Again he called out the name of his late companion, and again only the dull echoes answered him.
He reckoned that he must be at least a hundred yards from the hole made by the sunken driftwood.
To get back to the hole, therefore, was out of the question.
He thought the matter over for a while, and then, taking up some driftwood for a torch, walked slowly along the sandy shore of the black stream.
Presently he came to a bend, and here found that the stream shot downward, forming an underground waterfall.
"I can't go in that direction," he reasoned. "I want to go up, not down."
The stream was less than twelve feet wide, and did not run so swiftly but what he could cross it without much danger.
Obtaining a fresh firebrand, for the first was now burnt out, he swam over to the opposite shore and began an investigation on that side.
"Hurrah!"
The exclamation escaped from his lips involuntarily.