ON the Parade inside the Horse Guards, near where once ran the northern channel of the Kiln Burn, serving with the Chelsea Creek to enclose the Thorney Island, whereon Westminster Abbey was built, is a very long brass cannon, considerably shortened at the muzzle, brought we believe from Egypt in the days when our Sydney Smith baffled the elder Bonaparte; on the green, inside the gates of Woolwich Arsenal, there is a similar gun, also of Eastern origin: and both of them remarkable for their small bore compared wit their length.
In the United Service Museum there is an East Indian matchlock, with a small bore and an enormously long barrel. Why was this structure adopted ? Certainly not from mere fancy, for we find that these weapons are but types of the general form, and inasmuch as it is a more troublesome matter to cast, and bore, and forge long guns than short ones, we may be sure it was not done save for some useful purpose. The object was threefold. First, to obtain power.
A gun expels its charge or bullet by the expansion of powder burnt, precisely as a piston is moved along a cylinder by the expansion of steam heated. To produce the best effect with a steam-engine,the piston fits the cylinder with an elastic packing,both surfaces being truly turned and bored to make an accurate fit with the minimum of friction,yet without permitting any particle of steam to pass between cylinder and piston. If the cylinder or piston be rusty there will be no fit ; but if polished,the fit may be, and is, so accurate, and the friction so small, that the piston may be moved by hand,though the steam cannot escape. But the steam is not suffered to exert a violent force, like a man who wastes his power on mere passion.
When the cylinder is one-third or one-half full,the supply is stopped, and then the process called “expansion” takes place — the force going on by the swelling of the steam, and this expansion, of course, operates best in a long cylinder compared with a very short one. Precisely thus was the process with the long guns described before.
Whether they were truly bored and highly polished we do not now know; but the powder was of a slow burning quality, and had it been used in a short gun a large quantity would have been wasted by being thrown out at the muzzle,and the expansive action of the gases would not have taken place.
The second advantage was, that the two sights being a long way apart, a truer aim could be taken at the object. The third advantage was, that the truth of flight in the projectile was powerfully influenced by the length of the guide diminishing any tangential tendency, for which purpose rifle grooves were invented, as a mode of accomplishing the same object with a shorter barrel.
Whether the rifle groove is the best method is by no means proven, though the tendency of almost all modern effort sets in that direction. That there is some connection between length of barrel and length of range there is little doubt; and Queen Elizabeth’s pocket-pistol is a proof that our ancestors thought so ; and the Indian blowpipe, which throws a dart a hundred paces, acts by the expansion of a long column of air heated by the breath, as do our children’s pop-guns by the pressure of the hand.
The rifled barrel was invented for the use of leaden bullets which would take the impress of the grooves. The advantage of the spinning motion thus given was recognised by one of our earliest writers on gunnery, Robins—a member, it was said, of the Society of Friends—and he was the first to propound in print the making rifled cannon, to be fitted with iron balls with leaden projections fixed, precisely like those attributed to the French Emperor. But Robins dealt wholly with spherical balls, and did not dream of elongated shot; and the elongated shot is a more important matter than the rifle, which is subsidiary to it, tending to keep it from turning over in its flight.
Neither is this shot altogether new. It is simply a shortened arrow—shorter than the crossbow bolt or quarry, which was the first curtailment of the arrow. The great advantage of the elongated shot over the spherical bullet is,that with a given weight the cleavage resistance of the atmosphere is diminished. A smaller bore will throw an equally heavy shot, or an equal bore will throw a heavier shot. For years we have been working up to this; and one of the earliest experimenters was a German gun maker, named Staudennayer, who resided at Charing Cross, and made what he called thimble bullets-—in the form of a woman’s thimble, with a very thick end-—the germ in fact of the Minié, the Pritchett, and the Jacob shot of the present day.
The usual length of these modern shot is about two diameters for hand-guns, but for cannon Whitworth and Armstrong have increased the length to about four diameters. How far this length may be carried is still a matter for experiment.The “cloth-yard shaft” was a long cylindrico-parabolic tail, joined to a short cylindrico-parabolic head, at one-fourth the total length, which was about seventy-two diameters of the extreme thickness. Marvellous was the flight and range of this muscle-moved projectile, but nothing like this has been attempted with powder propulsion.
The rapid passage of bodies moving through fluids is mainly influenced by the forms of those are best adapted to cleave water, should not be best to cleave air, the difference being only in density. The longer the vessel, the less is the tendency to go to leeward. The cylinder or conical form is never used for cleaving water, but in preference the section of a bayonet is used. This, therefore, is the true form of a powder-propelled projectile.
If we wished to run a man through the body, thelast instrument we should use would be a spherical bullet on the end of a stick. This is precisely the kind of thing we put on to a bull’s horns to prevent penetration. The most effective instruments yet known for piercing flesh are the small sword and the bayonet — a three-edged sectionforming three hollows. And the metal mosteffective for constructing such weapons is steeL
We have hardness for penetration, strength for resistance, and facility for form, maximum result,and minimum resistance to the atmosphere. Where the ordinary leaden shot would pierce through one enemy, this projectile would pierce through half a-dozen. It would inflict a disabling wound, but not a cruel wound, lacerating and tearing open like a “ragged bullet.”
We have hitherto aimed at constructing projectiles necessary to be carried on the shoulder or to be drawn by horses. We have never made wheel guns to be drawn by men. For this reason our range is limited by size and weight, or our difficulties are greatly increased by the various contingencies attached to the use of horses in battle. Wheel guns, drawn and managed by men, would obviate all the difficulties. A gun twelve feet in length, and with an inch and a quarter bore, would weigh about two hundredweight, and would throw a shot from three to four pounds weight a distance of two miles.
This gun, placed upon a pair of high and light wheels, such as are used by the Americans for their travelling gigs, could be drawn by men with the utmost facility, and would easily pass through and over hedges, or be lifted over low walls. The length of these guns pre-supposes that they must be breech-loading, and with such an arrangement of breech, that in case of abandoning them, a small part could be taken away, so as to render them useless—a far more efficient process than what is called “spiking.” There are yet more advantages.
A soldier going into battle has a knapsack on his shoulders, a gun in his hand, and his ammunition slung about him. Now, it would be a great advantage that his body should be as unencumbered as possible. With this wheel-gun,in charge, say of three men, three knapsacks could all be slung to it as well as all the ammunition, three hand-guns, and three twelve feet pikes, without perceptibly increasing the resistance to draught. If cavalry were sent against a body of men so provided, the guns and the pikes would form a most effectual barricade. If artillery were sent, the long-range would enable them to shoot both horses and gunners, and disable their approach.
And in all transit the same advantage that a railway-navvy gets by using a wheelbarrow, instead of carrying his load on his back, would be obtainable by the use of this armed wheel-carriage. The men would get over more ground with less fatigue in the course of a day than with all their baggage strapped to their persons. This would be “flying artillery.” The particular modes of constructing such guns, and the analysis of the improved guns that have been constructed of late, must be left for a further number.
W. Bridges Adams