And as they became quiet again they heard another voice say:
"I guess it's all up with 'em now. We might as well light out and touch off the fuse!"
"Whew!" softly whistled Bud.
Together the party of searchers moved softly forward. Suddenly the passage along the bank of the mysterious stream turned sharply, almost at a right angle.
And there, in what appeared to be a small cave, excavation or cavern, high in the upper wall was disclosed a roughly circular opening, like a window or port hole. Through this port hole a light showed, and outlined in the light were several rough-appearing men, leaning together over what might have been a table.
"Del Pinzo!" murmured Dick.
"Conspirators!" exclaimed Bud. "They're the ones that's been turning this water on and off! We're on the track of the mystery now!"
Whether he spoke loudly enough to be heard, or whether some other sound made by the searchers alarmed the men in the upper niche, was not disclosed just then.
But the light suddenly went out, and confused sounds followed.
And chief among these sounds was the rushing, roaring noise, the blowing as of a mighty wind, and the water near the boy ranchers and their companions was strangely agitated.