black and yellow of Imperial Germany, everywhere the black eagles spread their wings. Even without these indications, the large vigorous neatness of everything would 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 manœuvre 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,
