On the other hand, it is to be presumed that the dirigible is armed. In this event it has a distinct advantage. It has a steady gun-platform enabling the weapons of offence to be trained more easily and an enhanced accuracy of fire to be obtained. In order to achieve success it is practically imperative that an aeroplane should obtain a position above the dirigible, but the latter can ascend in a much shorter space of time, because its ascent is vertical, whereas the aeroplane must describe a spiral in climbing. Under these circumstances it is relatively easy for the airship to outmanoeuvre the aeroplane in the vertical plane, and to hold the dominating position.

But even should the aeroplane obtain the upper position it is not regarded with fear. Some of the latest Zeppelins have a machine gun mounted upon the upper surface of the envelope, which can be trained through 360 degrees and elevated to about 80 degrees vertical. Owing to the steady gun platform offered it holds command in gun-fire, so that the aeroplane, unless the aviator is exceptionally daring, will not venture within the range of the dirigible. It is stated, however, that this upper gun has proved unsatisfactory, owing to the stresses and strains imposed upon the framework of the envelope of the Zeppelin during firing, and it has apparently been abandoned. The position, however, is still available for a sniper or sharpshooter.

The position in the sky between two such combatants is closely analogous to that of a torpedo boat and a Dreadnought. The latter, so long as it can keep the former at arm's, or rather gun's, distance is perfectly safe. The torpedo boat can only aspire to harass its enemy by buzzing around, hoping that a lucky opportunity will develop to enable it to rush in and to launch its torpedo. It is the same with the aeroplane when arrayed against a Zeppelin. It is the mosquito craft of the air.

How then can a heavier-than-air machine triumph over the unwieldy lighter-than-air antagonist? Two solutions are available. If it can get above the dirigible the adroplane may bring about the dirigible's destruction by the successful launch of a bomb. The detonation of the latter would fire the hydrogen within the gas-bag or bags, in which event the airship would fall to earth a tangled wreck. Even if the airship were inflated with a non-inflammable gas—the Germans claim that their Zeppelins now are so inflated—the damage wrought by the bomb would be so severe as to destroy the airship's buoyancy, and it would be forced to the ground.

The alternative is very much more desperate. It involves ramming the dirigible. This is undoubtedly possible owing to the speed and facile control of the aeroplane, but whether the operation would be successful remains to be proved. The aeroplane would be faced with such a concentrated hostile fire as to menace its own existence—its forward rush would be frustrated by the dirigible just as a naval vessel parries the ramming tactics of an enemy by sinking the latter before she reaches her target, while if it did crash into the hull of the dirigible, tearing it to shreds, firing its gas, or destroying its equilibrium, both protagonists would perish in the fatal dive to earth. For this reason ramming in mid-air is not likely to be essayed except when the situation is desperate.

What happens when two aeroplanes meet in dire combat in mid-air and one is vanquished? Does the unfortunate vessel drop to earth like a stone, or does it descend steadily and reach the ground uninjured? So far as actual experience has proved, either one of the foregoing contingencies may happen. In one such duel the German aeroplane was observed to start suddenly upon a vol-plane to the ground. Its descending flight carried it beyond the lines of the Allies into the territory of its friends. Both came to the conclusion that the aviator had effected his escape. But subsequent investigation revealed the fact that a lucky bullet from the Allies' aeroplane had lodged in the brain of the German pilot, killing him instantly. At the moment when Death over took him the aviator had set his plane for the descent to the ground, and the machine came to earth in the manner of a glider.

But in other instances the descent has been far more tragic. The aeroplane, deprived of its motive power, has taken the deadly headlong dive to earth. It has struck the ground with terrific violence, burying its nose in the soil, showing incidentally that a flying machine is an indifferent plough, and has shattered itself, the debris soaked with the escaping fuel becoming ignited. In any event, after such a fall the machine is certain to be a wreck. The motor may escape damage, in which event it is salvaged, the machine subsequently being purposely sacrificed to the flames, thereby rendering it no longer available to the enemy even if captured. In many instances the hostile fire has smashed some of the stays and wires, causing the aeroplane to lose its equilibrium, and sending it to earth in the manner of the proverbial stone, the aviators either being dashed to pieces or burned to death.

What are the vulnerable parts of the aeroplane? While the deliberate intention of either combatant is to put his antagonist hors de combat, the disablement of the machine may be achieved without necessarily killing or even seriously wounding the hostile airman. The prevailing type of aeroplane is highly susceptible to derangement: it is like a ship without armour plate protection. The objective of the antagonist is the motor or the fuel-tank, the vital parts of the machine, as much as the aviator seated within.

A well-planted shot, which upsets the mechanism of the engine, or a missile which perforates the fuel tank, thereby depriving the motor of its sustenance, will ensure victory as conclusively as the death of the aviator himself. Rifle fire can achieve either of these ends with little difficulty. Apart from these two nerve-centres, bombardment is not likely to effect the desired disablement, inasmuch as it cannot be rendered completely effective. The wings may be riddled like a sieve, but the equilibrium of the machine is not seriously imperilled thereby. Even many of the stays may be shot away, but bearing in mind the slender objective they offer, their destruction is likely to be due more to luck than judgment. On the other hand, the motor and fuel tank of the conventional machine offer attractive targets: both may be put out of action readily, and the disablement of the motive power of an enemy's craft, be it torpedo-boat, battleship, or aeroplane, immediately places the same at the assailant's mercy.

Nevertheless, of course, the disablement of the airman brings about the desired end very effectively. It deprives the driving force of its controlling hand; The aeroplane becomes like a ship without a rudder: a vessel whose helmsman has been shot down. It is unmanageable, and likely to become the sport of the element in which it moves. It is for this reason that aviators have been urged to direct their fire upon the men and mechanism of a dirigible in the effort to put it out of action. An uncontrolled airship is more likely to meet with its doom than an aeroplane. The latter will inevitably glide to earth, possibly damaging itself seriously in the process, as events in the war have demonstrated, but a helpless airship at once becomes the sport of the wind, and anyone who has assisted, like myself, in the descent of a vessel charged with gas and floating in the air, can appreciate the difficulties experienced in landing. An uncontrolled Zeppelin, for instance, would inevitably pile up in a tangled twisted ruin if forced to descend in the manner of an ordinary balloon. Consequently the pilot of a dirigible realises to the full the imperative urgency of keeping beyond the point-blank fire of aerial mosquito craft.