"We'll have to take chances on that, I suppose."
"Hark!" came suddenly from Jack.
Far back somewhere in the tunnels they had threaded they could hear loud shouts and cries. The sound of the pursuit boomed out even above the noise of the waterfall.
"They're after us!" exclaimed Jack.
"Shall we take the boat?" Walt's usually calm voice shook a little as he asked the question.
"It's our only chance. Come on, in with you, Ralph."
Ralph hesitated no longer, but jumped into the little contrivance. A sort of oar lay in the bottom. He thrust it over the side.
"The water's only about three feet deep," he announced.
"So much the less chance of our being drowned," rejoined Jack.
The lad had his knife out—a heavy-bladed hunting weapon. As soon as all was ready he would cut the ropes and set the boat free on the turbulent current.