have marked it German. Vast multitudes of men went to and fro, many in white and drab fatigue uniforms busy about the balloons, others drilling in sensible drab. Here and there a full uniform glittered. The airships chiefly engaged his attention, and he knew at once it was three of these he had seen on the previous night, taking advantage of the cloud welkin to manoeuvre unobserved. They were altogether fish-like. For the great airships with which Germany attacked New York in her last gigantic effort for world supremacy—before humanity realized that world supremacy was a dream—were the lineal descendants of the Zeppelin airship that flew over Lake Constance in 1906, and of the Lebaudy navigables that made their memorable excursions over Paris in 1907 and 1908.     

       These German airships were held together by rib-like skeletons of steel and aluminium and a stout inelastic canvas outer-skin, within which was an impervious rubber gas-bag, cut up by transverse dissepiments into from fifty to a hundred compartments. These were all absolutely gas tight and filled with hydrogen, and the entire aerostat was kept at any level by means of a long internal balloonette of oiled and toughened silk canvas, into which air could be forced and from which it could be pumped. So the airship could be made either heavier or lighter than air, and losses of weight through the consumption of fuel, the casting of bombs and so forth, could also be compensated by admitting air to sections of the general gas-bag. Ultimately that made a highly explosive mixture; but in all these matters risks must be taken and guarded against. There was a steel axis to the whole affair, a central backbone which terminated in the engine and propeller, and the men and magazines were forward in a series of cabins under the expanded headlike forepart. The engine, which was of the extraordinarily powerful Pforzheim type, that supreme triumph of German invention, was worked by wires from this forepart, which was indeed the only really habitable part of the ship. If anything went wrong, the engineers went aft along a rope ladder beneath the frame. The tendency of the whole affair to roll was partly corrected by a horizontal lateral fin on either side, and steering was chiefly effected by two vertical fins, which normally lay back like gill-flaps on either side of the head. It was indeed a most complete adaptation of the fish form to aerial conditions, the position of swimming bladder, eyes, and brain being, however, below instead of above. A 

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