GUNS THAT FIRE THEMSELVES
Many years ago a boy tried his hand at firing a United States Army
service rifle. It was a heavy rifle of the Civil War period, and the
lad did not know just how to hold it. He let the butt of the gun rest
uncertainly against him, instead of pressing it firmly to his shoulder,
and, in consequence, when the gun went off he received a powerful kick.
That kick made a deep impression on the lad, not only on his flesh but
on his mind as well. It gave him a good conception of the power of a
rifle cartridge.
Years afterward, when he had moved to England, the memory of that kick
was still with him. It was a useless prank of the gun, he thought, a
waste of good energy. Why could not the energy be put to use? And so he
set himself the task of harnessing the kick of the gun.
A very busy program he worked out for that kick to perform. He planned
to have the gun use up its exuberant energy in loading and firing
itself. So he arranged the cartridges on a belt and fed the belt into
the gun. When the gun was fired, the recoil would unlock the breech,
take out the empty case of the cartridge just fired, select a fresh
cartridge from the belt, and cock the main spring; then the mechanism
would return, throwing the empty cartridge-case out of the gun,
pushing the new cartridge into the barrel, closing the breech, and
finally pulling the trigger. All this was to be done by the energy of
a single kick, in about one tenth of a second, and the gun would keep
on repeating the operation as long as the supply of cartridges was fed
to it. The new gun proved so successful that the inventor was knighted,
and became Sir Hiram Maxim.
A DOCTOR'S TEN-BARRELED GUN
But Maxim's was by no means the first machine-gun. During the Civil War
a Chicago physician brought out a very ingenious ten-barreled gun, the
barrels of which were fired one after the other by the turning of a
hand-crank. Although Dr. Gatling was a graduate of a medical school,
he was far more fond of tinkering with machinery than of doling out
pills. He invented a number of clever mechanisms, but the one that made
him really famous was that machine-gun. At first our government did
not take the invention seriously. The gun was tried out in the war,
but whenever it went into battle it was fired not by soldiers but by
a representative of Dr. Gatling's company, who went into the army to
demonstrate the worth of the invention. Not until long after was the
Gatling gun officially adopted by our army. Then it was taken up by
many of the European armies as well.
Although many other machine-guns were invented, the Gatling was
easily the best and most serviceable, until the Maxim invention made
its appearance, and even then it held its own for many years; but
eventually it had to succumb. The Maxim did not have to be cranked:
it fired itself, which was a distinct advantage; and then, instead of
being a bundle of guns all bound up into a single machine, Maxim's was
a single-barreled gun and hence was much lighter and could be handled
much more easily.
A GUN AS A GAS-ENGINE
Another big advance was made by a third American, Mr. John M. Browning,
who is responsible for the Colt gun. It was not a kick that set
Browning to thinking. He looked upon a gun as an engine of the same
order as an automobile engine, and really the resemblance is very
close. The barrel of the gun is the cylinder of the engine; the bullet
is the piston; and for fuel gunpowder is used in place of gasolene. As
in the automobile engine, the charge is fired by a spark; but in the
case of the gun the spark is produced by a blow of the trigger upon a
bit of fulminate of mercury in the end of the cartridge.
[Illustration: Courtesy of "Scientific American"
The Lewis Gun which produces its own cooling current]
[Illustration: Courtesy of "Scientific American"
The Benèt-Mercié Gun operated by gas]
Explosion is the same thing as burning. The only way that the explosion
of gunpowder differs from the burning of a stick of wood is that the
latter is very slow, while the former goes like a flash. In both cases
the fuel turns into great volumes of gas. In the case of the gun the
gas is formed almost instantly and in such quantity that it has to
drive the bullet out of the barrel to make room for itself. In the
cartridge that our army uses, only about a tenth of an ounce of
smokeless powder is used, but this builds up so heavy a pressure of gas
that the bullet is sent speeding out of the gun at a rate of half a
mile a second. It travels so fast that it will plow through four feet
of solid wood before coming to a stop.
[Illustration: (C) Committee on Public Information
Browning Machine Rifle, weight only 15 pounds]
[Illustration: (C) Committee on Public Information
Browning Machine-Gun, weighing 34-1/2 pounds]
Now it occurred to Browning that it wouldn't really be stealing to
take a little of that gas-power and use it to work the mechanism of
his machine-gun. It was ever so little he wanted, and the bullet would
never miss it. The danger was not that he might take too much. His
problem was to take any power at all without getting more than his
mechanism could stand. What he did was to bore a hole through the side
of the gun-barrel. When the gun was fired, nothing happened until the
bullet passed this hole; then some of the gas that was pushing the
bullet before it would blow out through the hole. But this would be a
very small amount indeed, for the instant that the bullet passed out of
the barrel the gases would rush out after it, the pressure in the gun
would drop, and the gas would stop blowing through the hole. With the
bullet traveling at the rate of about half a mile in a second, imagine
how short a space of time elapses after it passes the hole before
it emerges from the muzzle, and what a small amount of gas can pass
through the hole in that brief interval!
The gas that Browning got in this way he led into a second cylinder,
fitted with a piston. This piston was given a shove, and that gave a
lever a kick which set going the mechanism that extracted the empty
cartridge-case, inserted a fresh cartridge, and fired it.
GETTING RID OF HEAT
The resemblance of a machine-gun to a gasolene-engine can be
demonstrated still further. One of the most important parts of an
automobile engine is the cooling-system. The gasolene burning in the
cylinders would soon make them red-hot, were not some means provided
to carry off the heat. The same is true of a machine-gun. In fact,
the heat is one of the biggest problems that has to be dealt with. In
a gasolene-engine the heat is carried off in one of three ways: (1)
by passing water around the cylinders; (2) by building flanges around
the cylinders to carry the heat off into the air; and (3) by using a
fan to blow cool air against the cylinders. All of these schemes are
used in the machine-gun. In Dr. Gatling's gun the cooling-problem was
very simple. As there were ten barrels, one barrel could be cooling
while the rest were taking their turn in the firing. In other words,
each barrel received only a tenth of the heat that the whole gun was
producing; and yet Gatling found it advisable to surround the barrels
for about half their length with a water-jacket.
In the Maxim gun a water-jacket is used that extends the full length
of the barrel, and into this water-jacket seven and a half pints of
water are poured. Yet in a minute and a half of steady firing at a
moderate rate, or before six hundred rounds are discharged, the water
will be boiling. After that, with every thousand rounds of continuous
fire a pint and a half of water will be evaporated. Now the water
and the water-jacket add a great deal of weight to the gun, and this
Browning decided to do away with in his machine-gun. Instead of water
he used air to carry off the heat. The more surface the air touches,
the more heat will it carry away; and so the Colt gun was at first made
with a very thick-walled barrel. But later the Colt was formed with
flanges, like the flanges on a motor-cycle engine, so as to increase
the surface of the barrel. Of course, air-cooling is not so effective
as water-cooling, but it is claimed for this gun, and for other
machine-guns of the same class, that the barrel is sufficiently cooled
for ordinary service. Although a machine-gun may be capable of firing
many hundred shots per minute, it is seldom that such a rate is kept
up very long in battle. Usually, only a few rounds are fired at a time
and then there is a pause, and there is plenty of time for the barrel
to cool. Once in a while, however, the gun has to be fired continuously
for several minutes, and then the barrel grows exceedingly hot.
EFFECT OF OVERHEATING
But what if the gun-barrel does become hot? The real trouble is not
that the cartridge will explode prematurely, but that the barrel will
expand as it grows hot, so that the bullet will fit too loosely in the
bore. Inside the barrel the bore is rifled; that is, there are spiral
grooves in it which give a twist to the bullet as it passes through,
setting it spinning like a top. The spin of the bullet keeps its nose
pointing forward. If it were not for the rifling, the bullet would
tumble over and over, every which way, and it could not go very far
through the air, to say nothing of penetrating steel armor. To gain
the spinning-motion the bullet must fit into the barrel snugly enough
to squeeze into the spiral grooves. Now there is another American
machine-gun known as the Hotchkiss, which was used to a considerable
extent by the French Army. It is a gas-operated gun, something like the
Colt, and it is air-cooled. It was found in tests of the Hotchkiss gun
that in from three to four minutes of firing the barrel was expanded so
much that the shots began to be a little uncertain. In seven minutes of
continuous firing the barrel had grown so large that the rifling failed
to grip the bullet at all. The gun was no better than an old-fashioned
smooth-bore. The bullets would not travel more than three hundred
yards. It is because of this danger of overheating that the Colt and
the Hotchkiss guns are always furnished with a spare barrel. As soon as
a barrel gets hot it is uncoupled and the spare one is inserted in its
place. Our men are trained to change the barrel of a colt in the dark
in a quarter of a minute.
But a gun that has to have a spare barrel and that has to have its
barrel changed in the midst of a hot engagement is not an ideal weapon,
by any means. And this brings us to still another invention--that,
too, by an American. Colonel I. N. Lewis, of the United States Army,
conceived of a machine-gun that would be cooled not by still air but by
air in motion. This would do away with all the bother of water-jackets.
It would keep the gun light so that it could be operated by one man,
and yet it would not have to be supplied with a spare barrel.
Like the Colt and the Hotchkiss, the Lewis gun takes its power from the
gas that comes through a small port in the barrel, near the muzzle. In
the plate facing page 44 the port may be seen leading into a cylinder
that lies under the barrel. It takes about one ten-thousandth part of a
second for a bullet to pass out of the barrel after clearing the port,
but in that brief interval there is a puff of gas in the cylinder which
drives back a piston. This piston has teeth on it which engage a small
gear connected with a main-spring. When the piston moves back, it winds
the spring, and it is this spring that operates the mechanism of the
gun. The cartridges, instead of being taken from a belt or a clip, are
taken from a magazine that is round and flat. There are forty-seven
cartridges in the magazine and they are arranged like the spokes of
a wheel, but in two layers. As soon as forty-seven rounds have been
fired, the shooting must stop while a new magazine is inserted. But to
insert it takes only a couple of seconds.
USING THE BULLET TO FAN THE GUN
The most ingenious part of the Lewis gun is the cooling-system. On
the barrel of the gun are sixteen flanges or fins. These, instead of
running around the gun, run lengthwise of the barrel. They are very
light fins, being made of aluminum, and are surrounded by a casing of
the same metal. The casing is open at each end so that the air can flow
through it, but it extends beyond the muzzle of the barrel, and there
it is narrowed down. At the end of the barrel there is a mouthpiece so
shaped that the bullet, as it flies through, sucks a lot of air in its
wake, making a strong current flow through the sixteen channels formed
between the fins inside the casing. This air flows at the rate of about
seventy miles per hour, which is enough to carry off all the heat that
is generated by the firing of the cartridges. The gun may be regulated
to fire between 350 and 750 rounds per minute, and its total weight is
only 25-1/2 pounds.
[Illustration: Lewis Machine-guns in action at the front]
America can justly claim the honor of inventing and developing the
machine-gun, although Hiram Maxim did give up his American citizenship
and become a British subject. By the way, he is not to be confused with
his younger brother, Hudson Maxim, the inventor of high explosives,
who has always been an American to the core. Of course we must not get
the impression that only Americans have invented machine-guns. There
have been inventors of such weapons in various countries of Europe,
and even in Japan. Our own army for a while used a gun known as the
Benèt-Mercié, which is something like the Hotchkiss. This was invented
by L. V. Benèt, an American, and H. A. Mercié, a Frenchman, both living
in St. Denis, France.
THE BROWNING MACHINE-GUN
When we entered the war, it was expected that we would immediately
equip our forces with the Lewis gun, because the British and the
Belgians had found it an excellent weapon and also because it was
invented by an American officer, who very patriotically offered it
to our government without charging patent royalties. But the army
officials would not accept it, although many Lewis guns were bought by
the navy. This raised a storm of protest throughout the country until
finally it was learned that there was another gun for which the army
was waiting, which it was said would be the very best yet. The public
was skeptical and finally a test was arranged in Washington at which
the worth of the new gun was demonstrated.
[Illustration: Courtesy of "Scientific American"
An elaborate German Machine-Gun Fort]
It was a new Browning model; or, rather, there were two distinct
models. One of them, known as the heavy model, weighed only 34-1/2
pounds, this with its water-jacket filled; for it was a water-cooled
gun. Without its charge of water the machine weighed but 22-1/2 pounds
and could be rated as a very light machine-gun. However, it was classed
as a heavy gun and was operated from a tripod. The new machine used
recoil to operate its mechanism. The construction was simple, there
were few parts, and the gun could very quickly be taken apart in case
of breakage or disarrangement of the mechanism. But the greatest care
was exercised to prevent jamming of cartridges, which was one of the
principal defects in the other types of machine-guns. In the test this
new weapon fired twenty thousand shots at the rate of six hundred per
minute, with interruptions of only four and a half seconds, due partly
to defective cartridges.
There was no doubt that the new Browning was a remarkable weapon. But
if that could be said of the heavy gun, the light gun was a marvel. It
weighed only fifteen pounds and was light enough to be fired from the
shoulder or from the hip, while the operator was walking or running. In
fact, it was really a machine-rifle. The regular .30-caliber service
cartridges were used, and these were stored in a clip holding twenty
cartridges. The cartridges could be fired one at a time, or the entire
clip could be fired in two and a half seconds. It took but a second to
drop an empty clip out of the gun and replace it with a fresh one. The
rifle was gas-operated and air-cooled, but no special cooling-device
was supplied because it would seldom be necessary to fire a shoulder
rifle fast enough and long enough for the barrel to become overheated.
After the Browning machine-rifle was demonstrated it was realized that
the army had been perfectly justified in waiting for the new weapon.
Like the heavy Browning, the new rifle was a very simple mechanism,
with few parts which needed no special tools to take them apart or
reassemble them; a single small wrench served this purpose. Both the
heavy and the light gun were proof against mud, sand, and dust of
the battle-field. But best of all, a man did not have to have highly
specialized training before he could use the Browning rifle. It did
not require a crew to operate one of these guns. Each soldier could
have his own machine-gun and carry it in a charge as he would a rifle.
The advantage of the machine-rifle was that the operator could fire
as he ran, watching where the bullets struck the ground by noting the
dust they kicked up and in that way correcting his aim until he was on
the target. Very accurate shooting was thus made possible, and the
machine-rifle proved invaluable in the closing months of the war.
Browning is unquestionably the foremost inventor of firearms in the
world. He was born of Mormon parents, in Ogden, Utah, in 1854, and
his father had a gun shop. As a boy Browning became familiar with the
use of firearms and when he was but fourteen years of age he invented
an improved breech mechanism which was later used in the Winchester
repeater. Curiously enough, it was a Browning pistol that was used
by the assassin at Serajevo who killed the Archduke of Austria and
precipitated the great European war, and it was with the Browning
machine-gun and rifle that our boys swept the Germans back through the
Argonne Forest and helped to bring the war to a successful end.
THE MACHINE-GUN IN SERVICE
Although the machine-gun has been used ever since the Civil War, it was
not a vital factor in warfare until the recent great conflict. Army
officials were very slow to take it up, because they did not understand
it. They used to think of it as an inferior piece of light artillery,
instead of a superior rifle. The Gatling was so heavy that it had to
be mounted on wheels, and naturally it was thought of as a cannon. In
the Franco-Prussian War the French had a machine-gun by which they
set great store. It was called a _mitrailleuse_, or a gun for firing
grape-shot. It was something like the Gatling. The French counted on
this machine to surprise and overwhelm the Germans. But they made the
mistake of considering it a piece of artillery and fired it from long
range, so that it did not have a chance to show its worth. Only on one
or two occasions was it used at close range, and then it did frightful
execution. However, it was a very unsatisfactory machine, and kept
getting out of order. It earned the contempt of the Germans, and later
when the Maxim gun was offered to the German Army they would have none
of it. They did not want to bother with "a toy cannon."
It really was not until the war between Russia and Japan that military
men began to realize the value of the machine-gun. As the war went on,
both the Russians and the Japanese bought up all the machine-guns they
could secure. They learned what could be done with the aid of barbed
wire to retard the enemy while the machine-guns mowed them down as they
were trying to get through.
A man with a machine-gun is worth a hundred men with rifles; such is
the military estimate of the weapon. The gun fires so fast that after
hitting a man it will hit him again ten times while he is falling to
the ground. And so it does not pay to fire the gun continuously in one
direction, unless there is a dense mass of troops charging upon it.
Usually the machine-gun is swept from side to side so as to cover as
wide a range as possible. It is played upon the enemy as you would play
the hose upon the lawn, scattering a shower of lead among the advancing
hosts.
MACHINE-GUN FORTS
It used to be thought that the Belgian forts of armored steel and
concrete, almost completely buried in the ground, would hold out
against any artillery. But when the Germans brought up their great
howitzers and hurled undreamed-of quantities of high explosives on
these forts, they broke and crumbled to pieces. Then it was predicted
that the day of the fort was over. But the machine-gun developed a new
type of warfare. Instead of great forts, mounting huge guns, little
machine-gun forts were built, and, they were far more troublesome than
the big fellows.
To the Germans belongs the credit for the new type of fort, which
consisted of a small concrete structure, hidden from view as far
as possible, but commanding some important part of the front.
"Pill-boxes," the British call them, because the first ones they ran
across were round in shape and something like a pill-box in appearance.
These pill-boxes were just large enough to house a few men and a
couple of machine-guns. Concealment was of the utmost importance;
safety depended upon it. Airplanes were particularly feared, because a
machine-gun emplacement was recognized to be so important that a whole
battery of artillery would be turned upon a suspected pill-box.
Some of the German machine-gun forts were very elaborate, consisting
of spacious underground chambers where a large garrison of gunners
could live. These forts were known as _Mebus_, a word made from the
initials of "_Maschinengewehr Eisen-Bettungs Unterstand_," meaning a
machine-gun iron-bedded foundation.
It was the machine-gun that was responsible for the enormous
expenditure of ammunition in the war. Before a body of troops dared
to make a charge, the ground had to be thoroughly searched by the big
guns for any machine-gun nests. Unless these were found and destroyed
by shell-fire, the only way that remained to get the best of them was
to crush them down with tanks. It was really the machine-gun that drove
the armies into trenches and under the ground.
[Illustration: Comparative diagram of the path of a projectile from the
German Super-gun]
But a machine-gun did not have to be housed in a fort, particularly
a light gun of the Lewis type. To be sure, the Lewis gun is a little
heavy to be used as a rifle, but it could easily be managed with a rest
for the muzzle in the crotch of a tree, and a strong man could actually
fire the piece from the shoulder. The light machine-gun could go right
along with a charging body of troops and do very efficient service,
particularly in fighting in a town or village, but it had to be kept
moving or it would be a target for the artillery. In a certain village
fight a machine-gunner kept changing his position. He would fire for
a few minutes from one building and then shift over to some other. He
did this no less than six times, never staying more than five minutes
at a time in the same spot. But each one of the houses was shelled
within fifteen minutes of the time he opened fire from it, which shows
the importance that the Germans attached to machine-gun fire.
[Illustration: Courtesy of "Scientific American"
One of our 16-inch Coast Defence Guns on a disappearing mount]
[Illustration: Height of gun as compared with the New York City Hall]