Off ran the sentries to investigate. They had shot a goat that had strayed from one of the adjacent gardens!
This diversion enabled the fugitives to gain the fence without detection, wriggle under the lowermost barbed wire, and find a temporary respite on the unpatrolled area between the entanglement and the brink of the Zeppelin pit.
With considerable difficulty the American located the topmost rungs of one of the vertical ladders.
"Guess I'll go first," he whispered. "You feel game?"
"Yes," replied the Sub grimly, yet he knew that he had hardly an ounce of strength left.
"Follow on," continued Detroit. "If you feel fagged, give me the word and I'll hang on to you while you rest."
Although the descent entailed considerable less exertion than the ascent a few hours before, Hamerton could hardly retain his grasp upon the slippery steel rungs. His downward motion was purely mechanical. His joints seemed so stiff that a sharp racking pain shot through his shoulders every time he lowered an arm to find the next rung.
"Here's the horizontal platform," whispered Detroit. "We'll rest awhile."
"No, carry on," begged the Sub, "if I stop I'm afraid I won't be able to continue. It's only another fifty feet or so."
"All right!" replied his comrade dubiously. "But, say, shall I carry you down? hang on my back."
"I'm too heavy," objected Hamerton. "Carry on. It will soon be over."
Suddenly Detroit came to a halt, groping aimlessly with his foot for the next rung.
"Hold on!" he hissed. "There's some low-down trick here."
Gripping one side of the ladder as far down as he could he felt with his free hand. The disconcerting discovery that the lowermost section of the ladder had been removed came as a sudden and nerve-racking shock.
"Up we go," he exclaimed, with false cheerfulness. "We've struck the wrong ladder. It ends here. We've only to get back to the horizontal platform."
Retracing that twenty feet was almost beyond Hamerton's strength. Had it not been for his companion's aid the Sub would certainly have relaxed his hold. Utterly exhausted, he threw himself upon the light, steel bridge connecting the vertical ladders, and shivered through sheer weakness and bodily anguish.
"Stay here," continued Detroit. "I'll go on a little tour of investigation. When I come back I'll rub your wrists and ankles, and then we'll make short work of getting to the ground."