Up and up climbed the Zeppelin. She was approaching the East Coast.
Von Eitelwurmer, overcoming his torpor, went to the window. One of the men was about to motion him to his seat, when another touched him on the shoulder and pointed.
Far below the whole country was in darkness. The spy could not tell whether it was land or water. Away to the southward a group of searchlights swept the sky, the beams impinging upon a bank of clouds that floated at a height of nearly a mile. Still further away more electric rays swayed slowly to and fro. At intervals the searchlights of the nearmost station crossed those of the one more remote, while in turn these effected a luminous exchange with rays still further away. As far as the eye could see there appeared to be a continuous barrage of light through which the returning raider must pass before gaining her base.
At an order the motors were switched off. Almost absolute silence succeeded the noisy roar of the seven 240-horse-power engines. The airship, at the mercy of the winds, began to turn broadside on to the aerial drift, yet the while, by means of ballast thrown overboard and the release of more compressed hydrogen from the cylinders into the ballonets, was steadily climbing.
It was von Loringhoven's aim to ascend until the Zeppelin was above the clouds. Screened from those dangerous searchlights the airship would then drift over the coast-line until such times as it would be deemed safe to restart the motors.
With the altitude gauge hovering at 4,000 metres the raider found herself just above the natural screen. The belt of clouds was not more than three hundred feet in height—sufficient to hide her from the earth, yet transparent enough to allow the rays of the searchlight to penetrate the vapour.
To the spy the outlook resembled the view from a railway carriage when dense clouds of steam waft past the windows. So powerful were the rays of the searchlights that the stratum of the vapour was flooded with silvery luminosity, while—ominous sign—the beams no longer swayed to and fro as previously, but hung with sinister persistence upon the bank of clouds with which the airship hoped to screen herself from observation.
Even as von Eitelwurmer looked a huge dark shadow eclipsed the concentrated beams. It was moving slowly at a rate hardly exceeding that of the airship. For that reason the object could not be an aeroplane. Perhaps it was some deadly invention that the English had brought into action against the Zeppelins—a sort of aerial torpedo steered by wireless electric waves?
The machine-gunners saw it too. The last atom of courage literally oozed out of their boots, yet almost automatically they gripped the handle that would liberate shots at the rate of 500 a minute if to the voidless night.
It was fortunate for them that they did not open fire. The shadow was that of another Zeppelin that at less than a hundred feet below was slowly forging ahead in a southerly direction under the action of her throttled-down motors, and with her exhausts carefully muffled.