They found nothing.
“It must come from the roof,” said Nick.
His voice was hoarse and rasping, and his lungs felt as though compressed under a ton’s weight.
“How are we going to do any searching up there?” queried Chick, rising on his tiptoes and stretching his arms. “I can’t come within three feet of the ceiling.”
“Take me on your shoulders,” said Nick.
This plan was carried out without loss of time.
Sitting astride Chick’s broad shoulders, Nick was able to reach the roof.
Beginning at one of the end walls, they proceeded to cover the flat stones of the ceiling with the utmost care.
“I can’t stand this much longer,” said Chick, staggering, and only saving himself and Nick a fall by a quick effort. “This gas seems to sap all my strength.”
“Hang to it, old man,” returned Nick. “By Jupiter! I’ve struck it! Let me down, Chick.”