The pace was so hot that Ashton was beginning to stumble and slip, but Blake kept by him and helped him along by word and deed. He asserted and repeated a dozen times over, that they were nearing the place where an ascent of the precipices might be possible. At last they rounded a turn in the winding chasm, and Blake was able to point to a break in the sheer wall on the Dry Mesa side, where the precipices were set back one above the other in a Cyclopean stepladder and their steeply-pitched faces were rough with crevices and shelves. "Look!" he cried. "There's the place--there's our ladder up from hell to heaven!" Ashton soon lowered his weary head. He stared dully downstream to where a fifty-foot cliff extended across from side to side of the canyon like a dam. "Part of the wall slid in," he stated with the simplicity of one who is nearing exhaustion. "That shall be our bridge to the ladder," shouted Blake. "It's all sheer cliff along here at the foot of the break, but the ledges run down sideways to the top of the cross cliff. We shall soon be lying up there, high and dry, getting our second wind for the run up the ladder." The engineer spoke confidently, and felt what he spoke. But as they struggled on down the turbulent stream to the cross cliff, the light left his face. From wall to wall of the canyon the great mass of fallen rock stretched across the bottom in a sheer-faced barrier, broken only by a tunnel barely large enough to suck in the swelling volume of the river. Blake came down close to the intake, scanning every foot of the cliff face for a scalable break or crevice. There was none to be found. He climbed along the cliff foot to a low shelf beside the roaring tunnel, and stood staring at the opening in deep thought. Even while he looked, the swelling volume of the river filled the tunnel to its roof. Blake peered at the fresh watermark twenty feet up the face of the cliff, and bent down beside Ashton, who had stretched out to rest on the shelf of rock. "There's only one thing to it, old man," he said. "We must dive through that tunnel." "Through that hole?" gasped Ashton. "No! I've done enough. I shall stay here." "To drown like a rat in a rainwater barrel!" rejoined Blake. "Look at that watermark. The tunnel is now running full. Inside a quarter-hour the river will be up over this ledge. It will keep rising till it reaches that mark, and it will not fall until after low water." "What do I care?" said Ashton hopelessly. "Go to the devil your own way. I'd rather drown here than in that underground hole. Leave me alone."