"Sir?"
"Rout out Anderson and Bell. Tell them we must get under way in five minutes."
Quickly the preparations for the urgent flight were completed. Squads of mechanics set to work, each man knowing exactly what was required of him, and doing it expeditiously and without undue noise. The petrol tank was filled by means of hose pipes communicating with the distant fuel reservoir, hydrogen was pumped into the pressure cylinders and thence into the envelope, until the manometer registered the requisite lifting power. Machine-gun ammunition was already on board, but the deadly aerial torpedoes, risky missiles to handle even with the safety caps in position over the sensitive detonating mechanism, had to be brought from a store at some distance from the sheds.
While this work was in progress, Barcroft and Kirkwood were busily engaged in testing controls and supervising the work of the mechanics. Long experience had taught them that "if you want a thing to be well done, you must do it yourself"; failing that, the next best course is personally to overlook the job.
Presently the two remaining members of the Blimp's complement hurried up. It occasioned them no surprise to be turned out almost as soon as one cruise had been completed. The airship patrol was much like the lifeboat service or a fire-brigade in the metropolis: its work was never ended. Beyond the ordinary routine there were emergency calls at any hour of the day or night.
"All ready?" asked the lieutenant.
He raised his hand. The motor began to purr, the swiftly revolving propeller churning up a cloud of dust that speedily rose as high as the recently vacated shed. The assistants, holding on to the restraining ropes, awaited the signal.
Barcroft lowered his hand smartly. With a motion not unlike that of a lift suddenly starting to ascend, the Blimp shot vertically upwards, the drag of her propeller being just sufficient to counteract the light head wind.
Not until the altitude gauge registered two hundred feet did the airship begin to forge ahead. Gradually the motor controls were opened out until the din of the whirling propeller grew terrific. At fifty miles an hour, and with the huge gasbag quivering under the enormous wind pressure, the Blimp tore to the aid of the torpedoed cruiser.
Kirkwood, who was searching the vast expanse of sea with his binoculars, raised the voice-tube to his lips.