Discoveries and Inventions of the Nineteenth Century

by Robert Routledge

Fig. 90.—32–pounder, 1807.

Now let us see of what kind was the ordnance used for some years after the middle of the century, in order that we may be the better able to appreciate the progress that has since been made. Ordnance is, as already noticed, of several species, as guns mounted on fortresses, naval guns, siege guns, field-guns, etc., and the size of the pieces under each of those heads is distinguished sometimes in one, sometimes in another of three different ways. We may name it by the weight of the gun itself in tons or hundredweights, as “a 35–ton gun,” etc.; or by the weight of its projectile, as “a 68–pounder,” etc.; or by its calibre, that is the diameter of its bore, as “a 4–inch gun,” etc. We may take the naval guns with which Nelson won his battles (Trafalgar, 1807) as representative of all except field ordnance up to about 1856. They were all made of cast iron, threw spherical projectiles, and were very rudely mounted. The gun most commonly mounted on board our ships of war was the 32–pounder, weighing 32 cwt., shown with its carriage in Fig. [90]. The carriage was of wood, and consisted of two side pieces joined back and front by two transverse pieces and carried by four low wooden wheels. The trunnions of the gun fitted into bearings at the top of the side-pieces, and were secured by iron plates that passed over them in a semi-cylindrical form and were bolted down to the wood. The position of the trunnions on the gun was always such that the breech end of the gun preponderated, being supported on an adjustable wooden wedge; and when the muzzle of the gun had to be lowered, this was done by raising the breech end with handspikes and pushing in the wedge so far as to prevent the breech from dropping down again. There was a vent or narrow passage to contain a train of powder from the touch-hole at the upper part of the breech to the rear of the charge. When the gun was fired, with its muzzle protruding a little way out of the port-hole, the recoil would trundle it inwards about its own length, when its course would be stayed by a thick rope attached to the sides of the vessel; and by other tackle it would be kept in position until loaded, when it would be allowed to roll back, or would be drawn by ropes and pulleys out to the port-hole, and by the same means such lateral inclination as might be required could be given. This last adjustment was called training the gun. A 32–pounder required the services altogether of a dozen or fourteen men, but these by virtue of constant drill would learn to handle the clumsy machine with a certain amount of expedition. If we except a notch on the highest point of the muzzle, the pieces were devoid of anything of the nature of sights, though sometimes marks were made on the adjustable wedge under the breech to correspond with certain elevations. Nor were sights required; for the mode of fighting then was to get quite close to the adversary’s ship and pour in a broadside by firing simultaneously all guns on the enemy’s side when they had been trained (by rough methods), so as to concentrate their effect as much as possible on one point of the antagonist. Nelson’s famous ship the Victory carried a few larger guns than the 32–pounders, namely, two 68–pounders, called carronades (from having first been cast at Carron in Scotland), and some 42–pounders. The 32– and 42–pounders numbered together thirty, and there were also as many 24–pounders, with forty 12–pounders. These were all simply cast of the required dimensions, and were not made with the one single improvement which after two centuries’ use of cast-iron guns had been introduced into France about fifty years before, namely, the boring of the chase out of a solid casting.

On the outbreak of the Crimean War (1854) the minds of many inventors were occupied by the problem of ordnance construction, and this also engaged the attention among others of two of the most eminent British mechanical engineers of the day. These were Sir W. Armstrong and Sir J. Whitworth, who, with others, were invited by our War Department to submit the best models of field and heavy guns their skill was severally able to produce. Two years afterward, Sir W. Armstrong had, after many experiments, completed a gun of 1·88 in. calibre. This had a forged steel barrel 6 feet in length; but it was only after eight such forgings had been bored and rejected on account of flaws revealed only by the boring that a sound barrel was at length obtained. This barrel was strengthened on the outside by jackets made from coils of wrought iron bars welded into a piece and shrunk on while hot (of which process we shall have something more to say presently); the barrel was rifled with many shallow grooves, and the pointed projectile, 3 calibres long, was made of lead, for which afterwards iron coated with lead was substituted. This gun was a breech-loader, the breech being closed by a block let into a slot after loading, and then pressed against the barrel by some turns of a screw which advanced parallel to the axis of the piece, and was made hollow for loading through, before the closing block was put in. In a trial of the various pieces ready in 1857, it was found that the Armstrong gun made as just described had an accuracy and range immensely greater than any weapon that had ever been tested, and the Government authorities approved of the system of construction, except that they preferred muzzle-loading pieces to breech-loading, as being simpler in action, more easily kept in repair, and cheaper in original cost and ammunition.

When Sir Joseph Whitworth’s gun was, in 1863, submitted to a competitive trial against the Armstrong, as to their endurance and mode of ultimate failure when fired with ever-increasing charges of powder and shot, at the forty-second round the Armstrong breech-loader split, and at the sixtieth the Armstrong muzzle-loader had one of its coils cracked; while it was not until the ninety-second round that the Whitworth gun burst violently into eleven pieces. These competing guns were 12–pounder field-guns weighing 8 cwts., and from each 2,800 regulation rounds had been fired before they were subjected to the bursting proofs. The result of these trials being that the authorities considered that steel was not then sufficiently reliable, and they decided to adopt the system of building up rifled guns with iron jackets over an inner tube of steel. Sir Joseph Whitworth made his guns entirely of steel, and they were striking examples of beautiful and accurate workmanship. His system of rifling consisted in forming the bore of the gun so that its section is a regular hexagon, and the projectile is an elongated bolt with sides exactly fitting the barrel of the gun: the projectile is, in fact, a twisted hexagonal prism. Fig. [91] shows at the left-hand side the section of the barrel, and on the right we see the form of the projectile on a smaller scale, this last representing, in fact, the exact size and shape of the bullet of the Whitworth rifle mentioned on another page. Sir Joseph’s guns were muzzle-loaders, and they were remarkable for their long range and accuracy of fire. One of these guns, with a charge of 50 lbs. of gunpowder, threw a 250–lb. shot a distance of nearly six miles, and on another occasion a 310–lb. shell was hurled through the air, and first touched the ground at a distance of more than six and a quarter miles from the gun. These distances are greater than any to which shot or shell had previously been thrown.

Fig. 91.—Whitworth Rifling and Projectile.

As the material of these Whitworth guns was very costly, and very perfect workmanship was required in the formation of the barrel and the shots, the expense attending their manufacture and use was much greater than that incurred in the case of the Armstrong guns. Sir W. Armstrong’s estimate for a 35–ton gun was £3,500, and Sir J. Whitworth’s, £6,000. The gun, as constructed at Woolwich on Mr. Fraser’s plan, was estimated to cost £2,500. The first cost of a gun is a matter for consideration, since each piece, even the strongest, is able only to fire a limited number of rounds before it becomes unsafe or useless. It appears that no cannon has yet been constructed capable of withstanding without alteration the tremendous shocks given by the explosion of the gunpowder, and these alterations, however small at any one discharge, are summed up and ultimately bring to an end what may be termed the “life of the piece.”

Fig. 92.—600–pounder Muzzle-loading Armstrong Gun.

About the year 1858 Sir William Armstrong (afterwards Lord Armstrong) established at Elswick, Newcastle-on-Tyne, a manufactory of ordnance, which has since developed into the great arsenal now so well known all over the world. Here all the resources of science have been applied to the problems of artillery, and experiments carried on with a prodigality of cost and promptness of execution impossible at a government establishment trammelled with official regulations. Here, and also at Woolwich, our national ordnance factory, guns have since always been constructed on the building-up plan advocated by Sir W. Armstrong, whose principle consists in disposing of the fibre of the iron so as best to resist the strains in the several parts of the gun. Wrought iron being fibrous in its texture has, like wood, much more strength in the direction of the grain than across it. The direction of the fibre in a bar of wrought iron is parallel to its length, and in that direction the iron is nearly twice as strong as it is transversely. A gun may give way either by the bursting of the barrel or by the blowing out of the breech. The force which tends to produce the first effect acts transversely to the axis of the gun; hence the best way to resist it is to wrap the iron round the barrel, so that the fibres of the metal encircle it like the hoops of a cask. The force which tends to blow out the breech is best resisted by disposing the fibres of the iron so as to be parallel to the axis of the gun; hence Sir W. Armstrong makes the breech-piece from a solid forging with the fibre in the required direction. But the Elswick building-up principle involves much more than the direction of the fibres of the iron, for each coil or jacket, after having its spires welded together, was bored out on a lathe, and the exterior of the part of the gun on which it was to be placed was also turned with the utmost exactness, so that when the enveloping piece was heated to a certain temperature and in this state brought into position, it would in cooling compress the parts it encircled just to that degree which careful calculations showed would best strengthen the gun without unduly straining the metal at any part. The Elswick guns being built up of several superimposed jackets of calculated lengths and thicknesses, the means was afforded of distributing the tensions throughout the whole mass of metal to the best advantage. In the simpler form, arranged by Mr. Fraser, and for the sake of economy adopted by the authorities at Woolwich in 1867, the greater part of the benefit derivable from adjustment of tension was no doubt sacrificed to cheapness of manufacture. These, and also the forms of Armstrong guns that have not yet been described, ceased to be made after 1880, by which time steel had replaced iron in every part of the construction and fittings of guns, and muzzle-loading had been definitely abandoned in favour of breech-loading.