“Maybe it’s a sort of gas that he’s unloading on us to render us unconscious, so he can capture the whole outfit!” conjectured Jack.
“I don’t believe it!” protested Ned. “I’m quite convinced that this is pure air. He seems to have quite a lot of it stored up!”
“Let’s pump out some of this foul air and change with the new!”
“Go ahead!” consented Ned. “It’s a good move, I’m sure!”
In a short time the boys began to feel the effects of the inflow of vitalized atmosphere. They were livelier, with less depression.
Directly their attention was attracted to the porthole again by a tapping. The stranger was once more trying to convey some information by signs. He repeated the motions of a short time before.
“I got you!” cried Harry, holding up a hand as a sign of understanding. “He wants us to shut the valve off. Perhaps he’s given us all the nice fresh air that he feels it possible to spare!”
“Shut the valve, then,” directed Ned.
“What’s next?” spoke up Jimmie, listening to a slight hammering outside of the hull. “He’s disconnecting the pipe now!”