We will now endeavour to describe the most striking features of Mr. Henrys invention. In his specification he claims a system or mode of rifling or grooving firearms, in which a series of planes or flat surfaces are combined with angular, curved or rectangular ridges or “lands.” In the explanatory sheet of drawings several modifications of this improved mode of rifling are shown. From four to ten planes and ridges are used in the various forms of the new rifle. The simplest modification is shown in Fig. 1.
This barrel is rifled so that its end view or transverse section forms a quadrilateral figure, with angular projections, or lands, extending inward from the angles of the planes. The periphery of the projectile, c, indicated by a dotted circle, touches the center of each plane, a. In addition to the bearing surfaces thus obtained there are the angular ridges, b, which project inward, so that the apex of each is exactly concentric with the centers of its contiguous planes. These four ridges thus afford a further bearing or support to the projectile. These angular ridges also fill up to a great extent the spaces between the angles of the planes, A, and the periphery of the projectile, thus reducing the windage by lessening the amount of expansion necessary to cause the projectile to fit the grooves of the rifle or other fire-arm, so that the rotary or spiral motion of the projectile is obtained with greater certainty, and consequently its flight is rendered more accurate.
Mr. Henry rarely makes rifles with this quadrilateral bore, but the figure shows this principle so clearly that we have reproduced it here. In Fig. 2 the favorite modification is shown :– There are seven planes, A, and a corresponding number of intervening ridges, B, which together afford fourteen points of bearing to the projectile, C, which very nearly fills up the whole of the bore. This is the form of the ordinary Henry. Rectangular or rounded ridges are occasionally substituted for the angular ones shown in the diagrams.
In another modification of the new system of rifling, curvilinear grooves are combined with a series of planes. The planes form a polygon, but in the center of each plane a curved groove is formed, and the ridges or boundary lines of the grooves form the bearing points for the projectile.
A larger charge of powder may be used with fire-arms rifled on Mr. Henry’s principle than with others, as there is less liability of stripping the bullet. The increased charge gives a lower trajectory, and ensures greater accuracy in the flight of the missile.
The bore of the Henry is somewhat larger than that of the Whitworth, and the ball is about the same length. The ball fits easily into the barrel, and there is very little recoil. The advantage of the bore seems to lie in the extent of surface which is made to present a resistance to the shifting of the ball in the slightest degree from the grooves, which give it its rotary motion and direction, and in the perfect manner in which the expansion of the ball fills the grooves. The resistance of the air to the ball is so slight that at the markers butt at the mile range, neither the report of the rifle nor the whistle of the ball is heard; and it is only by the ball hitting the ground or the target that the marker knows when a shot has been fired.
The arm does not foul so rapidly as other muzzle-loaders; indeed we heard the other day of a Hythe instructor who had been firing with a Henry for two months, and had never thoroughly cleaned it.
Mr. Henry’s patent wind-gage sight is a beautful and simple contrivance for regulating the aim according to the strength of the wind. The sight, either back or front, can be moved to the right or left by an ordinary watch key, and when set to the proper degree it may be shaken or handled without fear of altering its position. With the back windsight, if the wind blows from the right the sight must be moved to the right, and with the front windsight, to the left. The degrees are marked by alternate lines of gold and platinum.
The wonderful practice made with Mr. Henry’s rifles proves that the principle upon which they are constructed is a good one.
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