A TALK ON BIG GUNS
The First Projectiles--Introduction of Cannon--High Pressure
Guns--Machine Guns--Dimensions and Cost of Big Guns.
The first arms and machines employing gunpowder as the propelling
agency, came into use in the fourteenth century. Prior to this time
there were machines and instruments which threw stones and catapults
and large arrows by means of the reaction of a tightly twisted rope
made up of hemp, catgut or hair. Slings were also much employed for
hurling missiles.
The first cannons were used by the English against the Scots in 1327.
They were short and thick and wide in the bore and resembled bowls or
mortars; in fact this name is still applied to this kind of ordnance.
By the end of the fifteenth century a great advancement was shown in
the make of these implements of warfare. Bronze and brass as materials
came into general use and cannon were turned out with twenty to
twenty-five inch bore weighing twenty tons and capable of hurling to
a considerable distance projectiles weighing from two hundred pounds
to one thousand pounds with powder as the propelling force. In a short
time these large guns were mounted and carriages were introduced to
facilitate transportation with troops. Meantime stone projectiles were
replaced by cast iron shot, which, owing to its greater density,
necessitated a reduction in calibre, that is a narrowing of the bore,
consequently lighter and smaller guns came into the field, but with
a greater propelling force. When the cast iron balls first came into
use as projectiles, they weighed about twelve pounds, hence the cannons
shooting them were known as twelve-pounders. It was soon found, however,
that twelve pounds was too great a weight for long distances, so a
reduction took place until the missiles were cut down to four pounds
and the cannon discharging these, four pounders as they were called,
weighed about one-quarter of a ton. They were very effective and handy
for light field work.
The eighteenth century witnessed rapid progress in gun and ammunition
manufacture. "Grape" and "canister" were introduced and the names still
cling to the present day. Grape consisted of a number of tarred lead
balls, held together in a net. Canister consisted of a number of small
shot in a tin can, the shots being dispersed by the breaking of the
can on discharge. Grape now consists of cast iron balls arranged in
three tiers by means of circular plates, the whole secured by a pin
which passes through the centre. The number of shot in each tier varies
from three to five. Grape is very destructive up to three hundred yards
and effective up to six hundred yards. Canister shot as we know it at
present, is made up of a number of iron balls, placed in a tin cylinder
with a wooden bottom, the size of the piece of ordnance for which it
is intended.
Towards the close of the eighteenth century, short cast-iron guns
called "carronades" were introduced by Gascoigne of the Cannon Iron
Works, Scotland. They threw heavy shots at low velocity with great
battery effect. They were for a long time in use in the British navy.
The sailors called them "smashers."
The entire battery of the Victory, Nelson's famous flag-ship at the
battle of Trafalgar, amounting to a total of 102 guns, was composed
of "carronades" varying in size from thirty-two to sixty-eight
pounders. They were mounted on wooden truck carriages and were given
elevation by handspikes applied under the breech, a quoin or a wedge
shaped piece of wood being pushed in to hold the breech up in position.
They were trained by handspikes with the aid of side-tackle and their
recoil was limited by a stout rope, called the breeching, the ends of
which were secured to the sides of the ship. The slow match was used
for firing, the flint lock not being applied to naval guns until 1780.
About the middle of the nineteenth century, the design of guns began
to receive much scientific thought and consideration. The question of
high velocities and flat trajectories without lightening the weight
of the projectile was the desideratum; the minimum of weight in the
cannon itself with the maximum in the projectile and the force with
which it could be propelled were the ends to be attained.
In 1856 Admiral Dahlgren of the United States Navy designed the
_Dahlgren_ gun with shape proportioned to the "curve of pressure,"
which is to say that the gun was heavy at the breech and light at the
muzzle. This gun was well adapted to naval use at the time. From this,
onward, guns of high pressure were manufactured until the pressure
grew to such proportions that it exceeded the resisting power,
represented by the tensile strength of cast iron. When cast, the gun
cooled from the outside inwardly, thus placing the inside metal in a
state of tension and the outside in a state of compression. General
Rodman, Chief of Ordnance of the United States Army, came forward with
a remedy for this. He suggested the casting of guns hollow and the
cooling of them from the inside outwardly by circulating a stream of
cold water in the bore while the outside surface was kept at a high
temperature. This method placed the metal inside in a state of
compression and that on the outside in a state of tension, the right
condition to withstand successfully the pressure of the powder gas,
which tended to expand the inner portions beyond the normal diameter
and throw the strain of the supporting outer layers.
This system was universally employed and gave the best results
obtainable from cast iron for many years and was only superseded by
that of "built up" guns, when iron and steel were made available by
improved processes of production.
The great strides made in the manufacture and forging of steel during
the past quarter of a century, the improved tempering and annealing
processes have resulted in the turning out of big guns solely composed
of steel.
The various forms of modern ordnance are classified and named according
to size and weight, kind of projectiles used and their velocities;
angle of elevation at which they are fired; use; and mode of operation.
The guns known as breechloading rifles are from three inches to fourteen
inches in calibre, that is, across the bore, and in length from twelve
to over sixty feet. They weigh from one ton to fifty tons.
They fire solid shot or shells weighing up to eleven hundred pounds
at high velocities, from twenty-three to twenty-five hundred feet per
second. They can penetrate steel armor to a depth of fifteen to twenty
inches at 2,000 yards distance.
Rapid fire guns are those in which the operation of opening and closing
the breech is performed by a single motion of a lever actuated by the
hand, and in which the explosive used is closed in a metallic case.
These guns are made in various forms and are operated by several
different systems of breech mechanism generally named after their
respective inventors. The Vickers-Maxim and the Nordenfeldt are the
best known in America. A new type of the Vickers-Maxim was introduced
in 1897 in which a quick working breech mechanism automatically ejects
the primer and draws up the loading tray into position as the breech
is opened. This type was quickly adopted by the United States Navy and
materially increased the speed of fire in all calibres.
What are known as machine guns are rapid fire guns in which the speed
of firing is such that it is practically continuous. The best known
make is the famous Gatling gun invented by Dr. R. J. Gatling of
Indianapolis in 1860. This gun consists of ten parallel barrels grouped
around and secured firmly to a main central shaft to which is also
attached the grooved cartridge carrier and the lock cylinder. Each
barrel is provided with its own lock or firing mechanism, independent
of the other, but all of them revolve simultaneously with the barrels,
carrier and inner breech when the gun is in operation. In firing, one
end of the feed case containing the cartridges is placed in the hopper
on top and the operating crank is turned. The cartridges drop one by
one into the grooves of the carrier and are loaded and fired by the
forward motion of the locks, which also closes the breech while the
backward motion extracts and expels the empty shells. In its present
state of efficiency the Gatling gun fires at the rate of 1,200 shots
per minute, a speed, by separate discharges, not equaled by any other
gun.
Much larger guns were constructed in times past than are being built
now. In 1880 the English made guns weighing from 100 to 120 tons, from
18 to 20 inches bore and which fired projectiles weighing over 2,000
pounds at a velocity of almost 1,700 feet per second. At the same time
the United States fashioned a monster rifle of 127 tons which had a
bore of sixteen inches and fired a projectile of 2,400 pounds with a
velocity of 2,300 feet per second.
The largest guns ever placed on board ship were the Armstrong one-
hundred-and-ten-ton guns of the English battleships, _Sanspareil_,
_Benbow_ and _Victoria_. They were sixteen and one-fourth inch calibre.
The newest battleships of England, the _Dreadnought_ and the
_Temeraire_, are equipped with fourteen-inch guns, but they are not one-
half so heavy as the old guns. Many experts in naval ordnance think it a
mistake to have guns over twelve inch bore, basing their belief on the
experience of the past which showed that guns of a less calibre carrying
smaller shells did more effective work than the big bore guns with
larger projectiles.
The two titanic war-vessels now in course of construction for the
United States Navy will each carry a battery of ten fourteen-inch
rifles, which will be the most powerful weapons ever constructed and
will greatly exceed in range and hitting power the twelve-inch guns
of the _Delaware_ or _North Dakota_. Each of the new rifles will weigh
over sixty-three tons, the projectiles will each weigh 1,400 pounds and
the powder charge will be 450 pounds. At the moment of discharge each of
these guns will exert a muzzle energy of 65,600 foot tons, which simply
means that the energy will be so great that it could raise 65,600 tons a
foot from the ground. The fourteen-hundred-pound projectiles shall be
propelled through the air at the rate of half a mile a second. It will
be plainly seen that the metal of the guns must be of enormous
resistance to withstand such a force. The designers have taken this into
full consideration and will see to it that the powder chamber in which
the explosion takes place as well as the breech lock on which the shock
is exerted is of steel so wrought and tempered as to withstand the
terrific strain. At the moment of detonation the shock will be about
equal to that of a heavy engine and a train of Pullman coaches running
at seventy miles an hour, smashing into a stone wall. On leaving the
muzzle of the gun the shell will have an energy equivalent to that of a
train of cars weighing 580 tons and running at sixty miles an hour. Such
energy will be sufficient to send the projectile through twenty-two and
a half inches of the hardest of steel armour at the muzzle, while at a
range of 3,000 yards, the projectile moving at the rate of 2,235 feet
per second will pierce eighteen and a half inches of steel armor at
normal impact. The velocity of the projectile leaving the gun will be
2,600 feet per second, a speed which if maintained would carry it around
the world in less than fifteen hours.
Each of the mammoth guns will be a trifle over fifty-three feet in
length and the estimated cost of each will be $85,000. Judging from
the performance of the twelve-inch guns it is figured that these greater
weapons should be able to deliver three shots a minute. If all ten
guns of either of the projected _Dreadnoughts_ should be brought
into action at one time and maintain the three shot rapidity for one
hour, the cost of the ammunition expended in that hour would reach the
enormous sum of $2,520,000.
Very few, however, of the big guns are called upon for the three shots
a minute rate, for the metal would not stand the heating strain.
The big guns are expensive and even when only moderately used their
"life" is short, therefore, care is taken not to put them to too great
a strain. With the smaller guns it is different. Some of six-inch
bore fire as high as eight aimed shots a minute, but this is only under
ideal conditions.
Great care is being taken now to prolong the "life" of the big guns
by using non-corrosive material for the charges. The United States has
adopted a pure gun-cotton smokeless powder in which the temperature
of combustion is not only lower than that of nitro-glycerine, but
even lower than that of ordinary gunpowder. With the use of this there
has been a very material decrease in the corrosion of the big guns.
The former smokeless powder, containing a large percentage of
nitro-glycerine such as "cordite," produced such an effect that the
guns were used up and practically worthless, after firing fifty to
sixty rounds.
Now it is possible for a gun to be as good after two or even three
hundred rounds as at the beginning, but certainly not if a three minute
rate is maintained. At such a rate the "life" of the best gun made
would be short indeed.