Suddenly, he was flung against a hard substance. With outstretched fingers he clutched at the slimy surface as of what he realized was the end of his journey at last. The great stone was covered with slimy weed, however, and his grasping fingers refused to clutch at any friendly niche in its surface.
With a despairing cry the boy was being swept in to the terrible mouth of the pool when he felt himself seized and pulled up out of the grip of the torrent. He knew no more till he opened his eyes and found Frank by his side. Both boys were on the rock—sitting on it in two inches or more of water. Fortunately in that climate the water was not so chilly as to cause discomfort, but this was about the only crumb of satisfaction the situation held for them.
"Well done, old fellow," said Frank as Harry opened his eyes. "You had a narrow escape, though."
Harry could only look at his brother gratefully. How deep was his debt of gratitude to him both boys realized without their talking of it.
"How did you gain the rock, Frank?" asked Harry.
"When I saw you swept off the tree trunk I slipped off too," replied Frank, "and when I felt myself dragged into the pool I struck out for the rock. I confess, though, I didn't have much hope of reaching it till I was slammed into it with a blow that almost cracked my ribs and knocked all the wind out of me. I managed however to grab hold of a depression in the surface and maintain my grip on it. I had hardly dragged myself up when you were hurled against it. I thought I had lost you, for the water pulled like a draught-horse, but I managed to hold on to you and here we are."
"And a worse position we could not possibly be in," added Harry.
"Unless we were in there," retorted Frank pointing, not without a shudder, to the whirling open mouth of the pool which had sucked down the wreck of their canoe.
"What is it do you suppose?" asked Harry wonderingly.
"The mouth of a subterranean river I guess," replied Frank. "I have read of such things."