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.

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.

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 25½ pounds.

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.

It was a new Browning model; or, rather, there were two distinct models. One of them, known as the heavy model, weighed only 34½ pounds, this with its water-jacket filled; for it was a water-cooled gun. Without its charge of water the machine weighed but 22½ 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.

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.