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 The breech was closed with a screw which could be quickly withdrawn for loading and sponging the gun.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. [Illustration: 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. [Illustration: GENERAL WINFIELD SCOTT.]