Kelly Miller's History of the World War for Human Rights

THWARTING THE U-BOAT.

Nets To Entangle the Sea Sharks of War—"Chasers" or "Skimming-dish" Boats—"Blimps" and Seaplanes—Hunting the Submarine with "Lance," Bomb and Gun—A Sailor's Description.

The advantage which Germany gained by the development of what has been termed the super-submarine placed the other nations where it became absolutely necessary for them to concentrate their energies in an effort to counteract the devastation which the U-boats brought upon the seas. England tried first to protect the English channel and many of its ports with mines, floating bombs and submarine nets, and while the latter served as barriers which prevented the submarines penetrating into some of the important waters and harbors, they could act merely in a protective sense.

The submarine net is a specially devised net with heavy iron or wire meshes, similar to a fishing net. These nets—miles in length—were born of the nets originally devised to sweep harbors clear of mines. They are carried between two boats described as trawlers, which are a form of sea-going tug with powerful engines, that can draw a heavy load. A heavy cable runs from trawler to trawler, and from this the chain net is suspended in the water. It is heavily weighted at the bottom so as to hold it in a perpendicular position. The trawlers steaming along, side by side, sweep up with the net anything which may be placed in the water for the purpose of blowing up or injuring vessels.

The submarine nets in some places have been anchored to form a regular barrier against the passage of submarine boats, and in this way were effective, but their use could in no way restrict the underseas boats in their work upon the open seas.

The most effective plan of overcoming the dire consequences of the U-boat warfare was found, therefore, to lie in the use of submarine chasers and airships, the two operating together in conjunction with the battleships, cruisers and torpedo boat destroyers.

The submarine chaser is a light-draught, high-powered, skimming-dish type of husky motorboat, mounting rapid-fire, 3 or 4-inch guns. In order to prove effective against the submarine it is necessary to have many of these boats, and it is a matter of particular interest that the marvelous resources of the United States at the time of her entrance into the war enabled her to immediately begin a campaign for the construction of chasers, which would be able to guard the seas in the channels of traffic and along the ports into which the submarine might attempt to sneak.

NO EXPERT NAVAL KNOWLEDGE REQUIRED.

The operation of the chaser does not require the degree of technical skill and knowledge of naval strategy required in the handling of ships of the naval type. A fleet of chasers is manned largely by naval reserves, who have a certain amount of training, but who are neither navigators nor experts in naval affairs. The operations are, however, directed by the naval authorities.

The submarine chaser is effective because it draws very little water, has high speed, can be quickly turned and diverted from its course and does not present any great depth of hull at which the submarine can fire a torpedo. It would be possible for a torpedo to pass under a chaser without hitting it—if the submarine cared to waste such an expensive weapon on so small an adversary. When the submarine attempts to come to the surface and use the rapid-fire gun with which she is armed she is at a disadvantage, because it takes her several minutes to emerge. Additional time is required to swing the gun up through its automatic hatch while the men scramble to the deck to man it.

The chaser, with a speed of approximately 35 to 40 miles an hour, will travel somewhere between a mile and a half to two miles in this period. Its gun has been ready from the start, and the chaser has had half a dozen shots or so with only a single hit needed to put the submarine out of commission. Even if the submarine is at the surface and has her gun mounted ready for action, she is at a disadvantage with the chaser. The chaser, taking advantage of her speed and small size, goes skimming across the water at the rate of 40 miles an hour, and it takes a mighty fine gunner to be able to hit a small craft, going in a zigzag course over the water at such speed.

The chaser may continue to circle the submarine awaiting her opportunity which will of necessity come when the U-boat attempts to submerge. The submarine must go through the regular form of running back her gun, and battening down the water-tight hatches, before she can submerge, and the latter process again takes several minutes. Therefore while the submarine is preparing to dip, the chaser can run upon her and let loose the fire from its rapid-fire gun.

A POOR SURFACE FIGHTER.

The submarine, by very virtue of the qualities which make it a good submarine, is a poor boat for surface fighting. It can carry no very heavy armament, and it is not heavily armored. The problem of stowing away all the heavy machinery, supplies, torpedoes and devices necessary for her operations and maneuvering has presented about all the difficulties the constructors have been able to handle. The highest speed of the submarine is not in excess of 20 miles an hour. The submarine must be light and easy to handle. It gains in steadiness and certainty of operation with increased size, but it loses in capacity for quick and delicate maneuvering.

In addition the submarine has what is termed a strategic vulnerability. A shot which might mean nothing more serious than a hole in the side to a surface boat would end the submarine's usefulness for underseas work and convert her into a helpless hulk of surface craft.

The submarine is an easy quarry for a chaser, for even when submerged and moving along, the U-boat creates a distinct wave on the surface of the water which can be followed by the chaser. The little boats are just what their name implies—chasers—and besides having the qualities already described they may conceal themselves behind large steamers, and when the submarine in preparing to launch a torpedo makes its presence known the chaser may speed from its hiding place and drive the underseas craft away, even if it does not succeed in injuring it.

OPERATING IN CONNECTION WITH AN AEROPLANE.

The chasers also have a special facility of operation in connection with the aeroplane or seaplane, principally because of their high speed; and next to the chaser the aeroplane is one of the submarine's worst enemies. Used in conjunction with the regular torpedo boat destroyers of the navy, the chaser and the aeroplane promise in future wars to minimize the effectiveness of the underseas craft. This is proven by the fact that immediately after the United States naval forces joined those of the Allies in European waters, the disasters resultant upon submarine attacks were greatly reduced. The speedy destroyers, while not actually sinking many submarines, by their vigilance prevented the submarine from operating.

Large types of the chasers ordered in this country by the Russian Government are 72 feet long by 11 feet 3 inches wide and draw 3 feet 3 inches of water. Each boat carries three of the 8-cylinder 6-3/4 x 7-3/4 Duesenberg, 350 to 400 horsepower motors. The boats carry an 18-inch torpedo tube amidships and a 47-millimetre rapid-fire gun on the forward deck. They are controlled from the bridge deck with a sheltered cabin for the quartermaster, with controls from either the shelter or bridge deck. They have a guaranteed speed of twenty-eight knots.

Deck arrangements consist of the following: A hatch to the fo'castle, followed by; the emplacement for the rapid-fire gun. Following this is the steering shelter containing duplicate controls, &c., for the engine room and for the steering. Immediately aft of the steering shelter is the bridge deck, located on top of the engine room trunk house. The entire after half of the vessel is a clear sweep of deck with the exception of a booby hatch to crews' quarters well aft.

The boats are arranged for wireless with foremast and jigger mast. Rail stanchions in the way of the torpedo tube are hinged down, giving clear sweep to the tube for firing purposes.

PROVISION FOR OFFICERS AND CREW.

Below decks ample space has been provided for the crew and officers. The forepeak is arranged for chain lockers and bosun's gear lockers, followed by ship's galley, which has two pipe berths. Next to the galley is located the officers' cabin and wireless room, which is entered by a hatch from the steering shelter. This cabin accommodates two officers and includes lavatory, officers' desks, wireless desk and folding mess table.

Next aft is the machinery space, in which are located the three eight cylinder Duesenberg motors, a three k.w. universal lighting set, the necessary oil tanks, batteries and a work bench. The next compartment contains fuel tanks, with 1300 gallons capacity. Aft of this compartment is located the crew's quarters, berthing eight men, with lavatory attached. The hull is divided into six water-tight compartments by steel bulkheads.

The hull is of wooden construction, as developed for this service by the builders.

The 72-footers develop a speed of twenty-eight knots and have a cruising radius exceeding 1200 miles. The design of the hull is the concave bottom, square bilge type, developed for this particular service. It furnishes a steady gun platform, which, with the necessary speed, is the most vital feature of a submarine chaser.

The demand for speed and stability was borne out by the experience of the Russian and Italian navies in their active work and no consideration at all is given propositions from these two countries which do not range well about twenty-five knots.

Exceptional success was attained by the Russian Black Sea and by the Italian high speed fleets in actual use and their demand for exceptional speed was based on experience.

It is a well known fact that the Russian government was successful in patrolling its shores and in protecting its harbors and shipping. The Italian government also was exceptionally successful in maintaining its mercantile fleet in comparative safety and in protecting its harbors against the offensive work of enemy submarines. The entire Italian fleet of submarine chasers consists of high speed, high powered motor patrol boats, most of which were equipped with American made motors.

CATALOGUED AS "PATROL BOATS."

In a general way the "chasers" are catalogued in naval circles as "patrol boats." England has thousands of them, ranging from motorboats to naval auxiliaries, raking the English Channel, the North Sea and the waters all about the British Isles. As a rule the boats work in groups of five or six, one boat serving as a flagship—and often there is a "blimp" attached to the fleet. The armament of these small vessels is distinctive. Each carries, besides a deck gun, a "depth charge," half a dozen lance bombs and arms for each member of the crew. The deck gun fires a shell that weighs about thirteen pounds.

The "depth charge" is a submarine bomb, so constructed that it is discharged at any determined depth of water when thrown overboard. If the water is 100 feet deep the bomb will explode at that depth. The bombs are used to drop in places where the submarine has been located or is expected of lurking in the bottom of the sea. While the exploding bomb may not strike the underseas boat it will create havoc on board the underwater craft if discharged in close proximity, the extra water pressure exerted causing disarrangement of the delicate mechanism, if not rendering the boat unfit for service.

Some of the patrol boats of the English have been armed with "lance bombs." These are bombs of highly explosive character which are fastened to the end of a long pole or staff. They are used just as a harpoon is used when by chance a submarine may emerge from the water in too close proximity to the chaser. It is not of record that any U-boats have been sunk with these strange javelins, but official reports show that the boats are armed with them for emergencies.

CHASER TROUBLES THE SUBMARINE.

What with dragging bombs through the water, and setting traps and nests for the submarines, the chasers make great trouble for the underseas craft, but the ingenious Germans are constantly on the alert, and it has been proved that in one or two instances at least the submarines cut their way through the heavy chain nets which were set to catch them near Havre. It was said that the submarine was provided with steel knives or wire cutters, and shears operated by electricity or pneumatic pressure, which enabled the boat to cut its way through the barrier of chains and wires.

As a means of visualizing the operations of the "chaser" and giving some idea of the excitement which attends the attempt to run down the underseas craft, the following description by an English sailor is interesting. The chase occurred off the Isle of Wight:

"Offshore a short distance was a patrol boat lying very low and flying distress signals. We had run over to her and learned that about an hour before the periscope of a submarine had been stuck up not far from her, then the craft had submerged, appeared again about a mile away, and fired four shots, which let in enough water slowly to sink the patrol, which before the war had been nothing but a dirty little trawler.

"Finding the crew of the patrol could take care of themselves in their small boats and learning that the submarine had run over to the westward, where we knew chain net traps to be laid, we circled in that direction.

"Our powerful motors thrummed evenly. The water seemed to part ahead of us, and the gunners squinted along the surface, looking for the glimpse of a periscope or the first sign of the hull of the U-boat if she should be proceeding awash.

CREW THRILLED WITH JOY.

"Suddenly, off to the west, we made out her periscope. Intense joy thrilled our little crew. She was inshore from us. She was between our circular course and the chain nets—in the trap. The periscope we had seen might be a dummy, for a submarine frequently casts loose a phoney periscope to draw fire, but, at any rate, she must have been between us and the nets if she cut it loose.

"Presently, probably after a look around, the periscope suddenly disappeared, and we knew it was a real one with a German U-boat on the end of it. Like a flock of falcons we were swooping down on the prey.

"Abruptly the lead boat comes to a dead stop and lists heavily to starboard. Evidently something is wrong. We see men crawl out over the stern and fish around with boat hooks and poles. Cold as it is, one man goes overboard and remains under water so long we could not believe he would come up alive. The boat had fouled the chain nets.

"Circling round in an ever smaller radius, we search the water for a periscope, a shadow, or the conventional 'streak of dirty grease' or 'line of bubbles.'

"All of us have towing torpedoes out. These are bombs on long cables which are towed astern and sink to a certain specified depth. If the cable fouls anything at all, as the boat goes ahead, the bomb pulls up to it, and, when it bumps, it explodes.

"We are in line. Suddenly there is a crash and a roar just ahead of us. I am thrown off my feet. Barrels of water splash down into our cockpit and roll off the decks. The bow lifts itself clean for a second. I think that the submarine has blown us up. Perhaps I am dead already.

"Then we settle down again, and except for a scared look on the faces of a couple of men and rather nervous, forced jests on the lips of others, we are plowing ahead just as before.

"Nothing has happened except the towing torpedo of the boat in front of us in the line fouled a submerged spar, or a bit of wreckage, and exploded right under our bow. 'If we had been a few yards closer we would never have been there any more.'

FOULS A SUBMERGED SPAR.

"As we realized what had happened, our tongues were loosened, and, if the crew of the boat ahead could have heard what we said about them, we would have lost their friendship most assuredly.

"Way inshore, after a circling chase of perhaps twenty minutes, the submarine came up. She was in such shallow water that she probably was having trouble in operating submerged. She was gone then.

"What followed was very business-like. It illustrates the attitude the British have come to take toward the submarines because of their flagrant violations of every form of international law and decency. It is the attitude which any country, obliged to fight against them, will assume. To the British mind, submarines must be exterminated, just as one would exterminate a nest of poisonous vipers, or a nest of hornets. People ask me how many submarines are being captured now. Very few! Many are destroyed, but few captured.

"No sooner did the hull of the submarine show itself than we began to hammer her with our three-inch guns. She opened fire, but her shots went wild, and, in a few seconds, she disappeared.

"As fast as we could, we ran over to where she had gone down. If the principles which obtain on land, in the air or in the navy at large, existed in submarine warfare, we would have gone over to see if we could rescue any of the wounded, but it was a U-boat and we simply made sure that there was nothing left of the craft.

"About where she went down, a quantity of gas and air bubbles were rising, and the dirty patch of oil was once more in evidence. That was a pretty certain sign the career of one U-boat was at an end, for the sea must have been pouring into her, and even though all her crew did not drown, once the salt water reached the storage batteries, the chloride would do the work.

WERE TAKING NO CHANCES.

"But we are taking no chances. We circle round and round the spot and drop depth bombs—deadly machines. These are powerful explosives which are set so they will detonate at a certain depth. We first sounded the bottom and then set our bombs for ten fathoms. Suddenly I hear a cry from the boat behind us. One of the crew reaches out, grabs the collar of a man who has just dropped a depth bomb over the stern and yanks him unceremoniously into the cockpit. At a glance I see what has happened.

"The engineer has stalled his motor—just as the bomb was let go. It sinks slowly, and there is a slight momentum left in the submarine-chaser. We hold our breath and watch in suspense, expecting any second to see our comrades hurled into the air among a mushroom of water and splinters.

"There is no way to help them. Suddenly there is a muffled roar, a column of water rises to what seems a hundred feet, and falls back, drenching every one who is near it. But our comrades are unhurt. The momentum of their boat has carried them just far enough to save them from being blown to atoms. That is the second narrow escape for our little squadron in this chase after a single submarine.

"But our work is done. There is no doubt now about the fate of the U-boat. It is not necessary for one of the depth bombs actually to come in contact with the submerged craft to destroy it. When under water, a submarine's rigidity is multiplied. Its elasticity is next to nothing. An explosion as powerful as that of a depth bomb near it, is almost certain to cripple it if not destroy it. It is the same principle as that which kills fish in a pond when dynamite is exploded beneath the surface of the water. The shock is sufficient to kill the men in the U-boat, and so we glide along homeward, secure in the knowledge that even if our gunfire did not finish the enemy, the bombs have done the work. On the surface, we notice swarms of dead fish."

THE HAWK-EYED AEROPLANE.

The last wrinkle developed for submarine hunting was the aeroplane. Like a fish-hawk it can see its prey beneath the water by flying high in air. Another step just a bit in advance of aeroplane scouting for submarines is the use of a small dirigible for the same purpose. But the cleverest development of the aeroplane-submarine idea involved the use of seaplanes for the purpose of launching submarine torpedoes at enemy ships.

Here's how this is practiced. As most folks know, the seaplane differs from the land-flying craft in that it rides on floats instead of wheels. These floats permit the seaplane to come to rest on the waves, and to launch itself again. Between these floats, which resemble a pair of broad home-made sleds, may be slung a torpedo. The same type of missile, this, that is used by the submarine and the destroyer—a long, cigar-shaped cylinder, operated by compressed air driving a propeller, and equipped with a warhead filled with guncotton. The torpedo is held by slings, delicately adjusted so that they can be released in an instant.

The great seaplane, swinging the missile of death between its giant floats, climbs the skies in search of an enemy ship. From a distance of miles, perhaps, the seaplane looks like a gull. To the observer in the plane, however, sweeping the horizon with his binoculars, a ship is plainly and easily seen.

NOT TO BE OUT-DISTANCED.

Off in the distance is spied a ship suspected of being an enemy transport. It isn't hard to determine—the ship cannot steam away from them, no matter how swift its engines. A seaplane can go so fast that it makes the fastest torpedo boat destroyer look as if it were standing still. The attacked transport may try to bring its anti-aircraft guns to bear, if luckily it is equipped with them. Failing this, the soldiers will man the decks with their rifles ready. Then there is a duel of skill and daring between the men on the cruiser and the lone fighters in the seaplane.

The seaplane must swoop sufficiently close to the water to release the torpedo and let it drop without damage. And this must be done from a sufficient distance to safeguard the seaplane from the vessel's guns. The superior speed and mobility of the seaplane gives it a great advantage over the ship attacked.

Another of the weapons or instruments of warfare devised largely for use in destroying the evil submarine is the "blimp." This is nothing more nor less than a small dirigible balloon, hundreds of which the United States government started to build when it entered the war.

The blimp is an aerial sea-scout. Its principal employment is for observation. It is a watcher of enemy movements on the water. But it is also serviceable for attack, and especially for assailing submarines.

The British used blimps for the latter purpose, and to great advantage. The dirigible sausage-balloon, when a submarine is descried, can hover over it (as an aeroplane cannot), remaining as nearly stationary as may be desired, and waiting for an opportunity to drop a bomb with accurate aim.

If the submarine be under water, and its presence betrayed by the peculiar surface-ripple that marks its wake, a bomb with a delay-action fuse can be dropped upon it, the projectile not exploding until it reaches a depth of fifty feet or so. In case the first bomb does not score a hit, there are others to follow, with better luck perhaps.

THE IMPORTANCE OF THE "BLIMP."

Thus, it will be seen that the blimp is an important auxiliary of the flying-machine in the pursuit of the submarines. Both together, in this exciting sport, supplement the swift power-boats called "submarine-chasers."

For some time the Navy Department has trained enlisted men and officers for this work, chiefly at a Gulf port, where a school—it is no war secret—of aviation and ballooning has been maintained. Six officers and 40 men are required for each coast station.

The Navy Department adopted for the blimp a standardized pattern, with definite published specifications, in accordance with which contractors turned them out in numbers. It is a sausage-shaped balloon 160 feet long, with a great diameter of 31-1/2 feet, and containing, when inflated, 77,000 cubic feet of hydrogen gas.

The fabric of the "envelope"—that is to say, of the gas-bag—is coated both outside and inside with rubber. It is required that the balloon shall not lose more than 1 per cent of its gas-content in 24 hours. When inflated it must be able to carry (including its own weight) a total of 5275 pounds.

If the "Zeppelin" be excepted, the blimp is the most highly-developed and scientific heavier-than-air flying machine ever devised. It has a cruising speed of 35 miles an hour, but at a pinch can travel ten miles an hour faster. At the "cruising" rate, it carries enough gasoline to keep going for sixteen hours; at 45 miles, its load of "petrol" will suffice for ten hours.

Even the best war balloons of a few years ago were at the mercy of the winds. It is not so with the blimp. Barring storms, it is able to navigate the air as it wishes. It can rise safely to an altitude of a mile and a half. To furnish fuel for its engine of 100 horsepower it carries, in two tanks, 100 gallons of gasoline.

DESCRIPTION OF THE "BLIMP."

In effect, the blimp is a combination of balloon and aeroplane. Like the latter, it is provided with "skids" (resembling sled runners and made of ash wood), or sometimes with bicycle wheels, for safe landing on terra firma. When designed for sea scouting, floats—cylinders of waterproof fabric stuffed with vegetable fibre—are attached to the skids, or to the wheels, so that the airship, in calm weather, may be able to rest, like a sea bird, on the waves, if desired.

The blimp's balloon envelope must contain two smaller balloons, together holding 19,250 feet of hydrogen gas. The idea, of course, is that if anything happens to the major balloon—puncturing by gunfire or by other mishap—the "balloonets" inside of it will keep the machine afloat.

The wingless aeroplane is suspended from the balloon by cables of galvanized wire. There is a special arrangement by which the "pilot"—the man who steers and operates the airship—can at any time measure the pressure of hydrogen in the balloon, thus knowing what he has to count on in the way of carrying power.

The front part of the blimp's car is occupied by the engine and radiator, behind which is a bulkhead of sheet steel. In the rear of this bulkhead sits the pilot, and behind him the "observer," who makes sketches and takes notes of anything important that he sees. Behind the observer are the tanks for fuel oil and 300 gallons of water ballast. The body of the car is covered with aeroplane linen, save for the engine, which is sheathed with sheet aluminum.

In order to hold whatever position in the air may be desired, the blimp is equipped with two horizontal fins and three vertical fins. Not every blimp, that is to say, but the pattern approved and required of contractors by the Navy Department. These fins are made of wood and light steel tubing, reinforced with wire, covered with aeroplane linen rubber painted and finished with varnish.

THE "BLIMP" WELL EQUIPPED.

There are also two horizontal rudders and two vertical rudders, for steering up and down or sidewise. They work on ball bearings. A blimp, one should understand, is a fish in the ocean of air, a swimmer—just as the aeroplane is a flyer, like the bird.

The blimp's "car" carries an electric storage battery to furnish lights. The same battery energizes a searchlight for night scouting. A wireless apparatus, for transmitting information to the shore station, is part of the equipment.

The blimp, as already stated, is a sea scout. It is meant to be operated from a base on shore—which base is in constant communication by telegraph and wireless with the great radio stations that are strung all along our coasts at intervals of 200 miles. These stations, in turn, are in communication with the huge wireless outfit at Arlington (across the Potomac from Washington), whose "antennae," uplifted on tall steel towers, receive instantaneous war news from half the world.

Thus if (just for illustration) a blimp spies a hostile submarine, the news is instantly transmitted to the Navy Department. The department orders its "chasers" and warplanes nearest to the scene to go after the undersea boat. Within a few minutes the pursuit has started, and the U-boat finds itself in much the same situation as a fox hunted by hounds. In this case, however, the hounds are in the air, as well as "quartering" the aqueous terrain.

The United States' blimps are modeled on European patterns. But they are to have special improvements of their own. To make sure of their efficiency and structural correctness, each contractor, in offering bids to furnish them, was required to exhibit a model, exactly like the sausage balloons he proposed to make, but of toy size—one-thirtieth the length of the full-sized, completely equipped aerial sea scout.

THE EYES OF BATTLE.

Aeroplanes and Airships—They Spy the Movements of Forces on Land or Sea—Lead Disastrous Bomb Attacks—Valuable in "Spotting" Submarines—The Bombardment at Messines Ridge.

Just as the submarine has revolutionized warfare on the seas and presented new problems for the naval experts to solve, so the aircraft of the last decade has had its effect upon the operation of land forces. Probably the aeroplane and the dirigible balloon have had a greater influence on the conduct of battles and military campaigns as a whole than any other device utilized in connection with the war.

It is significant, too, that just as America produced the first submarine, and then failed as a nation to develop it to its highest state of efficiency for military use, so American inventors were pioneers in the construction and successful operation of aeroplanes, or airplanes, which were first developed to their greatest efficiency and utility by the French and Germans.

Some of the most striking events of the war centre around the use of the airplanes or dirigibles, and aside from the picturesqueness and thrilling atmosphere that seem to surround their use, the operator of the aircraft has proved himself one of the most valuable servants in modern warfare. He has reduced the proudest cavalry to second place in the matter of reconnoissance, and has rendered services which have heretofore been impossible.

The airman sails out over the lines of battle, so far above the earth when necessary as to be out of range of the most powerful guns, and with glasses looks down upon the whole country. His machine, whether it be a dirigible balloon or airplane, is equipped with a wireless telegraph instrument with which he is able to send brief messages back to his own line or military headquarters. He can and does mark the changed positions of the contending forces, note the entrenchments and reinforcements, follow movements, and last but not least, as was noticeable in one of the desperate attacks upon the German position in June, 1917, swoop down upon the enemy, attack the lines and forces with bombs, and rain bullets upon them from rapid-fire guns.

No longer can the enemy mask its heavy batteries or conceal them beneath earthen mounds, plant them in corners of the forests or in clumps of bushes without their being located. The "eyes of the sky," as the planes are now termed, can spy them out. And when the airman has communicated to his military commanders the positions of the opposing batteries, he acts as a director in instructing the friendly gunners in finding the range and cleaning out the enemy.

THE AIR SCOUT'S USEFULNESS.

The air scout can detect the enemy's lines of communication and raid it with bomb attacks. Even when the land forces cannot reach the enemy with gunfire he can rain missiles of all sorts upon them. Sometimes the airman flies over the enemy lines and drops glittering tinsel or bright metal devices, which falling to the ground serve as marks for the artillerymen in finding the range.

Where the cavalry scout or creeping scout of days gone by could never have proved successful, the airman has easily accomplished his purpose. He has carried messages from one frontier to another in hours, when it would have taken days for a scout on horseback or on foot to have rendered the service, if they could have accomplished it at all. He has eliminated distance.

Trench warfare developed in the world-war in a way that has never before been deemed necessary or possible, but the miles of trenches which conceal the men from the fire of the enemy are plainly visible to the airmen. And armed with cameras having powerful telescopic lenses they can photograph the entire scene and send to their own military headquarters not mere indicated plans of the battle lines, but exact photographs.

The war has shown conclusively that once the formation of the battle line has been decided upon it is, in a measure, a fixture. It may be subject to rearrangement, but this is when the force of battle demands, or for strategic purposes, but such an arrangement requires a great deal of time and much work. The battle fronts on the borders of France and Belgium have ranged from 100 to nearly 300 miles in length, with nearly 3,000,000 strung out in opposing lines along the entire distance.

LIKE AN IMMENSE GRIDIRON.

The ground has been dug up and trenched until the surface of the earth looks like an immense gridiron. The soldiers almost live within the trenches and dugouts beneath the ground. Telephone and telegraph wires run through the trenches and even railroad tracks are laid so that small engines go whirring through the ditches like "dinky" locomotives in a coal mine.

And the "eyes in the skies" make it possible for the commanders to know each other's strength and the disposition of the forces at all times.

Particularly has the air scout proved valuable in enabling commanders to execute their final orders without grievous error. There is danger of possible misjudgment because of the great length of the firing lines. The airmen verify positions and make last minute reports, taking minutes to perform services that cavalry forces or other scouting parties would have taken hours or days to render.

Operated in conjunction with cavalry scouts, and motor and cycle squads, the airplane is a destruction-directing and defensive force. And it was the large fleet of aircraft that aided Germany in making such rapid advance in its drive toward Paris in the early days of the war. The scouts reconnoitering in the early dawn were able to report the situation and give the commanders time to move their forces before the Belgians and French were aware of what was being done.

Germany had probably the largest fleet of airplanes at the beginning of the conflict and is said to have possessed upward of 500, of various sorts, and this does not include the famous Zeppelins or dirigible balloons. She also had something like two dozen factories which could turn out flying machines, and had been at work on the development of her aircraft long enough to have her patterns and methods of manufacture somewhat, if not entirely standardized. During the third year of the war it was estimated that she had more than quadrupled her force of flying machines.

GERMANY'S PREPAREDNESS.

Germany's preparedness in this as well as in other directions was what enabled her to obtain such a tremendous advantage in the beginning of the war. Later England and France concentrated on the development of aeroplane squads or corps, and when the United States entered the war one of the first detachments sent into France consisted of 100 aviators. How rapidly the aeroplane forces were developed is indicated by the statement made in the beginning of 1916 that the air forces of the Allies were represented by 3380 aeroplanes of various types and 64 dirigible balloons, while Austria and Germany had 2000 aeroplanes and 70 dirigibles.

The dirigibles—the type of airship commonly referred to as Zeppelins—have the advantage over the heavier-than-air machines of being almost silent in their operations, while at the same time they can remain for a longer time suspended in air over a camp or battleground without being detected. The Zeppelin is the development of the old balloon, made, however, in a conical shape with a long basket or car attached. They are driven by propellers similar to those used with aeroplanes, but as the power generated by the engines is merely used to drive the machines and has nothing to do with maintaining their position in the air, the motors do not have to be so powerful. They are steered by rudders.

Some of the largest Zeppelins which have been leading factors in night raids conducted by the Germans on London and English coast resorts are capable of maintaining a speed of 60 miles an hour. One of these immense Zeppelins was reported to have covered 1300 miles in less than forty hours, covering the German borders, and still keeping in touch with its base. The Zeppelins, because of their large size, can carry large quantities of bombs, wireless apparatus, signals and electric searchlights. They can rise to a height that places them fairly beyond the range of the aerial guns used for fighting the air forces of the army.

MANY KINDS OF BOMBS.

The bombs used are as diversified as the crafts on which they are carried. The French aviators at one time dropped long steel billets or arrows which had swedged heads and sharpened points. These missiles, dropped from the height of a thousand feet or more, attained a velocity and force which made them dangerous weapons of the minor sort.

The bombs, in the main, however, consist of jacketed shells containing high explosives, some of which are constructed on what is called the delayed-action principle. Such bombs explode after penetrating the fort or object which they strike, instead of going off by contact. Germany is said to have developed some of these that were of such size and power as to penetrate an armored ship. As much as 50 pounds of explosives or chemicals is declared to have been carried in some of the larger ones.

The big dirigibles mount machine guns of superior range. Some of them have been armored to an extent, and to make them less easily detected they have been painted tints and colors to harmonize with the clouds and sky. Special kinds of gas have been used to fill the envelopes or bags, and instead of one large bag they consist of a series of bags enclosed in an envelope or casing, so that if a bullet would penetrate the envelope it would only destroy one of the gas bags, and not cause the whole thing to collapse.

Besides having proved of great value in the land campaigns, the aircraft has shown itself to be one of the most effective devices of warfare for use against the submarine, and all manner of naval craft. From the heavens they can see the submarine under the water, and as either the dirigible or the aeroplane can develop a speed greater than that of any battleship or cruiser, it is not difficult for it to soar over the vessel and drop bombs upon it. Even gas bombs have been used in the raids by the aircraft.

ACCURACY THE GREAT DIFFICULTY.

The difficulty in the use of bombs has been in accurately directing the death-dealing devices when the airship or aeroplane is in motion. To assist in this work aerial range finders have been devised. These are constructed on the principle of the finder on a camera, with graded scale markings to indicate the allowance that must be made for speed and motion. Complete apparatus has been built up for launching the projectiles from the large dirigibles, and to insure the missiles traveling properly vanes have been attached to some of them.

In a test made under the auspices of the French Government and the Aerial Club of France, a few years ago, one of the bomb-launching machines on an aeroplane scored eleven bull's-eye shots in a target ten yards in diameter, from an altitude of more than 2000 feet, while the aeroplane was going at a speed of more than 65 miles an hour.

Though there has not been any widespread use of the plan the air has been "mined" in an experimental way to protect certain sections against night raids by the airmen. Mining the air consists of locating small balloons over an area, each balloon being attached to the other with wires. The small balloons have attached to them explosive bombs which would destroy the larger aircraft if it was to run into this nest of air vessels in the dark.

Reverting to the use of aircraft in naval warfare it may be said that to the aeroplane the relatively fast fleet is virtually stationary. About the only case parallel to the aeroplane looking over the hill and down on concealed enemy positions would be in rising above the smoke screen thrown out by destroyers.

THE SMOKE SCREEN.

The smoke screen, by the way, which has been used by the British with marked success in many instances, is an American invention. The low, swift craft are equipped with special oil burners which throw off dense volumes of heavy smoke, which float low over the surface of the water, concealing the maneuvers of the larger boats and protecting them from the skill of enemy gunners. Its effectiveness, of course, is influenced by the direction and strength of the wind. Used generously by small craft convoying a ship through a submarine area, it should be of great value.

A battleship can see about as far as it can shoot, anyhow. Except for smoke screen, or the famous "low visibility," which means foggy weather or darkness, no enemy within range can be concealed.

What the fleet commander wants to know is how those enemy vessels beyond the horizon, which may be within range of his guns tomorrow, the day after, or next week, may be distributed, and how many of them there are. This is where the speed of the airplane comes in.

A machine which can travel 100 miles an hour covers a thousand miles in 10 hours. Locating an approaching enemy fleet this distance away, it brings back the news of the approach in 10 hours. It takes the fleet, traveling at 15 miles an hour, two days and 18 hours to cover this distance. The aeroplane can beat it by two days and eight hours.

But the aeroplane flying high enough to give it the widest practical range of vision is able to see only over a path 75 miles wide under the most favorable weather conditions. Haze will cut this down considerably. This means that for anything like complete scouting work a fleet must be equipped with a large number of them.

PROPORTION OF FIGHTING PLANES.

Then, too, there must be a generous proportion of fighting planes to spread out in a very wide circle beyond the fleet. It will be appreciated that this circle must be a mighty wide one if the enemy planes be kept far enough away to prevent their counting the number and type of ships in the command. There is required also a large detail to guard against the submarines. While an aeroplane can see quite deep in the sea, this penetrating vision is limited to the water directly beneath it. It can see straight down in the water, but not off to the side at an angle.

If such a thing is possible, air control at sea is more important than over the land, and of first value is the fighting plane. In this connection there is an aeroplane gun which works well. It is a double-ender. That is, there is a breech in the middle, and the two ends are muzzles. In air fighting it is seconds and fractions of seconds that count, and the advantage of this gun lies in that it can be fired in opposite directions, thus cutting down the length of the arc through which it has to be swung to be brought to bear on the enemy.

Of exceptional value to the United States navy is the super-American type of planes which the Curtiss factories have developed and which have done such wonderful service for the British. In this type the fuselage is entirely enclosed, built with a hull much along the lines of the motorboat or hydroplane. The 'plane may thus come to rest safely in the open sea.

It weighs nearly 6000 pounds and can carry a useful load of more than 2000 pounds. The boat is slung well below the planes, eight feet below the lower one, which has a span of 66 feet. Eight feet above this is the upper plane, which overlaps the lower plane by 13 feet on each side. The complete span of the upper plane is 92 feet. It can carry six to eight men, if necessary, altogether a huge, sturdy, dependable machine with two powerful motors.

And what was done to give America the equipment of 'planes which we needed?

RESOURCES AT GOVERNMENT'S COMMAND.

Fifteen aeroplane manufacturers, with a combined capital of $30,000,000 and a total capacity of 175 machines a week, organized and placed all their resources at the command of the government. The organization provided for the interchange of ideas and plans and for the standardization of manufacture, which resulted in a material increase in output.

One hundred and seventy-five machines a week should give us, in a year, 9100. And there are other conditions which may modify the estimate both favorably and unfavorably. There is, for instance, a limit to the amount of seasoned lumber available in this country of the peculiar type and quality needed for airplane construction. Provision must be made for the future in this respect. All-steel machines have been made and used in Europe to some extent, but no metal alloy has been developed which is likely to take the place of wood in general construction. The manufacturers developed some interesting things along these lines which were not given to the public.

In the Spring of 1917 the fighting in the air took on an entirely new interest abroad, because of the German policy of painting their machines most grotesque patterns. They seemed to have taken this idea from the old American Indian custom of painting their faces to frighten their opponents, or else the fancies of the German airmen were allowed to run riot with vivid color effects.

British pilots daily brought home from over the lines new reports of fantastic creations encountered amid the clouds. The gayest feathered songsters that came north with the Spring did not rival the variegated hues of the harlequin birds that rose daily from the German airdromes. The coming of this fantastic order of things in the air was first heralded by a squadron of scarlet German planes. It then was noticed that some of the enemy machines were striped about the body like yellowjackets.

GAUDY TASTES OF AIRMEN.

Nothing appeared too gaudy to meet the tastes of the enemy airmen, who seemed to have been given carte blanche with the paint brush. There were green planes with yellow noses, silver planes with gold noses, khaki-colored planes with greenish-gray wings, planes with red bodies, green wings and yellow stripes, planes with red bodies and wings of green on top of blue, planes with light blue bodies and red wings. Virtually all the gaudiest machines were in red body effects, with every possible combination of colors for their wings. Some had one green wing and one white; some had green wings tipped with various colors.

One of the most fantastic met had a scarlet body, brown tail and reddish-brown wings, with white maltese crosses against a bright green background. One machine looked like a pear flying through the air. It had a pear-shaped tail and was painted a ruddy brown, just like a large ripe fruit. One of the piebald squadrons encountered was made up of white, red and green machines. There still were others palpably painted for what became known as "camouflage" purposes, as guns, wagons and tents often are painted to blend with the landscape and thus avoid detection.

This lavish use of paint, however, did not reduce the heavy daily loss inflicted on the Germans by the British flyers. But it must not be imagined that the Germans did not put up a stalwart fight. Just as their resistance was strengthened on land, so it was increased in the air. Just as the Germans threw in new divisions of infantry and new batteries of artillery to check the Allies' offensive, so they sent aloft hundreds of new machines to contest for the mastery of the air, an important phase of modern war.

The manner in which the British flying corps dominated the air during the battle of Messines Ridge in June, 1917, and completely smothered the German aviation service for the time being is one of the most thrilling and remarkable stories of the entire war.

Hundreds of British planes were well behind the German lines when the battle broke into its fury at dawn. They had stolen over during the darker intervals of the brief night when the moon was hidden by storm clouds. Other hundreds went aloft with the first faint streaks of coming day and, guided by the flashes of the guns, flew into the thick of the fighting.

COMBED BY MACHINE GUNS.

During the night British machines combed enemy railway stations, trains, ammunition dumps and troops coming up on the march. Others hovered above German airdromes and circled low among airplane sheds and fired hundreds of rounds from machine guns into them and prevented the enemy machines from coming out. Later in the day, while the fighting was most intense, British airmen dropped about three tons of bombs on the German flying grounds as a further deterrent, which proved highly effective.

In addition to shutting the German airmen out of any early participation in the battle, the British airplanes were in a large degree responsible for the fact that the Germans could not launch a counter-attack of appreciable strength until forty hours after the battle for the ridge began and every bit of ground desired by the British in this particular operation had been taken and secured.

Far back of the German lines the British planes searched out troops in every hamlet, town and village. In several places they saw them gathering or marching in the main streets, whereupon they flew down low at times and opened a fire which scattered the gray-clad soldiers in all directions. All pilots report that their accurate fire had a most demoralizing effect upon the hostile troops. Convoys and ammunition and supply columns were attacked while on the march and the disorganized men left their teams and automobiles on the roads while they sought shelter in nearby ditches.

AIRPLANES ATTACK TROOPS.

Airplanes attacked troops in the support trenches and sent them scurrying to the cover of their dugouts. One pilot made so many of these attacks that he finally ran out of ammunition, but he delivered his last stroke by letting go his signal rockets at a platoon of soldiers who, evidently mistaking this for some particularly horrible new style of war frightfulness, fled in all directions.

German troops were fired upon in the more distant back areas as they were entraining for the front. Many of the enemy retreating from the British attack and hiding in shell holes were seen by the low-flying airmen and pelted with bullets.

One British pilot patrolled a road for half an hour before he saw anything to shoot at. Then a German military automobile with three officers sitting in the back seat came along. The Britisher dived at them from a height of three hundred feet, firing at them as they came. He flew so low eventually that the wheels of his under carriage barely missed the automobile, which swerved into a ditch while going at about forty miles an hour and crashed into a tree.

This same pilot later came across an active field gun battery and charged it, scattering the gun crew and hitting a number of them. Still further along he attacked a column of Germans marching in fours. The column broke when he opened fire, scattering to both sides of the road. At no time during his stay inside the German lines was this pilot more than 500 feet from the ground.

ON CONTACT PATROL WORK.

Large numbers of British machines were on contact patrol work, flying low over the advancing lines of infantry, constantly watching their movements, their progress, any temporary reverse, any attempt to form counter-attacks and all the while sending detailed reports back to corps and army headquarters.

Of the fourteen planes lost during the day of the battle, a majority were those contact machines. They had to fly through a frightful storm of their own as well as the enemy's artillery fire, and they succumbed to chance blows from these exploding missiles.

Late on the day of the battle, when the enemy machines had finally arrived from more distant airdromes, there was some good fighting in the air, some of it at close quarters with collisions barely avoided. Twenty enemy machines were accounted for in the fighting, some flopping about until they broke up in the air and others being driven down on their noses in yellow buttercup fields so far back of the fighting line that no shell had ever marred the symmetry of the landscape.

Some of the most marvelous work was done by artillery airships. One squadron of these alone, acting with several batteries of British heavies, succeeded in silencing seventy-two German batteries before six o'clock on the morning of the attack which began at 3.10 o'clock in the morning. These planes also directed the firing on the enemy's guns en route to the front, some of the big weapons being drawn by caterpillar tractors. Wherever a thousand or more troops were observed forming for possible counter-attacks the artillery planes directed "shoots" upon them.

So complete was the British domination of the air along the front of attack that not a single one of the British artillery observing aeroplanes was lost during the week that the intense bombardment was going on. During the battle British aeroplanes also attacked and silenced a number of enemy machine-gun positions.

The growth of the aeroplane industry has developed as many makes of machines as there are makes of automobiles, but in a general way aeroplanes are divided into four classes—monoplanes, biplanes, triplanes and hydroplanes. About 90 per cent of all designs are monoplanes and biplanes, and the types are distinguished by their single set of wings or planes or the double planes or wings. Both types have their advantages in use, the biplane being regarded as more stable for certain scouting purposes than the monoplane. It can carry heavier weights—has greater lifting power—but is not capable of as great speed or as easily maneuvered.

MACHINE ON PRACTICAL BASIS.

The War has placed the machine on an intensely practical basis. The manufacturers have learned that machines constructed along certain lines will travel at such and such a speed and have a certain lifting capacity, will rise under a particular speed and may be expected to do certain things under certain circumstances, but with all the advance which has been made in the construction of the air machines, the designers do not yet understand all the "factors" that enter into the "why" of the case.

The makers have, however, succeeded in standardizing their machines to a degree. The story of how the aeroplane flies is a highly technical and scientific one, but the basic principle is the reaction of air and an inclined surface in motion. It might be likened to a stone skipping across the surface of a pond, if the imagination can conceive of the water as being air. It is simplicity itself to drive an inclined plane against the air with such force that the impact will produce a lifting power. In raising an ordinary kite, for instance, the boy runs into the teeth of the wind. His kite is so attached to a string as to stand at an angle, and as he runs the pressure against the air drives the kite upward. In the aeroplane the propellers drive the machine into the air with such force that the planes, standing at an angle, guide the machine upward.

There are innumerable problems to be solved—those of buoyancy, delicacy of balance and many others—but the designers themselves have not been able to determine upon a precise formula for their solution. It is sufficient that the aeroplane has reached a degree of practicability in construction and use which insures its permanent existence, and has given the military and the naval forces one of the greatest agencies in the world for protecting themselves and watching their enemies.

WAR'S STRANGE DEVICES.

Chemistry a Demon of Destruction—Poison Gas Bombs—Gas Masks—Hand Grenades—Mortars—"Tanks"—Feudal "Battering Rams"—Steel Helmets—Strange Bullets—Motor Plows—Real Dogs of War.

Things new and passing strange—thousands of them—have been brought into being by the great world war. Human minds have developed things undreamed of by science or fiction—things that a few years ago would have been considered too strange and fantastic for even the professional romancer to weave into the tissues of his stories.

Every known science has been called upon to produce its quota of new things which might be used for the destruction or the protection of men at war. The wonders of chemistry have always lent descriptive inspiration to the pen of writers, but mankind to get a vivid conception of the horrors of chemistry has had to wait for the great world war.

The conflict which has involved the entire world might almost be termed a warfare of chemists. Without their diabolical products, ranging all the way from high explosives to poison gases, it would have few of the characteristics of ultra-frightfulness that render it unique in the history of international struggles.

But of all the instruments of destruction used in this war, there is none more horrifying than the so-called "incendiary bomb," which sets instant fire to whatever it touches and which spreads flame in a manner so terrific that three or four such gravity-projectiles dropped from an aeroplane burned up the whole of a peaceful Dutch village in a few minutes.

Now, what is the fearsome stuff with which such bombs are loaded? A new chemical compound? Not at all. What they contain is simply the mixture of two of the most harmless things in the world—oxide of iron (which is simply iron rust) and powdered aluminum.

When these two innocent substances are mixed together the result is a compound truly infernal in its potentialities for mischief. It is not an explosive but if set on fire it burns with an intensity that is positively appalling. Nothing will put it out; no quantity of water has any effect upon the raging flames it engenders.

This is the material used for loading incendiary bombs. It is ignited in such projectiles by a mercury-fulminate cap that sets off a fuse containing powdered magnesium—the stuff photographers employ for flashlights.

THIN SHELLS OF STEEL.

These bombs are thin shells of steel or iron—mere containers for the mixture before described. They are so contrived that the fuse is instantly ignited when they strike.

Whereupon the shell is melted by the heat generated within it and a flood of fiercely burning metal is scattered in all directions. All of this seems rather extraordinary, and it is worth explaining.

Oxygen has an affinity for iron, readily combining with the latter—which is the reason why iron is liable to rust. This rust is a chemical compound of iron and oxygen; in other words, oxide of iron. But oxygen has a much greater affinity for aluminum. And so, when the two metals are powdered and mixed together and heat is applied the oxygen flies out of the iron rust and combines with the aluminum.

The process is started in the bomb by the burning magnesium. And then the oxygen passes out of the iron and into the aluminum so rapidly that an enormously high temperature is developed. It runs up to 3500 or 4000 degrees Fahrenheit—which means, of course, a tremendous combustion. The mixture of aluminum and iron burns like so much tinder—though such a way of putting it is absurdly feeble.

The present war has been conspicuously marked by reversions to ancient methods of fighting. In this line the incendiary bomb offers an excellent illustration. It is in effect merely an adaptation of an idea utilized by the Saracens—we should call them Turks nowadays—in their warfare with the Crusaders of the Middle Ages.

DREAD INSTRUMENT OF WAR.

The instrument of war most dreaded by the Crusaders, as they found it in the hands of the Turks, was the incendiary bomb—a projectile that flew through the air "like a fiery dragon" as they described it, and set fire to whatever it touched. Sometimes it was provided with iron barbs, by which it clung to buildings.

This was one of the ways in which the Saracens employed the celebrated "Greek fire"—an inflammable compound that is understood to have been a mixture of petroleum, saltpeter and pitch. The chief horror of it, from the Crusaders' point of view, was that it was unquenchable. Mere water had no effect upon it. Hence they were sure that it must be of diabolical origin.

But the up-to-date incendiary bomb is a great improvement on its original of the Middle Ages. The modern contrivance is thoroughly scientific, and it does its destructive business with certainty and dispatch.

No less effective are the gas bombs which were introduced by the German soldiers at Rheims, and which when exploding near the trenches occupied by the French and English threw off vapors and poisonous gases which killed or overwhelmed thousands of brave men. These devices used in violation of all rules of civilized warfare sent hundreds to the hospitals. Seventy-five victims were taken at one time from the trenches to the hospital at Zuydcoote, north of Dunkirk, where it was found that some of those who had inhaled the fumes turned a violet tinge.

Altogether it was estimated that from 3000 to 5000 men were affected by the gas fumes in this first onslaught and at least 10 per cent of those who were overcome succumbed to the deadly fumes. Many of those who inhaled the poisons expectorated blood and for days afterward were racked by terrible coughing. In many cases fever developed in a few days ending with pneumonia. When the men were not sufficiently poisoned to cause death they were so affected that their usefulness as soldiers was ended for all time. The poison made them confirmed invalids.

INTRODUCTION OF GAS MASK.

Naturally human ingenuity was called into play to protect men against the poisons and the gas mask came into being. These were of many types. The early creations consisted primarily of a nose and mouth covering with a receptacle for inclosing a sponge or gauze soaked with a chemical which possessed the power to neutralize the gas fumes. Such devices have been used by fire fighters in large cities the world over where the men battling to save buildings have been compelled to enter smoke-filled rooms and cellars. Other types which have proven more effective are designed after the fashion of the diving apparatus, and having a small tank of compressed oxygen with feeding tubes running to the mask. The oxygen combines with the contaminated air breathed through absorbent cotton or sponge and provides the wearer with the proportion of oxygen necessary to existence. And even the horses have been provided with such masks.

But to go back to bombs. All through France and Belgium, and wherever the Prussian soldiers found their way, there was evidence of the use of hand grenades which were thrown against the sides of or into buildings to set them in flames. Some of these devices, made of sheet metal, were in their action similar to the "Fourth of July torpedoes" familiar to every American school boy. When thrown they exploded throwing oil and chemicals over walls and floors. Some of them seem to have been loaded with bullets and were in effect hand shrapnel.

Then there developed from the primary use of these nefarious weapons the recognized hand grenade, which is actually hand-shrapnel, plied by men at close quarters. Thousands of these have been thrown by the armies in their charges on the trenches. And then, to offset the use of these devices in the offensive, there came into being also the smoke bombs. These when exploding throw up great clouds of black smoke which hang over everything.

EFFECTIVE IN A HUNDRED WAYS.

The use of such bombs has proved effective in a hundred ways. They have been used to create a perfect shield of smoke to conceal the movements of troops, or prevent the enemy from finding the range with their long distance guns. Similarly bombs which contained burning chemicals have been used to hold in check the approaching enemy forces.

Half way between the great gun and the hand grenade stand among war weapons the trench mortars. The first of these were used by the Japanese in their war with Russia. The Japanese mortars were mere logs hollowed out and strengthened by wrappings of bamboo rope. The projectiles fired from these were empty provision tins filled with high explosives, scraps of metal, bits of stone or whatever, in the emergency, could be found to fill them.

The mortars are pitched at an angle and the projectiles are shot with a skyrocket effect, to land in the trenches or camp of the enemy. The Germans developed the idea and the perfected mortars are of steel, and capable of throwing bombs weighing several hundred pounds.

And then the great moving fort which has been called "the tank!" Those snorting, fire-spitting dragons which were depicted for us in childhood can scarcely bring to our mind a greater element of the fanciful, the horrible, and the powerful than the steel hulks which came into being in this war under the name of "tanks."

We see them in our mind's eye spitting fire as they crossed No Man's Land, amid the smoke and dust of bursting shells. Keeping steadily on their courses they dived into huge craters made by exploding shells; stretched themselves across trenches, brushed trees and boulders aside, and kept steadily on their courses. German wire entanglements were as so many pieces of string before their huge frames. Nothing deterred them. They moved forward into the face of the enemy, reaching the first line of German trenches. There the soulless devices sat complacently astride the trenches, and turning their guns along the ditches swept them in both directions.

THE TANK DEFIES ALL OBSTACLES.

The tanks which were introduced by the English, move along on revolving platforms, so to speak. These platforms enable the tank to overcome all obstacles as the caterpillar tread is curved up in the arc of a huge circle at the front which gives the vehicle its wonderful tractive powers. This large curvature acts as a huge wheel with a tremendously long leverage equal to the radius of the circlet or the spokes of the imaginary wheel of the same diameter. Only that portion of the assumed wheel which would come in contact with the ground acts as the lever, and it is just this portion that is reproduced in the front end of a caterpillar belt.

Although varying in size and details, all tanks have the common characteristic of being divided into three main compartments between the two side caterpillar frames. The first is the observation compartment in which the driver and his helper are perched high above the ground to direct the movements of the huge steel beast.

In the middle is the ammunition room from which the guns carried in the two side turrets are fed. At the rear is the engine room. From two or four gasoline engines are used—these driving the rear axle and its integral sprockets over which the caterpillars run. The latter run an idler pulley or sprockets at the extreme front ends and are supported by means of rollers attached to the upper portion of the frame on each side when passing over the top. This movement of the caterpillar belts is exactly analogous to that of the ordinary variety of garden insect with the same name which similarly lays down his own track by humping his back continuously and regardless of the land surface.

The tanks are steered by a pair of small ordinary wheels at the rear. These are supported in a pivot on a frame extended from the rear. They are merely for steering, and support none of the weight of the tank except when bridging wide trenches or dips in the surface. Steering can be accomplished by making one caterpillar go faster than the other by manipulating clutches on the driving mechanism.

TANK'S "CATERPILLAR" FEATURE.

The "caterpillar" feature of the tank had its origin in the caterpillar belts or shoes which were first used on the great field guns and mortars—those tremendous weapons which shoot bombs and shells weighing tons and containing 500 or more pounds of guncotton or explosive which on contact is discharged, rending everything for yards around.

These guns, as well as the smaller field guns, have had attached to them great shields of steel behind which the gunners stand, so that they are protected against the old-fashioned sharpshooters whose duty it was to pick off the gunners.

The caterpillar or wheel belts on the big guns consist of flat blocks, or shoes, wider than the tires of the wheels. They are hinged and fastened together so as to form a great chain, and when placed on the wheels present broad surfaces to the ground and keep the gun carriages from sinking into the soft earth. With a set of these shoes a heavy gun can be drawn over soft and irregular ground, which would be almost impassable where the gun is mounted on wheels of ordinary width.

Before these belts were devised it was necessary for every gun crew to carry a supply of beams, jackscrews and devices to be used in extricating the heavy guns when they got fast in the mud. Now every gun has these belts which can be put on or detached in a few minutes.

Paradoxically, this is the day of the big gun's greatest effectiveness, and the day of its greatest limitations. The war has taught us more in two years about gunnery and the effect of various types of ordnance under varying conditions than could have been learned in twenty years of theoretical research—for actual experience proves where theoretical research merely gives ground on which to base an opinion.

NATIONAL RESOURCES TO DISLODGE A MAN.

One of the things that we have learned is that when man takes unto himself the humble pick and shovel and proceeds to dig a hole for himself in the ground, we can get him out of that hole only by drawing on the combined resources of a nation, by constructing one of the most complex and expensive instruments in the world, and with it hurling at man dug-in a projectile weighing a good part of a ton.

The blunder, perhaps unavoidable, which stands out with equal emphasis among the preliminary preparations of all the nations engaged in the struggle was the underestimation of the artillery power required for the conduct of a successful military campaign under modern conditions of warfare. It was an underestimation so great that in the light of developments it will some day prove ridiculous.

At the opening of the war two opposed theories of artillery effectiveness were held by the combatants. The French swore by the medium calibre, rapid-fire, low-trajectory field piece. The Teutons had devoted their best efforts to the development of guns so big that their opponents were tempted, before they learned better, to regard them as too unwieldy for effective field service. Both were right, the French in the full sense and intention of the term, the Teutons by pure accident.

It should be explained here that the word Teuton is used advisedly, for in reality it is to the Austrians before the Germans that the development of the 11-inch and bigger field gun, with its special carriage and caterpillar-tread wheels owes its existence. It was Austrian guns and Austrian gunners that first made the heavy artillery of the Teuton armies famous.