The Sun.
London, England, 1866-12-22 00:00:00

English and American Ordnance Compared.

The largest Armstrong gun yet made has the same
weight of metal, namely, 22 tons, as the 15-inch
Rodman, or Dahlgren, gun, which is the heaviest
gun in the American service. The English gun is
made of welded coils of wrought. iron, and is rifled ;
the American gun is made of cast-iron, and h a
smooth-bore. A vessel which can carry the Rod-
man gun can carry the Armstrong gun. Which
of these two guns is the mote effective ?
1. Charge of Powder—Armstrong gun, 100 lbs. ;
Rodman gun, 50 lbs. The powder used in the
English gun is the best of powder ; that used in
the American gun is purposely prepared in such a
manner that it shall burn slowly.
2. Initial Velocity—Armstrong gun, 1,420-1,460
feet per second, with 100 lbs. powder and 580 lb.
shot; Rodman gun, 1,114 feet per second, with
50 lbs. powder and 450 lb. shot. The charge of
powder which the Armstrong gun can bear being
double what the American gun can endure, the
initial velocity of the heavier English shot fired
from a rifled gun is considerably greater than that
of the lighter American shot fired from a smooth-
bore. Of course the range of the rifled gun is im-
mensely greater than that of the smooth-bore.
3. Accuracy—The Armstrong gun has shown an
accuracy which no smooth-bore can approach. In
a series of firings made to determine the accuracy
of the gun the lateral deviation of the 5801 b. shot at
4,000 yards varied from nothing to a maximum of four
yards. The charge of powder used was 701bs. There
is some good evidence on record touching the accu-
racy, or rather want of accuracy, of the Rodman
smooth-bores. In his elaborate report on the bom-
bardment of Fort Pulaski, General Gilmore states
distinctly his conclusions as to the value of smooth-
bores for breaching purposes ; they are as follows :
1. At ranges less than 700 yards, light smooth-
bores are inferior to rifles ; while heavy smooth-
bores are advantageous either alone or in combina-
tion with rifles. 2. At ranges greater than 700
yards, rifled guns are superior to any smooth-bores.
3. For ranges over 1,000 yards, smooth-bores
should be "scrupulously excluded." The reason
for excluding smooth-bores from batteries at a dis-
tance from the object to be hit greater than 1,000
yards is that at such ranges it is impossible to hit
anything with a shot from a smooth-bore gun. The
immense superiority of the wrought-iron rifled gun,
which can strike effectively a hostile ship, or a
hostile battery, at a distance of 4,000 yards, over
the cast-iron smooth-bore, which is absolutely use-,
less at a range above 1,000 yards, is painfully
apparent.
4. Work—ln order to give a distinct idea of the
work of which the Armstrong gun is capable, it will
be necessary to quote Captain Noble's description
of the Hercules target, the strongest targest ever
fired at Shoeburyness. The upper half of this target
was faced with a wrought-iron plate 9 inches thick,
and the lower half with a similar plate 8 inches
thick. Behind both plates was a compact backing,
consisting of 12-inch timber laid horizontally, and
divided by four horizontal iron plates placed edge-
wise. This backing rested against a skin of two 3-
inch plates. The whole of this structure was secured
to iron ribs 10 inches deep, with vertical timber
worked in between them. Behind the ribs were 18
inches of sold timber, confined by 7-inch iron ribs,
inside all, and au iron skin. Exclusive of the 7-
inch inside ribs this target was 4 feet thick. The
Armstrong gun, firing 5801 b. shot of steelor chilled
iron, with 100 lb. of powder, has repeatedly pene-
trated this target at a distance of 200 yards, and so
effectually that portions of some of the shot passed
completely through the target into the space behind
it. In contrast with this fact, let us place the sig-
nificant fact, mentioned in the last note on ordnance
and armour printed in the Nation (No. 70)
that the American 15-inch gun was unable, in
the fight of Mobile Bay, to pierce the
sides of the Tennessee, protected by only
6 inches of iron and 30 inches of wood, al-
though the range was only 10 feet. This result is
just what we should expect from the comparative
charges of powder employed. It is easy to under-
stand that 100 lbs. of powder should do more than
50 lbs. Meanwhile, where is the Parrott gun, the
only heavy American rifled gun, with its bursting
charge of 10 lbs. of powder.
Captain Noble proves conclusively, from the Eng-
lish tables of experimental firings, and from the cal-
culations he has based thereon, that the American
15-inch gun, firing 480 lb. steel shot (and we have
no such efficient projectile), with 50 lb. charges, the
heaviest the gun will bear, is incapable of piercing
the Lord Warden target—a target which represents
a wooden vessel, protected by one iron plate 41
inches thick, 161- inches of timber, and an inner
skin 11 inches thick. This target is readily pierced
at a range not exceeding 1,000 yards by an English
wrought-iron, muzzle-loading, 9-inch rifled gun,
weighing only 12 tons, and firing a steel shot of
221 lbs., with a charge of 44 lbs. of powder. Since
the publication of Captain Noble's comprehensive
report, a new set of experiments has shown that a
target composed of 18 inches of solid teak, covered
in front with a solid plate of iron 8 inches thick, and
strengthed at the back by an inner skin of finch
iron, can be completely pierced by a 2501 b. shell of
Palliser's chilled iron, fired with a charge of 44 lbs.
of powder from a 9-inch wrought-iron rifled gun.
This 9-inch gun, weighing about 12 tons, is there-
fore very much more effective than our 15-inch
gun, which weighs 22 tons.

The defenders of cast•iron guns have a theory
that an enemy's vessel is to be best destroyed or
disabled by firing against its sides shot which are
unable to penetrate, but which will " rack," the
vessel. Before the days of armour it was thought
best to send shells into an enemy's vessel, there to
kill men and dismount guns. It would have been
better, according to this " racking" theory, to throw
balls against, not through, the wooden walls, in
order to jar the sides of the vessel to pieces. The
absurdity of the theory is manifest. It gives up
all chances of destroying the propelling machinery,
blowing up boilers and magazines, and creating
leaks below the water-line ; it abandons the idea
of exploding shells among the enemy's crew and
guns, and relies upon heavy concussions against the
vessel's side. The reliance is a very feeble one.
The Tennessee was hammered as thoroughly as any
vessel could be, but not injured. Especially is this
"racking" theory absurd when applied to ordnance in-
tended for forts which protect harbours or road-

steads. There certainly would ba no time to " rack"
a strong iron-clad to pieces while she was steaming
by a fort, but she might very easily be " punched"

with fatal effect.

The opponents of rifled heavy guns have often
asserted that these guns were soon disabled by usage
—that the bore was " scoured out" by the hardened
projectiles employed in them. There seems to be

no foundation whatever for this assertion. The

GOOlb. Armstrong gun has been fired more than
150 times without sustaining the least injury, or
being perceptibly altered in any respect. This is
explicitly stated by the officers who superintended
the testing of the gun. The English have a very
large number of rifled guns in service, and no cre-
dible complaint of their " scouring out" has ever
been made. The question of the expediency of
rifling heavy guns i 9, however, one entirely distinct

from the question of the best material for guns—
cast or wrought iron. Smooth-bores, to fire around

projectile, may be made of wrought iron, and such

guns would be greatly more durable and more effec-
tive than smooth-bores made of cast iron ; it would

simply be necessary that the gun should be built up
of wrought-iron coils, around a hard core of steel

or cast iron.

The high cost of wrought-iron guns is sometimes
urged as an argument for the use of cast iron. The

question of expense, however, is the last one to be

considered in an inquiry of this nature. On the
day of battle, at the critical moment in preparation
for which guns are made, an effective gun which
sinks the enemy's ships is cheap whatever its cost ;
while an impotent gun, which imperils the national
honour or safety, is dear at any price. Captain
Noble, moreover, maintains that the total cost of

gun, carriage, and 100 rounds of ammunition, is
very nearly the same for the 9-inch, 12-ton,
wrought-iron, rifled English gun, and the 15-inch,
22-ton, cast iron, smooth-bore American gun. As we
have seen above, the English gun is much the more
effective of the two.

Although the whole influence of our Goyernme u