Alexander Henry's Patent for barrels is number 2802, dated 15 November 1860. In brief the patent abridgement reads: "The rifled bore is of polygonal cross-section, and is provided, in addition, with curved, square, or angular spiral projections or grooves, so as to increase the bearing points of the projectile."
The Ironmonger and Metal Trades Advertiser, a monthly trade circular published in London, included a favourable report on Alexander Henry's rifle in 1861, suggesting it surpassed the "famous Whitworth in precision." The article, which refers to Henry having "hit upon an entirely new principle in rifling fire-arms" was reprinted by Scientific American and is reprinted below.
Source: Scientific American, 19 October 1861
We take the following account of this famous weapon from The Ironmonger:–
At the close of last year we heard that some extraordinary practice had been made with a new rifle, patented by Mr. Alexander Henry, the well known gunmaker of Edinburgh, but as we could not obtain any information respecting the peculiar construction of the weapon, we concluded that its wonderful accuracy at long ranges was mainly owing to good workmanship. We imagined that the skillful gunsmith had turned out a very fine poly-grooved rifle, the novelty of which merely consisted in the number and form of the grooves. We never suspected that he had hit upon an entirely new principle in rifling fire-arms, and had produced a weapon far surpassing the famous Whitworth in precision. Had he been a military man, an engineer, or anything but a professed maker of guns, we should probably have given him credit for some originality.
At the meeting of the National Rifle Association on Wimbledon Common, in July last, the Henry Rifle was first brought before the notice of our English marksmen, who were amazed at its performances. Sixteen important prizes and most of the pools were won with the new arm. Major Moir used it in the contest for the Prince Consorts Prize of £100, which he eventually carried off. Seven shots were fired at each of the ranges, 800, 900 and 1,000 yards, and the winner made twenty-one points. On the last day of the meeting an interesting match came off between Oxford, with the Whitworth, and Cambridge, with the Henry. Each University was represented by two of her best shots. The contest was got up for the purpose of testing both men and rifles. The Cambridge men were undoubtedly the finest marksmen, but their extraordinary score, which, if we remember right, doubled that of their competitors, is partly to be accounted for by the superiority of the Henry Rifle. Mr. Peterkin, with thirty shots, ten at each range, 800, 900, and 1,000 yards, obtained thirty-one points, the highest score ever made on Wimbledon Common at these great distances. Some wonderful shooting was made at the pool targets with the new weapon. Sergeant Dillon got eleven consecutive two-inch bulls eyes at 100 yards. Lord Elcho with seven shots at 200 yards, made six consecutive four and a half-inch bulls eyes and one center.
At the recent meeting of Scottish marksmen at Montrose, the Henry has again made itself heard. With it Mr. Edward Ross won Scotland’s Cup, and the first long-range prize or Strangers Cup. Major Moir succeeded in carrying off the third prize with the very weapon which had proved such a trusty friend at Wimbledon.
In one of the early trials of the rifle Mr. Henry himself fired six shots with it at the extraordinary range of 1,100 yards, and hit the target with every ball, except the first, making three centers and two outers. At the mile range he afterward hit the target, which was six feet high by ten wide, three times out of seven shots. Several military men witnessed this wonderful shooting. In a quiet trial of skill between the famous marksman, Mr. Edward Ross, and his father, the old deer-stalker, near Aberdeen, the precision of the new weapon at long distances was strikingly shown. The ranges were 800, 900, and 1,000 yards, and each competitor fired ten shots from a Henry at each range. The father made with his thirty shots, thirty-four points the son no fewer than forty-three points, only missing the target once. Capt. Moir, on the 28d of April, fired twenty-one shots with this arm at 1,000 yards, and got seven centers, twelve outers, and two misses, counting twenty-six points. These examples of practice made with the Henry will suffice to account for the popularity of the arm. Though its history only begins in 1860, it is now the favourite weapon of many of our most skillful marksmen, and it is generally selected for the first prize by County Rifle Associations.
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.