Peering through the gap between the turntable and the encircling wall, Hamerton could see the sun shining upon the upper portion of the red sandstone cliffs that enclosed the vast artificial basin. His field of vision was limited, but he was able to come to the conclusion that the floor of the airship sheds was nearly two hundred feet below the surface of the tableland that comprised the major part of the island.
Between each pair of caverns constructed for the accommodation of the Zeppelins was an iron ladder running perpendicularly up the sheer wall of sandstone. These were connected by an open lattice platform just above the crown of the arch formed by the caves, and were evidently for the purpose of facilitating the movements of the airships when entering or leaving their bases. Curiously enough, both Hamerton and Detroit had previously failed to notice these ladders when making a circuit of the basin.
"They are naval airships," announced the Sub, for men were swarming up and down the ladders with a seeming recklessness that only seaman dare show, and they were wearing the uniforms of the German Imperial Navy.
"Here she comes," said Detroit, as the huge bulk of a Zeppelin emerged slowly yet steadily from its resting place.
"What a superb target!" commented the Sub. "A dose of shrapnel would knock the whole concern to smithereens, while one of our seaplanes with a one-pounder automatic gun would make rings round her."
"I don't know so much about that," said Detroit. "Just look at the aluminium body just abaft the 'midship car. It's been holed at one time, and they've put a patch on it."
"An accident, perhaps," rejoined Hamerton. "The airship looks rather old."
Over the heads of the two watchers passed the unwieldy craft. Now they could hear the jar of the framework as it settled on the turntable. Then, with hardly a sound and barely a tremor, the platform began to move until the bows of the Zeppelin pointed in the direction of the great incline. The six propellers began to revolve, and the airship, gathering way, rose rapidly and steadily, keeping almost parallel with the slope. Then, gaining an altitude of nearly five hundred feet, she circled slowly and disappeared beyond the limits of the vision of the two spectators in the pit.
