Many writers condemn in toto the Minié principle and its cup. Minié did not understand it; and the introduction of the cup by him was, I believe, an accident, or the best he could do by copying my mode of using it: it was not the production of his own brain.
It has been urged as an argument against the use of this cup, that sometimes expansion does not occur. This, however, may easily be accounted for by the fact that the cup is not tightly fitted into the cavity of the bullet; a space is left through which the elastic fluid penetrates the cavity, the cup then has as much pressure exerted upon it behind as in front, and hence it remains undisturbed.
Then the cup is sometimes driven in so violently that it becomes flattened against the flat surface of the upper portion of the cavity, cutting the lead so entirely as to leave the cylindrical portion of the bullet in the breech of the gun; this is well known to have been a frequent occurrence on the first introduction of this bullet. These defects are instanced, as evidence to show that Minié and others have no claim whatever to the production of the original idea—they cannot even now grasp it, but condemn it, because it is beyond the limits of their comprehension. True it is that, after blundering for several years, our Government have come back to my original idea, as the following quotation will show:—
“Colonel Hay,” says Sir Howard Douglas, “has introduced an important improvement in the shape of the cup, and in the figure of the cavity into which it is forced on the firing of the charge. It will be perceived that the cavity in the Minié shot has the form of the frustum of a cone, while that of the cup is a hemisphere: now all who have examined the shot picked up after having struck an iron target or penetrated into the earth, find that the hemispherical cup is very liable to be canted or turned instead of being forced directly into the hollow space; the lead of the shot is not driven equally into the grooves of the rifle. For this evil Colonel Hay has proposed a remedy, in giving both to the cup and the cavity in the shot conoidal forms; by which means the former must, by the force of the powder, proceed directly forward in the hollow space, and thus uniformly expand the lower part of the shot in the bore.”
If this is not conclusive evidence of the priority of my invention, then I cannot understand the English language.
The next object I sought to obtain in the invention was a reduction of opposing surface, and an increased momentum. The law of atmospheric resistance is as the area of displacement, and the velocity with which that displacement is effected. Thus, a spherical bullet of one ounce weight displaces a bulk of the atmosphere equal to the area of its hemisphere; whereas an elongated bullet of the same weight would have to displace so much less as is the difference between their diameters. These two bullets, started at equal velocities, are acted upon very differently by opposing forces; the velocity of the spherical is diminished much sooner than that of the elongated bullet, on account of its greater diameter: hence the increased range of the elongated bullet. Let us suppose an extreme case. Take a bullet produced from a description of hardened lead five diameters in length, and presenting to the atmosphere one-fifth the surface of a spherical bullet of equal weight; the reasonable assumption would be that this bullet would range a greater distance if projected at the same velocity, and if the same charge of gunpowder be used as with a spherical bullet.
The first series of experiments clearly established the fact that increased range could be obtained, and also with a vast reduction in the charge of gunpowder: with a saving, in fact, of nearly 50 per cent. Two drachms and a half were found equal to a range of fourteen hundred yards, whilst four drachms and a half on the old system would rarely reach half that distance. These important points were gradually developed, though not without many disappointments and much mental anxiety: the last discovery, to have rendered the task easy, should have been the first.
Extreme spiral curve in the rifle barrel is incompatible with the correct action of the expansive bullet. The old-established turns of one in four feet, one in three feet, and one in two feet nine inches, gave results in the order I have placed them; and it was not until the adoption of a spiral approximating to one turn in five and a half up to six feet, that I found the success of my experiments uniform: and this fact illustrates one great obstacle which my invention had to contend with before it was generally adopted.
The ordinary sporting rifles have invariably too much spiral; the amount of friction generated by an expansive bullet in a rifle of this construction is enormous, absorbing in many cases one half the power of the expellant. The result of this is most unsatisfactory: the bullet suddenly loosed from this immense friction, and freed from the column of air in the tube, rushes so wildly forward as entirely to destroy equilibrium in its flight; and hence the very loud complaints of disappointed experimenters.