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the effect of various methods of attaching the lead coating, some 12-pounder segment shells were burst in the same way, and the fragments collected. In one instance, 243 fragments; in a second, 292; in a third, 310 pieces resulted. The object of these experiments was to ascertain the method most effective in producing the separation of the projectile into the greatest number of fragments, and they will also serve to give some idea of the number

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of wounds which might possibly result from the explosion of a single Armstrong shell among a body of troops. If one of the high explosives should be employed as the bursting charge, the range and force of the fragments as missiles will be immensely increased.

Whitworth guns and their projectiles.--The main difference between the Whitworth and all other systems of rifled guns is, that the weapons are rifled by surfaces, and not by indentations,

FIG. 13.

so that none of the force of the gunpowder is expended in changing the shape of the projectile by jamming it into the grooves. The form of the shot is such that the least possible friction occurs during its passage through the gun, and afterwards through the air, whence its initial velocity and length of flight are usually greater than those of a lead-coated projectile which is forced to take the rifling of the gun, when fired with a like charge, and under corresponding conditions. Whitworth 3-lb. bolts have been projected nearly 10,000 yards, or between 5 and 6 miles. By the Whitworth method the barrel of the gun is rifled in a hexagonal, spiral form, and the projectiles are of the same hexagonal form externally that the bore of the gun is internally. Hence, neither the term 'balls,' nor that of cylindro-conoidal projectiles,' is applicable to them, and they have been usually referred to under the name of 'bolts.' They are required to fit the surfaces of the gun with the utmost mechanical precision, and they have not been adopted as service projectiles on account of the practical difficulties in the way of preserving their perfect coaptation after exposure in damp air, dust, and under other circumstances incidental to field service.

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Congreve Rocket Shell.

War rockets-Rockets in warfare used to partake both of the nature of shot and of shell, according to the manner in which they were used. Their use as shell projectiles has been discontinued. Instead of being discharged by an explosive force from guns, these weapons carry within themselves the means by which they are impelled onwards. A certain composition 15 within the case of the rocket constitutes the source of the impelling force. When this composition is ignited, its expansive energy exerts a pressure forwards, while the pressure at the rear of the rocket is neutralised by the flame and gases escaping into the air through apertures

provided for the purpose. This forward pressure lasts so long as the combustion continues. and causes a constantly accelerated motion of the projectile, until the resistance of the air counterbalances its progressive force.

Rods were originally attached to the sides of war rockets, as they are in firework rockets, and as still employed in some service signal and life-saving rockets; but serious irregularities

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in their flight occasionally resulted from this arrangement. Sir William Congreve placed the rod in a receptacle, called the choke or neck. fixed in the central axis of the rocket (fig. 13), making provision at the same time, by several openings around it, for the escape of the gas behind when the composition was ignited. Notwithstanding this improved position of the rod, however, accidents frequently occurred in rocket practice.

Rockets, when fired, are discharged out of portable rocket machines, or troughs, which rest on tripods. When directed against cavalry, they not only produce wounds by direct collision, but lead to many accidental injuries by the panic and disorder which they create among the horses. They were largely used for incendiary purposes at the siege of Sebastopol.

Hale war rocket.- In these rockets, which bear their inventor's name, the openings for the escape of the gas are placed obliquely to the long axis of the composition chamber, instead of being in the same line with it (tig 1) The direction in which the gas is caused to escape hom the projectile not only impels it forward, but at the same pump imparts to it a rotatory motion round its long axis, corresponding with the spinning movement which is impressed on bullets by the rifling of firearms, and thus gives steadiness to is thight, without the aid of a rod at the base. The only rockets AM wat at present as war rockets in the British service are

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24-pounder and 9-pounder rockets, and are constructed on the Hale system. They are only employed as shot rockets. A 24-pounder war rocket burns about ten seconds, and has an average range of 1500 yards; a 9-pounder rocket, burning eight seconds, has a similar average range, with a maximum of 2300 yards.

Star shells. These projectiles answer a similar purpose when fired from rifled guns to carcasses from smooth-bore guns. Each shell contains a number of stars, which, on the shell bursting, are blown away on all sides, and emit a powerful white light. They are not designed for wounding purposes, only for illumination. Magnesium, chlorate of potash, and nitrate of baryta are some of the ingredients in the composition used with them.

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Machine guns and their projectiles.-These are guns contrived for the purpose of discharging successive showers of comparatively small projectiles with great rapidity. As they stand upon their carriages they resemble the guns of light field-artillery; but as weapons, they belong essentially to rifled small arms. volley from a machine gun in many respects resembles a discharge of grape or canister, whence the French name of the gun-mitrailleuse, from mitraille, grape; but a machine gun is not only capable of directing a more rapid fire, but also of securing greater precision of aim, within certain ranges, than can be attained with case-shot and grape discharged from field-guns. There is no loss of aim from recoil with machine guns when once they have been put in position.

Many military men on their first introduction believed that machine guns were destined to be largely employed in the field in all future wars; but the experience of the Franco-German war of 1870 tended to shake that conviction. It is doubtful whether they offer any such advantages as will induce combatants in the future to use them much in the open field; but there seems to be no doubt that they will be largely employed against opponents in the defence of bridges, entrenchments, and fortresses. It therefore is still a matter of interest to surgeons to have some knowledge of the nature of these guns, and of their power in respect to the infliction of wounds.

The machine guns in the British service at the present time are the Nordenfelt 1-inch, the Gatling, Gardner, Nordenfelt, and Maxim 45-inch each, and the Gardner 4-inch. The projectile of the large Nordenfelt is made of solid steel, with a sharply pointed conical apex, weighs over 6 ounces, and is fired by a charge of 625 grs. of powder; the bullets used with the 45-inch machine guns are similar to those used with the Martini-Henry rifle; the 4-inch Gardner has a special projectile, weighing 385 grs., and made of an alloy of 56 parts lead, 1 part tin, and 1 part antimony. It would be useless to attempt to describe the peculiarities of the

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mechanism of the several guns above named in a work of this kind. The principles embodied in two machine guns, one of Belgian, the other of American invention, have been chiefly followed in Europe. The Belgian, known as the Montigny mitrailler,' from the name of its inventor, was furnished with 37 independent, externally hexagonal barrels, fitted together, and secured within a wrought-iron outer casing. The piece was fired by pulling a handle; the projectiles could be discharged in succession, slowly or rapidly, or they could be fired all at once in one second of time. The removal of the empty steel breech plate which had contained the cartridges, and the substitution of a full one, only occupied five seconds. Thus a continuous fire at the rate of ten discharges a minute could be kept up, equal to a delivery of 370 rifle-shots in a minute of time. The bullet used with this weapon was conical, about an inch in length, weighed 600 grains, and had a diameter of a little over half an inch (·534 in.). It was hardened, and had force enough at 60 yards from the gun to perforate 30 half-inch elm planks. When all the 37 bullets were fired together, they scattered in so comparatively small a degree, that at 800 yards the shower was limited to a space of about 12 feet in width by 10 feet in height; and at 1000 yards the further separation was only about two feet. Many experimental trials were made with this weapon at Woolwich and Shoeburyness, but technical defects were found in it which prevented its adoption in the British service, though it found favour in some other countries.

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On the occasion of the Franco-German war the French brought into the field a number of mitrailleuses,' in batteries of eight mitrailleuses each, as part of their regular war armament. mitrailleuse had 25 barrels ranged in 5 rows in juxtaposition, and to these 25 cartridges were brought by the mechanism and were fired simultaneously. They discharged a heavy bullet nearly 2 oz. in weight. It was expected that great execution would. be done by them, but they were overpowered by field-guns of other descriptions, and they failed to realise the anticipations that had been formed regarding them. They are now replaced by machine guns which more closely approach in principle the Gatling guns, and have the name of revolver-guns (Canons-révolver). They are each fitted with 5 barrels. The cartridge, which is over 2 lbs. in weight, contains 24 1-oz. bullets of hardened lead, and a charge of powder nearly 3 oz. in weight (90 grammes). (See life. 1.)

The American machine gun, or Gatling battery, was introduced by its inventor in 1862. In 1866 the United States Government adopted this gun as part of their armament. It was exhibited, and attracted a good deal of notice, in the Paris Exhibition of IN07, and was afterwards tried in all the principal countries of

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