Neither Joe nor Charlie had done so, or, if they had, they did not recall the matter when Blake questioned them. So that young man resumed:
"Well, I'll tell you what I saw: Labenstein was leaning over the rail on the side where the submarine showed, and he was holding a big white cloth over the side."
"A big white cloth?" cried Joe.
"That's what it was," went on Blake. "It looked to me like a signal."
"Do you mean a signal of surrender?" asked Charlie. "A white flag? He wouldn't have any right to display that, anyhow. It would have to come from Captain Merceau."
"Maybe he meant that he'd surrender personally," suggested Joe, "and didn't want his fellow-murderers to hurt him."
"I don't know what his object was," went on Blake, "but I saw him take from his pocket a big white cloth and hold it over the side. It could easily have been seen from the submarine, and must have been, for he displayed it just before the underwater boat came up."
"A white cloth," mused Joe. "From his pocket. Was it his handkerchief, Blake?"
"He wouldn't have one as large as that, even if he suffered from hay fever. I think it was a signal."
"A signal for what?" Charlie again asked.