"Well, Ripley, they have gone somewhere, that's as sure as guns," was the answer of the young major. "Move a portion of your men to the upper end of the brushwood, and another portion to the other side, and we'll endeavor to get to the bottom of this mystery." The command was obeyed, and meanwhile Deck sent back word to Major Truman to bring up the regiment and scatter it in a huge circle around the vicinity. "Unless they have slipped on ahead, we are bound to get them," he said to Tom Belthorpe. Captain Ripley had gone with six men to the upper end of the brush, Belthorpe remained with six others where the first stand had been taken, while Deck, with the remaining cavalrymen present, made a detour, coming up on the opposite side of the growth, and at a distance of three hundred yards. He was on a slight hill, and could look directly down upon the spot the Confederates, with the extra horses, had occupied. As Captain Ripley had said, the enemy was nowhere in sight. The men looked at Deck, and it must be confessed the major felt uncomfortable, for he had been certain that something would turn up when a better view of the ground back of the brush was obtained. "We will advance,--but do so cautiously," said the major, and drew his pistol. Hardly two hundred feet had been covered when he made a discovery. The brush overhung a small, rocky brook, probably three feet deep in the centre. But where the water came from and where it went to was another question. Certainly, in making the detour, he and his men had crossed no such watercourse. "It must come either from a powerful spring or from underground," he reasoned. "Forward!" he shouted. "That running stream must solve the mystery." The brook was soon gained, and found to flow to the southwestward. A detail was sent up the stream, and soon came back reporting that there were several small springs there, but the larger portion of the water came from a flow out of the side of a small hill. Major Truman now reported that the Riverlawns had surrounded the entire territory, and feeling certain he had the enemy secure, Deck continued his investigation. Several cavalrymen were sent down the centre of the brook, while he kept abreast of them beyond the brush. Almost the end of the wood was gained, when the cavalrymen shouted out that they had reached a small waterfall, and could go no further. Pressing over the rocky ground, Deck gained the waterfall, to find at its bottom a well-hole in the almost solid rock, some fifty or sixty feet in diameter. At the bottom was a pool, partly covered with dead brush and decayed tree trunks, and the water ran off in a large opening to one side of the well-hole. "Here are horses' hoof-prints, Major," said one of the men. "I shouldn't wonder if there is a winding path leading down to that 'air pool. But if the rebs went down there, what became of 'em?"