PROJECTILES FROM FIREARMS NOT CARRIED BY INFANTRY (GUNS)
These projectiles are those of field, mountain, garrison, siege, naval, and coast guns. Projectiles from garrison, siege, naval, and coast guns, being chiefly directed against armoured objects in defence or attack, are distinguished from the first by their massiveness and by the small tendency they have to divide. We will not stop to consider them. On the other hand, the two first-mentioned guns, mainly destined to be used against troops, will be minutely studied from the point of view of their construction, their ballistic qualities, and, lastly, of their effects.
Shells of Field Artillery. As a general rule, shells from field guns are metallic cylinders of cast iron or steel, cylindro-conoidal in shape, with thick walls; the shell is subdivided into cavities which contain the bursting charge, and usually the projectiles.
The shell's anterior extremity, which is well strengthened, and is called the ogive, contains the fuse, which is separable, and is formed by an irregular mass of copper.
The shell's posterior extremity, which is also strengthened, and can often be separated, is called the rear-piece.
On the outer surface of the shell are the forcing bands, which can be detached; they are formed of copper rings, of girdles of lead, of side-pieces, of nuts. Some howitzer shells are provided with discs.
The shell, when acted upon by the time fuse, explodes in the air; when acted upon by a percussion fuse it explodes on striking the ground. Some fuses have a double action, and are both time and percussion fuses.
Shells are designated according to their calibre: shell of 75, of 77 mm., etc., or according to their mode of bursting: shells having a systematic mode of bursting, shells containing grape-shot (mitraille), shrapnel, explosive shells.
I. Shells whose bursting is systematic are projectiles with double-lined sides, showing lines of rupture, and breaking up into large fragments; others of the same kind have in the interior of their thick external envelope a number of piled up cast-iron rings, which break up into large and sharp fragments. These shells are but little employed.
2. Shells containing Mitraille have an outer shell containing metallic discs hollowed out into alveoli, for round bullets from 12 to 15 millimetres (0.47 to 0.59 inch). Segmentation, which takes place at the level of the alveoli, sets free fragments of cast iron irregularly cubic in shape and with sharp angles. Such is the present French mitraille shell.
3. Shrapnel.--The outer shell in this instance is thin; it rests in front upon a heavy ogive, at the back, upon a thick rear-piece. The interior of the shell is filled with free spherical bullets (10 to 16 millimetres, 0.39 to 0.63 inches) of hardened lead. In some shrapnel the charge of powder is placed behind, by the rear-piece (Austria); great force is thus imparted to the bullets. In other cases the charge is placed in front; it then lessens the speed of the bullets, but facilitates their scattering. Lastly, the charge may be mixed with the bullets; this facilitates their scattering, and increases their power (French shells).
With this shell the ignition of the charge is secured by a central tube. The French shrapnel of 75 centimetres contains 290 bullets of grammes each 12 grains); the German shrapnel of 77 centimetres has 300 bullets of 10 grammes (134 grains) each. The shrapnel of the German field-howitzer contains 500 bullets of 10 grammes each.(Fig. 4)
4. Explosive Shells.--Their moderately thick steel walls are hollowed out into a large cavity filled with an explosive material (gun-cotton,, melinite, cresylite, etc.) The explosive shells are generally fired in the proportion of 1 to 3 by all artillery. The variable quantity of explosive material contained in a shell has a very great influence on the effects produced. The German shell containing but 150 grammes (2,315 grains) of melinite is far less destructive than the French grape shot shell, which contains 800 grammes (176 pounds) of the same material. From the outset of the war considerable difference has been observed between the injuries inflicted by German and French shells.
5. Mixed Universal Shells unite the characteristics of shrapnel and of explosive shells. --
A universal shell with a double effect has been adopted by Germany for her field-gun 98 and for her howitzer 105. In its posterior part there is a powder-charge to project the bullets; in the centre are the bullets mixed up with a charge of powder. This central part of the shell is crossed by a tube which secures the ignition of the charge in the posterior portion of the shell. Finally, the ogive in front contains a strong charge of an explosive. The shell may be used as shrapnel with time fuse, causing deflagration of the charge behind, or as an explosive shell with percussion fuse, with or without delay in the explosion after the contact shock, through detonation of the charge in front. Thus it may be easily understood that mixed shells which project shrapnel and sharp fragments of steel in the same way as an explosive shell may give rise to traumatisms of a special nature (Ferraton).
Case-shot are cylinders of sheet-zinc containing round leaden bullets held together by sulphur. When fired at a short range, these cylinders burst at once and scatter the leaden bullets; these are analogous to shrapnel bullets, although heavier (40 grammes, or 617 grains, France). Great use was made of these projectiles during the attack on Liege.
Grenades are explosive bombs thrown by hand; they are spherical in shape and loaded with explosives. The grenade is often an improvised bomb containing projectiles of every shape and weight. The effect produced by its fragments varies greatly, terrible in general at a short distance. Its action is quickly exhausted. The explosive action of the gases is exerted over only a small area, in which, however, it produces great havoc.
Following the method adopted in describing bullets, we shall now only consider the data that are of interest to the military surgeon. It may be said that shells only act through their splinters or their bullets. In the case of the ordinary shell with cast-iron walls, the large fragments are almost exclusively supplied by the rear-piece, the ogive, and the fuse. Fragments of average size weigh from 100 to 300 grammes (1543 to 4,630 grains); small splinters are about the size of a walnut. The present steel shells eject from their entire periphery small elongated splinters, not very thick, about I or 1.5 centimetres (0.39 or 0.59 inch), sometimes they are as large as a pea; their dimension however, may even be that of a small fragment.
Fragments of these shells rapidly lose their velocity. The slightest obstacle--a clod of earth, a helmet, a haversack, etc.--may serve as a protection from them. The Serbians use the shovels with which entrenchments are being made; the Bulgarians use earth; the French soldier his knapsack, which protects his head and shoulders, whilst leaving his hands perfectly free.
The French mitraille shell discharges 416 bullets of 25 grammes (386 grains), besides 288 disc fragments, weighing on an average 40 grammes (617 grains).
The larger fragments of shrapnel are supplied by the ogive and the rear-part.
The principal projectiles of shrapnel are round bullets, from 10 to 15 millimetres (0.9 to 0.59 inch) in diameter, of small weight, and low velocity; they may be compared to the old smooth-bore bullets.
They inflict, in general, slight injuries, such as contusions or incomplete perforations, the projectile remaining in the wound, rather than through-and-through perforations, and their "cul-de sac " wounds are often complicated by the presence of foreign bodies derived from the soldier's clothes, which favour suppuration.
Fragments from the much sub-divided wall of an explosive shell are usually broken up into small, thin, striated and sharp lamellae; nevertheless, some of them spread out and act like a badly sharpened knife. These fragments are very small, and sometimes become localized in the body as if they had been sown like seed.
Most frequently the shell explodes in the air (time fuse) at more or less distance above the combatants. The distance separating the shell from the ground is called bursting height. When this height is small, the shower of fragments or bullets is dense, that is to say, closely charged with projectiles, and the velocity of these secondary projectiles is increased; the shell then is very deadly. It would appear that it is of very little use when the bursting height is great, the shower of projectiles is then more spread out, less dense, more apt to produce wounds, but dangerous effects upon the human body are less conspicuous.
The shell with percussion fuse, which is rarely used, must strike the ground before exploding. When it falls perpendicularly, it either buries itself in the earth or forms a funnel-like excavation, in which its fragments are retained. If it strikes the ground obliquely, it rebounds, gives off a shower of projectiles, the marks of which are shown on the ground as an elongated ellipse. The splinters and the bullets close to the bursting-point have a greater penetrating force than those from a greater distance. In general, these last are the ones that cause wounds.
The velocity of the fragments and of the bullets at the point of explosion is that of the shell at the time of falling. The velocity is--
At 1000 metres: 422 metres, French shell; 369 metres, German shell.
At 2000 metres: 346 metres, French shell; 310 metres, German shell.
At 3000 metres: 300 metres, French shell; 279 metres, German shell.
In the case of the time-fuse shell, this velocity is increased by the active power (vis viva), communicated by the charge in the interior. With the percussion-fuse shell, the bullet has to travel over several hundred metres before reaching the body; and during its course in the air, owing to its shape and size, it undergoes great loss of velocity.
Whether the bullets or splinters proceed from a shell with a percussion fuse or from a shell with a time fuse, when they penetrate into the tissues the large rounded shape of the former, the spread out and irregular shape of the latter, considerably limit the power of penetration, as the resistance of the tissues is proportional to the square of the diameters of the projectiles.
Consequently, one may say that these bullets or splinters do not possess half the penetrating power of rifle bullets.
Explosive shells directed against obstacles, but which reach the defending troops, are commonly and deliberately used at the present time against the enemy. These explosion shells, as well as the ordinary percussion shells, under certain circumstances, may loosen and hurl about stones and debris that play the part of accessory projectiles.
Explosive shells are often productive of multiple wounds. Six, seven, ten, and more, have been observed in one wounded man.