperous trade.

With good common sense he took the best thing that was next to him — the rifle — and set to work to enlarge it. He adhered to length and weight with a small diameter of bore, and he elongated his shot and covered it with soft metal to fill the grooves by expansion in forcing through.

The grooves were a serious consideration, and to ensure an easy fit he filled the barrel with small W-shaped grooves alternating with similar ribs,precisely like an old French plan used in the pistols of the elder Bonaparte, as may have been observed at Madame Tussaud’s Exhibition.

To load a gun of this kind from the muzzle was not conveniently practicable, so he determined on breech loading. The plan he chose is that used by the Chinese, and in the East Indian jingals [sic]. A longitudinal piece of metal with a handle like that of a saucepan-lid is inserted in a slit on the upper side of the barrel cut in to the bore. At the back of the breech piece the bore is continued through of a larger size, and a hollow screw, the hollow being the size of the bore, is screwed into it.

The object of this hollow screw is to pass the charge through it into the barrel, and then the breech piece being put in situ, the screw is screwed up against it to tighten the barrel, and prevent the escape of gas. This is an exceedingly ingenious arrangement, and effective for a small-barrel gun,and not more likely to get out of order than the ordinary screw breech of a fowling-piece or musket, but if applied to larger-sized guns it is doubtful if so heavy a strain on the screw threads will be found to answer. The weakness is of the same kind as the threads of the bolts in Mallet’s gun.

In the manufacture of these guns of wrought iron, Mr. — now Sir William — Armstrong has also shown good sense and judgment. He combines the processes well known in ordinary gun-barrelmaking. First he takes a welded tube made asmusket barrels are made, and round that he wraps a spiral riband of iron in the mode in whichfowling-piece barrels are made. A second ribandof iron is wound spirally in the opposite direction,and the whole is welded together. While this isdone on a small scale, there will probably be littledifficulty in success, but the success in very large guns is dubious. But neither is the non-success
of any importance, as guns of any size may now be produced at pleasure.

W. Bridges Adams.

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