nge and accuracy.
Incidentally, gunners had to "run out" (push the gun into firing
position) both smoothbore and rifled muzzle-loaders carefully. A
sudden stop might make the shot start forward as much as 2 feet.

When the U. S. Ordnance Board recommended the conversion to rifles, it
also recommended that all large caliber iron guns be manufactured on
the method perfected by Capt. T. J. Rodman, which involved casting the
gun around a water-cooled core. The inner walls of the gun thus
solidified first, were compressed by the contraction of the outer
metal as it cooled down more slowly, and had much greater strength to
resist explosion of the charge. The Rodman smoothbore, founded in 8-,
10-, 15-, and 20-inch calibers, was the best cast-iron ordnance of its
time (fig. 14f). The 20-inch gun, produced in 1864, fired a
1,080-pound shot. The 15-incher was retained in service through the
rest of the century, and these monsters are still to be seen at Fort
McHenry National Monument and Historic Shrine or on the ramparts of
Fort Jefferson, in the national monument of that name, in the Dry
Tortugas Islands. In later years, a number of 10-inch Rodmans were
converted into 8-inch rifles by enlarging the bore and inserting a
grooved steel tube.

THE WAR BETWEEN THE STATES

At the opening of this civil conflict most of the materiel for both
armies was of the same type--smoothbore. The various guns included
weapons in the great masonry fortifications built on the long United
States coast line since the 1820's--weapons such as the Columbiad, a
heavy, long-chambered American muzzle-loader of iron, developed from
its bronze forerunner of 1810. The Columbiad (fig. 14d) was made in
8-, 10-, and 12-inch calibers and could throw shot and shell well over
5,000 yards. "New" Columbiads came out of the foundries at the start
of the 1860's, minus the powder chamber and with smoother lines.
Behind the parapets or in fort gunrooms were 32- and 42-pounder iron
seacoast guns (fig. 10); 24-pounder bronze howitzers lay in the
bastions to flank the long reaches of the fort walls. There were
8-inch seacoast howitzers for heavier work. The largest caliber piece
was the ponderous 13-inch seacoast mortar.

[Illustration: Figure 14--U. S. ARTILLERY TYPES (1861-1865). a--Siege
mortar, b--8-inch siege howitzer, c--24-pounder siege gun, d--8-inch
Columbiad, e--3-inch wrought-iron rifle, f--10-inch Rodman.]

Siege and garrison cannon included 24-pounder a