In 1854 a breech-loading rifled field-piece was invented by Sir William George Armstrong. It was made of wrought-iron bars coiled into spiral tubes, and welded by forging. The breech was closed with a screw which could be quickly withdrawn for loading and sponging the gun. The projectile was made of cast-iron, thinly coated with lead, and was (with its coating) slightly larger in diameter than the bore. The lead coating was crushed into the grooves by the force of the powder, the necessary rotation being thus given to the projectile. This gun gave excellent results in range and in rapidity and accuracy of fire, but it was not until some years after its invention that it was adopted in the British service. Other breech-loading cannon soon appeared; but in the United States army the 3-inch Rodman muzzle-loading rifled gun was preferred to any breech-loader then devised, and was used with great effect throughout the War of Secession. This gun was made by wrapping boiler plate around an iron bar, so as to form a cylindrical mass, the whole being brought to a welding heat in a furnace and then passed through rollers to unite it solidly. The piece was then bored and turned to the proper shape and dimensions. The projectiles for rifled guns were generally coated with soft metal, or furnished with an expanding base or cup of similar metal or papier maché; though in some systems they were furnished with studs or buttons which fitted into the grooves of the bore. In the case of the Whitworth gun, the projectile was made nearly of the exact size and form of the bore, so as to fit accurately into the grooves.
RODMAN GUN.
Breech-loading cannon were not, however, quickly adopted, owing, perhaps, to conservatism on the part of artillerists, and partly because the guns first produced did not seem to give appreciably better results in range, accuracy, or even in rapidity of fire than the muzzle-loaders. Not only were breech-loading cannon adopted with seeming reluctance, but rifled cannon generally were looked upon with disfavor by many artillerists of the old school. Hohenlohe tells of an old Prussian general of artillery who was so prejudiced against the rifled innovation that he requested, on his death-bed, that the salute over his grave should be fired with nothing but smooth-bore guns. It must be confessed, however, that the 12-pound smooth-bore Napoleon gun long held its own against the new rifled field-pieces, as many a bloody battle in our Civil War well attested.
GENERAL WINFIELD SCOTT.
In the manufacture of heavy guns the United States for some time led the world. In 1860, General Rodman, of the Ordnance Department, produced the first 15-inch gun ever made. This gun was made of cast-iron, and was cast on a hollow core, cooled by a stream of water passing through it, by which means the metal nearest the bore was made the hardest and most dense, and the tendency towards bursting was thus reduced to a minimum. General Rodman was also the inventor of the hollow cake powder, which consisted of cakes perforated with numerous small holes for the passage of the flame, thus enabling the powder to be progressively consumed, and causing the amount of gas at the last moments of the discharge to be greater than at the instant of ignition. A large-grain powder, known as “mammoth powder,” was afterwards devised by him to produce the same results. It will be seen later that this invention has rendered possible the powerful ordnance of the present day; and it is perhaps not too much to say, that Rodman is really thus the father of the modern high-power guns.
At the beginning of the War of Secession the heaviest gun in the United States was the 15-inch Rodman, the projectile of which weighed 320 lbs., the charge of powder weighing 35 lbs. Next to this was the 10-inch Columbiad, which fired a 100-lb. shell with a charge of 18 lbs. of powder. The effective range of these guns was a little less than three miles. The heaviest mortar was of 13-inch caliber, fired a 200-lb. shell, with a charge of 20 lbs. of powder, and had a range of 4325 yards. This mortar was, like all others then in use, manipulated by means of handspikes, and not only was much less powerful, but was much more clumsy than the admirable mortar of the present day.
OLD SMOOTH-BORE MORTAR.