although, until 1842, the flint lock was generally employed in the
British navy, having replaced the priming horn and match in 1780.
In 1807 there was discovered a composition which could be ignited
by friction or concussion, and in 1839 the French had adopted the
percussion lock, which exploded the cap and retracted, uncovering the
vent before the backward rush of the gas could strike it. Later, a
similar composition was used with “friction-primers,” or tubes filled
with mealed powder and capped with composition, the tube forming a
train leading to the charge, and the composition being fired by the
friction of a rough wire drawn briskly through it. Percussion and
friction have been in turn largely displaced by the electric primer,
which consists essentially of a fine wire, or “bridge,” passing through
a highly inflammable mixture. The bridge offers a resistance to the
electric current, is heated thereby, ignites the composition, and fires
the gun.
The older type of the cast-iron smooth-bore gun for solid shot reached
its ultimate development in the 68-pounder, which endured until the
advent of armor. In 1819 the system of firing shells loaded with
gunpowder from smooth-bore guns was suggested by General Paixhans, of
France. In 1824, it was introduced into the French navy, and about
1840 into that of the United States. At Sinope, in 1853, the terrible
effect of shell fire upon wooden ships startled the world, when a
Russian fleet destroyed absolutely 11 Turkish vessels, with their force
of 4000 men. The Paixhans gun was modified and its form improved by
Admiral Dahlgren, U. S. N., and in the late 50’s the armament—designed
by him—of United States vessels was superior to that of any other in
the world. The 9, 11, and 15-inch Dahlgrens formed the bulk of our guns
afloat during the Civil War, the remainder being almost wholly rifles
of the Parrott type.
[Illustration: _The Growth of Ordnance_
_32pdr 6m Smooth-bore, Muzzle-loader
Weight 3600 lbs. Muzzle Energy, 642 Foot-tons_
_U S (Dahlgren) 440pdr 15m Smooth-bore, Muzzle-loader
Weight 42000 lbs. Muzzle Energy, 7273 Foot-tons_
_Italian (Armstrong) 2000pdr 17in Rifle, Breech-loader
Weight 101.5 tons, Muzzle Energy, 51930 Foot-tons_
_U S Naval 1100pdr 13in Rifle, Breech-loader
Weight 60 tons, Muzzle Energy, 33627 Foot-tons_
PLATE V.]
The resistance which spherical projectiles met from the air, their
deviation in flight, owing to the frequent lack of coincidence of the
centres of gravity and form, their excessive “windage,” and their light
weight relatively to calibre, led to the adoption of the rifled gun
and the cylindrical projectile. The principle of the former—making
the shot act as a screw-bolt and the bore as a screw-thread—is very
old, there being at Woolwich a barrel of this type bearing date of
1547. The objects aimed at in rifling are to give a pointed cylindrical
shot rotation on its axis that it may keep steady during flight,
and secondly, to obtain increased weight in the projectile from its
elongated form. As to the latter consideration, it may be noted that
the old 32-pounder smooth-bore was of 6-inch calibre, while the United
States 6-inch rifle of to-day throws a shot of 100 lbs. weight.
France, during the Crimean War, brought out the first heavy rifled gun.
In 1860–61, Armstrong rifles were introduced in the British navy. The
labors of Krupp met such success that at Paris, in 1867, he exhibited
a rifle weighing 50 tons with a projectile of 1080 pounds. The Parrott
rifle was brought out about 1856 in the United States, and was so
developed that in 1862 it was the most powerful gun, for its weight and
size, in existence. The adoption of rifling was the first great step
on the road which engineering had laid toward the growth in power of
modern ordnance.
Having thus secured a projectile of great weight and moderate calibre
which would bore through the air a true path to the distant mark,
there remained to seek but four chief elements in the magnificent
advance made within a generation by the naval artillery of our day.
These factors were: 1st. Increased strength in the material of the
gun. 2d. A method of construction which would not only permit enormous
pressures in the powder-chamber, but would make possible the continuous
acceleration of the projectile during its passage through the bore.
3d. An explosive which would satisfy the objects of the method of
construction; and, 4th. A system of loading which would enable guns of
great length to be charged with ease. The mounting of ordnance of any
weight, its control, and its rapid and facile handling were but minor
matters of engineering.
In a paper such as this, of limited length and addressed to laymen,
it is possible to give but a glance at the progress in the various
elements of gun-construction which have been noted. Of material, little
need be said. The rifle of Crimean days was a cast-iron piece; Parrott
ordnance was of cast and wrought iron; and the first Armstrong gun was
built of wrought iron and steel. Cast and compound materials, however,
have vanished with the past. Steel—hardened and toughened to the last
degree by every refinement of manufacture—forms the “reeking tube” for
the “iron shard” of the century’s close.
The method of construction is the “built-up” process, shown by the
partial section on Plate V., the barrel being reinforced by tubes
which are shrunk on—like the tire of a wagon-wheel—so as to produce
initial compression. The explosion in the powder chamber strains and
expands temporarily the barrel, and the application of the shrinkage
principle enables a portion of the strength of the tubes to be employed
in preliminary internal pressure. The barrel thus supported can be
strained by the charge, not only to its own limit of safety, but to an
additional amount equal to this initial compression. The all-steel,
built-up gun has a possible rival in wire-wound ordnance, a system
which replaces the tubes, to a greater or less extent, by layers of
wire, wound while in tension around the barrel.
Powder is the soul of the gun; it transforms the huge inert mass into
a flaming engine of death. The great development of explosives began
but a generation since. The researches of Robins and Rumford in the
last century, and of Hutton in the dawn of this, formed the world’s
knowledge of the gun’s internal ballistics until the year 1870. To the
genius of Noble and Abel is due the stimulus to growth since then.
The powders have kept pace with gun-construction in its advance.
The increased strength of the chamber has been met by heavier and
slow-burning charges—cocoa, brown prismatic, and the like—which have
given not only greater initial velocity, but a continuous acceleration
through bores whose maximum length has exceeded 47 feet. Indeed, to
the production of this lingering combustion is due the great linear
dimension and power of modern guns. Initial pressure had its limit;
advance lay only in the subsequent acceleration given by late ignition
of a portion of the charge.
Gunpowder, however, after a reign of more than five hundred years,
has been dethroned. The “villainous saltpetre” of the monk, with its
allies, charcoal and sulphur, yields now to nitro compounds, which
produce not only far greater energy, but are as well smokeless. The
sea-fights of our war with Spain saw the last contending fleets to
be wrapped in a cloud, lingering and baffling, of their own making.
Cordite, one of these compounds in use abroad, is prepared in long
“cords” from di-nitro-cellulose and nitro-glycerine. The new smokeless
“powder” of the United States navy is made from nitro-cellulose
dissolved in ether alcohol. France was the first in employing
explosives such as these, which, in their offensive and tactical
advantages, form one of the signal triumphs of the century’s last years.
The long gun of modern days is of necessity breech-loading. The
development of other elements gave, as a resultant, great length;
and this, in turn, required a system of charging which would
permit protection for the men while loading, and would obviate the
intolerable inconvenience of ramming home powder and shot in a long
muzzle-loader—an operation which was, in fact, impossible beyond a
certain limit of length. The advocates of the older construction,
especially in England, urged long and earnestly its simplicity and
the superior strength of a solid breech; but the logic of events was
against them, and the breech-loader won a complete triumph. It is
worthy of note that it, like rifling and the principle of building up,
was but a revival. From the warship Mary Rose, sunk in 1545 in action
off Spithead, there were recovered in 1836 a number of guns, some of
which are of wrought iron, built-up and breech-loading. There are in
use two methods of closing the breech when the gun is loaded from the
rear. In French, English, and American ordnance an axial screw-plug is
inserted; in the Krupp system a cylindro-prismatic breech-block slides
in a horizontal opening cut across the bore. The former, or interrupted
screw mechanism, was first set forth in the United States’ patent of
1849 to Chambers.
In projectiles the tendency of the modern era has been towards
simplification. Bar-shot, chain-shot, and grape have disappeared, while
canister and solid shot are becoming obsolete. There remain shrapnel as
the “man-killer” of this age, and explosive shell, differentiated into
armor-piercing and that for attack on unarmored structures. Lieutenant
Shrapnel, in 1796, invented the projectile which bears his name. In its
modern form, it consists of a steel case containing lead or iron balls
and a light bursting charge of powder, ignited by a time-fuse carried
in the head. This projectile is most formidable against bodies of men,
boats, and the embrasures of forts, since, when it is ruptured, the
balls are dispersed, covering a wide area.
The use of explosive shell in high-angle discharge dates back to
the fifteenth century. From Paixhans’ works, “La Nouvelle Arme,”
published in 1821, came the stimulus to its development and to its
deadly service, in our time, in horizontal fire. The “common shell”
for the United States 13-inch rifle is made of forged steel, weighs
1100 pounds, and carries within it a bursting charge of 50 pounds of
powder, ignited by a percussion fuse set in its base. It will penetrate
6 or 7 inches of armor and then explode within the ship. The United
States “armor-piercing shell” is manufactured from crucible steel,
alloyed with chromium; it is tempered to extreme hardness at the point,
which carries a cap of soft metal. The function of the latter would
appear to be that of a support to the shoulder of the projectile, or
as a lubricant thereto, since, without the cap, the shell is broken or
deformed in the attack on armor of surface hardened steel. To resist
the crushing strain in its passage through massive plate, the walls
of this shell must be so thick that no charge of gunpowder will burst
it. Hence, as a rule, the shell is fired unloaded, although recently
there have been adopted to some extent bursting charges of some high
explosive, such as gun-cotton, joveite, or picric acid.
In closing this brief review of the progress of ordnance, but passing
mention can be made of matters minor, but in themselves of much
importance. Gun carriages, or mounts, are now intricate mechanisms,
practically the whole service of large ordnance being performed by
electric and hydraulic machinery. The rapid fire principle has been
extended to pieces of 6-inch calibre, and bids fair to pass beyond that
limit. Its success in increasing largely the number of shots within a
given time lies in special breech-blocks, aiming devices, and prepared
cartridges. Machine guns of rifle-calibre, partly or wholly automatic,
have been so developed as to be capable of firing 1200 rounds per
minute. The discharge of high explosives in large quantity was effected
with success by the United States steamer Vesuvius off Santiago. The
torpedo-gun afloat, however, would appear to be still in a tentative
condition.
A brief lapse into technical terms may be permitted in summarizing the
gun’s growth in power. The term “muzzle energy” is used to describe the
work which the projectile is capable of performing when it leaves the
bore. It is expressed in foot-tons, i. e., the number of tons which
the energy stored in the shot would lift to a height of one foot. The
figures as to this for the 32-pounder of the century’s beginning, for
the United States 13-inch rifle and for the 111-ton English gun, are,
respectively, 642, 33,627, and 54,690 foot-tons. Again, the round shot
from the 32-pounder lost from the resistance of the air, in a range of
1200 yards, 76 per cent of its energy; while this loss, with the United
States 13-inch, in a range of 1000 yards, is but 11 per cent. Finally,
if the cast-iron shot of the 32-pounder were fired against armor-plate,
it would lose, in breaking itself up, two thirds of its remaining
energy, leaving at 1200 yards but 51 foot-tons for effective work;
while with the modern armor-piercing shell the entire energy left at
the end of the range is expended upon the armor-plate.
It will be seen then that the immeasurable superiority of modern guns
is owing both to their great increase in energy and to their wiser
disposition of that which has been attained. The gun has maintained
fully during the century its primacy among naval weapons. It is
true that, in theory and on paper, its supremacy has at times been
questioned; but as to its two rivals, the ram would seem to be rather
the weapon of accident than action, and the torpedo has yet to score
in battle against ships in motion, while the precision, rapidity, and
power of the gun grow more deadly with every passing year.
VI. THE DEVELOPMENT OF ARMOR.
Armor and the gun are natural and now hereditary foes. The function
of the one is to resist, that of the other ever to attack. Since the
beginning of the modern era in navies, there has been ceaseless strife
for mastery between these two elements of warship design, the gun
ever becoming more powerful, and the armor—at first through growing
thickness and later through improved material—opposing a steadily more
stubborn front. The official report of an English committee made in the
year 1860 states that,—
“Vessels clothed in rolled-iron plates of four and a half inches’
thickness are to all practicable purposes invulnerable against any
projectile that can be brought to bear against them at any range.”
The advance which forty years have seen may be shown by the single
statement that the Krupp 15.7-inch gun develops sufficient energy to
penetrate at the muzzle 47 inches of wrought iron. The battleship is at
best but a series of compromises, each factor of the structure yielding
or growing as the skill or whim of her designer may indicate. In the
present stage of this unceasing change, the gun would appear to be
the victor, and the power of this mighty 132-ton rifle seems scarcely
needed on the sea. The distinguished chief of ordnance of the United
States navy, in his annual report for 1898, says:—
“The development of the 12-inch gun has been so great and its power so
much increased that the Bureau is of opinion that hereafter it will
be the maximum calibre that it will be advisable to install on future
battleships.”
With armor, as with the torpedo, the talent of Europe reaped where
the genius of America had sown. John Stevens of New Jersey was the
first inventor of modern times to suggest the application of armor to
a floating battery, his plans being submitted to the United States
government during the war of 1812. They received, however, no serious
consideration, and to France, forty-two years later, fell the honor of
attaining the first practical results in the building of ironclads.
Members of the Stevens family, however, continued the experiments of
its founder, until by the year 1841 they had determined the thickness
of iron necessary to stop spherical projectiles at point blank range,
and the comparative resisting powers of iron and oak. These results led
to an appropriation by Congress, in 1854, of $500,000 to begin work
upon an ironclad,—the Stevens battery,—which vessel, however, never
left the ways and was eventually broken up.
[Illustration: PLATE VI. THE DISTRIBUTION OF ARMOR.]
[Illustration: PLATE VII. THE DISTRIBUTION OF ARMOR.]
General Paixhans, who revolutionized naval artillery by the invention
of the modern shell, prophesied, in an official letter to the French
government in 1824, that the new projectile would force the creation
of armored ships. In 1841 he recommended officially the clothing of
vessels with iron armor, as a protection against his own missiles; and
in 1853 his words of warning met complete and terrible fulfillment in
the annihilation by shell guns of the Turkish fleet at Sinope. This
action was the immediate cause of the introduction of armor in modern
navies.
The British admiralty, in 1843, had duplicated the Stevens experiments,
using a target of 14 plates of boiler iron riveted together, which gave
a total thickness of 6 inches; and experiments on laminated plating
had been also at this time carried on at Gavres, in France. In 1845
Dupuy de Lôme, the famous naval architect, submitted to the French
government the first European design for an armored frigate. His plans
were, however, rejected; and only with the outbreak of the Crimean War
was the construction of armored vessels begun. On October 17, 1855,
the three French batteries which were the first results of this new
departure went into action off Kinburn, in the Crimea, silencing in
four hours forts which had held at bay the combined fleets of England
and France. Armor had won its first victory, and had shown most
signally its position as one of the main factors in the warship design
of the years which were to come.
These vessels, with three similar batteries constructed immediately
thereafter by the British government, were clad with solid iron plates
4½ inches thick, backed by 27¾ inches of oak, comparative experiments
at Vincennes, France, having shown the marked superiority of solid
over laminated plating. They were, however, in but a most limited
sense sea-going ships, their low speed and other inferior qualities
being radical defects as to this. France led in a further advance,
beginning in 1857 and completing in 1859 the transformation of the
wooden line-of-battle ship Napoleon into the armored vessel of 5000
tons, which, as La Gloire, is famous as the first sea-going ironclad.
She carried a strake of 4¾-inch plating at the water line, and 4½-inch
plates in wake of the battery. England answered the challenge of her
hereditary foe with the Warrior, an iron vessel of 9210 tons, completed
in 1861. While her rival had a fully armored side, but 212 of the
Warrior’s 380 feet of length carried plating. Its thickness was 4½
inches.
[Illustration:
_“La Gloire” (France) 1857.
Side Armor Iron 4½ in. Solid._
_“Warrior” (England) 1859.
Side Armor Iron 4½ in. Solid._
_U.S. Monitor “Passaic” 1862.
Side Armor Iron 3 to 5 in. Laminated.
Turret Armor Iron 11 in. Laminated._
_“Inflexible” (England) 1876.
Belt & Citadel Armor Iron Sandwiched._
_“Duilio” (Italy) 1876.
Belt Armor Steel Solid._
_U.S. Battleship Oregon.
Belt Armor Harveyed Nickel Steel Solid.
13 in. Turret Armor Harveyed Nickel Steel Solid._
PLATE VIII. THE GROWTH OF ARMOR.
]
At the outbreak of the Civil War in the United States, the government
appointed a special naval committee to report upon types of ironclads.
The conclusions of this board are of interest, in showing the state of
armor development at that period. They required rolled armor of solid
iron, whose minimum thickness was 4½ inches. Ericsson’s Monitor,
however, carried laminated plating from 3 to 5 inches thick on her
low sides, and 11 layers, each one inch thick, on her turret. This
construction, which the difficulties in the manufacture of solid plate
necessitated, made the record of endurance of this type far from good.
The defect lay mainly with fastening bolts, which broke frequently,
thus loosening or detaching the side armor, and the heads or nuts of
which, flying off with violence when the armor was struck by shot,
became sometimes fatal missiles against those within the turrets. In
contrast with this, the behavior of the New Ironsides, clothed with
solid armor, was most excellent. She was a casemated ironclad frigate
with unarmored ends, her plating was 4½ inches thick, and inclined
throughout the citadel, at an angle of 30° from the perpendicular. For
two years she was subjected to the most severe test that a war-vessel
must meet, the tossing and straining of blockade duty and the fiery
ordeal of close action with fortifications. In one engagement, she
sustained alone a fight against the combined fire of the forts in
Charleston harbor, and, although struck on her side-armor sixty times,
came out of the struggle unhurt. The record of this ship is one which
does honor to the flag.
The achievement of the Confederacy during this war, in the matter of
armor, was remarkable. With iron worth almost its weight in gold, and
with most limited facilities for manufacturing, they yet succeeded in
constructing some of the most formidable ironclads of their day. The
Merrimac, for instance—with 3-inch armor, in two layers of narrow
bars, at an angle of 30° with the horizontal—sustained no material
damage to her plating from the fire of the Monitor; although had the
full charge of 30 lbs. of powder been used in the 11-inch smooth-bores
of the latter, the story would have been different. Every fair blow
would have smashed a hole completely through the armor, and driven a
shower of splinters about the battery-deck. Again, the armor of the
Atlanta and the Tennessee—both casemated ships, with the sides of the
citadel inclined at a sharp angle to the horizontal—was sufficiently
strong, with the former vessel, to withstand, at 500 yards, the 11-inch
projectile fired with a 20-lbs. charge, and, with the latter, the same
shot practically at the muzzle, although the 15-inch projectile broke
through completely in both cases.
It is unnecessary to follow in detail, through its many tests in peace,
the advance of iron armor. Its growth in strength, as the power of
the gun developed, came almost solely from increase in thickness, the
latter reaching its maximum with the British Inflexible, completed
in 1876, which carries from 16 to 24 inches of iron on her belt and
citadel. This plating, however, is divided and “sandwiched” with wood,
there being, exterior to the skin, 6 inches of teak, then 12 inches
iron, 11 inches teak, and an outer 12-inch plate. As armor, iron
received its death-blow in the famous tests at Spezia, Italy, during
the autumn of 1876, when the 100-ton gun, with a full charge, at a
range of 100 yards, attacked solid and “sandwich” targets of iron and
solid targets of steel—the single or aggregate thickness of metal
in each case being 22 inches. These trials were undertaken through
Italy’s desire to build, in the Duilio and Dandolo, the most formidable
vessels afloat. Steel won the day, and the roar of that mighty gun,
thundering from the Spezia firing ground, sounded the knell of iron
armor, deprived the as yet unlaunched Inflexible of her crown of
invulnerability, and demanded, with success, a revolution in the armor
manufacture of Europe.