“Oh! I know what ails him!” exclaimed Donald, with a laugh; “see, he’s gripping his little kodak in his hand. Billie has suddenly remembered that one of his purposes in coming here was to snap off some pictures, and that strikes him as the finest thing ever.” “And I reckon Billie knows a good subject when he sees it,” chuckled Adrian, as he sat at ease in his saddle, and watched operations on the part of the kodak fiend. Billie had judged where he might get a fine, unobstructed view of the retiring medicine man; and it was really laughable to see how quickly all his past troubles were forgotten when this glorious chance to get a splendid snapshot came along. He stumbled several times, and once the boys feared he had smashed his camera against a rock; but as Billie kept right along they concluded that he had been smart enough to protect it in some way, possibly at the expense of his hands. “Now he’s got to the place he was aiming for; watch him shoot!” said Adrian. They plainly heard the sharp “click” of the shutter as Billie made his exposure. So did the Witch Doctor, evidently, because Donald always said he gave an involuntary “duck,” as if that metallic sound might have made him think of the hammer of a gun being raised. The weird old Zuni humbug whirled around, and looked at Billie. He even raised a hand, and made some sort of threatening gesture. When he took a couple of steps in his direction poor Billie really believed he must be about to visit some terrible punishment upon his head as a judgment for his rashness; at any rate the boy spun around, and came hurrying back toward his chums, looking quite concerned. But he need not have worried, for the medicine man was apparently not annoyed enough to give chase, or else he proved to be averse to exerting himself when he had serious business on his hands. He turned again, and walked away, vanishing among the rocks and brush. “Oh! I got him, and believe me that was a splendid snapshot!” gurgled Billie, as he joined the others; and after finding that he was not being pursued, showing signs of considerable relief. Again Adrian and Donald exchanged glances. It was as though the same thought might have come suddenly into both their minds. “I dare you to make the try!” said Donald, aggressively, as though he knew how such a proposition would meet with instant favor from Adrian, who would not be held in contempt for anything. “I got you!” was the ready response, as the other jumped to the ground. “What are you fellows meaning to do?” demanded the surprised Billie. “Oh! just trail after that old humbug, and see where he goes,” replied Donald. CHAPTER XVI. THE BLANK WALL. Billie wanted to go with them very much; not that he felt any great desire to come into close contact with that grim looking old medicine man; but he disliked being left alone worse still. After his recent experience on the desert he felt like having company, no matter under what conditions.