It seemed reasonable to suppose that the water would rise to no greater height than it had when the searchers had discovered Nort on the rock. And as this boulder was well out of water, and large enough for them all to stand on, they would run no risk, even if the flood should start to return when they were in the middle of the pool, which, however, was a pool no longer, but merely a wet reservoir, so to speak. "But I don't believe the water will flow back here until you shift that lever again, Bud," declared the old ranchman. "And I'm going to have a try at it!" "Isn't it takin' a chance?" asked Snake. "You got t' take chances in this world!" declared Old Billee. "Well, let's go!" suggested Bud. "I think I'll stay here," spoke Nort. "I don't feel quite up to walking over those rocks. And you may need some one on this side who can throw a rope," he added, as he looked at the lariats. "All right," assented Bud. "You stay here, Nort." They left him on the shore, as I call the rocky edge of the pool, with a lantern, and, taking other lanterns with them, the little party set out. It took them only about three minutes to walk across to the great rock, which stood upright in the middle of the cavern floor. Rising up in almost the very centre was the heavy, copper lever. By the light of the lanterns it was examined, and seen to extend down through the rock, whither no one knew. "It works a water gate all right," declared Old Billee. "Let's pull it back to where you found it, Bud, and see what happens." It was with some feelings of apprehension that the others watched as Old Billee reached for the copper lever and pulled it toward him, It operated as easily as it had for Bud. And almost as quickly as had taken place on the other occasion, there was that roaring, rumbling sound, a noise as of the blowing of a great wind, and then the waters began to rush back into the pool. "Here they come!" yelled Dick, as he stood beside Bud on the rock. Truly the waters were returning as the hidden gate was closed when Billee pulled the lever. Would they go down again? That was what each one asked himself. CHAPTER XXIII THE CONSPIRATORS Rapidly rushing, foaming, bubbling and boiling, the waters rushed into the mysterious cavern, until they again filled the pool across which Bud and Dick had swam to the rescue of Nort on the rock. Now the situation was reversed. It was Nort who was on the mainland, or shore, so to speak, and the others who were on the rock. But it was one of their own choosing, in an endeavor to solve the mystery, though as Bud and his companions watched the waters creeping higher and higher up the surface of the rock on which they stood, their hearts were not altogether easy. "Suppose it covers the rock?" asked Dick. "Then we'll have to swim back where Nort is," Bud answered. "Shucks! You won't have to do nothin' of the sort!" declared Old Billee stoutly. "She won't come up any farther than it did before!"