"They do it to make a wet place so they can drive my cattle across it, and no hoof marks are left to tell which way the animals have gone. Then, when the cattle are safely away, the waters are let run down where they always flow, and they come into my spring again. The taking of the cattle and the drying up of my spring are all done by the same band of men. That's why, whenever any cattle were taken, the spring dried up. One went with the other."
"How did Sam Thurston know all this?" asked Daddy Bunker.
"This cowboy with the broken leg used to be one of the band of men who took my cattle," went on Uncle Fred. "He just told me. He was on his way to see about taking more of my steers when his horse threw him at the bridge. That's why he didn't want to come to Three Star Ranch—because he had treated us so meanly.
"But when he saw how good we were to him he made up his mind not to be bad any more and to tell about the men. He knows where they hide the cattle after they steal them, and he says if we go there now we can get back the steers, and also catch the men who took them. And after this the spring won't go dry any more."
"Well, well!" exclaimed the children's father. "And to think that two of the six little Bunkers, by finding the cowboy with the broken leg, should help solve the spring mystery!"
"It is extraordinary!" exclaimed Uncle Fred. "But I knew as soon as I saw the little Bunkers in the attic that day I walked into your house, that they could do something. And they have. Now, Captain Roy, you and the cowboys ride on and see if you can get back our cattle."
Away rode Captain Roy and the cowboys, and some hours later they came back with the men, whom they had easily caught. They found the cattle hidden in a gully, or deep valley, near the creek, and the steers were driven back to their pasturage on Three Star Ranch.
Then the whole story came out. Sam Thurston and the others of the band, instead of raising cattle of their own, used to take those belonging to other ranchmen. They found it easy to take Uncle Fred's, and, by making a dam, or wall of earth, across the place where the stream started that fed his spring, they could turn it in another direction, making it flow over a path, or trail.
Along this trail, when the water covered it, the men drove the cattle they took from Uncle Fred's field, and the water covered, and washed away, any marks the cattle's feet made. So no one could see which way they had been driven.
When the stream was thus dammed it did not flow into the spring, which went dry. After the dam was taken away the spring filled again.