“What are you going to do?” the professor asked, as he settled himself on the middle of the mass.

“Try to get back to the Sherman,” Bob answered. “She can’t be very far away.”

“Hadn’t we better yell again?” asked Professor Snodgrass, after a period of silence. “We ought to let them know we’re here.”

“Yes,” agreed Bob, “we had.”

Now, again, they raised their voices, but after several trials, there came no answer.

“They must have got up steam, and are going away from us,” said Bob. “Or else they’ve sunk,” he added, after a moment.

“I can hardly believe that,” answered the professor. “The blow struck by the derelict, as you say it was, I am sure was not hard enough to sink our ship so soon. Besides, if she had gone down we’d see signs of more wreckage, or the lifeboats. As it is, we have seen nothing.”

“That’s right,” admitted Bob. “It surely is queer.”

Bob Baker had paused in his efforts to push the raft, and now was resting himself while he held this conversation with his friend.