"Impossible!" said Shandon, warmly. "I know all the men in the crew; can he have smuggled himself into their number since we left? It's impossible, I tell you. For more than two years I've seen every one of them more than a hundred times in Liverpool; so your conjecture, Doctor, is untenable."
"Well, what do you admit, Shandon?"
"Everything, except that. I admit that the captain or some tool of his, for all I know, may have taken advantage of the darkness, the mist, or whatever you please, to slip on board; we are not far from shore; there are the kayaks of the Esquimaux which could get through the ice without our seeing them; so some one may have come on board the ship, left the letter,—the fog was thick enough to make this possible."
"And to prevent them from seeing the brig," answered the doctor; "if we didn't see the intruder slip aboard the Forward, how could he see the Forward in the fog?"
"That's true," said Johnson.
"So I return to my explanation," said the doctor; "what do you think of it, Shandon?"
"Whatever you please," answered Shandon, hotly, "except that the man is on board."
"Perhaps," added Wall, "there is some man in the crew who is acting under his instructions."
"Perhaps," said the doctor.
"But who can it be?" asked Shandon. "I've known all my men for a long time."