"As to giving you the paper, here you are," said Rob, quietly handing the engineer the mechanical sketches. "If I'd known they were yours, I'd have returned them to you at once. I must ask you, however, to be a little less rough in your manners. I don't know what harm we've ever done you, that you should show such a dislike for us."
"Bah!" growled Barton as he turned away, thrusting the paper into a pocket of his jumper.
After this incident neither of the boys cared to remain in the engine room, and soon joined their companions in the main cabin.
They found them chatting and laughing over different boyish topics, and Merritt joined in the fun.
But Rob, usually talkative and bright, was strangely silent. He found himself musing over the incident of the scrap of paper covered with mechanical sketches. Why had Barton become so agitated when the boy picked it up? What was there about the affair to excite the man so strangely?
Suddenly into the boy's mind there flashed a startling suspicion. But so grave was the idea that he dismissed it, or rather tried to; but with all his efforts the idea kept recurring like a dominant note in a piece of music. Rob decided to be on the watch and try to verify or disprove his suspicion, which was nothing more nor less than an idea that Barton was a traitor to his employer, and was also in the service of some powerful interests striving to get a grip on the secrets of the Peacemaker.
"That man will bear watching," decided Rob.
Scarcely had he come to this conclusion when Mr. Barr shouted down from the conning tower:
"I'm going to dive!"
The hearts of all the lads beat perceptibly quicker at the words.