ENGINES OF DESTRUCTION - MACHINES

AT THE VERY beginning of this book we observed that war is a most potent stimulus to invention among primitive men. Despite all our advances in civilization we still have our wars, each more dreadful than the preceding one; for each important conflict brings forth new engines of destruction or stimulates the invention of new death-dealing machines which are developed during intervals of peace. So terrible has modern war become that with each great conflict it has seemed as if its very dreadfulness would stay the hand of the invader and make him hesitate to expose his men to the horrible monsters which science and invention have created. To-day, after a titanic struggle which cost millions of human lives, which destroyed billions of dollars’ worth of property, and which made itself felt to the remotest corners of the earth, serious efforts are being made to banish war, but at the same time inventors here and abroad are busy inventing new and more powerful engines of death, and the prospects are that the next big war, should there ever be one, will be even more horrible and destructive than the one we have just passed through.

Fortunately engines of death are not the only inventions produced by war. Many machines, apparatus, and processes are originated or developed which have a distinct value in time of peace; hence[360] war is a great constructive as well as a destructive agency. In this respect the great World War was no exception and we are already reaping benefits which in a small way compensate for the havoc that was wrought. It advanced scientific research to a point it would not have reached in fifty years of peace. The stimulus was felt in every field of science from chemistry to acoustics, from geology to meteorology. Wonderful progress was made in radiotelephony, in submarine navigation, in aviation, and there were scores of inventions which will add to our comfort and aid us in the mastery of Nature.
Many of these inventions have already been described; others do not properly belong in this volume as they have to do chiefly with electricity or chemistry. In this chapter we shall take up mainly the machines built for the purpose of destroying men and their works.

PRIMITIVE “ENGINES” OF WAR

Of course the main objects of war are offense and defense, the destruction of the opponent and the protection of one’s self. This first fighting was a hand-to-hand struggle which gave way to fighting at a distance as spears and arrows were invented. Shields and armor were then invented to ward off these missiles. Cities were surrounded with walls to hold off the enemy. Then came the Roman war “engines,” catapults and battering rams, to destroy the walls and towers which would enable the besiegers to fight on an equal level and in personal contact with the besieged. Although a battle might start with long-distance fighting it was always a hand-to-hand encounter that clinched the victory. Even to-day, although we have our big guns which[361] fight at ranges of five to twenty miles, it is the rifle or bayonet which wins or loses the battle.

INVENTION OF GUNPOWDER

The introduction of gunpowder from China in the fifteenth century did not immediately revolutionize warfare. It was used only in cannon or mortars for hurling large stones at city walls. The range of those cannon was so limited and the time it took to load and fire them was so great that they were of little use on an open battlefield. A cannon, although a comparatively powerful offensive weapon, was helpless against attack and was only suitable for use in forts or behind breastworks. Later when its range was increased and it came to be used on the battlefield it had to be protected from capture by men supplied with small arms.
This defect of the cannon also applied to the use of the hand gun. Its range was small and consequently the blunderbuss type was invented to spread the charge of shot as much as possible so as to tear a wide gap in the enemy’s line and prevent it from closing in upon the operator of the gun. But the loading and firing of these early firearms was extremely slow and the battle-ax and even the arrow and the crossbow were much more effective weapons. So unreliable were the muskets of our Revolutionary War that in battle more dependence was placed upon the bayonet than the firearm.

THE SPINNING BULLET

Three important improvements were necessary to make the small gun a really effective weapon. First was the invention of a reliable means of igniting the powder; second the rifling of the barrel so that[362] the bullet would not tumble but would hold a true course, and finally the invention of a cartridge and a rifle that could be loaded from the breech. These improvements were not completely effected until the time of the Civil War. Since then there have been further marked improvements: The power of cartridges has been increased; the bullets have been given a stream-line form so as to increase the range of the rifle and its power of penetration; the rifle has been equipped with a magazine for carrying a number of cartridges; and a simple mechanism has been provided for discharging empty shells and inserting fresh cartridges in a minimum of time.
Gyroscopic action plays a very important part in the flight of a bullet or shell. The spiral grooves cut in the bore of the rifle give the projectile a twist that sets it to spinning rapidly. The spinning bullet is virtually a gyroscope and maintains its axis in the line of flight. Hence it is possible to use a long pointed bullet instead of the round ball of earlier days and to give the projectile a shape that will enable it to cut through the air with comparatively little resistance. The same bullet fired from a smooth bore gun would begin to tumble and would encounter so much air resistance that it would fall short in the space of a few hundred feet, besides which it would wander far off its course.

MACHINE GUNS

A rifle is really a machine for hurling small projectiles. During the Civil War a Chicago physician named Gatling fell to pondering over the inefficiency of using a machine that would fire only one bullet at a time with a considerable interval of time between shots for reloading, and he hit upon the idea[363] of developing a machine that would discharge a continuous stream of bullets. So he built a ten-barrel revolving gun operated by a hand crank. The barrels were automatically loaded and fired one after the other. Although it was slow to accept the Gatling machine gun, the U. S. Army after once accepting it was loath to give it up even after better machine guns were invented.

UTILIZING THE KICK OF A GUN

In the Gatling gun hand power was required to operate the loading, firing and shell-ejecting mechanism, but it occurred to another inventor that a small portion of the energy developed in exploding the cartridge could very well be utilized to replace the hand power and thus make the machine gun completely automatic. It was Hiram Maxim who first carried out this idea to a successful conclusion. When a rifle is fired the suddenly expanding gases push back against the breech of the gun with just as much pressure as they do against the bullet and this shows itself in the recoil or “kick” of the gun. Maxim utilized the kick of the gun to cock the gun, open the breech, eject the empty shell, take a fresh cartridge out of a magazine belt, insert it in the breech chamber, lock the breech and fire the gun. All these operations occupied but an instant of time and the gun kept on firing as long as the belt of cartridges held out.
John M. Browning, inventor of the Colt gun, instead of using the recoil, employed a small portion of the gases to operate the mechanism. A minute hole in the barrel of the gun, near the muzzle, communicated with a small cylinder in which was a spring-pressed piston. The gases pursuing the[364] bullet out of the barrel would find this tiny hole and, entering it, push back the piston. The pressure against the piston would be only a small fraction of that exerted against the bullet and would last for only the briefest part of a second, from the time the bullet uncovered the hole to the time it emerged from the barrel and liberated the gases, but this minute portion of the energy of the powder was sufficient to actuate the mechanism which performed all the operations necessary to reload and fire the gun.

COOLING THE GUN BARREL

The advantage of these machine guns over Gatling’s lay not only in the saving of human labor, but in the fact that a single barrel was employed in place of ten, thereby greatly reducing the weight of the gun. But a serious handicap was encountered in the heat developed by the burning powder. Dr. Gatling, by using ten barrels, could let nine be cooling while the tenth was discharging, but even he found it necessary to place a water jacket about half the length of the barrels. In the Maxim machine gun a large water jacket enveloped the whole length of the barrel and when the gun was firing continuously at a moderate rate the 7½ pints of water contained in the water jacket would come to a boil inside of a minute and a half, and thereafter more than a pint would be evaporated each minute of firing, or about a pint and a half per thousand rounds. The necessity of using water-cooling added considerably to the weight of the gun and made it occupy in the service an intermediate place between the shoulder rifle and the big gun.
Another method of cooling was to use a barrel with a large outer diameter and depend upon the[365] radiation of heat from the outer surface to prevent overheating. This was later improved by putting flanges on the outer surface of the barrel, so as to increase the radiating surface, in the same way that the cylinders of a motorcycle are kept cool. The barrel was made easily detachable and a spare one provided, so that as soon as the barrel grew excessively hot it could be removed and replaced with a cool barrel. The fault of overheating is not that it might explode the cartridge prematurely but that the bore will be enlarged by heat expansion so that the bullets will not take the rifling and will come out of the barrel as if from a smooth-bore gun. In a test of a Hotchkiss machine gun which was fired continuously the expansion was sufficient at the end of four minutes to make the course of the bullets very uncertain and in seven minutes the bullets, emerging without any spin, tumbled over and over and failed to carry more than three hundred yards.

A GUN THAT FANS ITSELF

The next marked step in the development of the machine gun was to make it fan itself and thus keep its barrel cool. Col. I. N. Lewis designed a gun operated by gas pressure somewhat on the principle of the Colt gun and around the barrel he fitted sixteen deep flanges or fins of aluminum that ran lengthwise of the gun. Around these fins he fitted a casing, thus forming 16 long narrow chambers about the barrel. The casing was open at the breech end, but at the outer end was contracted into a narrow mouthpiece that extended beyond the muzzle. The mouthpiece was so formed that as the bullets passed through it they sucked air through the chambers, thereby cooling the gun. The air travels[366] through the casing at the rate of about seventy miles per hour.
This design permitted Col. Lewis to build a very light gun. Its total weight was but 25½ pounds and it could be handled by a single man if the muzzle was supported on some sort of a rest. It represented a marked step toward a shoulder machine gun which would increase enormously the efficiency of infantry equipped with this weapon. The difference between rifle fire and machine-gun fire has been likened to the difference between trying to hit a tin can with a stone and with a stream of water from a hose. In the latter case the hose may be raised or lowered to correct the course of the stream and bring it to bear on the target. In the same way by watching the effect of the machine-gun bullets the leaden stream may be corrected to bring it directly upon the target. The advantages of a weapon such as this, which may be fired from the shoulder or from the hip, are perfectly obvious.
As the war was nearing its end John M. Browning produced two machine guns, one a water-cooled heavy model fired from a stand. The total weight of this gun was 34½ pounds and with the water jacket empty it weighed but 22½ pounds. It was operated by the recoil of the gun, but the mechanism was greatly simplified and there were but few parts. These could be taken apart and replaced with new ones in a minimum of time in case of breakage. The other gun was a shoulder rifle weighing only 16 pounds, which carried a clip of twenty cartridges. These could be fired singly or in rapid succession in the space of two and a half seconds. Only a second was required to replace the empty clip with a filled one. No special cooling apparatus was provided[367] because it was not likely that a shoulder rifle would be fired long enough at a time to become excessively heated.

POCKET-SIZED MACHINE GUN

The latest development in machine guns is a pocket edition weapon—a firearm weighing only 7 pounds and measuring but 22 inches over all. This little gun which is too small to be classed as a rifle and yet rather large for a pistol, has two grips so that it may be fired from the waist line, and it may be fitted with a gun butt so that it may be fired from the shoulder. It operates at the astounding rate of 1,500 shots per minute or three times the speed of the average machine gun. The cartridges are fed either from a box magazine containing 20 rounds or from a drum-shaped magazine loaded with 50 to 100 cartridges. The operating mechanism of this gun is entirely different from anything produced heretofore and depends upon a discovery made by Commander Blish of the United States Navy. He found that a wedge of a certain angle will hold a breechblock closed against the pressure of an exploding cartridge while the pressure is high, but will slide when the pressure falls. Apparently at first the adhesion due to friction is too great to permit the wedge to move, but the adhesion falls off more rapidly than the pressure does and a point is reached at which the wedge yields to the pressure. In the “submachine” gun, as the new weapon is called, the barrel (or rather an extension of the barrel) and the receiver, in which the operating mechanism is contained, are locked together by a wedge. The wedge slides in slots set at an angle of 80 degrees with the axis of the barrel. When a cartridge[368] is fired the wedge remains fast while the bullet is traveling through the bore, but when it emerges and the pressure of the gases falls off the wedge slides, unlocking the breech mechanism. The gun is remarkable for its simplicity and the fewness of its parts. It has been adopted by the Police Department of New York City.

ARTILLERY VS. ARMOR

As has been stated above, gunpowder was first introduced in warfare not for the purpose of destroying men, but for smashing city walls and fortifications, so that infantry could pour through the breeches made by the heavy stone or iron projectiles. As artillery grew more powerful and the aim more accurate walls of masonry gave way to earthworks and to masses of concrete and armored steel. However the World War demonstrated the impossibility of building any fortifications above ground that would stand up against modern high-powered guns.

GUNS, MORTARS, AND HOWITZERS

In military parlance a “gun” is a long-barreled piece that fires its projectiles with a flat trajectory, that is, the projectile is fired at a low angle and describes a long flat curve. A “mortar” is a short-ranged weapon which fires at a high angle so as to land its projectile over the walls of a fortification. The barrel of the mortar was formerly very short and had a smooth bore, but later the barrel was extended and the bore rifled so as to give a greater range, developing what is known as the “howitzer.” The famous 42-centimeter gun with which the Germans started the war was a howitzer which fired a shell a yard and a half long weighing 2,108 pounds.[369] We have big guns to defend our coasts which fire a shell 16 inches in diameter, which is half an inch less than 42 centimeters, and the weight of the shell is 2,400 pounds. But the startling thing about the German big howitzers was that they were portable and could be brought up to smash fixed defenses. As the war proceeded enormous guns as well as howitzers were set on railroad mounts and moved about from time to time to avoid discovery by spying aviators.

THE 76-MILE GUN

The 76-mile gun which bombarded Paris fired projectiles of only 8.27-inch caliber. The projectile described a wide curve which carried it about twenty-four miles above the surface of the earth or about 3½ times as high as the greatest altitude ever reached by man in an aeroplane. Had it pursued a perfectly straight line from the forest of St. Gobain to Paris its course would have carried it 3,750 feet below the surface, because of the curvature of the earth. The range of the projectile was very materially increased by rising to such a great elevation because of the extreme tenuity of the atmosphere. The air resistance that a shell is obliged to overcome is not generally appreciated. In the denser strata of the lower atmosphere the resistance is very great, but as a shell mounts to higher levels the air resistance falls off considerably and at twenty miles it is practically nonexistent.
It was not until the summer after the armistice that details of this gun were disclosed. There were seven of these powerful guns that participated in the various bombardments. They wore out very quickly under the terrific strain to which they were subjected and were rebored to a diameter of 9.4[370] inches. In the last bombardment a number of shells of this size reached Paris. The guns were fired at an angle of 55 degrees from the horizontal so as to pass quickly through the denser layers of the air. The shell left the muzzle of the gun with the velocity of about 5,000 feet per second and arrived in Paris about three minutes later with a velocity of about half that amount. The enormous muzzle velocity was obtained by using a very long gun so that the powder could keep pushing the projectile for a comparatively long time. The guns were built out of worn-out 15-inch naval guns. These guns which were 56 feet long were rebored, fitted with a heavy tube and pieced out to a length of 118 feet. The last 20 feet of the bore was not rifled and served as a guide to keep the shell in perfect axial alignment when it emerged from the muzzle. A comparatively slow powder was used so as not to put too severe a strain on the gun at the breech, but gradually to accelerate the shell in its travel through the bore.
Spectacular as was the performance of these huge guns, they were of little military value. The slightest variation in the powder would cause a wide variation of range and they could not hope to hit a target smaller than a large city. All seven guns fired a total of 303 shells in 44 days of bombardment, only 183 of which fell within the city. They killed 256 persons and wounded 620. Far more damage at far less expense could have been effected by dropping bombs from aircraft.

A 121-MILE GUN

Just as a problem in ordnance, American officers designed a gun 225 feet long which would fire a 400-pound shell of 10-inch caliber. It was estimated that with a charge of 1,440 pounds of[371] powder the shell would leave the muzzle with a velocity of 8,500 feet per second and, if fired at an angle of 55 degrees, would have a range of 121 miles. The shell would rise to a height of 46 miles above the earth and would make the 121 miles in about 4 minutes. The gun was never built, because its military value would in no way be commensurate with its cost of construction and operation. The purpose of the German long-range bombardment was to produce a moral rather than a military effect. The Germans hoped to intimidate the French people by this spectacular performance, and in this they failed completely.

TIMED AND PERCUSSION SHELLS

In modern warfare large guns are used either to rain a storm of death upon infantry or to destroy their defensive works. In earlier days the effectiveness of gunfire against a charging enemy was increased by the use of grapeshot. A cannon was thus converted into a gigantic shotgun. But although a wide dispersion of projectiles was obtained the range was very limited. This handicap was then overcome by having the gun fire another gun which would discharge when it had reached the enemy’s lines. In other words, the grapeshot or leaden balls were packed into a shell which was fired like a solid projectile, and this exploded when it struck the target, scattering death broadcast. An improvement on this was the timed shell, which would explode while still in the air and scatter its rain of lead over a wide area. The time fuse of a shrapnel shell must be very delicately adjusted to explode at the desired instant. A train of powder is used which may be short-circuited to give the[372] exact length required for any given distance. The powder is ignited by a cap which is exploded by concussion when the gun is fired. The fuse then burns until it reaches the main charge of the shell. This explodes, bursting the shell open and scattering shell fragments as well as the scores of lead balls with which the shell is packed. Should the fuse fail, a detonating pin is provided which will explode the shell when it reaches the ground. Where the object is to destroy defensive works the shell is charged with a high explosive which is detonated not by a time fuse, but by concussion when the shell strikes its target.
The war brought forth many new types of projectiles: shells loaded with lethal gases; shells which left a trail of smoke whereby their course could be followed when fired at aircraft; shells that illuminated the battlefield at night, etc. The searchlight shells carried a number of “candles,” each furnished with a little parachute so that when the shell exploded the burning candles would settle slowly to the ground, all the while casting a brilliant light on operations below.

AERIAL BOMBS

Obviously, hurling projectiles from the air is a much simpler matter than projecting them from the ground. No propellant is required to carry them to the target and no rifling is necessary to keep them head-on in the direction of flight. They are pulled instead of being pushed and can easily be kept in their course by means of rudder planes. But hitting a target from an aeroplane is like hitting a swiftly moving object from the ground. The target is seemingly flying past the aeroplane and in calculating where the aerial bomb will strike the[373] speed of the plane through the air and its height above the ground must all be taken into consideration.
Naval warfare is a fight of fort against fort and consequently the high explosive projectile is the principal one used. The shells must be able to penetrate heavy steel armor and explode within the hull of the vessel. In addition to these we have the torpedoes fired by destroyers and submarines which explode an enormous quantity of high explosive against the hull of the vessel. No attempt is made to penetrate the skin of the vessel, but the explosive, tamped by a considerable depth of water, delivers a very heavy crushing blow against the side of the hull.

AUTOMATIC CONTROL OF SUBMARINE TORPEDOES

It is wrong to speak of firing a torpedo. A torpedo is really an automatic, self-propelled, submarine boat. All that the destroyer or submarine does is to set the steering gear in this little boat and then launch it at the enemy with a blast of air that ejects it from the torpedo tube. Most of the body of the torpedo is filled with compressed air which drives a small air motor coupled to a pair of propellers. These propellers run in opposite directions so as to balance each other and they drive the torpedo through the water at a speed of about forty miles per hour. The speed falls off gradually as the air supply is exhausted.
To hold the torpedo on its course horizontal and vertical rudders are employed. The vertical rudder is controlled by a gyroscope which turns it this way or that according as the torpedo tends to veer off its course.
[374]
The value of a torpedo lies in its concealment. Were it to travel on the surface the vessel against which it was directed might be able to avoid it; furthermore the action of the waves would tend to disturb the gyroscopic steering mechanism and the torpedo would pursue an erratic course. For this reason it must travel under water at a depth sufficient to avoid surface disturbances. There is also a distinct advantage in having a good cover of water over the torpedo when it strikes its target because the force of the explosion, although felt in all directions, is mainly expended along the line of the least resistance. If the depth of water over the torpedo is slight, most of the force will be expended upward and only a comparatively small part will act against the hull of the vessel. It was the practice of the Germans to set their torpedoes for a depth of about ten feet.
To hold a torpedo at a fixed depth a very delicate hydrostatic valve is employed which operates the diving rudders. The valve is set for a certain depth or weight of water. If the torpedo goes below this depth, the weight of the water bearing on this valve presses it down and thereby tilts the diving rudders until the torpedo comes back to the required depth. If it rises above the depth for which it is set, the valve feels the reduction of water pressure and tilts the rudders in the opposite direction to correct the deviation from the predetermined line of travel. Once the valve has been set the torpedo takes care of itself automatically. It may be discharged from any depth or be dropped from torpedo tubes on the deck of a ship and after a few undulations it will find its depth and hold it as long as it keeps running.
[375]
Torpedoes have actually been discharged from aeroplanes and it is possible that in the next great war swiftly flying aeroplanes may actually bring death and destruction to powerful dreadnoughts. In fact winged destroyers and battle cruisers of the air may render obsolete all our modern fighting machines.
As we have already observed, it was war that first aroused the inventive instincts in man. Fortunately this instinct was not confined to destructive devices and engines, and the mechanical conquest of the earth, although it continues to derive much benefit from the stimulus of war, may well afford to break off relations with so grim and horrible a partner and proceed to develop under the stimulus of its own successes.

 by A. Russell Bond