NAVAL GUNNERY IN THE OLD DAYS
An 18-ton gun in action at the bombardment of Alexandria. The gun has just recoiled after firing. No. 1 is "serving the vent". The sponge end is being passed to be thrust out of the small scuttle in the middle of the port (which is closed as soon as the gun is fired), so that the big wet end can be placed in the gun.
The consequence was that while the Germans went in for the Krupp breech-loading system, in which the breech is closed by a sliding block across it, and the French for the interrupted-screw breech-closing plug, the prototype of our present system, we gave up breech-loaders and went in for built-up, muzzle-loading guns. Their advocates claimed for them simplicity, comparative cheapness, and other virtues, but, as a matter of fact, we were entirely on "the wrong tack" and were gradually being left behind in gun-construction by other nations. These big muzzle-loaders were formed by shrinking successive jackets over a steel tube which formed the bore. They were rifled with a few wide, shallow grooves, their projectiles being fitted with gun-metal studs intended to travel along the rifling and so give them the spinning movement requisite for accuracy. The biggest guns of this class constructed in this country were the 80-ton guns carried by the Inflexible at the bombardment of Alexandria, though the Italians, who followed us in sticking to muzzle-loaders for a time, had guns of 100 tons. Of course the biggest guns had special hydraulic mountings, but the broadside guns of 7-, 8-, 9-, or 10-inch bore were mounted on carriages invented by a Captain Scott. These consisted of a pair of iron brackets, or sides, supporting the gun, which ran in and out on slides made of iron girders that could be trained to the right or left by means of tackles, or in most cases by cog wheels working on curved and cogged racers. The carriage on which the gun was mounted had rollers beneath it with eccentric axles, so that, unless these were raised by levers supplied for the purpose, the carriage itself rested on the slide. This helped to check the recoil, further restrained by a system of interlocking plates on the carriage and slide which could be compressed together by a hand-wheel and screw.
After the gun had recoiled inboard and had been reloaded, the compressors were slackened and the gun-carriage put on its rollers, so that it ran down the slightly-sloping slide to its firing-position. But for all its simplicity there were very many disadvantages attendant on the muzzle-loader. One very important one was the impossibility of preventing the gases caused by the explosion of the powder from escaping past the projectile, so that part of the force of the explosion was wasted. In breech-loading guns the projectile fits the rifling closely—it could not be forced through the gun by the rammer from the rear—being provided with a copper driving-band of slightly bigger circumference than the bore. When the gun is fired, this is driven into the grooves of the rifling, rotates the shot, and at the same time stops any escape of gas and consequently of energy. Thus, size for size, a breech-loading gun must have greater range and penetration than a muzzle-loader. A breech-loader can be made much longer than a muzzle-loader into the bargain, as it is not necessary to get to the muzzle to load it. This also makes for accuracy and penetration.
Photo. Cribb, Southsea
The muzzles of the monster cannon are closed by plugs or "tompions" with handsome designs in burnished gun-metal. Above the higher turret is seen a "Barr & Stroud" range-finder in a canvas case.
It was a considerable time before those in this country who had stuck to the muzzle-loading system through thick and thin could be brought to see the error of their ways, but after 1880 breech-loaders much of the French type were introduced into the navy, till we reached the monster 110-ton guns carried in the Benbow, Sanspareil, and the ill-fated Victoria. As I have already mentioned, the French guns were closed at the breech by an "interrupted screw". What this is may be shortly explained. Imagine a screw plug about one and a half times as long as its diameter, with a close thread to it. Now, to screw this in and out of the breech of the gun would be a matter taking an appreciable time. Suppose, now, that we take this screw plug and divide the outside of it—the screw part—perpendicularly into six equal parts. Then, if we cut away the thread of the screw on every other sixth, we shall have three-sixths smooth and the other three-sixths with the screw-thread still standing out upon them. If now we treat the corresponding screw-thread in the breech of the gun itself in a similar manner, and then insert the plug with the three threaded portions in line with the three smooth portions cut in the gun, we can push it directly in to its full length, after which a sixth of a turn will lock the threaded parts together and securely close the breech. This has proved amply strong enough to resist the immense strain imposed by the explosion of the charge; but while the principle has been retained in all our cannon—except the small 3- and 6-pounder Hotchkiss guns, which have a sliding block—it has been so improved that the locking of the breech is still stronger, and in all but our very big guns it can be opened and closed with just about as much ease as a cupboard door. Of course, in monsters like the 12-, 13·5-, and 15-inch guns, hydraulic machinery is brought into play, by means of which their immense breech-blocks are manipulated with the greatest ease by the movement of various levers.
Machine-guns at one period were introduced into the naval service for the special purpose of defence against torpedo-boats, but smaller rifle-calibre weapons were also supplied for use in the tops, boats, and in landing operations. The first-mentioned were "Nordenfeldt" guns, firing steel projectiles of 1 inch diameter in volleys of two or five. These proved too small to deal with the torpedo-boat, which grew bigger and bigger and was superseded by the destroyer; and were replaced successively by 3-, 6-, and 12-pounder rapid-fire guns. But at the present time a 4- or 6-inch shell is required to be really effective against the big destroyers which are now in commission. The rifle-calibre guns were at first Gatlings with revolving barrels, then Gardner and Nordenfeldt volley-firing guns, and lastly the well-known Maxim. Some of these are still carried on board ship but are not now of use in a naval action, though they are most valuable when bluejackets and marines are landed for shore service, and, upon occasion, in the boats.