ou to be driven back by over-exertion."

"But I could try and give up if I got tired."

"Yes, but I don't want you to grow tired, so you must content yourself
here. There is plenty to see along the shore here."

"And suppose a lot of blacks come while you are away."

"Pick up the gun I shall leave with you; they will not face that. But I
have no fear of that happening. I feel sure that there are no
inhabitants. Still, I only feel so, and I want to be perfectly
certain."

"You'll be ever so long," said Carey, gloomily, "and it will not be very
pleasant to be quite alone. All right, though, sir, I don't mind."

"You are not going to be alone," said the doctor, quietly. "Bostock
will stay with you."

"Oh, but that will not be right," cried the boy, eagerly. "Who knows
what dangers you may run into?"

"I have my gun, and I daresay I can take care of myself."

"But you ought to take Bostock with you, doctor."

"I think not: and besides, as we have to divide our force it ought to be
done as equally as possible. There, I shall take six hours for my
expedition--that is to say, if it is necessary--and I shall go straight
away for three hours, and then turn back."

"And suppose you lose yourself?"

"I have no fear of that," said the doctor. "But don't you go far in
either direction. Consider that you have to guard the raft till I come
back."

Carey felt ready to make fresh objections, but the doctor gave him no
time. He stepped to the provision basket, took out one of the bread
cakes that Bostock made every other morning, thrust it into his pocket,
and gave his patient a final word or two of advice.

"Don't be tempted to over-heat yourself in the sun," he said. "Get into
the shade of the grove here if you begin to grow tired," and,
shouldering his gun, he stepped off through the sand, disappearing
directly after among the trees, but only to step back and shout:

"I shall try and follow the stream as near as I can to its source in the
lake that must be up yonder. _Au revoir_."

He disappeared once more, and Carey and Bostock stood looking at one
another on the sandy shore.

CHAPTER ELEVEN.

"What's that here mean as the doctor said, sir?" growled Bostock, when
the last rustle of the growth made by their companion died out.

"Till you see me again," said Carey.

"Why couldn't he say it in plain English so as a man could understand
him?"

"Don't know," said Carey, shortly. "Ask him when h