ENFIELD BARREL AND PRITCHETT BULLETS.
WHITWORTH BARREL AND BULLETS.
Thus it will be seen that the amount of resistance or displacement of atmospheric air by one bullet is nearly double that of the other, and this is a most important point in Mr. Whitworth’s favour; but the quantity of gunpowder used in the one is precisely the same as that used in the other, though Mr. Whitworth’s rifle is little more than half the size of bore, the pressure on the square inch being consequently nearly double; hence the circumstances are not sufficiently equal for Mr. Whitworth to claim for his rifle any great superiority: the gun may take the attention of the unwary, but its principles will not bear investigation.
Let me change the circumstances of the case, by retaining the principle of the Enfield, but changing the bore to the same as Mr. Whitworth’s, increasing at the same time the length of projectile, and I will engage to beat it with a much reduced charge. The extreme degree of female screw or spiral, one turn in twenty inches, or two turns in the whole length of the barrel, creates, as must be familiar to the most obtuse mind, an enormous amount of friction, and in consequence of this an equal quantity of force is absorbed: in other words, there is a useless waste of force.
The Enfield barrel has but a proportion of turn, one in six feet six inches, or exactly half a spiral in the three feet three, generating 300 per cent. less friction than in the Whitworth rifle; so that on this score alone the saving would be very great, and in this trial the Whitworth would be inferior to the Enfield; the inventor, therefore, has unjustly laid claim to superiority, as the trial has been conducted on very unequal terms.
Mr. Whitworth says his bullet rotates at the rate of 15,000 revolutions in a minute; now the friction on the periphery of a bullet having this extreme spinning on an axis, must very much lessen its range. If we weigh force, and carefully calculate its expenditure in 2,000 yards, the periphery has made 4,000 revolutions. Now look at the shape of the hexagonal body depicted in the [woodcut] at page 377, and estimate the friction it will undergo. The Enfield in the same distance would rotate only 1,000 times, thus affording another gain of 300 per cent. The question, therefore, which arises is this: If all this can be done equally well with the Enfield, why not do it? And the answer is, because there is nothing to be gained by it. Great doubts now exist whether the bore 25 is not too great a reduction: in fact, you will find no military advocates for it. The faculty will tell you that small wounds are not so destructive as large ones: the human body is as much affected by the shock as by the penetration of a bullet. Many other reasons might be advanced in favour of increased size of bullet, and much more important reasons must be given, before the whole military system has to be re-changed, than a mere gain of 300 or 400 yards; whilst there can be little doubt that the ranges we now possess in the Enfield are more than equivalent to our wants. The human eye cannot define precisely at 900 or 1,000 yards, and yet greater accuracy is required to fire a ball at a distance of 2,000 yards; again, it is a question which has frequently arisen in my mind, in how many situations in England or on the Continent can we get a clear view of 2,000 yards. The effort, indeed, to increase range appears like seeking after a remedy for a disease which has never yet been discovered.
If ranges of 2,000 yards and upwards are required, rifled cannon will again take their proper place; for on investigating the tables of practice published by General Jacob, I find the average distance of shot from the centre of butt to be, at 2,000 yards, nearly 9 feet, with 13·7 degrees elevation; whilst the Whitworth is said to be 111⁄2 feet, with about 8 degrees of elevation. I saw, some time ago, some practice at Shoeburyness with an 18-pounder rifle cannon, which gave a range of 3,650 yards, with an elevation of 0·103⁄4 degrees, and a breeze blowing across, a mean deflection of only 30 inches from the centre. This throws Jacob, Whitworth, and the Enfield all into the shade together; yet there can be no doubt that this can be excelled, when heavier guns are brought to the same state of perfection as this 18-pounder. The case therefore stands thus: the Jacob rifle has a greater range than the Enfield, at a cost of 100 per cent. more friction, and an expenditure of 50 per cent. more of projectile force; the Whitworth has also a greater range, but at a cost of 300 per cent. more friction, and 100 per cent. additional projectile force. With these observations I leave this subject in the hands of the public, being convinced that projectile power obtained at such a cost will never come into general use; though the production of the Whitworth rifle will always be looked upon as an experiment of very great interest.
There is but one other point relating to the use of guns on such a principle, and that is their safety; which is always of the greatest importance. It is a well-known fact that the first movement of projectiles depends very much on the amount of inertia in that projectile; and different forms of projectiles, though of the same weight, will offer very different amounts of resistance to motion. No one can doubt that two columns of lead, each of an ounce in weight, one being as high again as the other, will offer different amounts of resistance; first, from the law that the time occupied in overcoming inertia is in proportion to the length of that body; secondly, if these columns of metals are confined in tubes, then the friction on the one which is half an inch long will be much less than on the other, which is one inch in length: and this is, on the mildest terms, the relative position of the two. There can be no doubt that a much greater pressure is required to start the longer column of double the length; but when we consider that there are the facets of six angles, with a spiral inclination of one in nineteen, the difficulty of starting this bullet becomes still more apparent. Now suppose the gun has been loaded a few hours, and a certain amount of adhesion has been effected between the bullet and sides of the barrel, by the unctuous deposit from previous discharges, then the difficulty of starting the bullet instantaneously will be still more increased: supposing the breech end of a barrel, with the ordinary charge of the Enfield cartridge and bullet, has a force exerted upon it of 2,000 pounds in the square inch, then in the hexagonal not much less than double that strength will be requisite to meet the contingencies of dirty guns: in fact I know that a serious accident did occur very recently with a double rifle constructed on Whitworth’s principle, notwithstanding all the care bestowed upon it by a first-rate maker; and I believe that this gun, if it is to be used with safety, must have a barrel double the strength of other rifles.