The Project Gutenberg eBook, Inventions of the Great War, by A. Russell (Alexander Russell) Bond

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Oil-tempering the lining of a Big Gun (See [page 76])

INVENTIONS OF THE
GREAT WAR

INVENTIONS OF THE
GREAT WAR

BY
A. RUSSELL BOND

Managing Editor of "Scientific American,"
Author of "On the Battle-Front
of Engineering," etc.

WITH MANY
ILLUSTRATIONS

NEW YORK
THE CENTURY CO.
1919

Copyright, 1918, 1919, by
The Century Co.

Published, June, 1919

[PREFACE]

The great World War was more than two-thirds over when America entered the struggle, and yet in a sense this country was in the war from its very beginning. Three great inventions controlled the character of the fighting and made it different from any other the world has ever seen. These three inventions were American. The submarine was our invention; it carried the war into the sea. The airplane was an American invention; it carried the war into the sky. We invented the machine-gun; it drove the war into the ground.

It is not my purpose to boast of American genius but, rather, to show that we entered the war with heavy responsibilities. The inventions we had given to the world had been developed marvelously in other lands. Furthermore they were in the hands of a determined and unscrupulous foe, and we found before us the task of overcoming the very machines that we had created. Yankee ingenuity was faced with a real test.

The only way of overcoming the airplane was to build more and better machines than the enemy possessed. This we tried to do, but first we had to be taught by our allies the latest refinements of this machine, and the war was over before we had more than started our aërial program. The machine-gun and its accessory, barbed wire (also an American invention), were overcome by the tank; and we may find what little comfort we can in the fact that its invention was inspired by the sight of an American farm tractor. But the tank was a British creation and was undoubtedly the most important invention of the war. On the sea we were faced with a most baffling problem. The U-boat could not be coped with by the building of swarms of submarines. The essential here was a means of locating the enemy and destroying him even while he lurked under the surface. Two American inventions, the hydrophone and the depth bomb, made the lot of the U-boat decidedly unenviable and they hastened if they did not actually end German frightfulness on the sea.

But these were by no means the only inventions of the war. Great Britain showed wonderful ingenuity and resourcefulness in many directions; France did marvels with the airplane and showed great cleverness in her development of the tank and there was a host of minor inventions to her credit; while Italy showed marked skill in the creation of large airplanes and small seacraft.

The Central Powers, on the other hand, were less originative but showed marked resourcefulness in developing the inventions of others. Forts were made valueless by the large portable Austrian guns. The long range gun that shelled Paris was a sensational achievement, but it cannot be called a great invention because it was of little military value. The great German Zeppelins were far from a success because they depended for their buoyancy on a highly inflammable gas. It is interesting to note that while the Germans were acknowledging the failure of their dirigibles the British were launching an airship program, and here in America we had found an economical way of producing a non-inflammable balloon gas which promises a great future for aërial navigation.

The most important German contribution to the war—it cannot be classed as an invention—was poison gas, and it was not long ere they regretted this infraction of the rules of civilized warfare adopted at the Hague Conference; for the Allies soon gave them a big dose of their own medicine and before the war was over, fairly deluged them with lethal gases of every variety.

Many inventions of our own and of our allies were not fully developed when the war ended, and there were some which, although primarily intended for purposes of war, will be most serviceable in time of peace. For this war was not one of mere destruction. It set men to thinking as they had never thought before. It intensified their inventive faculties, and as a result, the world is richer in many ways. Lessons of thrift and economy have been taught us. Manufacturers have learned the value of standardization. The business man has gained an appreciation of scientific research.

The whole story is too big to be contained within the covers of a single book, but I have selected the more important and interesting inventions and have endeavored to describe them in simple language for the benefit of the reader who is not technically trained.

A. Russell Bond

New York, May, 1919

[CONTENTS]

[LIST OF ILLUSTRATIONS]

[INVENTIONS OF THE GREAT WAR]

[CHAPTER I]
The War in and Under the Ground

For years the Germans had been preparing for war. The whole world knew this, but it had no idea how elaborate were their preparations, and how these were carried out to the very minutest detail. When the call to arms was sounded, it was a matter of only a few hours before a vast army had been assembled—fully armed, completely equipped, ready to swarm over the frontiers into Belgium and thence into France. It took much longer for the French to raise their armies of defense, and still longer for the British to furnish France with any adequate help. Despite the heroic resistance of Belgium, the Entente Allies were unprepared to stem the tide of German soldiers who poured into the northern part of France.

So easy did the march to Paris seem, that the Germans grew careless in their advance and then suddenly they met with a reverse that sent them back in full retreat. However, the military authorities of Germany had studied not only how to attack but also how to retreat and how to stand on the defensive. In this, as in every other phase of the conflict, they were far in advance of the rest of the world, and after their defeat in the First Battle of the Marne, they retired to a strong position and hastily prepared to stand on the defensive. When the Allies tried to drive them farther back, they found that the German army had simply sunk into the ground. The war of manœuver had given way to trench warfare, which lasted through long, tedious months nearly to the end of the great conflict.

The Germans found it necessary to make the stand because the Russians were putting up such a strong fight on Germany's eastern frontier. Men had to be withdrawn from the western front to stem the Russian tide, which meant that the western armies of the kaiser had to cease their offensive activities for the time being. The delay was fatal to the Germans, for they had opposed to them not only brave men but intelligent men who were quick to learn. And when the Germans were ready to resume operations in the West, they found that the Allies also had sunk into the ground and had learned all their tricks of trench warfare, adding a number of new ones of their own.

The whole character of the war was changed. The opposing forces were dead-locked and neither could break through the other's lines. The idea of digging into the ground did not originate with this war, but never before had it been carried out on so extensive a scale. The inventive faculties of both sides were vainly exercised to find some way of breaking the dead-lock. Hundreds of new inventions were developed. The history of war from the days of the ancient Romans up to the present time was searched for some means of breaking down the opposing lines. However, the dead-lock was not broken until a special machine had been invented, a traveling fort. But the story of that machine is told in another chapter.

At the outset the Allies dug very shallow ditches, such as had been used in previous wars. When it was found that these burrows would have to be occupied for weeks and months, the French and British imitated the Germans and dug their trenches so deep that men could walk through them freely, without danger of exposing their heads above ground; and as the ditches grew deeper, they had to be provided with a firing-step on which the riflemen could stand to fire over the top of the trenches. The trenches were zig-zagged so that they could not be flanked, otherwise they would have made dangerous traps for the defenders; for had the enemy gained one end of the trench, he could have fired down the full length of it, killing or wounding every man it contained. But zig-zagging made it necessary to capture each turn separately. There were lines upon lines of these trenches. Ordinarily there were but three lines, several hundred feet apart, with communicating trenches connecting them, and then several kilometers[1] farther back were reserve trenches, also connected by communicating trenches with the front lines.

[1] A kilometer is, roughly, six tenths of a mile; or six miles would equal ten kilometers.

Men did not dare to show themselves out in the open near the battle-front for a mile or more behind the front-line trenches, for the enemy's sharp-shooters were always on the watch for a target. The men had to stay in the trenches day and night for two or more weeks at a time, and sleeping-accommodations of a very rough sort were provided for them in dugouts which opened into the trenches. The dugouts of the Allies were comparatively crude affairs, but the Germans spent a great deal of time upon their burrows.

UNDERGROUND VILLAGES

When the French first swept the Germans back out of their trenches along the Aisne, they were astonished to find how elaborate were these underground dwellings. They found that the ground was literally honeycombed with rooms and passageways. Often the dugouts were two stories in depth and extended as much as sixty feet below the level of the ground. In fact, all along this part of the front, the Germans had a continuous underground village in which thousands of men were maintained. The officers' quarters were particularly well fitted up, and every attention was given to the comfort of their occupants. There were steel door-mats at the entrances of the quarters. The walls were boarded and even papered. The bedrooms were fitted with spring beds, chiffoniers, and wash-stands, and all the rooms were lighted with electric lamps. There were spacious quarters for the men, with regular underground mess halls and elaborate kitchens. There were power-plants to furnish steam for the operation of pumps and for the lighting-plants and for other purposes.

(C) Underwood & Underwood

Lines of Zig-Zag Trenches as viewed from an Airplane

There was a chalk formation here in which were many large natural caves. One enormous cave was said to have held thirty thousand soldiers, and in this section the Germans kept large reserve forces. By digging far into the ground, the German troops secured protection from shell-fire; in fact, the horrible noise of battle was heard only as a murmur, down in these depths. With characteristic thoroughness, the Germans built their trench system for a long stay; while the Allies, on the other hand, looked upon their trenches as merely temporary quarters, which would hold the enemy at bay until they could build up armies large enough to drive the invaders out of the country. The construction of the trenches along some parts of the battle-line was particularly difficult, because of the problem of drainage. This was especially true in Flanders, where the trenches in many cases were below water-level, and elaborate pumping-systems had to be installed to keep them dry. Some of them were concrete-lined to make them waterproof. In the early stages of the war, before the trenches were drained, the men had to stand in water for a good part of the time, and the only way they could get about at all in the miry trenches was by having "duck-boards" in them. Duck-boards are sections of wooden sidewalk such as we find in small villages in this country, consisting of a couple of rails on which crosspieces of wood are nailed. These duck-boards fairly floated in the mud.

Courtesy of "Scientific American"

French Sappers using Stethoscopes to detect the Mining Operations of the Enemy

Some of the trenches were provided with barbed wire barriers or gates calculated to halt a raiding-party if it succeeded in getting into the trench. These gates were swung up out of the way, but when lowered they were kept closed with a rather complicated system of bolts which the enemy would be unable to unfasten without some delay; and while he was struggling to get through the gate, he would be a target for the bullets of the defenders.

HIDING RAILROADS IN DITCHES

Because of the elaborate system of trenches, and the distance from the front line to that part of the country where it was safe to operate in the open, it was necessary to build railways which would travel through tunnels and communicating trenches to the front lines. These were narrow-gage railroads and a special standard form of track section was designed, which was entirely of metal, something like the track sections of toy railroads. The tracks were very quickly laid and taken up at need. The locomotives had to be silent and smokeless and so a special form of gasolene locomotive was invented to haul the little cars along these miniature railroads to the front lines. Usually the trench railroads did not come to the very front of the battle-line, but their principal use was to carry shell to the guns which were located in concealed positions. Railroad or tramway trenches could not be sharply zig-zagged but had to have easy curves, which were apt to be recognized by enemy airplanes, and so they were often concealed under a covering of wire strewn with leaves.

PERISCOPES AND "SNIPERSCOPES"

But while the armies were buried underground, it was necessary for them to keep their eyes upon each other so that each might be ready for any sudden onslaught of the other. Snipers were always ready to fire at any head that showed itself above the parapet of the trench and so the soldiers had to steal an idea from the submarines and build them periscopes with which they could look over the top of their trenches without exposing themselves. A trench periscope was a very simple affair, consisting of a tube with two mirrors, one at the top and one at the bottom, set at such an angle that a person looking into the side of the tube at the bottom could see out of the opposite side of the tube at the top.

Observation posts were established wherever there was a slight rise in the ground. Sometimes these posts were placed far in advance of the trenches and sometimes even behind the trenches where it was possible to obtain a good view of the opposing lines. Sometimes a tunnel would be dug forward, leading to an outlet close to the enemy's lines, and here an observer would take his position at night to spy with his ears upon the activities of the enemy. Observers who watched the enemy by day would often not dare to use periscopes, which might be seen by the enemy and draw a concentrated fire of rifles and even shell. So that every manner of concealment was employed to make the observation posts invisible and to have them blend with their surroundings. Observers even wore veils so that the white of their skin would not betray them.

Redrawn from Military Map Reading by permission of E. C. McKay

Fig 1. A "sniperscope" with which a sharp­shooter could take aim without showing his head above the parapet

Snipers were equally ingenious in concealing themselves. They frequently used rifles which were connected with a dummy butt and had a periscope sighting-attachment. This attachment was called a "sniperscope." The rifle-barrel could be pushed through a loophole in the parapet and the sniper standing safely below the parapet could hold the dummy butt to his shoulder and aim his rifle with perfect accuracy by means of the periscope. It was next to impossible to locate a sniper hidden in this way. One method of doing it was to examine rubbish, tin cans, or any object that had been penetrated by a bullet and note the direction taken by the bullet. This would give a line leading toward the source of the shot, and when a number of such lines were traced, they would cross at a spot where the sniper or his gun was stationed, and a few shell would put the man out of business. Dummy heads of papier mâché were sometimes stuck above the parapet to draw the fire of enemy snipers and the bullet-holes which quickly appeared in them were studied to discover the location of the snipers.

Redrawn from Military Map Reading by permission of E. C. McKay

Fig. 2. A fixed rifle stand arranged to be fired after dark

Sometimes fixed rifles were used. These were set on stands so that they could be very accurately trained upon some important enemy post. Then they could be fired in the dark, without aiming, to disturb night operations of the enemy. Often a brace of rifles, as many as six, would be coupled up to be fired simultaneously, and by operating a single lever each gun would throw out the empty cartridge shell and bring a fresh one into position.

STEEL BRIER PATCHES

The most important defense of a trench system consisted in the barbed wire entanglements placed before it. Barbed wire, by the way, is an American invention, but it was originally intended for the very peaceful purpose for keeping cattle within bounds. Long ago it was used in war, but never to the extent to which it was employed in this world struggle. The entanglements were usually set up at night and were merely fences consisting of stout posts driven into the ground and strung with barbed wire running in all directions, so as to make an impenetrable tangle. Where it was possible to prepare the entanglements without disturbance and the position was an important one, the mass of barbed wire often extended for a hundred yards or more in depth. Just beyond the entanglements trip-wires were sometimes used. A trip-wire was a slack wire which was laid on the ground. Before being laid, the wire was tightly coiled so that it would not lie flat, but would catch the feet of raiders and trip them up. Each side had "gates" in the line through which this wire could quickly be removed to let its own raiding-parties through. Sometimes raiders used tunnels, with outlets beyond the barbed wire, but they had to cut their way through the metal brier patches of their opponents.

Early in the war, various schemes were devised for destroying the entanglements. There were bombs in the form of a rod about twelve feet long, which could be pushed under the wire and upon exploding would tear it apart. Another scheme was to fire a projectile formed like a grapnel. The projectile was attached to the end of a cable and was fired from a small gun in the same way that life-lines are thrown out to wrecks near shore. Then the cable would be wound up on a winch and the grapnel hooks would tear the wire from its fastenings. Such schemes, however, did not prove very practicable, and it was eventually found that a much better way of destroying barbed wire was to bombard it with high-explosive shell, which would literally blow the wire apart. But it required a great deal of shelling to destroy these entanglements, and it was really not until the tank was invented that such obstructions could be flattened out so that they formed no bar to the passage of the soldiers.

The Germans not only used fixed entanglements, but they had large standard sections of barbed wire arranged in the form of big cylindrical frames which would be carried easily by a couple of men and could be placed in position at a moment's notice to close a gap in the line or even to build up new lines of wire obstruction.

MINES AND COUNTER-MINES

In the earlier stages of the war it proved so impossible to capture a trench when it was well defended by machine-guns that efforts were made to blow up the enemy by means of mines. Tunnels were dug reaching out under the enemy's lines and large quantities of explosives were stored in them. At the moment when it was intended to make an assault, there would be a heavy cannonading to disconcert the enemy, and then the mine would be touched off. In the demoralizing confusion that resulted, the storming-party would sweep over the enemy. Such mines were tried on both sides, and the only protection against them was to out-guess the other side and build counter-mines.

If it were suspected, from the importance of a certain position and the nature of the ground, that the enemy would probably try to undermine it, the defenders would dig tunnels of their own toward the enemy at a safe distance beyond their own lines and establish listeners there to see if they could hear the mining-operations of their opponents. Very delicate microphones were used, which the listeners would place on the ground or against the walls of their tunnel. Then they would listen for the faintest sound of digging, just as a doctor listens through a stethoscope to the beating of a patient's heart or the rush of air through his lungs. When these listening-instruments picked up the noise of digging, the general direction of the digging could be followed out by placing the instrument at different positions and noting where the noise was loudest. Then a counter-mine would be extended in that direction, far enough down to pass under the enemy's tunnel, and at the right moment, a charge of TNT (trinitrotoluol) would be exploded, which would destroy the enemy's sappers and put an end to their ambitious plans.

A very interesting case of mining was furnished by the British when they blew up the important post of Messines Ridge. This was strongly held by the Germans and the only way of dislodging the enemy was to blow off the top of the ridge. Before work was started, geologists were called upon to determine whether or not the ground were suitable for mining-operations. They picked out a spot where the digging was good from the British side, but where, if counter-mines were attempted from the German side, quicksands would be encountered and tunneling of any sort would be difficult. The British sappers could, therefore, proceed with comparative safety. The Germans suspected that something of the sort was being undertaken, but they found it very difficult to dig counter-mines. However, one day their suspicions were confirmed, when the whole top of the hill was blown off, with a big loss of German lives. In the assault that followed the British captured the position and it was annexed to the British lines.

[CHAPTER II]
Hand-Grenades and Trench Mortars

In primitive times battles were fought hand-to-hand. The first implements of war were clubs and spears and battle-axes, all intended for fighting at close quarters. The bow and arrow enabled men to fight at a distance, but shields and armor were so effective a defense that it was only by hand-to-hand fighting that a brave enemy could be defeated. Even the invention of gunpowder did not separate the combatants permanently, for although it was possible to hurl missiles at a great distance, cannon were so slow in their action that the enemy could rush them between shots. Shoulder firearms also were comparatively slow in the early days, and liable to miss fire, and it was not until the automatic rifle of recent years was fully developed that soldiers learned to keep their distance.

When the great European war started, military authorities had come to look upon war at close quarters as something relegated to bygone days. Even the bayonet was beginning to be thought of little use. Rifles could be charged and fired so rapidly and machine-guns could play such a rapid tattoo of bullets, that it seemed impossible for men to come near enough for hand-to-hand fighting, except at a fearful cost of life. In developing the rifle, every effort was made to increase its range so that it could be used with accuracy at a distance of a thousand yards and more. But when the Germans, after their retreat in the First Battle of the Marne, dug themselves in behind the Aisne, and the French and British too found it necessary to seek shelter from machine-gun and rifle fire by burrowing into the ground, it became apparent that while rifles and machine-guns could drive the fighting into the ground, they were of little value in continuing the fight after the opposing sides had buried themselves. The trenches were carried close to one another, in some instances being so close that the soldiers could actually hear the conversation of their opponents across the intervening gap. Under such conditions long-distance firearms were of very little practical value. What was needed was a short-distance gun which would get down into the enemy trenches. To be sure, the trenches could be shelled, but the shelling had to be conducted from a considerable distance, where the artillery would be immune to attack, and it was impossible to give a trench the particular and individual attention which it would receive at the hands of men attacking it at close quarters.

Before we go any farther we must learn the meaning of the word "trajectory." No bullet or shell travels in a straight line. As soon as it leaves the muzzle of the gun, it begins to fall, and its course through the air is a vertical curve that brings it eventually down to the ground. This curve is called the "trajectory." No gun is pointed directly at a target, but above it, so as to allow for the pull of gravity. The faster the bullet travels, the flatter is this curve or trajectory, because there is less time for it to fall before it reaches its target. Modern rifles fire their missiles at so high a speed that the bullets have a very flat trajectory. But in trench warfare a flat trajectory was not desired. What was the use of a missile that traveled in a nearly straight line, when the object to be hit was hiding in the ground? Trench fighting called for a missile that had a very high trajectory, so that it would drop right into the enemy trench.

HAND-ARTILLERY

Trench warfare is really a close-quarters fight of fort against fort, and the soldiers who manned the forts had to revert to the ancient methods of fighting an enemy intrenched behind fortifications. Centuries ago, not long after the first use of gunpowder in war, small explosive missiles were invented which could be thrown by hand. These were originally known as "flying mortars." The missile was about the size of an orange or a pomegranate, and it was filled with powder and slugs. A small fuse, which was ignited just before the device was thrown, was timed to explode the missile when it reached the enemy. Because of its size and shape, and because the slugs it contained corresponded, in a manner, to the pulp-covered seeds with which a pomegranate is filled, the missile was called a "grenade."

Grenades had fallen out of use in modern warfare, although they had been revived to a small extent in the Russo-Japanese war, and had been used with some success by the Bulgarians and the Turks in the Balkan wars. And yet they had not been taken very seriously by the military powers of Europe, except Germany. Germany was always on the lookout for any device that might prove useful in war, and when the Germans dug themselves in after the First Battle of the Marne, they had large quantities of hand-grenades for their men to toss over into the trenches of the Allies. These missiles proved very destructive indeed. They took the place of artillery, and were virtually hand-thrown shrapnel.

The French and British were entirely unprepared for this kind of fighting, and they had hastily to improvise offensive and defensive weapons for trench warfare. Their hand-grenades were at first merely tin cans filled with bits of iron and a high explosive in which a fuse-cord was inserted. The cord was lighted by means of a cigarette and then the can with its spluttering fuse was thrown into the enemy lines. As time went on and the art of grenade fighting was learned, the first crude missiles were greatly improved upon and grenades were made in many forms for special service.

There was a difference between grenades hurled from sheltered positions and those used in open fighting. When the throwers were sheltered behind their own breastworks, it mattered not how powerful was the explosion of the grenade. We must remember that in "hand-artillery" the shell is far more powerful in proportion to the distance it is thrown than the shell fired from a gun, and many grenades were so heavily charged with explosives that they would scatter death and destruction farther than they could be thrown by hand. The grenadier who cast one of these grenades had to duck under cover or hide under the walls of his trench, else the fragments scattered by the exploding missile might fly back and injure him. Some grenades would spread destruction to a distance of over three hundred feet from the point of explosion. For close work, grenades of smaller radius were used. These were employed to fight off a raiding-party after it had invaded a trench, and the destructive range of these grenades was usually about twenty-five feet.

Hand-grenades came to be used in all the different ways that artillery was used. There were grenades which were filled with gas, not only of the suffocating and tear-producing types, but also of the deadly poisonous variety. There were incendiary grenades which would set fire to enemy stores, and smoke grenades which would produce a dense black screen behind which operations could be concealed from the enemy. Grenades were used in the same way that shrapnel was used to produce a barrage or curtain of fire, through which the enemy could not pass without facing almost certain death. Curtains of fire were used not only for defensive purposes when the enemy was attacking, but also to cut off a part of the enemy so that it could not receive assistance and would be obliged to surrender. In attacks upon the enemy lines, grenades were used to throw a barrage in advance of the attacking soldiers so as to sweep the ground ahead clear of the enemy.

The French paid particular attention to the training of grenadiers. A man had to be a good, cool-headed pitcher before he could be classed as a grenadier. He must be able to throw his grenade with perfect accuracy up to a distance of seventy yards, and to maintain an effective barrage. The grenadier carried his grenades in large pockets attached to his belt, and he was attended by a carrier who brought up grenades to him in baskets, so that he was served with a continuous supply.

LONG-DISTANCE GRENADE-THROWING

Fig. 3. A rifle grenade fitted to the muzzle of a rifle

All this relates to short-distance fighting, but grenades were also used for ranges beyond the reach of the pitcher's arm. Even back in the sixteenth century, the range of the human arm was not great enough to satisfy the combatants and grenadiers used a throwing-implement, something like a shovel, with which the grenade was slung to a greater distance, in much the same way as a lacrosse ball is thrown. Later, grenades were fitted with light, flexible wooden handles and were thrown, handle and all, at the enemy. By this means they could be slung to a considerable distance. Such grenades were used in the recent war, particularly by the Germans. The handle was provided with streamers so as to keep the grenade head-on to the enemy, and it was usually exploded by percussion on striking its target. These long-handled grenades, however, were clumsy and bulky, and the grenadier required a good deal of elbow-room when throwing them.

A much better plan was to hurl them with the aid of a gun. A rifle made an excellent short-distance mortar. With it grenades could be thrown from three to four hundred yards. The grenade was fastened on a rod which was inserted in the barrel of the rifle and then it was fired out of the gun by the explosion of a blank cartridge. The butt of the rifle was rested on the ground and the rifle was tilted so as to throw the grenade up into the air in the way that a mortar projects its shell.

STRIKING A LIGHT

The lighting of the grenade fuses with a cigarette did very well for the early tin-can grenades, but the cigarettes were not always handy, particularly in the heat of battle, and something better had to be devised. One scheme was to use a safety-match composition on the end of a fuse. This was covered with waxed paper to protect it from the weather. The grenadier wore an armlet covered with a friction composition such as is used on a safety-match box. Before the grenade was thrown, the waxed paper was stripped off and the fuse was lighted by being scratched on the armlet. In another type the fuse was lighted by the twisting of a cap which scratched a match composition on a friction surface. A safety-pin kept the cap from turning until the grenadier was ready to throw the grenade.

The Mills hand-grenade, which proved to be the most popular type used by the British Army, was provided with a lever which was normally strapped down and held by means of a safety-pin. [Fig 4] shows a sectional view of this grenade. Just before the missile was thrown, it was seized in the hand so that the lever was held down. Then the safety-pin was removed and when the grenade was thrown, the lever would spring up under pull of the spring A. This would cause the pin B to strike the percussion cap C, which would light the fuse D. The burning fuse would eventually carry the fire to the detonator E, which would touch off the main explosive, shattering the shell of the grenade and scattering its fragments in all directions. The shell of the grenade was indented so that it would break easily into a great many small pieces.

Fig. 4. Details of the Mills hand grenade

There were some advantages in using grenades lighted by fuse instead of percussion, and also there were many disadvantages. If too long a time-fuse were used, the enemy might catch the grenade, as you would a baseball and hurl it back before it exploded. This was a hazardous game, but it was often done.

Fig. 5. A German parachute grenade

Fig. 6. British rifle grenade with a safety-device which is unlocked by the rush of air against a set of inclined vanes, D, when the missile is in flight

Among the different types of grenades which the Germans used was one provided with a parachute as shown in [Fig. 5]. The object of the parachute was to keep the head of the grenade toward the enemy, so that when it exploded it would expend its energies forward and would not cast fragments back toward the man who had thrown it. This was a very sensitive grenade, arranged to be fired by percussion, but it was so easily exploded that the firing-mechanism was not released until after the grenade had been thrown. In the handle of this grenade there was a bit of cord about twenty feet long. One end of this was attached to a safety-needle, A, while the other end, formed into a loop, was held by the grenadier when he threw the grenade. Not until the missile had reached a height of twelve or thirteen feet would the pull of the string withdraw the needle A. This would permit a safety-hook, B, to drop out of a ring, C, on the end of a striker pellet, D. When the grenade struck, the pellet D would move forward and a pin, E, would strike a cap on the detonator F, exploding the missile. This form of safety-device was used on a number of German grenades.

The British had another scheme for locking the mechanism until after the grenade had traveled some distance through the air. Details of this grenade, which was of the type adopted to be fired from a rifle, are shown in [Fig. 6.] The striker A is retained by a couple of bolts, B, which in turn are held in place by a sleeve, C. On the sleeve is a set of wind-vanes, D. As the grenade travels through the air, the wind-vanes cause the sleeve C to revolve, screwing it down clear of the bolts B, which then drop out, permitting the pin A to strike the detonator E upon impact of the grenade with its target.

Fig. 7. Front, side, and sectional views of a disk-shaped German grenade

Fig. 8. A curious German hand grenade shaped like a hair brush

The Germans had one peculiar type which was in the shape of a disk. In the disk were six tubes, four of which carried percussion caps so that the grenade was sure to explode no matter on which tube it fell. The disk was thrown with the edge up, and it would roll through the air. Another type of grenade was known as the hair-brush grenade because it had a rectangular body of tin about six inches long and two and three quarter inches wide and deep, which was nailed to a wooden handle.

MINIATURE ARTILLERY

Hand-artillery was very effective as far as it went, but it had its limitations. Grenades could not be made heavier than two pounds in weight if they were to be thrown by hand; in fact, most of them were much lighter than that. If they were fired from a rifle, the range was increased but the missile could not be made very much heavier. TNT is a very powerful explosive, but there is not room for much of it in a grenade the size of a large lemon. Trench fighting was a duel between forts, and while the hand-artillery provided a means of attacking the defenders of a fort, it made no impression on the walls of the fort. It corresponded to shrapnel fire on a miniature scale, and something corresponding to high-explosive fire on a small scale was necessary if the opposing fortifications were to be destroyed. To meet this problem, men cast their thoughts back to the primitive artillery of the Romans, who used to hurl great rocks at the enemy with catapults. And the trench fighters actually rigged up catapults with which they hurled heavy bombs at the enemy lines. All sorts of ingenious catapults were built, some modeled after the old Roman machines. In some of these stout timbers were used as springs, in others there were powerful coil springs. It was not necessary to cast the bombs far. For distant work the regular artillery could be used. What was needed was a short-distance gun for heavy missiles and that is what the catapult was.

Press Illustrating Service

A 3-inch Stokes mortar and two of its shells

Press Illustrating Service

Dropping a shell into a 6-inch trench mortar

But the work of the catapult was not really satisfactory. The machine was clumsy; it occupied too much space, and it could not be aimed very accurately. It soon gave way to a more modern apparatus, fashioned after the old smooth-bore mortars. This was a miniature mortar, short and wide-mouthed. A rifled barrel was not required, because, since the missile was not to be hurled far, it was not necessary to set it spinning by means of rifling so as to hold it head-on to the wind.

GIANT PEA-SHOOTERS

Better aim was secured when a longer-barreled trench mortar came to be used. In the trench, weight was an important item. There was no room in which to handle heavy guns, and the mortar had to be portable so that it could be carried forward by the infantry in a charge. As the walls of a light barrel might be burst by the shock of exploding powder, compressed air was used instead. The shell was virtually blown out of the gun in the same way that a boy blows missiles out of a pea-shooter. That the shell might be kept from tumbling, it was fitted with vanes at the rear. These acted like the feathers of an arrow to hold the missile head-on to its course.

Courtesy of "Scientific American"

The Maxim Machine-gun Operated by the Energy of the Recoil

Courtesy of "Scientific American"

Colt Machine-gun partly broken away to show the Operating Mechanism

Gas from port A pushes down piston B, rocking lever C, which compresses coil-spring D. The cartridge fed into the gun by wheel E, is extracted by F, raised by G to breech H, and rammed in by bolt I. J, piston firing-hammer.

The French in particular used this type of mortar and the air-pump was used to compress the air that propelled the shell or aërial torpedo, or else the propelling charge was taken from a compressed-air tank. Carbon-dioxide, the gas used in soda-water, is commonly stored in tanks under high pressure and this gas was sometimes used in place of compressed air. When the gas in the tank was exhausted the latter could be recharged with air by using a hand-pump. Two or three hundred strokes of the pump would give a pressure of one hundred and twenty to one hundred and fifty pounds per inch, and would supply enough air to discharge a number of shell. The air was let into the barrel of the mortar in a single puff sufficient to launch the shell; then the tank was cut off at once, so that the air it contained would not escape and go to waste.

THE STOKES MORTAR

However, the most useful trench mortar developed during the war was invented by Wilfred Stokes, a British inventor. In this a comparatively slow-acting powder was used to propel the missile, and so a thin-walled barrel could be used. The light Stokes mortar can easily be carried over the shoulder by one man. It has two legs and the barrel itself serves as a third leg, and the mortar stands like a tripod. The two legs are adjustable, so that the barrel can be inclined to any desired angle. It took but a moment to set up the mortar for action in a trench or shell-hole.

Fig. 9. Sectional view of a 3-inch Stokes mortar showing a shell at the instant of striking the anvil

Fig. 10. A 6-inch trench mortar shell fitted with tail-vanes

Curiously enough, there is no breech-block, trigger or fire-hole in this mortar. It is fired merely by the dropping of the missile into the mouth of the barrel. The shell carries its own propelling charge, as shown in [Fig. 9.] This is in the form of rings, A, which are fitted on a stem, B. At the end of the stem are a detonating cap and a cartridge, to ignite the propellant, A. At the bottom of the mortar barrel, there is a steel point, E, known as the "anvil." When the shell is dropped into the mortar, the cap strikes the anvil, exploding the cartridge and touching off the propelling charge, A. The gases formed by the burning charge hurl the shell out of the barrel to a distance of several hundred yards.

The first Stokes mortar was made to fire a 3-inch shell, but the mortar grew in size until it could hurl shell of 6-inch and even 8½-inch size. Of course, the larger mortars had to have a very substantial base. They were not so readily portable as the smaller ones and they could not be carried by one man; but compared with ordinary artillery of the same bore they were immeasurably lighter and could be brought to advanced positions and set up in a very short time. The larger shell have tail-vanes, as shown in [Fig. 10], to keep them from tumbling when in flight.

[CHAPTER III]
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.

Courtesy of "Scientific American"

The Lewis Gun which produces its own cooling current

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.

(C) Committee on Public Information

Browning Machine Rifle, weight only 15 pounds

(C) Committee on Public Information

Browning Machine-Gun, weighing 34½ 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 25½ pounds.

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.

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 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.

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.

Courtesy of "Scientific American"

One of our 16-inch Coast Defence Guns on a disappearing mount

Height of gun as compared with the New York City Hall

[CHAPTER IV]
Guns and Super-Guns

When the news came that big shells were dropping into Paris from a gun which must be at least seventy miles away, the world at first refused to believe; then it imagined that some brand-new form of gun or shell or powder had been invented by the Germans. However, while the public marveled, ordnance experts were interested but not astonished. They knew that it was perfectly feasible to build a gun that would hurl a shell fifty, or seventy-five, or even a hundred miles, without involving anything new in the science of gunnery.

SHOOTING AROUND THE EDGE OF THE EARTH

But if such ranges were known to be possible, why was no such long-distance gun built before? Simply because none but the Germans would ever think of shooting around the edge of the earth at a target so far away that it would have to be as big as a whole city to be hit at all. In a distance of seventy miles, the curve of the earth is considerable. Paris is far below the horizon of a man standing at St. Gobain, where the big German gun was located. And if a hole were bored from St. Gobain straight to Paris, so that you could see the city from the gun, it would pass, midway of its course, three thousand, seven hundred and fifty feet below the surface of the earth. With the target so far off, it was impossible to aim at any particular fort, ammunition depot, or other point of military importance. There is always some uncertainty as to just where a shell will fall, due to slight differences in quality and quantity of the powder used, in the density of the air, the direction of the wind, etc. This variation is bad enough when a shell is to be fired ten miles, but when the missile has to travel seventy miles, it is out of the question to try to hit a target that is not miles in extent.

Twenty years before the war our Ordnance Department had designed a fifty-mile gun, but it was not built, because we could see no possible use for it. Our big guns were built for fighting naval battles or for the defense of our coasts from naval attacks, and there is certainly no use in firing at a ship that is so far below the horizon that we cannot even see the tips of its masts; and so our big guns, though they were capable of firing a shell twenty-seven miles, if aimed high enough, were usually mounted in carriages that would not let them shoot more than twelve or fifteen miles.

The distance to which a shell can be hurled depends to a large extent upon the angle of the gun. If the gun is tilted up to an angle of 15 degrees, the shell will go only about half as far as if it were tilted up to 43½ degrees, which is the angle that will carry a shell to its greatest distance. If the long-range German gun was fired at that angle, the shell must have risen to a height of about twenty-four miles.

BEYOND THE EARTH'S ATMOSPHERE

Most of the air that surrounds our globe lies within four miles of the surface. Few airplanes can rise to a greater height than this, because the air is so thin that it gives no support to the wings of the machine. The greatest height to which a man has ever ascended is seven miles. A balloon once carried two men to such a height. One of them lost consciousness, and the other, who was nearly paralyzed, succeeded in pulling the safety-valve rope, with his teeth. That brought the balloon down, and their instruments showed that they had gone up thirty-six thousand feet. What the ocean of air contains above that elevation, we do not know, but judging by the way the atmosphere thins out as we rise from the surface of the earth, we reckon that nine tenths of the air lies within ten miles of the surface of the earth. At twenty-four miles, or the top of the curve described by the shell of the German long-range guns, there must be an almost complete vacuum.

If only we could accompany a shell on its course, we should find a strange condition of affairs. The higher we rose, the darker would the heavens become, until the sun would shine like a fiery ball in a black sky. All around, the stars would twinkle, and below would be the glare of light reflected from the earth's surface and its atmosphere, while the cold would be far more intense than anything suffered on earth. Up at that height, there would be nothing to indicate that the shell was moving—no rush of air against the ears. We should seem detached from earth and out in the endless reaches of space.

It seems absurd to think that a shell weighing close to a quarter of a ton could be retarded appreciably by mere air. But when we realize that the shell left the gun at the rate of over half a mile a second—traveling about thirty times faster than an express-train—we know that the air-pressure mounts up to a respectable figure. The pressure is the same whether a shell is moving through the air or the air is blowing against the shell. When the wind blows at the rate of 100 to 120 miles per hour, it is strong enough to lift houses off their foundations, to wrench trees out of the ground, to pick up cattle and carry them sailing through the air. Imagine what it would do if its velocity were increased to 1,800 miles per hour. That is what the shell of a big gun has to contend with. As most of the air lies near the earth, the shell of long-range guns meet with less and less resistance the higher they rise, until they get up into such thin air that there is virtually no obstruction. The main trouble is to pierce the blanket of heavy air that lies near the earth.

WAYS OF INCREASING THE RANGE

The big 16-inch guns that protect our coasts fire a shell that weighs 2,400 pounds. Nine hundred pounds of smokeless powder is used to propel the shell, which leaves the muzzle of the gun with a speed of 2,600 feet per second. Now, the larger the diameter of the shell, the greater will be its speed at the muzzle of the gun, because there will be a greater surface for the powder gases to press against. On the other hand, the larger the shell, the more will it be retarded by the air, because there will be a larger surface for the air to press against. It has been proposed by some ordnance experts that a shell might be provided with a disk at each end, which would make it fit a gun of larger caliber. A 10-inch shell, for instance, could then be fired from a 16-inch gun. Being lighter than the 16-inch shell, it would leave the muzzle of the gun at a higher speed. The disks could be so arranged that as soon as the shell left the gun they would be thrown off, and then the 10-inch shell, although starting with a higher velocity than a 16-inch shell, would offer less resistance to the air. In that way it could be made to cover a much greater range. By the way, the shell of the German long-range gun was of but 8.2-inch caliber.

Another way of increasing the range is to lengthen the gun. Right here we must become acquainted with the word "caliber." Caliber means the diameter of the shell. A 16-inch gun, for instance, fires a shell of 16-inch caliber; but when we read that the gun is a 40-or 50-caliber gun, it means that the length of the gun is forty or fifty times the diameter of the shell. Our biggest coast-defense guns are 50-caliber 16-inch guns, which means that they are fifty times 16 inches long, or 66-2/3 feet in length. When a gun is as long as that, care has to be taken to prevent it from sagging at the muzzle of its own weight. These guns actually do sag a little, and when the shell is fired through the long barrel it straightens up the gun, making the muzzle "whip" upward, just as a drooping garden hose does when the water shoots through it.

Courtesy of "Scientific American"

The 121-Mile Gun designed by American Ordnance Officers

Now the longer the caliber length of a gun, the farther it will send a shell, because the powder gases will have a longer time to push the shell. But we cannot lengthen our big guns much more without using some special support for the muzzle end of the gun, to keep it from "whipping" too much. It is likely that the long-range German gun was provided with a substantial support at the muzzle to keep it from sagging.

(C) Underwood & Underwood

American 16-Inch Rifle on a Railway Mount

Every once in a while a man comes forth with a "new idea" for increasing the range. One plan is to increase the powder-pressure. We have powders that will produce far more pressure than an ordinary gun can stand. But we have to use powders that will burn comparatively slowly. We do not want too sudden a shock to start with, but we wish the powder to give off an enormous quantity of gas which will keep on pushing and speeding up the shell until the latter emerges from the muzzle. The fifty-mile gun that was proposed twenty years ago was designed to stand a much higher pressure than is commonly used, and it would have fired a 10-inch shell weighing 600 pounds with a velocity of 4,000 feet per second at the muzzle.

The Allies built no "super-guns," because they knew that they could drop a far greater quantity of explosives with much greater accuracy from airplanes, and at a much lower cost. The German gun at St. Gobain was spectacular and it did some damage, but it had no military value and it did not intimidate the French as the Germans had hoped it would.

A GUN WITH A RANGE OF A HUNDRED AND TWENTY MILES

But although we built no such gun, after the Germans began shelling Paris our Ordnance Department designed a gun that would fire a shell to a distance of over 120 miles! There was no intention of constructing the gun, but the design was worked out just as if it were actually to be built. It was to fire a shell of 10-inch caliber, weighing 400 pounds. Now, an Elswick standard 10-inch gun is 42 feet long and its shell weighs 500 pounds. Two hundred pounds of powder are used to propel the shell, which leaves the muzzle with a velocity of 3,000 feet per second. If the gun is elevated to the proper angle, it will send the shell 25 miles, and it will take the shell a minute and thirty-seven seconds to cover that distance. But the long-range gun our ordnance experts designed would have to be charged with 1,440 pounds of powder and the shell would leave the muzzle of the gun with a velocity of 8,500 feet per second. It would be in the air four minutes and nine seconds and would travel 121.3 miles. Were the gun fired from the Aberdeen Proving Grounds, near Baltimore, Maryland, its shell would travel across three states and fall into New York Bay at Perth Amboy. At the top of its trajectory it would rise 46 miles above the earth.

But the most astonishing part of the design was the length of the gun, which worked out to 225 feet. An enormous powder-chamber would have to be used, so that the powder gases would keep speeding up the shell until it reached the required velocity at the muzzle. The weight of the barrel alone was estimated at 325 tons.

It would have to be built up in four sections screwed together and because of its great length and weight it would have to be supported on a steel truss. The gun would be mounted like a roller lift-bridge with a heavy counter-weight at its lower end so that it could be elevated or depressed at will and a powerful hydraulic jack would be required to raise it.

The recoil of a big gun is always a most important matter. Unless a gun can recoil, it will be smashed by the shock of the powder explosion. Usually, heavy springs are used to take up the shock, or cylinders filled with oil in which pistons slide. The pistons have small holes in them through which the oil is forced as the piston moves and this retards the gun in its recoil. But this "super-gun" was designed to be mounted on a carriage running on a set of tracks laid in a long concrete pit. On the recoil the gun would run back along the tracks, and its motion would be retarded by friction blocks between the carriage and the tracks and also by a steel cable attached to the forward end of the carriage and running over a pulley on the front wall of the pit, to a friction drum.

The engraving facing page [68] gives some idea of the enormous size of the gun. Note the man at the breech of the gun. The hydraulic jack is collapsible, so that the gun may be brought to the horizontal position for loading, as shown by the dotted lines. The cost of building this gun is estimated at two and a half million dollars and its 400-pound shell would land only about sixty pounds of high explosives on the target. A bombing-plane costing but thirty thousand dollars could land twenty-five times as big a charge of high explosives with far greater accuracy. Aside from this, the gun lining would soon wear out because of the tremendous erosion of the powder gases.

THE THREE-SECOND LIFE OF A GUN

Powder gases are very hot indeed—hot enough to melt steel. The greater the pressure in the gun, the hotter they are. It is only because they pass through the gun so quickly, that they do not melt it. As a matter of fact, they do wear it out rapidly because of their heat and velocity. They say that the life of a big gun is only three seconds. Of course, a shell passes through the gun in a very minute part of a second, but if we add up these tiny periods until we have a total of three seconds, during which the gun may have fired two hundred rounds, we shall find that the lining of the barrel is so badly eroded that the gun is unfit for accurate shooting, and it must go back to the shops for a new inner tube.

ELASTIC GUNS

We had better go back with it and learn something about the manufacture of a big gun. Guns used to be cast as a solid chunk of metal. Now they are built up in layers. To understand why this is necessary, we must realize that steel is not a dead mass, but is highly elastic—far more elastic than rubber, although, of course, it does not stretch nor compress so far. When a charge of powder is exploded in the barrel of a gun, it expands in all directions. Of course, the projectile yields to the pressure of the powder gases and is sent kiting out of the muzzle of the gun. But for an instant before the shell starts to move, an enormous force is exerted against the walls of the bore of the gun, and, because steel is elastic, the barrel is expanded by this pressure, and the bore is actually made larger for a moment, only to spring back in the next instant. You can picture this action if you imagine a gun made of rubber; as soon as the powder was fired, the rubber gun would bulge out around the powder-chamber, only to collapse to its normal size when the pressure was relieved by the discharge of the bullet.

Now, every elastic body has what is called its elastic limit. If you take a coil spring, you can pull it out or you can compress it, and it will always return to its original shape, unless you pull it out or compress it beyond a certain point; that point is its elastic limit. The same is true of a piece of steel: if you stretch it beyond a certain point, it will not return to its original shape. When the charge of powder in a cannon exceeds a certain amount, it stretches the steel beyond its elastic limit, so that the bore becomes permanently larger. Making the walls of the gun heavier would not prevent this, because steel is so elastic that the inside of the walls expands beyond its elastic limit before the outside is affected at all.

Years ago an American inventor named Treadwell worked out a scheme for allowing the bore to expand more without exceeding its elastic limit. He built up his gun in layers, and shrunk the outer layers upon the inner layers, just as a blacksmith shrinks a tire on a wheel, so that the inner tube of the gun would be squeezed, or compressed. When the powder was fired, this inner layer could expand farther without danger, because it was compressed to start with. The built-up gun was also independently invented by a British inventor. All modern big guns are built up.

HOW BIG GUNS ARE MADE

The inside tube, known as the lining, is cast roughly to shape, then it is bored out, after which it is forged by the blows of a powerful steam-hammer. Of course, while under the hammer, the tube is mounted on a mandrel, or bar, that just fits the bore. The metal is then softened in an annealing furnace, after which it is turned down to the proper diameter and re-bored to the exact caliber. The diameter of the lining is made three ten-thousandths of an inch larger than the inside of the hoop or sleeve that fits over it. This sleeve, which is formed in the same way, is heated up to 800 degrees, or until its inside diameter is eight tenths of an inch larger than the outside diameter of the lining. The lining is stood up on end and the sleeve is fitted over it. Then it is cooled by means of water, so that it grips the lining and compresses it. In this way, layer after layer is added until the gun is built up to the proper size.

Photograph from Underwood & Underwood

A Long-distance Sub-calibered French Gun on a Railway Mount

Instead of having a lining that is compressed by means of sleeves or jackets, many big guns are wound with wire which is pulled so tight as to compress the lining. The gun-tube is placed in a lathe, and is turned so as to wind up the wire upon it. A heavy brake on the wire keeps it drawn very tight. This wire, also, is put on in layers, so that each layer can expand considerably without exceeding its elastic limit. Our big 16-inch coast-defense guns are wound with wire that is one tenth of an inch square. The length of wire on one gun is sufficient to reach all the way from New York to Boston with fifty or sixty miles of wire left over.

Courtesy of "Scientific American"

Inside of a Shrapnel Shell and Details
of the Fuse Cap

Search-light Shell and
one of its Candles

GUNS THAT PLAY HIDE-AND-SEEK

A very ingenious invention is the disappearing-mount which is used on our coast fortifications. By means of this a gun is hidden beyond its breastworks so that it is absolutely invisible to the enemy. In this sheltered position it is loaded and aimed. It is not necessary to sight the gun on the target as you would sight a rifle. The aiming is done mathematically. Off at some convenient observation post, an observer gets the range of the target and telephones this range to the plotting-room, where a rapid calculation is made as to how much the gun should be elevated and swung to the right or the left. This calculation is then sent on to the gunners, who adjust the gun accordingly. When all is ready, the gun is raised by hydraulic pressure, and just as it rises above the parapet it is automatically fired. The recoil throws the gun back to its crouching position behind the breastworks. All that the enemy sees, if anything, is the flash of the discharge.

Now that airplanes have been invented, the disappearing-mount has lost much of its usefulness. Big guns have to be hidden from above. They are usually located behind a hill, five or six miles back of the trenches, where the enemy cannot see them from the ground, and they are carefully hidden under trees or a canopy of foliage or are disguised with paint.

The huge guns recently built to defend our coasts are intended to fire a shell that will pierce the heavy armor of a modern dreadnought. The shell is arranged to explode after it has penetrated the armor, and the penetrating-power is a very important matter. About thirty years ago the British built three battle-ships, each fitted with two guns of 16¼-inch caliber and 30-caliber length. In order to test the penetrating-power of this gun a target was built, consisting first of twenty inches of steel armor and eight inches of wrought-iron; this was backed by twenty feet of oak, five feet of granite, eleven feet of concrete, and six feet of brick. When the shell struck this target it passed through the steel, the iron, the oak, the granite, and the concrete, and did not stop until it had penetrated three feet of the brick. We have not subjected our 16-inch gun to such a test, but we know that it would go through two such targets and still have plenty of energy left. Incidentally, it costs us $1,680 each time the big gun is fired.

THE FAMOUS FORTY-TWO-CENTIMETER GUN

One of the early surprises of the war was the huge gun used by the Germans to destroy the powerful Belgian forts. Properly speaking, this was not a gun, but a howitzer; and right here we must learn the difference between mortars, howitzers, and guns. What we usually mean by "gun" is a piece of long caliber which is designed to hurl its shell with a flat trajectory. But long ago it was found advantageous to throw a projectile not at but upon a fortification, and for this purpose short pieces of large bore were built. These would fire at a high angle, so that the projectile would fall almost vertically on the target.

As we have said, the bore of a gun is rifled; that is, it is provided with spiral grooves that will set the shell spinning, so as to keep its nose pointing in the direction of its flight. Mortars, on the other hand, were originally intended for short-range firing, and their bore was not rifled. In recent years, however, mortars have been made longer and with rifled bores, so as to increase their range, and such long mortars are called "howitzers." The German 42-centimeter howitzer fired a shell that was 2,108 pounds in weight and was about 1½ yards long. The diameter of the shell was 42 centimeters, which is about 16½ inches. It carried an enormous amount of high explosive, which was designed to go off after the shell had penetrated its target. The marvel of this howitzer was not that it could fire so big a shell but that so large a piece of artillery could be transported over the highroads and be set for use in battle. But although the 42-centimeter gun was widely advertised, the real work of smashing the Belgian forts was done by the Austrian "Skoda" howitzers, which fired a shell of 30.5-centimeter (12-inch) caliber, and not by the 42-centimeter gun. The Skoda howitzer could be taken apart and transported by three motor-cars of 100 horse-power each. The cars traveled at a rate of about twelve miles per hour. It is claimed the gun could be put together in twenty-four minutes, and would fire at the rate of one shot per minute.

FIELD-GUNS

So far, we have talked only of the big guns, but in a modern battle the field-gun plays a very important part. This fires a shell that weighs between fourteen and eighteen pounds and is about three inches in diameter. The shell and the powder that fires it are contained in a cartridge that is just like the cartridge of a shoulder rifle. These field-pieces are built to be fired rapidly. The French 75-millimeter gun, which is considered one of the best, will fire at the rate of twenty shots per minute, and its effective range is considerably over three miles. The French supplied us with all 75-millimeter guns we needed in the war, while we concentrated our efforts on the manufacture of ammunition.

GUNS THAT FIRE GUNS

During the War of the Revolution, cannon were fired at short range, and it was the custom to load them with grape-shot, or small iron balls, when firing against a charging enemy, because the grape would scatter like the shot of a shot-gun and tear a bigger gap in the ranks of the enemy than would a single solid cannon-ball. In modern warfare, guns are fired from a greater distance, so that there will be little danger of their capture. It is impossible for them to fire grape, because the ranges are far too great; besides, it would be impossible to aim a charge of grape-shot over any considerable distance, because the shot would start spreading as soon as they left the muzzle of the gun and would scatter too far and wide to be of much service. But this difficulty has been overcome by the making of a shell which is really a gun in itself. Within this shell is the grape-shot, which consists of two hundred and fifty half-inch balls of lead. The shell is fired over the lines of the enemy, and just at the right moment it explodes and scatters a hail of leaden balls over a fairly wide area.

It is not a simple matter to time a shrapnel shell so that it will explode at just the right moment. Spring-driven clockwork has been tried, which would explode a cap after the lapse of a certain amount of time; but this way of timing shells has not proved satisfactory. Nowadays a train of gunpowder is used. When the shell is fired, the shock makes a cap (see drawing facing page [77]) strike a pin, E, which ignites the train of powder, A. The head of the shell is made of two parts, in each of which there is a powder-fuse. There is a vent, or short cut, leading from one fuse to the other, and, by the turning of one part of the fuse-head with respect to the other, this short cut is made to carry the train of fire from the upper to the lower fuse sooner or later, according to the adjustment. The fire burns along one powder-train A, and then jumps through the short cut B to the other, or movable train, as it is called, until it finally reaches, through hole C, the main charge F, in the shell. The movable part of the fuse-head is graduated so that the fuse may be set to explode the shell at any desired distance. In the fuse-head there is also a detonating-pin K, which will strike the primer L and explode the shell when the latter strikes the ground, if the time-fuse has failed to act.

When attacking airplanes, it is important to be able to follow the flight of the shell, so some shrapnel shell are provided with a smoke-producing mixture, which is set on fire when the shell is discharged, so as to produce a trail of smoke.

(C) Committee on Public Information

Putting on the Gas Masks to Meet a Gas Cloud Attack

In meeting the attack of any enemy at night, search-light shell are sometimes used. On exploding they discharge a number of "candles," each provided with a tiny parachute that lets the candle drop slowly to the ground. Their brilliant light lasts fifteen or twenty minutes. Obviously, ordinary search-lights could not be used on the battle-field, because the lamp would at once be a target for enemy batteries, but with search-light shell the gun that fires them can remain hidden and one's own lines be shrouded in darkness while the enemy lines are brilliantly illuminated.

(C) Kadel & Herbert

Even the Horses had to be Masked

Photograph by Kadel & Herbert

Portable Flame-throwing Apparatus

[CHAPTER V]
The Battle of the Chemists

Some years ago the nations of the world gathered at the city of The Hague, in Holland, to see what could be done to put an end to war. They did not accomplish much in that direction, but they did draw up certain rules of warfare which they agreed to abide by. There were some practices which were considered too horrible for any civilized nation to indulge in. Among these was the use of poisonous gases, and Germany was one of the nations that took a solemn pledge not to use gas in war.

Eighteen years later the German Army had dug itself into a line of trenches reaching from the English Channel to Switzerland, and facing them in another line of trenches were the armies of France and England, determined to hold back the invaders. Neither side could make an advance without frightful loss of life. But a German scientist came forth with a scheme for breaking the dead-lock. This was Professor Nernst, the inventor of a well-known electric lamp and a man who had always violently hated the British. His plan was to drown out the British with a flood of poisonous gas. To be sure, there was the pledge taken at The Hague Conference, but why should that stand in Germany's way? What cared the Germans for promises now? Already they had broken a pledge in their violation of Belgium. Already they had rained explosives from the sky on unfortified British cities (thus violating another pledge of The Hague Conference); already they had determined to war on defenseless merchantmen. To them promises meant nothing, if such promises interfered with the success of German arms. They led the world in the field of chemistry; why, they reasoned, shouldn't they make use of this advantage?

POURING GAS LIKE WATER

It was really a new mode of warfare that the Germans were about to launch and it called for much study. In the first place, they had to decide what sort of gas to use. It must be a gas that could be obtained in large quantities. It must be a very poisonous gas, that would act quickly on the enemy; it must be easily compressed and liquefied so that it could be carried in containers that were not too bulky; it must vaporize when the pressure was released; and it must be heavier than air, so that it would not be diluted by the atmosphere but would hug the ground. You can pour gas just as you pour water, if it is heavier than air. A heavy gas will stay in the bottom of an unstoppered bottle and can be poured from one bottle into another like water. If the gas is colored, you can see it flowing just as if it were a liquid. On the other hand, a gas which is much lighter than air can also be kept in unstoppered bottles if the bottles are turned upside down, and the gas can be poured from one bottle into another; but it flows up instead of down.

Chlorine gas was selected because it seemed to meet all requirements. For the gas attack a point was chosen where the ground sloped gently toward the opposing lines, so that the gas would actually flow down hill into them. Preparations were carried out with the utmost secrecy. Just under the parapet of the trenches deep pits were dug, about a yard apart on a front of fifteen miles, or over twenty-five thousand pits. In these pits were placed the chlorine tanks, each weighing about ninety pounds. Each pit was then closed with a plank and this was covered with a quilt filled with peat moss soaked in potash, so that in case of any leakage the chlorine would be taken up by the potash and rendered harmless. Over the quilts sandbags were piled to a considerable height, to protect the tanks from shell-fragments.

Liquid chlorine will boil even in a temperature of 28 degrees below zero Fahrenheit, but in tanks it cannot boil because there is no room for it to turn into a gas. Upon release of the pressure at ordinary temperatures, the liquid boils violently and big clouds of gas are produced. If the gas were tapped off from the top of the cylinder, it would freeze on pouring out, because any liquid that turns into a gas has to draw heat from its surroundings. The greater the expansion, the more heat the gas absorbs, and in the case of the chlorine tanks, had the nozzles been set in the top of the tank they would very quickly have been crusted with frost and choked, stopping the flow.

But the Germans had anticipated this difficulty, and instead of drawing off the gas from the top of the tank, they drew off the liquid from the bottom in small leaden tubes which passed up through the liquid in the tank and were kept as warm as the surrounding liquid. In fact, it was not gas from the top of the tank, but liquid from the bottom, that was streamed out and this did not turn into gas until it had left the nozzle.

WAITING FOR THE WIND

Everything was ready for the attack on the British in April, 1915. A point had been chosen where the British lines made a juncture with the French. The Germans reckoned that a joint of this sort in the opponent's lines would be a spot of weakness. Also, they had very craftily picked out this particular spot because the French portion of the line was manned by Turcos, or Algerians, who would be likely to think there was something supernatural about a death-dealing cloud. On the left of the Africans was a division of Canadians, but the main brunt of the gas was designed to fall upon the Turcos. Several times the attack was about to be made, but was abandoned because the wind was not just right. The Germans wished to pick out a time when the breeze was blowing steadily—not so fast as to scatter the gas, but yet so fast that it would overtake men who attempted to run away from it. It was not until April 22 that conditions were ideal, and then the new mode of warfare was launched.

Just as had been expected, the Turcos were awe-struck when they saw, coming out of the German trenches, volumes of greenish-yellow gas, which rolled toward them, pouring down into shell-holes and flowing over into the trenches as if it were a liquid. They were seized with superstitious fear, particularly when the gas overcame numbers of them, stifling them and leaving them gasping for breath. Immediately there was a panic and they raced back, striving to out-speed the pursuing cloud.

For a stretch of fifteen miles the Allied trenches were emptied, and the Germans, who followed in the wake of the gas, met with no opposition except in the sector held by the Canadians. Here, on the fringe of the gas cloud, so determined a fight was put up that the Germans faltered, and the brave Canadians held them until reinforcements arrived and the gap in the line was closed.

The Germans themselves were new at the game or they could have made a complete success of this surprise attack. Had they made the attack on a broader front, nothing could have kept them from breaking through to Calais. The valiant Canadians who struggled and fought without protection in the stifling clouds of chlorine, were almost wiped out. But many of them who were on the fringe of the cloud escaped by wetting handkerchiefs, socks, or other pieces of cloth, and wrapping them around their mouths and noses.