They could only guess, however, for though the men talked rapidly and eagerly, as evidenced by their gestures, what they said was not audible. Though both transoms were open, no sound came from the room opposite where the boys were gathered. The men spoke too low for that.
"I guess they know it's dangerous to be found out," said Joe.
"But we ought to find out what it's about!" declared Macaroni.
"Yes, I think we ought," assented Blake. "This Frenchman has been in our country, going about from camp to camp according to his own story, and he must have picked up a lot of information."
"And he knows about our pictures, too!"
"Well, I don't imagine what we have taken, so far, will be of any great value to Germany, assuming that Lieutenant Secor is a spy and has told about them," Blake said.
"We've got to find out something about this, though, haven't we?" asked Joe.
"I think we ought to try," agreed his chum. "Perhaps we should tell Captain Merceau. He's a Frenchman, and will know how to deal with Secor."
"Good idea!" exclaimed Joe. "If we could only get him down here to see what we've seen, it would clinch matters. I wonder——"
But Joe ceased talking at a motion from Blake, who silently pointed at the mirror. In that way they saw the reflection of the men in the other cabin. They arose from their seats at the table, and the map or whatever papers they had been looking at, were put away quietly in the Frenchman's pocket.