“Well,” Case went on, “the dog has been captured, for here are the marks where he pulled back as he was dragged away! And I guess it was no ghost that did it, either. Just listen to that!”

CHAPTER XVII.—THE SUNBURST ON THE WALL.

The sound to which Case called attention was a long, quavering howl, such as a dog in captivity will sometimes make. It sounded far away.

“There’s the proof of it!” the boy said. “Captain Joe has been taken prisoner, and he’s trying to tell us about it. Now, how the Old Harry did any living person get him into a mess he couldn’t get out of?”

“What we want to know, just now,” said Alex, “is where he is, and not how he got there. The sound came from up above?” he asked.

“I thought so,” was the reply.

“Well, how are we going to get up there?” demanded the other.

The boys passed to the east of the precipice and came to a rugged incline which seemed to lead to the vicinity of the shelf of rock from which the ghostly visitors had apparently fallen. It was hard climbing for those unused to such exercise, but at last they stood on a summit which connected with the shelf farther along.

Below, five hundred feet or more, ran the Colorado river, its red waters hidden from the moonlight except in spots, for the outcropping walls make a view of the river from the top almost impossible. The boys could see the Rambler lying at anchor, however, and see the embers of the cooking fire not far away. There were no lights on board the boat when they first looked, but presently a glimmer was seen on the aft deck.

“What is it?” asked Case, mystified.