It would effect a great improvement in the mortars used by the navy, destroying the tremendous vibration and shake given to the ship, increasing their efficiency and aiding the projecting power, to place them on beds of the softest lead, not less than twelve inches in thickness. Though this suggestion is only theoretical, experience would soon determine the least degree of substance available. Advantage would arise, in the first place, from the non-conducting tendency of the lead; in the second, from its density, and, of course, incompressibility. The one protecting the ship, the other being the most solid bed for the mortar that can by possibility be obtained.
The weight of a hollow 13-inch shell is 190 lbs.; the bursting powder 6 lbs. 8 oz.; the weight, if cast solid, would be 290 lbs.: thus the action of so large a body on the atmosphere must be immense of itself. There seems to be much difficulty in projecting masses of great diameter, from this cause; and this should lead us to seek, as indeed it points to, another material for fabricating projectiles. As weight is less in substance, and, of course, less in space, much less resistance, in proportion, will exist in a bore of six inches than in one of twelve; and a greater projectile force will be generated with fewer countervailing disadvantages.
The first step in the vast improvements about to be effected in gunnery, has been successfully taken by Mr. Monk, of Woolwich arsenal, who has induced the authorities to allow a gun to be made from drawings and calculations of his own. The dimensions of the gun are as follows: length from cascable to muzzle, 11 feet; weight, 97 cwt. 3 qrs.; bore, 77⁄10 inches; weight of solid shot, 55 lbs.; shell, 42 lbs.; windage, 0·175; charge, 16 lbs. of powder; giving a range, at 32° of elevation, of 5,327 yards. A compound shot, (a shell filled with lead), was projected 5,720 yards, or three miles and a quarter, at a velocity, during the first second of time, of 2,400 feet per second, and occupying during the whole flight only 291⁄2 seconds. The comparative weight of gun and shot is 1 to 220.
A course of experiments, extending over seventeen years, has firmly established this gun as the best ever yet constructed. Many attempts have been made to excel it, but all have failed. Guns have been made on drawings varying not more than three-tenths of an inch in their dimensions from those of his gun, and, with extreme modesty, the individuals have claimed a right to compete with Mr. Monk; and have even obtained competing trials, without any claim whatever to the discovery of the principle of it; coming into competition by no just claim or merit, but solely from the tendency to supersede any improvement emanating from a civilian. Eighteen, twenty-four, and thirty-two pounders are now, however, constructed on this model;—indeed the improvement is so great and so apparent, as to overcome every obstacle as yet thrown in its way.
With no wish to detract from the merit of Mr. Monk’s invention (upon which I congratulate him and the country) but, in justice to myself, I may remind some of my readers, that in “The Gun,” published early in 1835, I clearly laid down the principle in projectile force, on which this gun is constructed; and as he has since so successfully accomplished this great improvement, he must permit me to say, that the principle is the same which I have striven for, for many years.
Wilkinson says, “Guns cast on this principle, although several hundredweight lighter altogether, recoil less than those on the old plan, with equal charges of powder and ball, in consequence of the weight being properly distributed.” He adds, “One remarkable fact attended these experiments, namely, that by increasing the windage a little, the range was increased also, contrary to the received opinion; but this may be explained by the circumstance, that with very great velocities, and long guns, the column of air to be displaced before the ball quits the gun is considerable, and is condensed so rapidly, that it offers immense resistance to the passage of the bullet, if it fit the bore closely; but, by reducing the size of the ball, and thus increasing the windage, the air has more space to rush round it, and the ball escapes with greater facility.”
If the condensed air prevented the velocity being greater, it argues most clearly, that there was an insufficiency of explosive matter to keep up the velocity until the ball of less windage left the muzzle; and the result with the ball of greater windage establishes this assumption. For if the condensed air was allowed to pass the ball by the windage into the tube, it proves beyond doubt that there was a deficiency of matter there, or that the pressure without was greater than that within. How otherwise could such a result occur? It is a clearly established fact, that with the generality of ordnance, a full waste of one-fourth of explosive force, if not more, occurs by the elastic fluid escaping past the ball by the windage, instead of the reverse. Neither could the condensed air rush into the gun by the windage if there are any permanent gases generated; which Mr. Wilkinson himself says there are, to the extent of “250 times the bulk of the powder in grain.” These would offer a sufficient resistance to prevent the condensed air rushing in. I have found, by an experiment before described, that a ball driven against a column of air which has no escape, if the velocity be trifling, say 800 feet per second, the air will escape by the windage; but double this even, and it is so condensed as to form a cushion for the ball to strike against. Then how much less will the chance be of its escaping, if the velocity become two thousand four hundred feet per second. No, the cause is remote from that of Mr. Wilkinson’s supposition. There is a want of force—an accelerative propellant force—which should continue to the end of the tube, be that length ever so great; and on this point, for one, turns the whole future improvement of gunnery.
The result wished for can be obtained by a systematical arrangement of the granulation of powder. That a much greater velocity than is obtained in this gun—at present the greatest in any piece of ordnance in use, and possessing a longer range than has been obtained by any power in Europe—may and will be attained, I fearlessly assert. I have obtained a velocity with an ounce ball nearly doubling this; and though, as it will be argued, this may be too limited an experiment, yet let us not forget that great results most frequently spring from little causes. Large rivers owe their origin to small springs, and if the same principle by which we can penetrate a plate of iron half an inch thick with an ounce of lead, be fearlessly and judiciously carried through, we may (and no doubt we shall) live to see projectiles thrown 51⁄4 miles. That this will be difficult to accomplish I deny: no difficulty attends it, provided the principles before explained are duly carried out.
The great principle in a propellant force is so to arrange it that you do not obtain too great a velocity at the first move of the projectile; as no mass can be forced from a state of rest to a rapid state of motion, without communicating to the gun a corresponding motion, which will create a recoil: and the greater the motion, the greater the recoil. If the explosive matter merely expands for a brief period, and is burnt out before the shot has reached midway the length of the gun, the velocity there acquired will be reduced, by the condensed column of air in the other half of the barrel, to the velocity it possessed when only one fourth the length of the whole from the breech; consequently it would be advantageous to cut the gun in two at the middle, as a greater force would be then generated advantageously, than by the whole. But if you so arrange the granulation of your powder that it shall proceed into motion more gradually, a rapidly increasing force of elastic fluid will continue to be generated, until it reaches its greatest maximum of velocity (which it should do just as the ball leaves the muzzle) then you obtain with your means the greatest result possible.
We believe that the generality of gunpowder used by our Government is vastly inferior in strength to some made by private makers; yet it is not advisable to jump from one extreme to another. What is wanted is the proper blending of the qualities; an addition of a quantity of Harvey’s quick powder to a charge, when it has driven the ball up three-fourths of the tube of a gun, and probably had acquired a velocity of 2,000 feet per second, might so aid it, that it would leave the muzzle with a velocity of 3,000.