« ՆախորդըՇարունակել »
side of a comparatively light field-gun at which it was fired: it killed the man who was laying the gun, but did no more damage. The gun continued to fire, bearing on its side a glorious scar. Many similar incidents occurred in the Franco - German war, which showed that shell were not more liable to disable a gun than shot. Thus gun-wheels were hit without injury to the carriage; the breech-wedge was demolished, leaving the gun still serviceable; the sight was shot away, and no further damage was done. And though the splinters of shells were often fatal to men who would have escaped altogether had roundshot been used, the destruction due to the introduction of shells was far less than had been anticipated. Indeed it is extremely doubtful if the destruction caused by modern artillery will ever come up to that wrought by the smooth-bore guns of one hundred years ago-not because the modern guns are inferior to their prototypes, quite the contrary, but because the latter fought at such close ranges, and the target was also far more favourable.
The disappointment which was felt by many as to the effect produced by common shells with percussion - fuses is not altogether a thing of the past. Only a short time ago there appeared in the papers a statement that the Boer shells were very inferior: one had struck between a man's feet and burst, and had done him no harm. Now this was just what was to be expected from a thoroughly efficient common
shell: the man between whose feet the shell struck was almost bound to escape, whatever may have happened to any one else.
In order to explain what happens on the percussion-fuse of a common shell acting, it is necessary to describe the shell itself and its properties.
A common shell for a fieldgun is in shape and size very like an ordinary pint - bottle: the head, however, is domeshaped, so that if the neck of the bottle be knocked off, the similarity is greater. The metal of the the shell may be either cast-iron or steel. If the former is used, there is less room for powder, because the weakness of the cast-iron necessitates thicker sides to the shell than if it was made of steel. Cast-iron, however, breaks up well. What is required in a shell is that it should stand a heavy pressure from outside safely, and yet burst readily into a a large number of pieces. It is also desirable that it should hold as large a bursting - charge as possible. The metal most in favour in England for the manufacture of shells is caststeel: it is much stronger than cast-iron, and therefore allows of the walls of the shell being made comparatively thin, so as to admit of a large bursting-charge. It also breaks up into numerous fragments on the burst taking place. Forged steel has also been used; but it is too tough, so that a shell made of this metal only tears up into a few large pieces, very much as if it was made of leather. The preparation of
a shell is a very simple matter: not very dissimilar to those
that case there is a hole through the base (corresponding to the bottom of the bottle), through which the shell is filled and into which the fuse screws. The fuse is invariably made of metal, and acts as a plug for completely closing the shell.
When a shell bursts the action is not by any means instantaneous. After the ignition of the fuse the burstingcharge of the shell takes some little time to develop sufficient pressure to burst the shell. This is owing to the comparatively deliberate way in which gunpowder behaves on being ignited. There are many explosives that detonate in onemillionth of a second or thereabouts, but a shell charged with gunpowder will take some fivethousandths of a second to burst. The time does not appear long; but if the shell be travelling at 1000 f.s., it will have moved 5 feet from the point of impact before impact before it bursts. If the velocity be as much as 2000 f.s., the shell will not burst till it has gone 10 feet from the point struck. Hence a shell which glances off the object struck flies from 5 to 10 feet in the new direction before exploding, and then bursts well clear of the object.
And what is the effect of the burst? Our bottle-shaped shell breaks up into fragments
into which a glass bottle breaks. It is common to find the base of a shell entire, though it sometimes breaks into two or three pieces. A bottle behaves in much the same way. The sides break up very unevenly; there are some large splinters, each one constituting, say, one-twelfth of the original shell, whilst there are some tiny fragments smaller than a pea. The head, like the base, sometimes remains entire, and sometimes breaks into two or three pieces. The distribution of the fragments depends in the first place on the velocity and direction of the shell at the instant when it burst. Most shells in the field are exploded by striking the ground. If the ground be hard, and the range be moderate, so that the shell is not falling at a very steep angle, it rebounds from the ground, commonly turning to the right as it does so, and bursts when it has risen a foot or two. The effect of the burst is that the head and base continue to travel in the same direction that the shell was taking before it exploded-that is, they continue to rise sharply. The head goes somewhat faster than it did before, the base somewhat slower. The pieces from the walls are thrown to either side of the new track of the shell, at varying angles and at various velocities. But all continue to travel onward with about the same velocity at which they were going when the shell burst. The result is that the fragments diverge
from the place of burst, forming a cone, the angle at the apex being about 45°, which is sufficiently nearly represented by the capital A in "Magazine on the outside of 'Blackwood.' Outside this cone there is absolute safety, whilst inside it there is some chance of being hit, depending mainly on the number of pieces into which the shell breaks and the distance from the point of burst. An ordinary common shell may furnish from twenty to forty pieces: half of these fly up into the air and come down "spent " at some distance off, hurting no one. A few from the under side of the shell strike the ground a few feet beyond the place of burst and stick there. From half-a-dozen to a dozen remain which may be dangerous, as they fly more or less along the ground, and these alone are likely to do any harm. But their velocity is very speedily reduced by the great resistance of the air, and unless there are a number of men within, say, ten yards of the place of burst, it is most probable that no one will be hit.
A man standing upright and fairly in the cone of fragments, but 20 yards from the place of burst, would escape seven times out of eight; or if eight men were standing at this distance from the place of burst, only one would be hit. If the shell be large and the ground stony, this might be somewhat modified, for the gases from the shell will pick up a certain number of stones and thus increase the number of splinters,
which are always more numerous from a large than a small shell; but even then a common shell is not very much to be feared in the open.
When the range is long and the ground is soft, the shell simply plunges into the ground, where the burst is completely smothered, and no harm whatever is done. Much dust is thrown up, much more than when the shell bursts above ground, and unpractised gunners are often encouraged to continue firing at too great range because the fire appears to them to be very effective, especially when the enemy are seen to be close to the place of burst. A shell, especially when fired at a moderate range, may very frequently penetrate some distance into the ground and then turn upwards, bursting on or near the surface: such a shell, if it has stopped before it burst, may do a good deal of harm, but if it is rising rapidly, when it bursts the fragments are thrown harmlessly into the air. The bursting of a shell will not in itself drive the fragments very far or very fast. The injuries caused by the pieces of a shell are mainly due to the velocity with which it was travelling before it burst. Thus a "spent" shell from a fieldgun bursting on the surface, though it throws a good many fragments along the ground, does not give them much energy, and only the large pieces are likely to cause serious wounds. Larger shell, such as those fired from guns of position, are more formidable in this respect, but mainly be
When a common shell bursts amongst walls or buildings or in a confined space it is seen at its best. The fragments and gases from the shell glance off the walls and strike those who would otherwise have escaped; men are blown down who would have been untouched in the open; and the moral effect is generally much greater.
cause the fragments are larger: which weigh fourteen to the they do not travel with much pound. But the anxiety to more velocity than those from obtain more hits has resulted a small shell. in the reduction of the size of the bullets, which now run thirty-five per pound-that is to say, they weigh somewhat less than half an ounce, and being round they greatly resemble the pistol - bullet of a hundred years ago. The head of the shell is somewhat loosely riveted on, so that it is readily blown off by the small burstingcharge. At the apex of the head is the combined time and percussion fuse which communicates by a tube passing through the bullets to the burstingcharge in the base. The fuse is the most important part of the shrapnel, and indeed without good fuses it is impossible to obtain any satisfactory results with modern Field Artillery. And not only must the fuses be good but they must be properly set. be properly set. The best fuses will give but poor results when manipulated by unpractised hands.
But even under the most favourable conditions a common shell leaves much to be desired, and it has therefore been almost entirely superseded in the field by shrapnel.
The common shell fails because of the small number of hits that can be obtained with
a single shell. The shrapnel is designed to carry a large number of bullets which remain in the shell until it has almost reached the object. The bullets are then blown out by the bursting-charge, and act like a volley from a number of muskets or pistols, so that a hundred hits may be made by a single shell.
Externally the shrapnel is very like the common shell, but the bursting-charge is very small, and lies in the bottom of the shell. The body of the shell is filled with bullets numbering some two hundred in the ordinary field-gun shrapnel. They rest on a diaphragm which separates them from the bursting charge. In the older patterns of shrapnel these bullets were not very dissimilar to that of the old Brown-Bess,
In shrapnel practice a certain number of rounds are deliberately wasted on opening fire in order to ensure the efficiency of the remainder. The initial rounds are fired with the safetypin locking the time arrangement of the fuse, so that the shell does not burst till it strikes the ground, when it is exploded by the percussion part of the fuse. There is some effect, but not anything like that obtained by a burst in the air. The point of graze of the shell is, however, most carefully observed, the object being to ascertain whether it is short
of or beyond the target. short, the elevation of the gun is then increased, if over, it is decreased, and this is continued until it is certain that the shells are striking close to the object. This finding the range, as it is called, sounds easy enough, but really is most difficult, and there are various systems in vogue for carrying it out. Here is an instance from Prince Kraft, taken from his experience at Sedan:
"I betook myself to the other bat
teries in order to see if they were hitting the mark; I was in that mood which inclines us to interfere a little too quickly. Captain,' said I, 'your shells are all over.' The captain laughed and said, on the contrary, they were all short. I pointed out to him the burst of a shell far in rear of the enemy. 'That is not one of mine,' he said, decidedly. But I desired him to give 500 paces less elevation; he did so, and I saw that he had been right. I then allowed him to find his own range, which he very soon did. What struck me was that he never looked at the target, but only at his battery, on the flank of which he stood. I asked why this was, and the captain answered, "The one-year volunteer, Klopsch, is watch ing the flight of each shell, standing to windward of each gun as it is fired, and gives me a sign which we have agreed on after each shot.' You may observe that there are many ways of finding the range. If each battery had a one-year volunteer with eyes as sharp as Klopsch's there would be no difficulty in finding the range. But there is no general, fixed, and certain receipt for doing so. Practice is the only one that I can recommend.”
When the range has been found, it is still necessary to find the proper setting of the fuse, the object being to burst the shell some 50 to 100 yards short of the target. The distance short is judged by the
height above ground that the shell bursts. Since the shell is falling as it approaches the target, the higher it bursts the farther it is from the target. Thus at 2000 yards' range a shell bursting 20 feet high is 100 yards short, one 10 feet high is 50 yards short, and so on. If a burst 100 yards short is desired, the fuses are adjusted to that graduation which it is estimated will cause the shells to burst 20 feet above the
object. If the shells burst too low or too high, the fuse is altered till the desired result is obtained. But why should the shell be burst 100 yards short, and how is the fuse set? When a shrapnel bursts, the body of the shell remains entire, the bullets are projected out the head simply flies off, and of the body of the shell and go on towards the target with a slight increase of velocity, due to the push from the bursting-charge.
But they do not hold together like the charge of shot from a choke-bore, for the spin of the shell scatters the outer rows of bullets considerably, only those coming from the middle of the shell go straight on. In this way the bullets form a cone, the angle at the apex being from 8° to 10°. This cone is very similar to the cone of rays coming from the lens of a magic-lantern, which from the extremity of a room 50 feet long throws a picture some 8 feet in diameter on the screen. At 50 yards from the point of burst the bullets would fill a circle some 7 to 9 yards in diameter, and there would be from five to