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.
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.
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.
of the Fuse Cap
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.
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.
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.
The world was horrified when it read of this German gas attack, but there was no time to be lost. Immediately orders went out for gas-masks, and in all parts of England, and of France as well, women were busy sewing the masks. These were very simple affairs—merely a pad of cotton soaked in washing-soda and arranged to be tied over the mouth and nose. But when the next attack came, not long after the first, the men were prepared in some measure for it, and again it failed to bring the Germans the success they had counted upon.
One thing that the Germans had not counted upon was the fact that the prevailing winds in Flanders blow from west to east. During the entire summer and autumn of 1915, the winds refused to favor them, and no gas attacks were staged from June to December. This gave the British a long respite and enabled them not only to prepare better gas-masks, but also to make plans to give the Hun a dose of his own medicine.
WHEN THE WIND PLAYED A TRICK ON THE GERMANS
There were many disadvantages in the use of gas clouds, which developed as the Germans gathered experience. The gas started from their own lines in a very dense cloud, but the cloud grew thinner and thinner as it traveled toward the enemy, and lost a great deal of its strength. If the wind were higher than fifteen miles an hour, it would swirl the gas around and dissipate it before it did much harm to the opposing fighters. If the wind were light, there were other dangers. On one occasion in 1916 a cloud of gas was released upon an Irish regiment. The wind was rather fickle. It carried the gas toward the British trenches, but before reaching them the cloud hesitated, the wind veered around, and soon the gas began to pour back upon the German lines. The Germans were entirely unprepared for this boomerang attack. Many of the Huns had no gas-masks on, and those who had, found that the masks were not in proper working-order. As a result of this whim of the winds, eleven thousand Germans were killed.
While chlorine was the first gas used, it was evident that it was not the only one that could be employed. British chemists had suspected that the Germans would use phosgene, which was a much more deadly gas, and in the long interval between June and December, 1915, masks were constructed which would keep out not only the fumes of chlorine but also the more poisonous phosgene. In one of their sorties the British succeeded in capturing some valuable notes on gas attacks, belonging to a German general, which showed that the Germans were actually preparing to use phosgene. This deadly gas is more insidious in its action than chlorine. The man who inhales phosgene may not know that he is gassed. He may experience no ill effects, but hours afterward, particularly if he has exercised in the meantime, he may suddenly fall dead, owing to its paralyzing action on the heart.
FREEING THE BRITISH TRENCHES OF RATS
Phosgene was not used alone, but had to be mixed with chlorine, and the deadly combination of the two destroyed all life for miles behind the trenches. However, the British were ready for it. They had been drilled to put on their masks in a few seconds' time, on the first warning of a gas attack. When the clouds of chlorine and phosgene came over No Man's Land, they were prepared, and, except for casualties among men whose masks proved defective, the soldiers in the trenches came through with very few losses. All animal life, however, was destroyed. This was a blessing to the British Tommy, whose trenches had been overrun with rats. The British had tried every known method to get rid of these pests, and now, thanks to the Germans, their quarters were most effectively fumigated with phosgene and every rat was killed. If only the "cooties" could have been destroyed in the same way, the Germans might have been forgiven many of their offenses.
The disadvantages in the use of gas clouds became increasingly apparent. What was wanted was some method of placing the gas among the opponents in concentrated form, without wasting any of it on its way across from one line to the other. This led to the use of shell filled with materials which would produce gas. There were many advantages in these shell. They could be thrown exactly where it was desired that they should fall, without the help of the fickle winds. When the shell landed and burst, the full effect of its contents was expended upon the enemy. A gas cloud would rise over a wood, but with shell the wood could be filled with gas, which, once there, would lurk among the trees for days. Chemicals could be used in shell which could not be used in a cloud attack. The shell could be filled with a liquid, or even with a solid, because when it burst the filling would be minutely pulverized. And so German chemists were set to work devising all sorts of fiendish schemes for poisoning, choking, or merely annoying their opponents.
GAS THAT MADE ONE WEEP
One of the novel shell the Germans used was known as the "tear-gas" shell. This was filled with a liquid, the vapor of which was very irritating to the eyes. The liquid vaporized very slowly and so its effect would last a long time. However, the vapor did not permanently injure the eyes; it merely filled them with tears to such an extent that a soldier was unable to see and consequently was confused and retarded in his work. The "tear-gas" shell were marked with a "T" by the Germans and were known as "T-shell."
Another type of shell, known as the "K-shell," contained a very poisonous liquid, the object of which was to destroy the enemy quickly. The effect of this shell was felt at once, but it left no slow vapors on the ground, and so it could be followed up almost immediately by an attack. Later on, the Germans developed three types of gas shell—one known as the "Green Cross," another as the "Yellow Cross," and the third as the "Blue Cross." The Green Cross shell was filled with diphosgene, or a particularly dangerous combination of phosgene in liquid form, which would remain in pools on the ground or soak into the ground and would vaporize when it became warm. Its vapors were deadly. One had always to be on his guard against them. In the morning, when the sun warmed the earth and vapors were seen to rise from the damp soil, tests were made of the vapors to see whether it was mere water vapor or diphosgene, before men were allowed to walk through it.
These vapors were heavier than air and would flow down into a trench, filling every nook and cranny. If phosgene entered a trench by a direct hit, the liquid would remain there for days, rendering that part of the trench uninhabitable except by men in gas-masks. The infected part of the trench, however, was cut off from the rest of the trench by means of gas-locks. In other words, blankets were used to keep the gas out, and usually two blankets were hung so that a man in passing from one part of the trench to another could lift up the first blanket, pass under it, and close it carefully behind him before opening the second blanket which led into the portion of the trench that was not infected.
The Germans had all sorts of fiendish schemes for increasing the discomfort of the Allies. For instance, to some of their diphosgene shell they added a gas which caused intense vomiting.
The Yellow Cross shell was another fiendish invention of the Huns. It was popularly known as "mustard gas" and was intended not to kill but merely to discomfort the enemy. The gas had a peculiar penetrating smell, something like garlic, and its fumes would burn the flesh wherever it was exposed to them, producing great blisters and sores that were most distressing. The material in the shell was a liquid which was very hard to get rid of because it would vaporize so slowly. On account of the persistence of this vapor, lasting as it did for days, these gas shell were usually not fired by the Germans on lines that they expected to attack immediately.
THE SNEEZING-SHELL
The Blue Cross shell was comparatively harmless, although very annoying. It contained a solid which was atomized by the explosion of the shell, and which, after it got into the nostrils, caused a violent sneezing. The material, however, was not poisonous and did not produce any casualties to speak of, although it was most unpleasant. A storm of Blue Cross shell could be followed almost immediately by an attack, because the effect of the shell would have been dissipated before the attackers reached the enemy who were still suffering from the irritation of their nostrils.
GAS-MASKS
As the different kinds of gas shell were developed, the gas-masks were improved to meet them. In every attack there were "duds" or unexploded shell, which the chemists of the Allies analyzed. Also, they were constantly experimenting with new gases, themselves, and often could anticipate the Germans. The Allies were better able to protect themselves against gas attacks than the Germans, because there was a scarcity of rubber in Germany for the manufacture of masks. When it was found that phosgene was going to be used, the simple cotton-wad masks had to give way to more elaborate affairs with chemicals that would neutralize this deadly gas. And later when the mustard gas was used which attacked the eyes, and the sneezing-gas that attacked the nose, it was found necessary to cover the face completely, particularly the eyes; and so helmets of rubber were constructed which were tightly fitted around the neck under the coat collar. The inhaled air was purified by passage through a box or can filled with chemicals and charcoal made of various materials, such as cocoanut shells, peach pits, horse-chestnuts, and the like. Because the Germans had no rubber to spare, they were obliged to use leather, which made their masks stiff and heavy.
GLASS THAT WILL NOT SHATTER
One of the greatest difficulties that had to be contended with was the covering of the eyes. There was danger in the use of glass, because it was liable to be cracked or broken, letting in the deadly fumes and gassing the wearer. Experiments were made with celluloid and similar materials, but the finest gas-masks produced in the war were those made for our own soldiers, in which the goggles were of glass, built up in layers, with a celluloid-like material between, which makes a tough composition that will stand up against a very hard blow. Even if it cracks, this glass will not shatter.
The glasses were apt to become coated on the inside with moisture coming from the perspiration of the face, and some means had to be provided for wiping them off. The French hit upon a clever scheme of having the inhaled air strike the glasses in a jet which would dry off the moisture and keep the glasses clear. Before this was done, the masks were provided with little sponges on the end of a finger-piece, with which the glasses could be wiped dry without taking the masks off.
But all this time, the Allies were not merely standing on the defensive. No sooner had the Germans launched their first attack than the British and French chemists began to pay back the Hun in kind. More attention was paid to the shell than the cloud attack, and soon gas shell began to rain upon the Germans. Not only were the German shell copied, but new gases were tried. Gas shell were manufactured in immense quantities.
Then America took a hand in the war and our chemists added their help, while our factories turned out steady streams of shell. If Germany wanted gas warfare, the Allies were determined that she should have it. Our chemists were not afraid to be pitted against the German chemists and the factories of the Allies were more than a match for those of the Central Powers. When the Germans first started the use of gas, apparently they counted only their own success, which they thought would be immediate and overwhelming. They soon learned that they must take what they gave. The Allies set them a pace that they could not keep up with.
When the armistice brought the war to a sudden stop, the United States alone was making each day two tons of gas for every mile of the western front. If the war had continued, the Germans would have been simply deluged. As it was, they were getting far more gas than they could possibly produce in their own factories and they had plenty of reason to regret their rash disregard of their contract at The Hague Conference. One gas we were making was of the same order as mustard gas but far more volatile, and had we had a chance to use it against the Germans they would have found it very difficult to protect themselves against its penetrating fumes.
BATTLING WITH LIQUID FIRE
Somewhat associated with gas warfare was another form of offensive which was introduced with the purpose of breaking up the dead-lock of trench warfare. A man could protect himself against gas by using a suitable mask and clothing, but what could he do against fire? It looked as if trench defenders would have to give up if attacked with fire, and so, early in the war, the Germans devised apparatus for shooting forth streams of liquid fire, and the Allies were not slow to copy the idea.
The apparatus was either fixed or portable, but it was not often that the fixed apparatus could be used to advantage, because at best the range of the flame-thrower was limited and in few places were the trenches near enough for flaming oil to be thrown across the intervening gap. For this reason portable apparatus was chiefly used, with which a man could send out a stream for from a hundred to a hundred and fifty feet. On his back he carried the oil-tank, in the upper part of which there was a charge of compressed air. A pipe led from the tank to a nozzle which the man held in his hand, using it to direct the spray.
There was some danger to the operator in handling a highly inflammable oil. The blaze might flare back and burn him, particularly when he was lighting the stream, and so a special way of setting fire to the spray had to be devised. Of course, the value of the apparatus lay in its power to shoot the stream as far as possible. The compressed air would send the stream to a good distance, but after lighting, the oil might be consumed before it reached the desired range. Some way had to be found of igniting the oil stream far from the nozzle or as near the limit of its range as possible. And so two nozzles were used, one with a small opening so that it would send out a fine jet of long range, while the main stream of oil issued from the second nozzle. The first nozzle was movable with respect to the second and the two streams could be regulated to come together at any desired distance from the operator within the range of the apparatus. The fine stream was ignited and carried the flame out to the main stream, setting fire to it near the limit of its range. In this way a flare-back was avoided and the oil blazed where the flame was needed. The same sort of double nozzle was used on the stationary apparatus and because weight was not a consideration, heavier apparatus was used which shot the stream to a greater distance.
But flame-throwing apparatus had its drawbacks: there was always the danger that the tank of highly inflammable oil might be burst open by a shell or hand-grenade and its contents set on fire. The fixed apparatus was buried under bags of sand, but the man who carried flame-throwing apparatus on his back had to take his chances, not knowing at what instant the oil he carried might be set ablaze, turning him into a living, writhing, human torch. Because of this hazard, liquid fire did not play a very important part in trench warfare; to set fire to the spray at its source with a well directed hand-grenade was too easy.
THE "FIRE BROOM"
There were certain situations, however, in which liquid fire played a very important part. After a line of trenches had been captured it was difficult to clear out the enemy who lurked in dugouts and underground passages. They would not surrender, and from their hidden recesses they could pour out a deadly machine-gun fire. The only way of dislodging them was to use the "fire broom." In other words, a stream of liquid fire was poured into the dugout, burning out the men trapped in it. If there were a second exit, they would come tumbling out in a hurry. If not, they would be burned to death. After the first sweep of the "broom," if there were any survivors, there would not be any fight left in them, and they would be quick to surrender before being subjected to a second dose of fire.
CHAPTER VI
Tanks
There is no race-horse that can keep up with an automobile, no deer that can out-run a locomotive. A bicyclist can soon tire out the hardiest of hounds. Why? Because animals run on legs, while machines run on wheels.
As wheels are so much more speedy than legs, it seems odd that we do not find this form of locomotion in nature. There are many animals that owe their very existence to the fact that they can run fast. Why hasn't nature put them on wheels so that when their enemy appears they can roll away, sedately, instead of having to jerk their legs frantically back and forth at the rate of a hundred strokes a minute?
But one thing we must not overlook. Our wheeled machines must have a special road prepared for them, either a macadam highway or a steel track. They are absolutely helpless when they are obliged to travel over rough country. No wheeled vehicle can run through fields broken by ditches and swampy spots, or over ground obstructed with boulders and tree-stumps.
But it is not always possible or practicable to build a road for the machines to travel upon, and it is necessary to have some sort of self-propelled vehicle that can travel over all kinds of ground.
Some time ago a British inventor developed a machine with large wheels on which were mounted the equivalent of feet. As the wheels revolved, these feet would be planted firmly on the ground, one after the other, and the machine would proceed step by step. It could travel over comparatively rough ground, and could actually walk up a flight of stairs. We have a very curious walking-machine in this country. It is a big dredge provided with two broad feet and a "swivel chair." The machine makes progress by alternately planting its feet on the ground, lifting itself up, chair and all, pushing itself forward, and sitting down again.
Although many other types of walking-machines have been patented, none of them has amounted to very much. Clearly, nature hopelessly outclasses us in this form of propulsion.
Years ago it occured to one ingenious man that if wheeled machines must have tracks or roads for their wheels to run on, they might be allowed to lay their own tracks. And so he arranged his track in the form of an endless chain of plates that ran around the wheels of his machine. The wheels merely rolled on this chain, and as they progressed, new links of the track were laid down before them and the links they had passed over were picked up behind them. A number of inventors worked on this idea, but one man in particular, Benjamin Holt, of Peoria, Illinois, brought the invention to a high state of perfection. He arranged a series of wheels along the chain track, each carrying a share of the load of the machine, and each mounted on springs so that it would yield to any unevenness of the ground, just as a caterpillar conforms itself to the hills and dales of the surface it creeps over. In fact, the machine was called a "caterpillar" tractor because of its crawling locomotion.
But it was no worm of a machine. In power it was a very elephant. It could haul loads that would tax the strength of scores of horses. Stumps and boulders were no obstacles in its path. Even ditches could not bar its progress. The machine would waddle down one bank and up the other without the slightest difficulty. It was easily steered; in fact, it could turn around in its own length by traveling forward on one of its chains, or traction-belts, and backward on the other. The machine was particularly adapted to travel on soft or plowed ground, because the broad traction-belts gave it a very wide bearing and spread its weight over a large surface. It was set to work on large farms, hauling gangs of plows and cultivators. Little did Mr. Holt think, as he watched his powerful mechanical elephants at work on the vast Western wheat-fields, that they, or rather their offspring, would some day play a leading role in a war that would rack the whole world.