These powerful weapons fire a projectile which weighs from 700 to 1,046
pounds, depending on the range desired, and which is capable of piercing
the deck armor of any battleship. They have a range of 20,000 yards with
the 700-pound projectile. The gun is 16-2/3 feet long and is fired only
at elevations between 45° and 65°.]
[Illustration: GIANT GUNS--THEIR MUZZLE-ENERGY, PROJECTILES, AND
PENETRATING POWERS
The British 13.5, which was known as the 12-inch-A until the “Lion” was
launched, has a length of 45 calibers, and a muzzle-energy ten per cent
greater than that of the 50-caliber 12-inch of 1909 and 1910. It may be
noted that the caliber is the diameter of the bore of a gun. The
statement that a gun has a length of 45 calibers, for example, implies
that the gun is forty-five times the bore’s diameter. Thus a 12-inch gun
of 45 calibers is 45 feet long.]
These pieces are prepared with the utmost care to prevent any defective
material entering into the make-up of the gun. After the parts are put
together a thorough forging follows, either by use of hammer or press,
the latter being now used in preference. The usual practice in forging
is to continue it until the ingot is decreased to one-half its original
thickness and is within two inches of the desired diameter of the
finished work. It is then annealed with great care to relieve the
strains set up in the metal by the forging and next goes to the machine
shop to be rough bored and turned. The final boring takes place after a
second annealing. The above is only a rapid sketch of the total process,
in which elaborate care is taken to prevent imperfection of any kind.
[Illustration: ORDNANCE PROVING GROUND
View showing smoke cone occurring during the proof firing of a
twelve-inch gun with brown powder.
_Courtesy of the Bethlehem Steel Co._]
In a wire-wound gun an inner tube of steel is thoroughly wrapped by
successive layers of ribbon wire, each layer being wound with wire at a
different tension. This type of gun is preferred by foreign
manufacturers, but within the United States the built-up system is in
higher favor and is almost exclusively employed. The makers of the
wire-wound cannon claim for it a positive soundness of material
impossible to secure in a built-up gun, and that it has greater firmness
of material and superior tangential strength. But with this come certain
disadvantages, a notable one being a lack of rigidity in the
longitudinal direction, this tending to increase the “droop” of the
muzzle and give a certain “whip” to the piece when fired that reduces
accuracy. This and other disadvantages have given the built-up guns
general preference in this country, they being found strong enough to
bear any pressure desirable in service. In addition they are much
cheaper to build than the wire-wound guns.
Modern heavy guns are made of medium open-hearth carbon steel, forged as
stated. The liner and tube are then placed upright in an assembling pit,
the jacket and hoops shrunk on, and the finishing work done, as above
said, the breech mechanism being finally fitted. Within recent years
there has been a steady increase in the size and range of cannon, until
an immense size and weight have been attained. For naval purposes the
14-inch gun is the largest now used in American battleships, but in the
United States coast defense forts, 16-inch guns are installed. England
has equipped several of her latest battleships with 15-inch guns and
other nations are following in the same direction. In recent great
battleships four turrets are used, each carrying three of these great
guns, giving a broadside of twelve of these monster weapons of war. Of
the three guns, the middle one is raised above the line of the others. A
battleship thus armed is able to fire six guns ahead and six astern by
raising the second and third turrets so as to fire over the others.
[Illustration: FOUR-INCH FIFTY CALIBER RAPID-FIRE GUN ON PEDESTAL MOUNT
Extraction of cartridge case by opening of breech mechanism. Weight of
gun, 6,170 pounds. Length of gun, 205 inches (51.2 calibers). Weight of
projectile, 33 pounds. Travel of projectile in bore, 165.6 inches (41.4
calibers). Weight of charge, 15 pounds of smokeless powder. Muzzle
velocity, 2,900-foot seconds. Muzzle energy, 1,928-foot tons. Weight of
mount with shield, 9,470 pounds. Thickness of shield, 2 inches of nickel
steel. Gun equipped with telescopic and night sights and with electric
and percussion pull-off firing gear.
_Courtesy of the Bethlehem Steel Co._]
Military cannon are divided into three classes, based upon the length of
caliber, and technically known as guns, mortars and howitzers. In guns
the length is relatively great, in mortars relatively small, compared to
their calibers. Howitzers form a class between guns and mortars in
length. The field guns of the American army are the 3.6-inch
breech-loading mortars, and the 3.6-inch heavy and 3.2-inch light guns.
The siege guns in the service are the 5-inch siege guns, the 7-inch
howitzer, and the 7-inch mortar. The coast defense artillery consists of
the 8-, 10-, 12- and 16-inch guns and the 12-inch mortars. In the recent
European war very heavy cannon were used for field service, pieces of
the size usually placed in forts being drawn to the field by powerful
tractors, set on concrete platforms and used in attacks on fortified
cities. It was through the use of such ordnance that the German army so
easily reduced the strongly fortified Belgian cities.
[Illustration: FLUID COMPRESSION PLANT
While still in a molten condition in the mold, the steel used in
manufacturing guns and shafting is subjected to hydraulic pressure until
the ingot has cooled, thus insuring the solidity of the metal. The upper
head of the compressor weighs 125 tons, and the lower one, including the
cylinder through which the hydraulic pressure is applied, 135 tons.
_Courtesy of the Bethlehem Steel Co._]
[Illustration: AMMUNITION.[32] (See page 410.)]
[Illustration: TWO-HANDED ELEVATING GEAR.[32] (See page 410.)]
[Illustration: RANGE FINDER AND PREDICTOR; HOME AND DISTANT STATION
INSTRUMENTS.[33]
(See page 410.)]
[Illustration: ARMOR PIERCING PROJECTILES, CAPPED AND UNCAPPED.[33] (See
page 410.)]
[Illustration: RANGE FINDER AND CHART ATTACHMENT[34]. (See page 410.)]
[Illustration: EIGHTEEN-INCH, THIRTY-CALIBER TORPEDO GUN.[34] (See page
410.)]
[Illustration: FIRING GEAR FOR GUNS.[35] (See page 410.)]
[Illustration: FUSES.[35] (See page 410.)]
The range of these giant cannon is enormous and their destructive power
great, this being added to by the fact that the explosive shell has
replaced the solid round shot of old-time gunnery. A 14-inch gun of 45
caliber can discharge a 1,400-pound projectile at a muzzle velocity of
2,600 feet per second. If we compare this with a locomotive going at the
speed of sixty miles an hour, we have in the latter a speed of
eighty-eight feet per second to compare with the 2,600 feet per second
of the cannon ball. From this we can well conjecture the vast speed with
which the latter moves, its enormous range and vast powers of
destruction.
[Illustration: THREE-INCH HORSE ARTILLERY GUN, LONG RECOIL CARRIAGE AND
LIMBER
Length of gun, 85 inches (28 calibers). Weight of projectile, 12 pounds.
Travel of projectile in bore, 74.65 inches (24.88 calibers). Weight of
charge, 17.1 ounces of smokeless powder. Muzzle velocity, 1,750-foot
seconds. Muzzle energy, 255-foot tons. Weight of gun, carriage and
limber, containing 36 rounds of ammunition, 3,355 pounds. Ground
clearance, 18 inches.
_Courtesy of the Bethlehem Steel Co._]
As facts are better than theories, it will be of interest to adduce a
recent example of gunnery of a most illuminating type, but as regards
distance and remarkable accuracy of aim. In September, 1916, the
American battleship “Pennsylvania,” armed with a main battery of twelve
14-inch guns, fired these simultaneously at a target in the Chesapeake
22,000 yards, or more than twelve miles, away. The target was the sunken
hulk of the “San Marcos,” formerly the battleship “Texas,” which for
several years had been used for similar purposes. As the target was
invisible to the gunners it was hardly to be expected that any of the
shots should fall near the target. But the extraordinary result appeared
that five of these twelve shots struck the hulk. As each of these
projectiles weighed 1,400 pounds any battleship receiving such a
broadside would probably have gone promptly to the bottom. The result,
which has never before been equaled in accuracy, sufficiently attests
the remarkable proficiency in range-finding that modern engineers have
developed.
As for the penetrating powers of such huge shot we may take the 15-inch
gun, the type of the largest guns in our fortifications and which is
claimed to be able to pierce sixteen inches of armor at a range of
18,000 yards and ten inches at a range of 20,000 yards. A notable
example of this took place on September 15, 1916, at the proving grounds
at Indian Head, on the Potomac River, when a 16-inch, 2,100-pound, solid
steel shell, said to be the first ever fired from a naval gun of that
caliber, with a small charge of explosive, went through a plate of
armor, penetrated a thick sand backing, and continued its course,
striking the house of an employee of the proving grounds and plunging
through the kitchen rending all before it. This was a naval gun, the
largest yet made for naval purposes.
[Illustration: PATENTED CHAIN RAMMER
As applied to loading twelve-inch turret guns. The space occupied by
this rammer in the rear of the gun is less than one foot, with a
possible ramming stroke of fifteen feet. The rammer being attached to
the gun’s cradle or slide, moves with the gun in elevation and
depression. The ammunition car also moves with the gun. Loading can be
performed while the gun is kept in motion following a moving target.
This rammer is stiff in all directions when extended.
_Courtesy of the Bethlehem Steel Co._]
In the make-up of modern guns the breech-loading mechanism is of
essential importance, it being necessary that the breech should be
capable of rapid opening for the insertion of the charge into the
loading chamber, as rapidly closed and firmly secured to prevent it
being forced open by the reaction of the discharge. It also must fit
with such tightness as to prevent any escape of the gas in that
direction, and force it to exert all its impelling power upon the ball.
Various methods are used for this purpose, with the result that loading
and firing can be very quickly and effectively performed. In the case of
guns in fortifications, the disappearing carriage is a highly important
invention of recent date. By its aid the gun is quickly lifted to fire
over the walls of the fort and is driven backward by the force of its
discharge, sinking to a place of safety behind the walls. This saves the
gun and its crew from injury by return fire.
We may say in conclusion that the great European war was notable for the
use of artillery to an extent far surpassing its employment in any
previous war. This great conflict, indeed, was very largely a contest of
gun fire, in which the opposing fields of the battling armies were so
swept with shells and other explosives as to render life impossible on
the open land, trench digging being one of the main employments of the
embattled hosts. Never before had the supreme value of gunnery in
warfare been so fully demonstrated.
[Illustration: GEAR WHEEL AND DRUM FOR COAL HOISTING PLANE
Diameter of wheel, 20 feet 9-1/2 inches; face, 43-1/2 inches; diameter
of hub, 26 inches; number of teeth, 128; pitch, 6-1/8 inches; pitch
diameter, 249.554 inches; shipping weight, 108,873 pounds.
_Courtesy of the Bethlehem Steel Co._]
[Illustration: SIX-INCH RIBBED CAVITY ARMOR-PIERCING SHELL
Projectile was loaded with two pounds of black charcoal powder and fused
with magazine fuse. Fired at six-inch Krupp hard-faced armor plate.
Shell burst about eight feet to rear of plate after penetrating the
same. Weight of largest fragment recovered 10-1/4 pounds. Average weight
of fragments, 2-5/16 ounces. Total number of pieces recovered, 650.
_Courtesy of the Bethlehem Steel Co._]