"Good! Now we'll follow its course and see if it approaches the mouth of the cave."
The rivulet, for it was nothing more, wended its way in an almost semicircular direction, till, at about two hundred yards from where the lads had struck it, it emptied itself into a rift in the rocks, the splash of its fall echoing dimly from apparently unfathomable depths.
"Look! We are not very far from that part of the cliff that overhangs the mouth of the cave," exclaimed Ellerton. "What is to prevent us from digging a shallow trench and conducting the water right to the entrance to the tunnel?"
"It's fairly hard rock," objected Andy, "It will be no end of a task cutting a new watercourse."
"Then we can use some of the cast-iron pipes we brought ashore," continued the young seaman, determined not to be overcome by early difficulties. "There are more than enough to cover this distance, and by damming the stream we can——"
"Yes, that's all very well, but if we are compelled to beat a retreat to the cave the savages will find the pipes and so discover our hiding-place."
"I'm afraid that will make but little difference. The trail from the house up the mouth of the tunnel is so well defined that a blind man might follow it. Why, whatever is the matter with you, Andy? You seem to throw cold water on every suggestion that is made. You are not always like that. Are you ill?"
"I believe I am," replied Andy. "At least, I do not feel quite up to the mark."
"Then let's get back," said Ellerton, and assisting his chum over the rough ground the pair returned to the mouth of the tunnel just as the others were emerging.
"Any luck?" asked Mr. McKay cheerfully; then realising that his son looked ill, he exclaimed: "What have you been doing, Andy?"