"I want a look at those wipers," said Frank.

"You shall have it. Mr. Gregory and I were talking together over here all the time you were gone."

"Oh, I do not suspect you," said Merry; "but I want a good look at those wipers."

"Did you see the man who threw you into the stoke-hole?"

"No, but—"

"Then how will you know who it was if you see him?"

"Whoever did so had a reason for the act—a motive. He must have known me before. I may know him."

"Come," invited the engineer.

He called one of the wipers down from amid the sliding shafts and moving machinery. The man came unhesitatingly.

Frank took a square look at this man, who did not seek to avoid inspection.