"I don't believe he's here," said Jack as he paused in the hunt.
"Say, do you know, I have an idea," said Mark. "Maybe that motor broke itself."
"How could it do that?"
"Well, it might have got to going too fast, and the power may have broken the plates. Anyhow, we didn't hear any person in the engine–room, and there doesn't seem to be any one here."
"That's so."
"I'll make an affidavit that there ain't a person on this airship but ourselves," declared Andy.
"Let's ask Mr. Roumann if it's possible that the motor smashed itself," proposed Jack, and, having no further place to search, they went back to where the two scientists and Washington were busily engaged.
"Yes," replied Mr. Roumann, after Jack had stated his question. "It's possible for that to have happened, but not very probable. I think some person is hiding on board here, and that he did it."
"But we can't find any one."
"That may be. He is well concealed. Well you can't do anything more. Suppose you two boys turn in and help us?"