"But we didn't see anything like this when we were here before," remarked Dick. "Because we weren't on this side," Bud answered. "And I have an idea that, in time, this second passage finally fills with water completely, and when it does the stream again flows along the cross stem of the T and we get it." "Mebby you're right," Old Billee agreed. "But this isn't finding Nort." "Will we--will we ever find him?" faltered Dick. "Sure!" declared Bud, as heartily as he could. But as they progressed in the darkness, stopping now and then to look about by means of the light, calling again and again, and as no reply came, even the heart of the stoutest of them sank in despair. All they could see was black, rushing water, flowing in a channel it appeared to have cut, after countless years, in the solid rock. There was a narrow footpath, so to speak, on either side of this stream, and it was along this the searchers were walking. Suddenly Bud, who was in the lead, uttered a strange cry. "What's the matter?" exclaimed Dick. "Do you see him?" "No! But look!" went on Bud. "We have come out into a regular underground cave! It's as big as a house!" He flashed his lantern around in a circle, and as the others came up and stood beside him, at a spot where the passageway beside the stream widened, they saw that they had emerged into a great vault. And as they stood there, awed and marveling, there came to them, above the rustle and whispering of the rushing waters, the sound of a human voice--it was as though someone, sorely hurt, had moaned. "Listen!" cried Dick. "Hold up your lanterns!" commanded Bud sharply. As they raised them, throwing the combined light farther out across the stream that had widened into a pool in the vault, Dick uttered a cry. "I see him! I see Nort!" yelled Dick. "There, on the rock!" And he pointed to the huddled figure of some one on a great rock in the middle of the pool of black water, which seemed, a short distance from the inflowing stream, to be as quiet as a lake. And, as they watched in the gleam of the lights, the figure on the rock moved slightly. "Nort! Nort!" cried Dick, and his voice was flung back in deafening echoes from the vaulted roof. CHAPTER XXII THE WATER GATE While they eagerly watched, the solitary figure on the big rock in the midst of that sinister pool again moved slightly, and as it became partly erect it was seen to be Nort Shannon. "We've found him! We've found him!" joyfully cried Dick. "An' alive, too, if I'm any judge," added Billee. Dick was stripping off his coat, when Bud placed a hand on his shoulder. "Wait a minute," advised the western lad. "But I'm going to get him!" objected the brother. "I'm going to save Nort!" "Maybe it isn't safe, and we may be able to save him in another way," suggested Bud. "I say, Nort," he called. "Are you hurt?" How eagerly they all waited for the answer, after the echo of Bud's voice had ceased reverberating in the big cave!