"Can we trust him?" Bob asked, as evening came on again. "I've always heard that Chinamen are treacherous fellows." "Then you've heard what isn't true," Frank replied. "A Chinaman never breaks his word. Over in the Far East I've read that all the merchants of British cities are Chinese. The Japs are a different kind of people. Yes, we can trust Charley Moi. He would never betray us to our enemies." Nevertheless, that night the boys also slept on their arms, so to speak. One of them remained on guard at different times, the entire night. Frank had learned caution on the range. He did not mean to be taken by surprise; though he really believed that nothing would be done to injure them until after they had found some trace of the hidden hermit of Echo Cave. Before another twelve hours had passed he had occasion to change his opinion. The night did not bring any alarm in its train. Charley Moi was up several times, shuffling around, looking at the fire, and sitting there smoking his little pipe, as though in satisfaction over having struck such a profitable job so easily; but he gave no sign of holding any intercourse with outsiders. With the coming of morning they were once more on the way. Frank noticed with considerable satisfaction that now they seemed to be beyond the ordinary limit of the various trails taken by the regular tourist parties. They were walking along, about the middle of the morning, when they found themselves in a lonely region, where the dim trail led along the foot of rugged walls stretching up, red and apparently unscalable, to the height of hundreds of feet. Frank was craning his neck as he looked up overhead, wondering if it could be possible that there was any sign of an abandoned cliff dwellers' village there, when he saw something move, and at the same instant he jumped forward to pull his chum violently back. CHAPTER XVI A WONDERFUL DISCOVERY Bob opened his mouth to call out, and ask what was the matter, that his chum had seized upon him so fiercely. But he held his breath, for something came to pass just then that made words entirely unnecessary. A huge rock seemed to slip from its notch up on the side of the cliff, and come crashing down, loosening others on the way, until finally the rush and roar almost partook of the nature of a small avalanche. Charley Moi had skipped out in a lively manner, and thus managed to avoid being caught. Bob stared at the pile of broken rock, about which hung a little cloud of dust. "Wow! that was as close a call as I ever hope to have, Frank!" he exclaimed, with a little quiver to his voice. Frank himself was a bit white, and his hand trembled as he laid it on that of his chum. "I just happened to be looking up, and saw it trembling on the break," he said. "Only for that we might have been underneath all that stuff." "But did you notice the clever way Charley Moi avoided the deluge?" said Bob, trying to smile, though he found it hard work.