You cannot put a locomotive train in motion at once: if it were attempted, you would break all the carriages; but if you gradually add your force, you gain in time the greatest possible velocity. I have drawn a parallel case: it is the same with gunpowder; only the velocities are widely different. Therefore, I may be pardoned, if I say gunnery is like steam, but in its infancy. Let us but clearly see and understand aright the principle—knowing that the greater momentum the less the action of the atmosphere—and if 31⁄4 miles can be obtained with a ball 60 lbs. weight, 51⁄4 may be easily accomplished by a ball of 120 lbs. Powder is made, and can be had, that will do this.
The use of compound-shot has of late years become quite common in experiments: why lead, with its alloys, has not been more extensively used as a projectile for large guns, has always appeared to me extraordinary. Its weight and density peculiarly fit it for this purpose, and its non-conducting principle is its greatest recommendation. How is it? In no instance, except as compound-shot, do we find any record of the use of leaden bullets on a large scale, save in Sir Howard Douglas’s “Naval Gunnery,” where, in a note, he says, “A very distinguished naval commander mentioned to me, that he knew a person who had served in an American privateer, which, being out of shot, and unable to procure a supply of iron balls, used leaden shot as substitutes. This person always mentioned with great surprise the superior effect of leaden balls.” Well he might; for the reader need not be told that its greater specific gravity would add to its momentum, and a longer medium velocity be retained during its flight. But it possesses another recommendation, superior to all these, in warfare: that of communicating all its force, all its velocity, be they ever so great, to the body struck. Iron does not possess this quality; except to a certain extent, and that at low velocities. Hence the cause of its being found in naval warfare, that balls at low velocities damage and destroy ships’ sides more than at higher velocities, even when passing quite through. Lead, in the act of striking hard substances, iron or stone for instance, is partially flattened, until the flat surface is nearly equal to the diameter of the sphere of the ball; thus parting with all the force it struck the object with, and in most instances falling motionless at the base of the object struck; while in the stone, the surrounding crystals or grains are, by their abrasion on each other, pounded into dust, in proportion to the size and force of the body of lead striking them: in many instances to many times the shot’s bulk, and only flattening the lead, less or more, in proportion to the capability of the stone to resist. Iron striking stone retains its shape: the grains are driven back upon each other, and each offering its proportion of elasticity, the ball is enabled to rebound back; which it does in many instances to a considerable percentage of the whole distance it had been projected. The greater the velocity with which an iron ball is projected the greater the rebound back from a hard substance such as stone. Reversely, the greater the velocity of lead, the greater its effect on the object struck. Walls or fortifications struck by leaden balls at the same velocities (waiving the advantage to lead by its greater specific gravity) would be pounded into sand by less than two-thirds the same number of lead as of iron shot. Any unprejudiced person may soon satisfy himself of this, by trying it with a musket or fowling piece. A leaden ball will pound itself a hole many times its own bulk, while an iron ball will not make a hole half its size.
I have tried many experiments to ascertain the penetrating powers of iron and lead relatively, by striking various objects, from a boiler plate of half an inch thickness down to fir deals. The same size of lead will, under certain circumstances, punch a perfect hole in a plate of half-inch thickness, as I shall have occasion to show; while, under precisely the same arrangement, the iron ball would rebound back with very little diminution of force; and if the plate of iron be at a perfect right angle, the iron ball would nearly return into the muzzle, of the gun. In truth, I had a narrow escape seventeen years ago, from a bullet actually cutting the rim of my hat: so that it will be well, when experimenting in this way, to be sure that the person is well esconced, for fear of unpleasant results.
Lead, therefore, for destroying ships, as well as stone walls, is unquestionably highly advantageous; even if projected with the same velocities as at present adopted for iron. The additional weight would not decrease the destructive effects; it would augment them. I perfectly agree with the American privateer, that the wonderfully destructive power of leaden cannon balls will create surprise, whenever they shall come generally into use. Imagine the effect from a gun of the dimensions of a 10-inch bore. It is dreadful to contemplate.
The effect of lead will be easily understood when explained in the following way. If a 36 lb. shot have a velocity of 2,000 feet per second, the force is equal to the velocity multiplied by the weight, or 72,000 lbs. The whole of this force would strike a wall, and be left there, if communicated by soft lead; if by iron, at the same velocity, it would be minus the amount of force required to make it rebound to the great distance to which iron invariably returns. Though created by the elasticity of the iron itself, this must be deducted from the effect produced, and hence arises the great advantage the lead possesses. We are aware that iron driven with a slight velocity rebounds less; true, and less is its real effect; for under the very same circumstances would the great advantages of the lead predominate. It may be objected, that lead is too easily misshaped; “pure it is, but with alloys not so.” At low velocities it might, but the greater velocities diminish that chance, as it is a well known fact that all dense incompressible bodies are least affected by an extremely sharp motion. All our arrangements in warlike preparations, at present, involve great weight of projectile for fracturing, not perforating. During the siege of Ciudad Rodrigo, 2,159 rounds, of twenty-four and eighteen pounders, were requisite to form the small breach of thirty feet wide, and 6,478 rounds for the larger of 100 feet. At Badajos there was expended, to form three breaches of 40, 90, and 150 feet respectively, the enormous amount of 31,861 rounds of the same sized iron shot. We may be pardoned if we presume to say, one-half the number of lead shot would have done more, and done it better.
If we bear in mind, that the whole round of experiments from which Hutton drew his deductions, were conducted with iron projectiles, the inconsistency of taking his data as the standard will be apparent. The dissimilitude of specific gravities being great, namely, 7,425 and 11,327—or one-third difference—it clearly shows, without any effort of the imagination, that the range must be in the same proportion, with the addition of greater momentum. For it will scarcely be denied, that a ball of gold or platina, from the same cause, will maintain a velocity longer, and consequently range further, than even lead. Hutton’s theory only establishes the principle, that the lighter the body projected, the sooner it is acted upon by atmospheric resistance, and a medium velocity induced. We cannot attribute his preferring iron to arise from an opinion of its penetrating to greater depths; for a man of his extensive knowledge and research could scarcely be guilty of such an error. But even in our enlightened times we are told that elephants cannot be killed with any projectile but steel: leaden balls cannot do it. I should like to try, and receive the tusks in return.
The shrapnell shell (invented by General Shrapnell), or spherical case shot, introduced into the British service of late years, is probably the most destructive of any missile in use. It was intended to supersede—which it has done—canister and grape shot; effecting the same results at treble the range. The construction and principle are very simple, being merely a shell of an unusually light description; in fact, little more than a light cast-iron hollow ball, with a fuse hole. A certain quantity of leaden, or iron bullets is put into it, and the interstices around the ball shaken full of powder; a fuse of the length required is inserted, and explodes the shell during its flight: the peculiarity being, that the body of small balls retain their medium velocity and travel on, merely diverging, latterly, like an immense charge of bird shot. They are usually fired from howitzers, carronades, and other wide bored-guns, at or near horizontal ranges. A considerable delay occurred before they were successfully perfected. It was found that when the small balls did not pack perfectly tight, or were packed overtight, the case frequently exploded in the gun: occasioned, no doubt, by the friction creating a spark at the moment of the howitzer being fired, and thus exploding the shell before its time; but we believe such an occurrence rarely happens now, from other improvements since adopted.
The preceding pages appeared in my last work published in 1846. They are still so much in keeping with the state of gunnery at the present day, and so prophetic of what has, and is about to occur, that they will be regarded, I trust, as bearing the stamp of authority.
Progress, in its rapid advance, has made many English guns objects for the furnace or the museum; and many guns, which formerly ranked high as useful and important weapons, have become things of the past.
Monsters are now all the rage, with a range of three miles, and artillerists contemplate extending the range to double that distance; whilst the projectiles used are not “pounders,” but approximating to tons. So much for improvement. In political economy we are told that improvement to be good must be gradual; but only effect some slight improvement in gunnery, make but one step in advance, and the desire for further improvement then ranges at will, and impossibilities are craved for and sought to be attained.