For heavy guns or cannon the charge is carefully weighed and made up in a serge cartridge sewn with worsted, which entirely consumes in firing—any residue left ignited in the bore being liable to cause explosion when the cartridge of the succeeding round is rammed down on it, and so to blow off the arms of the gunner using the sponge stave. The shell or other projectile employed is forced home on the cartridge {vide fig. 1) in muzzle-loading guns. In breech-loaders the shell is introduced first, and pressed into the shot chamber, beyond which it can only pass by the “lands” of the rifling cutting into the lead coat, which is effected by the explosion of the charge. The cartridge is pressed forward against the base of the projectile.

Rifled guns—that is, guns constructed to impart rotation to the projectiles they discharge—have superseded smooth-bored cannon in the armaments of all civilised nations; elongated projectiles, which are impeded by the resistance of the air much less than spherical ones, being in all cases employed. Fig. 1 shows a section of the bore of the muzzle-loading gun, whose projectiles are made to rotate by means of gun-metal studs which fit in the spiral grooves of the bore. The following kinds of projectiles are fired from rifled cannon in the British service :—Common shell, Shrapnel shell, Palliser shell and shot, and case-shot. Light balls, carcasses, and spherical shells are discharged from smooth-bored mortars. The two last mentioned, as well as spherical Shrapnel, round shot, grape, and case, are fired from smooth-bored guns.

Common shell for rifled guns are simply hollow elongated projectiles filled with powder, which is fired by the action of a fuse, and bursts the shell with great violence, acting in walls or earth into which it has penetrated like a small mine, the largest shells, which are twelve inches in diameter, containing nearly 37 lb of powder. Gun cotton, nitroglycerine, and other substances, have been tried for bursting purposes, but it has been found very difficult to prevent premature explosion from the sudden shock of discharge of the gun. Picrate of potash, or “picric powder,” has been recommended as stronger than gunpowder and quite cafe, but it is not as yet adopted. Common shells are generally fired at earthworks, buildings, and wooden ships. When carried, as in English men-of-war, filled and fused with percussion fuses, they can be discharged as rapidly as shot. The most terrible instance of their use in history is the entire destruction of the Turkish frigates by the Russian fleet at Sinope on November 30th, 1853. At the battle of Sedan in 1870 the Prussians made such havoc among the crowded French troops that the ground became covered with “heaps of flesh and rags;” and a similar result was produced by the fire of mortars concentrated on the Russian troops in the Redan at the termination of the siege of Sebastopol. The slaughter in the two last named instances is, however, to be attributed to the concentration of fire on masses of men rather than to the description of shell used, for the showers of bullets ejected by Shrapnel shell would have struck many more men, although the ghastly spectacle of dismembered human bodies would not have been exhibited.

Shrapnel shell are hollow projectiles containing bullets and a very small bursting charge. Fig. 2 exhibits the construction of the Boxer Shrapnel shell for the 40-pounder breech-loading Armstrong gun, and is a good specimen of this class of projectile. The shell follows the usual course of flight up to within about 100 yards of the object, when the time fuse, if properly set, fires the bursting charge, and opens the shell by splitting it along certain grooves forming lines of least resistance. The bullets and fragments then continue their course in the form of a shower of missiles. This class of shell was designed for smooth-bore guns by General Shrapnel. It was used with great effect during the Peninsular war, especially in clearing the breach and ramparts of St Sebastian of defenders, over the heads of the English storming party, who drew back into the ditch for a time. The projectile has never been understood and thoroughly taken up by foreign powers, and has never been used to full advantage on service. In skilful hands it is capable of producing results far beyond any that have as yet been achieved.

The Armstrong segment shell fulfills the same general purpose,—that is to say, it is designed to sweep down bodies of troops, but it opens rather more suddenly, segments of iron taking the place of lead and antimony bullets, which segments being built up in a ring with the bursting charge in the centre, are dispersed more widely when the shell opens than·the bullets of the Shrapnel. The segment shell consequently is rather suited for the action of a percussion fuse on striking the head of a column of men, or the ground close in front of it. In this way results have been obtained which are out of all proportion to anything that has ever occurred in actual service. At Dartmoor in 1869 the average number of hits for every segment shell fired during the series of experiments, including failures of all kinds, was 17Ί. The meaning of this estimate maybe appreciated by applying it to some action. For example, at Waterloo the English artillery fired 9467 rounds. On the Dartmoor scale this would give 161,885 casualties. This result shows that after making the most liberal deductions for the peculiar circumstances of war, appalling effects might be produced by modern artillery with segment or Shrapnel shells.

Palliser shell and shot are projectiles made with specially hard and rigid heads, with the object of piercing the sides of armour-clad vessels. The form of the head, which is termed “ogival,” is seen inside the gun in Fig. 1. A point of this shape causes the resistance of the plate to fall on the shell as an increasing pressure, acting inwards towards points distributed along the axis, rather than as the full sudden blow that would be experienced by a round shot. This enables chilled iron to be used, which has great hardness and crushing strength, but is very brittle. Sir W. Palliser first proposed chilled projectiles; subsequently mottled iron projectiles with chilled heads have been used. Sir J. Whitworth has obtained great results with flat-headed projectiles of a special quality of steel, which have been made to penetrate iron plates at an angle even more oblique than 45°. Solid and hollow shot, as well as shell, have been employed against plates. The shot, having thicker sides or walls, have some advantage in penetration. Shells, by their explosion, destroy wood backing better than shot, when the front plating is not too thick for them to penetrate. They are charged with powder through a filling hole in the base of the shell, closed with a strong screw plug. No fuse is required, impact against thick iron being sufficient to explode the bursting charge of a shell without any fuse. The greatest penetration that has yet been obtained in armour was achieved by the 35-ton Woolwich gun (termed the Woolwich “infant”), at Shoeburyness on June 2Oth, 1872, the head of a Palliser projectile passing entirely through 18∣ inches of iron and 12 of teak, a thickness of armour exceeding that of any iron-clad vessel afloat. Solid shot have gradually disappeared since the introduction of rifled guns, and the reasons are obvious. A round shot fired from a smooth-bored gun, after its first graze, continued to ricochet in a straight line; it produced, therefore, a considerable moral effect, and on smooth ground was actually formidable. A rifled shot, on the other hand, is violently deflected after each graze, from the fact that it is rotating rapidly as it touches the ground, and this, coupled with its liability to bury itself, detracts greatly from its efficiency. Shells for any rifled gun may be made of such length as .to bring them to the same weight as the corresponding shot, which was not the case with smoothbore projectiles, they being all of one size instead of one weight. In short, Palliser shell with thick walls (fired as hollow shot) excepted, the only projectiles of the shot class now employed with rifled guns are case shot. Owing, however, to the fact that the charge of a rifled gun varies from ⅜th to I th the weight of the projectile, while in smooth-bored guns it was sometimes as great as ⅜d that of the shot, the effect of rifled case is comparatively weak. At any time the range of case shot hardly exceeds 300 yards, while its efficiency depends on the ground along which it bounds being hard and level. Each shot consists of a number of balls enclosed in a thin metal cylinder, which breaks up in the gun, the balls scattering from the muzzle, but sweeping the ground with great effect under favourable circumstances. Grape differs only in the balls being larger. At the battle of Friedland, at the bridge of Lodi, and at Sebastopol, grape and case were fired with great effect.

Time and percussion fuses have been mentioned. Time fuses are those which open a shell at any given time, whether in the air or during penetration. Fig. 2 shows the “Boxer 9-second fuse” for breech-loading guns, fixed in the shell. On the shell moving, the hammer in the head, by its inertia, shears a copper wire, fires a detonating patch of composition beneath it, and lights the fuse composition. This burns until it reaches the point at which a hole is bored in the fuse, when it flashes down the channel shown on the left side of the cut, and fires the powder primer and bursting charge of loose powder. The action of this fuse therefore depends on its correct boring and regular burning. A percussion fuse is one that acts on impact or graze. Fig. 3 shows the Pettman general service fuse. On the first movement of the shell, the detonating ball A, and the plugs above and below it, by their inertia, crush the lead cap C, and shear the copper pin above F. During flight the ball becomes detached from the upper or steady plug B, and on impact is fired by its momentum against the part in front of it. Thè steady plug itself has also a ring of detonating composition, DD, which, should the plug fail to escape from the detonating ball, and so hold against it, is thrown against the little plain ball E. The flash in either case acts down the tube F, and fires the bursting charge of the shell. This fuse is made not to explode against a wave, being chiefly used for sea service. It acts both with smooth-bored and rifled guns. For land service more sensitive ones are employed to explode on graze.

Friction tubes are copper tubes driven with mealed powder, and pierced from end to end. A friction bar in the head is rubbed against patches of detonating composition by pulling a lanyard, which hooks into a loop at the end of it. The tube is entered in the vent of a gun, which is thus fired by pulling the lanyard.

For mitrailleuses and breech-loading small arms, lead bullets or lead and tin bullets, fixed in central-fire cartridges, are used. The cases are made of sheet brass, with a thick base disc containing a cap chamber, cap, and anvil. Fig. 4 shows the Boxer-Henry ammunition for the Martini-Henry rifle. These metal-cased cartridges are not liable to explode in store, even from the firing of a small charge of powder confined inside the same packing-case with them. They admit of a very rapid rate of firing. The Gatling mitrailleuse has discharged 657 rounds in two minutes at Shoeburyness. The Martini-Henry rifle has fired 25 rounds in a minute.

Rockets are projectiles containing composition which, as it burns, generates sufficient gas to drive forward the rocket by an action resembling that of the recoil of a gun. Of rockets there are three kinds: first, war rockets, with iron cases, introduced by Sir W. Congreve, and subsequently brought by Mr Hale to the form shown in Fig. 5. Congreve rockets were kept point first by sticks screwed into their bases, which acted on the principle of the feathers of an arrow. The Hale rocket is kept point first by rotation, caused by the gas escaping from the vents pressing against the curved shields. The second class of rockets are signal rockets, made of paper, and containing stars, which throw a bright light in falling. The third class are the rockets used to carry a line and establish communication between a wrecked vessel and the sea-shore. (c. o. b.)