On the upper side of the rounded aluminium envelope was a small platform on which stood another automatic gun on a vertical mounting, so as to be able to fire at any aeroplane that might venture to assail the Zeppelin from above.
To each of these platforms were attached two small cigar-shaped ballonettes, fitted with life-lines. These were obviously intended to act as aerial life-buoys should disaster overtake this mammoth of the air; but what struck Hamerton most forcibly was the sight of a couple of officers standing in the rearmost nacelle and actually smoking cigarettes.
"These fellows have a supreme faith in the nonporosity of their gasbag," he thought. "With that immense volume of hydrogen, and the fate of previous Zeppelins in their minds, I am surprised that they dare risk such a thing. I wonder if they've discovered another gas of the same or greater lifting-power than hydrogen? Or perhaps some of the German savants have found a means of rendering hydrogen non-inflammable. I'd like to find out, by Jove!"
The Zeppelin came to a standstill with her nose almost touching the Waalhorn monument, and her tail within a few feet of the disused lifeboat slip. With the utmost celerity several lengths of hose were coupled up, and the work of replenishing the petrol tanks was begun. The two officers who were smoking descended from the nacelle and walked away in the direction of the Oberland, a mechanic gave the signal, the hoses began to swell, and the liquid, under the force of gravity, poured into the storage tanks.
The sound of approaching footsteps caused Hamerton somewhat reluctantly to descend. Detroit, red in the face, had already begun to realize that, muscular though he was, the Sub's weight could not be borne with equanimity.
The door was unlocked and thrown open. A file of marines with side-arms entered, headed by a sergeant. Without a word the men surrounded the two prisoners; the non-commissioned officer pointed meaningly towards the open door.
Through the cleanly kept streets of the Unterland the two comrades were hurried, then up the zigzag path communicating with the plateau known as the Oberland, where the larger portion of the residential buildings was situated. Hamerton recognized the old and the new lighthouses and the Bull Beacon from sketches on the Admiralty chart; but he was somewhat surprised to find that even in the short journey between the Unterland and the Government House there were no less than ten large guns in armoured casemates, searchlights galore, and a network of ammunition lines, on which ran trucks actuated by electric power.