The earliest guns were made of cast-iron, but this being prone to burst with a large charge, bronze, brass, and other tougher materials were for a long time employed. Most elaborately chased and ornamented specimens of these old weapons are to be seen in the Tower, and many other collections. In the utilitarian days of the past century cheapness and speed in manufacture were more sought after than show. Iron was worked in many new ways to resist the pressure of explosion. Armstrong of Elswick conceived the idea of building up a barrel of _coiled_ iron by joining a series of short welded cylinders together, and closing them by a solid forged breech-piece. Over all, again, wrought-iron coils were shrunk. Subsequently he tried a solid forged-iron barrel bored out to form a tube. Neither make proving very satisfactory, steel tubes were next used, but were too expensive and uncertain at that stage of manufacture. Again coiled iron was called into requisition, and Mr. Frazer of the Royal Gun Factory introduced a system of double and triple coils which was found very successful, especially when a thin steel inner tube was substituted for the iron one (1869). All these weapons were rifled, so that there was of necessity a corresponding difference in the projectile employed. Conical shells being used, studs were now placed on the body of the shell to fit into the rifling grooves, which were made few in number and deeply cut. This was apt to weaken the bore of the gun; but on the other hand many studs to fit into several shallow grooves weakened the cover of the shells. Various modifications were tried, and finally a gas-check which expands into the grooves was placed at the base of the shell. The muzzle-loader having thus been turned into a very efficient modern weapon the next problem to be solved was how to throw a projectile with sufficient force to penetrate the iron and steel armour-plates then being generally applied to war-ships. “Build larger guns” was the conclusion arrived at, and presently the arsenals of the Powers were turning out mammoth weapons up to 100 tons, and even 110 tons in weight with a calibre of 16 inches and more for their huge shells. Then was the mighty 35-ton “Woolwich Infant” born (1872), and its younger but still bigger brothers, 81 tons, 16-inch bore, followed by the Elswick 100-ton giants, some of which were mounted on our defences in the Mediterranean. But the fearful concussion of such enormous guns when fixed in action on board ship injured the superstruction, and even destroyed the boats, and the great improvements made in steel both for guns and armour soon led to a fresh revolution. Henceforward instead of mounting a few very heavy guns we have preferred to trust to the weight of metal projected by an increased number of smaller size, but much higher velocity. And these guns are the quick-firing breech-loaders.