Once a Week (magazine)/Series 1/Volume 3/Great guns and armoured war-ships
GREAT GUNS AND ARMOURED WAR-SHIPS.
The work-people of our “faithful ally” across the Channel have just launched for him an armoured frigate christened La Gloire. We know nothing about it save what the scribes of the ruler have set down by his permission, and if all be gold that glitters, wonders have been achieved, for the craft is wholly impregnable to shot—at what distance we are not told—and may defy and vanquish the whole British fleet. In fact, the Gallic Emperor is now the ruler of the seas, and the “meteor flag” of England is no better than a shooting star gone out, while a decree has gone forth that henceforth the Gallic cock is to be a web-footed bird. And Captain Halsted, writing to the “Times,” seems to think that there is something in it—that the Gauls have stolen a sea march over the descendants of the Norse coursers, and that the indigenous gnomes of the iron mines are to be conjured beyond seas, the Red Sea inclusive.
Well, before we sit down under this last Imperial dispensation, let us at least look into it. In the first place, “whatever man has done man may do,” was a maxim written over my schoolroom-door; but climbing, as the world still is, over the threshold of progress, we may assume, that whatever man has done, man may yet do a great deal more. Until we have tried with our own guns the ribs of La Gloire, and with our own craft her locomotive qualities, we must not take for granted all that the imaginations of Imperial editors may assert. We remember that La Gloire was once highly spoken of as a steam-ram, and her ram-like qualities were to have been tested on the old Suffrein line-of-battle ship, but the experiment never came off.
The first question in a sea-vessel is stability on the water, as a security against “capsizing,” a word derived from the act of turning head over heels. Ten-gun brigs were formerly remarkable for their facility in this kind of sea-gymnastic, and there was once a Greek fleet built in England wherein the planners were so taken up with the one idea of diminishing resistance by decreasing the breadth of beam, that none of the craft would stand upright either under sail or steam.
The principle of stability consists in keeping the centre of gravity within the base, and so long as this is done we can build a column like the London Monument or the St. Rollox chimney, though the centre of gravity is very elevated. But if an earthquake were to take place, down would topple the columns by reason of the elevated centre of gravity overtopping the base. Therefore the lower the centre of gravity the more secure would be the column. If instead of the column we make a pyramid, we get a form which it is almost impossible to overthrow by any earthquake.
If now we form a body, with the water for a base, the movement of the water represents the earthquake, and the body will be stable, or incapable of turning over head and heels, in proportion as the base exceeds the height and the low level of the centre of gravity. Thus a flat thin board thrown into the water will always float on its flat side, the centre of gravity being in the centre of the mass, and at a very low elevation. But if a sufficiently heavy piece of metal be placed at one edge of the board, it may be made to float with the opposite edge upwards, like a fish.
Again, if we throw a solid cube foot of floatable timber into water, it will float with one corner upwards and the opposite corner downwards, the particular corner being determined by the density of one part of the material over the rest. If the cubic foot of timber be cut diagonally into two equal parts, each of them will float nearly equally well on the broad diagonal surface, or on the two rectangular surfaces. If a long cylinder of wood be placed in the water, the centre of gravity being in the central axis, it will float any side upwards. If a long squared log be placed in the water it will float on any one of the four sides equally well, unless the centre of gravity be nearer one than the other, in which case the heavy side will tend to be the base, and the log will turn to that side if the water be agitated. If the log be cut in two, diagonally, through the whole length, and weight be added at the apex of the rectangle, it may float on its broad base; but every disturbance of the water would tend to roll it over, and it would then take the position of greatest stability indicated by the diagram Fig. 1, which is intended to represent the mid-ship section of a sharp vessel, a a being the water level, and b b the surfaces pressing on the water; c c the deck, and d d the top sides, or bulwarks, above the deck, e the ballast, or weight, tending to keep the apex f in a vertical line, and restore the vessel to equilibrium after disturbance. For a sailing vessel this is the best sectional form to preserve a straight line in the water and prevent lee-way. It is, in fact, almost all keel. But there are many reasons why vessels are not constructed so. First, with ordinary timber framing it is not a strong form to resist the pressure of the water; and, secondly, the sharp vessel will not carry so bulky or so heavy a cargo. The circular form, shown by the dotted lines g g, gives the strongest form to the vessel with a larger carrying power, but with the defect of rolling easily on the water like a cask; and the dotted lines h h show the form of largest capacity in volume and weight, but comparatively a weak form to resist the pressure of the water. For sailing on a wind, the lines b b are the best, the lines h h the worst. For a vessel moved by internal power the form is immaterial, provided the stem and stern be sufficiently acute, and therefore while the mid-ship section is denoted by the lines h h, the stem and stern taper off in the form of the dotted lines i i, and the sharper the taper, the less will be the resistance.
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Fig. 1.
A ship, unless of fir-timber, does not float by reason of the lightness of the material of which it is built, as a raft does, but by reason of what is called its displacement, i. e., in other words, the cubic contents of internal air space, and if compatible with other considerations, the more air space it contains the better, wherefore the lines h h would be the best, being double the lines of b b, and this brings us to the consideration, supposing air space, or, in other words, carrying power, to be sufficient, what is then the best form of hull, and more especially a hull intended to avoid the effect of cannon-shot by a sheathing of armour plates?
A shot produces its destructive effect either by its great weight or force of propulsion, or both combined. If the shot be light, the effects must come from force of propulsion. In any case great range is important. In throwing a shell, the chief effect of which is by the explosion of internal powder, the elevation at which it is fired is of little importance; but in battering ships, or breaching forts, shells are used to strike point blank as well as solid shot.
The armour used for covering vessels, consists of plates of iron or steel in as large sizes as possible. Probably soft steel is the best, being most homogeneous. These plates are bolted to the sides of wooden or iron vessels; the greatest thickness as yet conveniently attained in manufacture being about 4½ inches. In the experiments which have been made, Whitworth rifle shots have punched holes in these plates at 400 yards, and 68-pound shot, not rifled, have shaken the whole fabric of plates and the wooden framework behind it. Whether the rifled shot is essential to penetration is not yet made certain by the “crucial instance” of a plain shot fired from an equivalent smooth bore with an equal windage and equal charge of powder.
Now it must be quite clear, that if a shot be fired point-blank at a ship’s hull constructed with vertical sides, as h h, it would have the most favourable circumstances for penetration. But if the sides were of the section above water d, fig. 1, and below water b, a point-blank shot propelled parallel to the surface of the water would not pierce, but glance off from the surface of the armour-plates, j j, and the only mode in which they could strike the upper plates point-blank, would be by firing at a high elevation, with simply a falling force proportioned to the weight of the shot. And the lower plates below the surface of the water could scarcely be struck at all. And the practical strength of the plates at point-blank is one-third greater than if placed vertical. In other words, one plate 3 inches thick, at an angle of 45 degrees to the propelled shot will offer as great resistance as a plate of 4 inches and a-half in thickness at an angle of 90 degrees, independently of the glancing effect. I alluded to this in a former paper about a year ago. Three-inch plates would be better even, and cheaper than four-and-a-half.
In building a war-vessel in the present day, a wooden hull is an anomaly. The fact of breaching the vertical sides of iron ships an inch thick with round shot, on experimental trial, does not prove any deficiency in iron ships, but only ignorance in constructing them. With armour-plates stretching 8 feet above and 8 feet below the water line, at an angle of 45 degrees, it would be a very difficult thing to pierce them, and the experiment is worth trying, finding out at the same time whether the rifle or smooth bore is preferable. The breadth of beam and the length of vessel, as regards displacement, is simply a question of the load to be carried.
In a vessel constructed on this principle, it is obvious that the armour-plates should be bent at an angle to ensure strength, the length of the plate being up and down, and this form would facilitate the fixture of the plates with much lighter fastenings. But, inasmuch as the topsides or bulwarks incline inwards all round the deck to a height of 8 feet, a very large tank would be formed, tending to capsize the vessel in case of a wave breaking over her. Therefore a sufficient number of these plates should be hinged at or below the water line, allowing them to fall outwards with the pressure of the water, and so discharge it.
In regard to the question of guns, the usual mode is, to allow them to recoil and run in and out from a wide open port. From the recoil and breaking away of the gun, and from the missiles entering in at the port, an enormous loss of life ensues.
To diminish this waste of life, the first essential is, to use non-recoiling guns; and, secondly, breech-loaders. There is only one principle of preventing recoil, and that is, making the gun either by its own weight, or by its weight and that of the carriage combined, very far in excess of the weight of the shot. In a service-gun, weight 95 cwt., the 68-lb. shot is about 1 to 157, and this does not prevent recoil: diameter of bore, 8 inches; length of bore, 15 diameters.
At the diagram fig. 1, illustrating the section of a vessel’s hull formed to elude the force of shot, is a breech-loading gun A, exaggerated in apparent size, compared with the vessel. This gun is of 10-inch bore, and about 50 diameters in length. The weight of the gun is 50 tons, and the weight of the shot 3 cwt., or five times that of the 68-pound shot. There are no trunnions, but the muzzle is formed into a sphere or ball (k), which revolves in a socket formed in the iron topside of the vessel, entirely closing the opening, save a channel cut through the upper part of the ball for the purpose of sighting. The muzzle, therefore, would act as a port sufficing to keep out water, and in rolling, by the action of the waves, the gun would be as a part of the ship’s side.
The thickness of the gun is equal to the bore, the breech (l) being reinforced where the greatest strain of the powder is taken. The breech is closed by a breech-pin (m) flat on the face next the powder and circular behind. This pin can be moved in and out by a moveable pinion and winch, working in the back of the pin, so as to close or open the bore, which is smooth and not rifled, and the vent is on the pin, where it projects at the side of the gun—a cap being struck by a hammer on the upper surface as with an ordinary shoulder-gun. This arrangement facilitates the renewal of the vent in case of wear, but it is yet a problem, whether it is not better to fire the powder in front next the shot. In charging the gun a thick wad of papier-maché, placed between the powder and the breech, will effectually prevent any escape of gas.
The hinder part of the gun is supported by two or (if preferred) by four wheels (n) of small diameter, connected by a frame running in a circle, the centre of which is the ball at the muzzle. The gun is supported on a pivot formed by a water-ram, with a small pump to work it, involving but little labour. In this mode the horizontal and vertical movement can be given to the gun with great accuracy. The wheels may be geared, and not half the number of men will be required to work this gun of five times the usual power.
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Fig. 2.
Fig. 2 represents an outline of the deck of a vessel of say 60 feet beam and 400 feet in length, or any larger size that may be needed for the requisite displacement. Two guns (a a) are placed stem and stern, or rather at either end, being both alike, and five on each side, fourteen in all, being 700 tons of metal on one deck, and capable of throwing fifteen cwt. of metal at a broadside, being equal in weight to the shot of 25 service guns of 95 cwt., but with something like twenty times the destructive effect. If this vessel be covered with armour plates, 11 feet above and 11 feet below the water line, 4½ inches in thickness, the weight will be about 1300 tons, with the guns 2000 tons, or about one-eleventh the carrying power of the Great Eastern. If 3-inch thickness of wrought-iron plates placed at the angle proved better than 4½ inches vertical, the total weight would be about 1570 tons. If the draught of water formed by the apex at f were too great, the inverted pyramid could be truncated say to the ballast-line at e, or any higher elevation, giving sufficient longitudinal stiffness as a beam; but it is obvious that making a perfect apex forms a stronger beam. In any case the angle downwards from the water-line must be preserved.
Now, suppose two vessels of this class to be opposed to each other, they could produce very little effect at long shots. What they would do yard-arm and yard-arm with small charges of powder is a problem. With the muzzles depressed possibly the guns might batter in the top sides, but they could scarcely effect anything below the water-line, and the men would be quite sheltered till the topsides were burst in. No bursting of the guns need take place, for the steam power could easily pour a stream of water through them to cool and cleanse them. Supposing the guns inefficient, there would be two other modes of attack. First by a duel, like two rams butting each other, which would give room for every kind of skill in manœuvring. If one craft could strike the other amidships, it would probably involve destruction; but if, like two rams, they only presented their stems to attack, it would be very difficult to strike. In such case a small quantity of powder might pitch the heavy shot over each other’s bows, rolling them from stem to stern, dismounting the guns, and sweeping away the men. This would be more than ever a fight of skill and energy, and the web-footed people would have the advantage, as of old, over the shore-goers.
If the vessels were side by side there would be a kind of ditch between them, formed by their top sides, eight feet in depth, with the sides sloping at an angle of forty-five degrees, and sixteen feet in width. There would be more skill in hitching the two craft together and boarding. It would then be a question of riflemen picking off and boarding parties encountering. In that kind of fray, muscle and cool courage would certainly have the advantage as ever, over nerves and mere élan.
Of the principles I have endeavoured to set forth in the foregoing columns there can hardly be a doubt. First: iron vessels without any combustible material to be affected by the furnace-fires of the engines, or the combustible compounds of the foe. Secondly: the armour plates, placed at such an angle as to increase their strength and elude the force of the shot. Thirdly: great speed to manœuvre. Fourthly: closed portholes. Fifthly: high iron buttresses—as means of defence. Sixthly: Heavy non-recoiling guns of great weight. Seventhly: spherical muzzles, moving on sockets in the vessel’s side. Eighthly: breech-loaders without complication. Ninthly: smooth bores without rifles. Tenthly: very heavy shot. Eleventhly: elevating water-ram, cheap and powerful—as means of offence.
This is the class of vessels which will outmatch La Gloire, and this also is the class of vessels which, if our enemies obtain before we do, we have, nevertheless, any number of the descendants of the old Norse Coursers, who would try conclusions in getting on their decks, even from the “ships that are but boards,” and may serve only as bridges to get at them, while dodging their shot as best may be.
In all that needs doing there is no need of great expenditure of the public money, but only of our economically putting in practice the system of trial and error. When a thing can be demonstrated to be right, and cannot be demonstrated to be wrong by the use of the English language, it ought to be tried, if probably useful, and not too costly. The costly thing is the obstinate avoidal of trials, and the rushing into large manufactures without the trials, discovering what is wrong, only on a large scale, making a nine days’ wonder at the cost of a hundred thousand pounds, where a single thousand would suffice. There is, it is true, no royal road to originality, but so also there is no royal road to the selection of judges; only a judge in a condition of ignorance is much more damaging to the public than a pretended originator, who turns out to be a quack. Better blunder over a hundred mistakes, than mistake the one right thing when it starts up.
In this matter of war-tools lies physical salvation. When war-tools shall have culminated, war-work will be at an end. Men will cease to fight when destruction shall be rendered certain.
W. Bridges Adams.