A new era in the science of gunnery may be dated from the commencement of the latter half of the nineteenth century; and long before its close other improvements may be effected which shall eclipse even those of our day. A new elementary principle has been infused into the science. Rifles are now really weapons of the highest order; in truth we may be said to have only recently become acquainted with the principles on which they should be constructed. Little of science had hitherto been applied to them; as military arms they were neglected for centuries, to be ushered into notice at last by the unassisted efforts of private individuals; Government, to whom arms were of the greatest importance, having systematically neglected all improvement, by invariably refusing pecuniary aid, the only grease at all calculated to overcome the friction retarding the wheels of progress. It is an old proverb, that “one extreme begets another,” and when changes are once started, the difficulty is to stop them; the tendency is to rush on from one alteration to another, before we are really well acquainted with what we have so hastily thrown aside. Improvement does not always follow a change; the human race, and the English more especially, have an inordinate desire for “the marvellous;” and multitudes of “wonderful discoveries” and inventions of the utmost value are heralded daily by the ever eager press, often to be as hastily forgotten, or discovered, even by their promulgators, to be myths.
Improvement, to be at all beneficial, must bring with it all the elements of improvement; and to render it easy of attainment, none of its essential points should be costly. In gunnery more especially, it is essential to avoid all unnecessary friction, excess of recoil, and waste of gunpowder; whilst, at the same time, transport of the gun must not be cumbersome, and durability in all its points is essential.
How few study the subject in all its bearings! How rapidly conclusions are jumped at! Even in getting range, if it is to be purchased at the cost of other essential principles, it is not economy to sacrifice several even moderately valuable principles for the sake of range alone. The experience of the present age has shown that all our important discoveries have their limits: the locomotive cannot be used with advantage beyond a certain limited speed; steam vessels attempted to be propelled at an unusual velocity have but a very brief endurance, and rapidly decay. All matter has power only to effect a certain amount of work, and this is endured best at a medium application; showing most clearly that “the race is not always to the swift or the battle to the strong.”
Experience is required in the greatest of modern inventions. Electricity, at a moderate immersion, subjected to a moderate superincumbent weight, is an effectual messenger, swift as thought; but when overweighted by immersion to depths where the superincumbent pressure amounts to thousands of pounds upon the square inch, then the messenger becomes paralysed, and refuses to obey man’s will; showing very clearly that until that pressure be artificially removed by insulating the conducting wire in tubes equal to restrain or keep from it that enormous load, the lasting success of an Atlantic telegraph is very doubtful. Many similar instances might be cited to show the necessity of considering well the established laws of nature, and their bearing on the object pursued. In no science is this of more importance than in gunnery; and the hundreds of useless inventions in gunnery are to be ascribed to the non-observance of these rules. The two-grooved rifle, the “steam gun,” “the sciva,” “Warner’s long-range myth,” and many other inventions equally absurd, engage the attention for a time, but soon vanish: in fact, all experience shows that improvement can only be effected in accordance with certain established principles of nature and practical science.
Iron, in quantities sufficient for all reasonable requirements, is a dutiful servant; but, when required of colossal proportions, it refuses to obey: giving us a hint from nature, that we should be content with moderation.
All the principles appertaining to science are based on certain established laws; the unsoundness of one renders the superstructure unsound also; and any deductions drawn from unsound principles are comparatively worthless. Gunnery, as a science, must be in uniformity with truth in all its parts, or no science exists in its arrangements. This will be best illustrated by dividing the subject into several heads: 1st, the explosive power and its velocity; 2nd, the retarding agents, air and friction; 3rd, the construction of the projectile tubes; and 4th, the form of projectile best calculated to attain a perfect result.
1st. The explosive power. Gunpowder has been stated by different authorities to liberate its gases with very different degrees of rapidity. Hutton has given to it a much greater rapidity than Robins has evidently even surmised; though, no doubt, as we have already shown, high velocity in gunpowder depends on several circumstances—the degree of purification of its ingredients, their intimate mechanical mixture (that the elements may exert their affinities with the utmost facility), and, lastly, the degree of granulation observed: and in addition, the suitability of the tubes or vessels for carrying on correctly such important experiments. Robins and Hutton unquestionably may be regarded as the English, if not the European, authorities, and any work on the science of gunnery would be very incomplete without their valuable elucidations.
Previously to the researches of Robins, the theory of atmospheric resistance was but imperfectly surmised, and when he made his statements of the immense resistance which the fluidity of the air offered to projectiles in a high state of velocity, they were treated as the idle chimeras of a speculative brain; and yet he only was enabled to estimate the real effect of the explosive nature and force of gunpowder to a very limited extent: indeed, so limited, that Hutton, only twenty years subsequently, speaking of Robins’ theory, says, “Mr. Robins and other authors, it may be said, have only guessed at, rather than determined. That ingenious philosopher, in a simple experiment, truly showed that, by the firing of a parcel of gunpowder, a quantity of elastic air was disengaged; which, when confined in the space only occupied by the powder before it was fired, was found to be nearly 250 times stronger than the weight or elasticity of the common air. He then heated the same parcel of air to the degree of red hot iron, and found it in that temperature to be about four times as strong as before; whence he inferred, that the first strength of the inflamed fluid must be nearly 1,000 times the pressure of the atmosphere. But this was merely guessing at the degree of heat in the inflamed fluid, and, consequently, of its first strength; both which in fact are found to be much greater. It is true that this assumed degree of strength accorded pretty well with that author’s experiments; but this seeming agreement, it might easily be shown, could only be owing to the inaccuracy of his own further experiments; and, in fact, with far better opportunities than fell to the lot of Mr. Robins, we have shown that inflamed gunpowder is about double the strength that he has assigned to it, and that it expands itself with the velocity of about 5,000 feet per second.” On the same subject he further says:—“On this principle it was that Mr. Robins made all his experiments and performed all his calculations in gunnery. But it is manifest that this method of guessing at the degree of heat of the flame must be very uncertain and unsatisfactory, being much below the truth; since all our notions and experience of the heat of inflamed powder convince us that it is higher than that of red hot iron, and, indeed, it has clearly appeared from our experiments, that its heat is at least double that of red hot iron, and that it increases the elasticity of the elastic fluid more than eight times.”
Here is evidence, though not conclusive, of the immense force of gunpowder, and also of the progress of knowledge on the subject; yet it clearly shows the evil of coming to hasty conclusions, however well supported by apparent facts, as it has had in this case a tendency to check inquiry and retard the advancement of knowledge. For the extensive experiments of Hutton were but limited in discovery, because they were not carried to a sufficient extent, and thus, they are quite unsuited to the present day. He was satisfied because he had gone further than any of his predecessors; and though he established and clearly proved the soundness of his own theory, yet he could not either view the subject to its utmost bounds, nor yet go sufficiently far, but that others, taking up the question where he left it, may pursue the subject to a much more remote limit. The subject, indeed, was limited to him. He far excelled Robins, no doubt, as he has shown; but that involves no detraction from the merit due to Robins for his experiments and discoveries, no more than any individual proving the subject to be a more extensive one than Hutton did, would excel Hutton; for the value of improvement is more to be attributed to him who lays the foundation, than to him who raises the building. So is it in this case; Robins laid the foundation for an extensive knowledge of the nature and power of the explosive fluids, and Hutton built upon that foundation a certain extent of superstructure, and there he left it, without roofing the building: he considered the question as settled. Common consent has, as yet, received his conclusion as unshaken and uncontroverted; and it is not my intention to make the attempt to controvert it, but merely to show that his deductions fall short of what the principles of gunpowder-making admit—carried out in the more extensive way it has been within the last few years—owing to the limited nature of his experiments. This is rather an extensive position for me to occupy, or endeavour to hold: but I do not mean the size of the tools of experiment so much as the diversity of them; for exploding ten thousand tons of powder in the same machine and in the same way, would but give the same or similar results; it is the variety and the singularity of experiments that expand and increase the fund of knowledge, and enable the mind to conceive and comprehend the immensity of the power and velocity of this wonderful combination. We have been principally indebted to the exertions of the chemist for means of purifying and extracting from the ingredients which form this astonishing compound force, the impurities and foreign substances which exist, to a certain extent, in all the three, and thus tending to form a more perfect combustion by increasing the affinities.
Hutton shows that gunpowder is but so much condensed air; for he says “We may hence, also, deduce the amazing degree of condensation of the elastic air in the nitre and gunpowder, and the astonishing force experienced by its explosion. It has been found by Mr. Robins, and other philosophers, that 3-10ths of the mass of the powder consists of the pure condensed air, or that the weight of the condensed air is equal to 3-10ths of the whole composition. But the whole composition of the powder consists of eight parts by weight, of which six parts are nitre, one part sulphur, one charcoal; of which the nitre or 3-4ths of the composition furnishes the whole of the condensed air, while the sulphur and charcoal only give the fire that produces the explosion. But 3-10ths of the whole mass of eight parts is equal to 4-10ths of the six parts of nitre, that is 4-10ths or 2-5ths of the nitre consists of condensed air, or the weight of the gross matter in the nitre as four to six, or as two to three; and these two parts, it is probable, are of equal density or specific gravity. Yet the specific gravity of nitre is 1,900, that of water being 1,000, and of air 1·2, which is contained in 1,900, as much as 1,583 times; that is, the air in the nitre must be condensed the amazing quantity of 1,583 times, if its specific gravity be equal to the compound nitre itself.” Also, “The air is condensed in the nitre about 1,600 times, nearly double the density of water, which may well be considered as probably the greatest degree of compression that air is capable of. Hence it may be perceived that a prodigious force must be exerted by nature in generating nitre; and as this great force actually exists in nature, it is very probable that the air in the nitre is thus compressed into the most dense state possible, and in this consists the similitude among the different particles of nitre.”