There was a pleasant smile on his face, and he did not seem at all alarmed at the menacing aspect of affairs.

"Gentlemen," he said, "we resume our voyage at twelve o'clock exactly."

"It is now a quarter to," said the professor, regarding his chronometer.

"Precisely. I shall open the flap, and take in air directly."

"And the niggers?" said Mont.

"The Papouans?" replied the captain, shrugging his shoulders.

"Won't they get in?"

"How?"

"Easily enough, by walking down the ladder. They can do that when the flap is up, and can kill us all without any trouble."

"Gentlemen," said Captain Vindex, "the Papouans will not descend the staircase, although the flap is open."