Bill had been hunted from camp to camp by the thing which he had never seen. He had been robbed and his food supplies destroyed until at last he had fled the place only to fall into the hands of the watchful sheriff. Abington couldn’t blame Bill for his fears. All the same, Abington did not want to place a gun in the hands of an escaped prisoner. That, it seemed to him, would be going rather strong, even in the interests of science. He was sitting with his back against the cliff with the dying fire before him, rubbing his numbed ankle to which sensation was returning with sharp stabs of pain, when Bill came up out of the cañon mouth with his bundle still on his shoulders and his eyes staring. “It’s been to the cave,” he announced in a suppressed tone. “Clawed out the rocks I walled the opening up with and raised hell with my stuff. Professor, how bad do you want them stone Adamses?” CHAPTER V--GALLOPING BURROS Across the valley the moon peered over a jagged pinnacle, looking as if broken teeth had bitten deep into its lower rim. That effect was soon brushed away as the pale disk swung higher, and the blood-red sandstone peaks stood fantastically revealed in the swimming radiance. The valley straightway became enchanted ground wherein fairy folk might dance on the smooth sand strips or play laughing games of hide and seek among the strange pillars and jutting crags. Beside the dying fire Bill Jonathan dozed, head bent with now and then an involuntary drop forward, whereupon he would rouse and glance sharply to left and right--the habit of a man who knows himself hunted, a man whose safety lies in unsleeping vigilance. “Lie down on the tent, Bill,” Abington advised him, after his third startled awakening. “Lie down and make yourself comfortable. To-morrow you can watch while I sleep.” “Aw, I can keep awake, professor. All that climbing around to-day made me kinda tired, is all. If I know you’re asleep, I’ll keep my eyes open wide enough.” “But I don’t want to sleep, Bill. This little mystery must be solved before we go any farther with our chief business. Couldn’t sleep if I wanted to.” “You’ll stay awake a darn long while, professor, if you wait to put salt on the tail of the thing that haunts this valley,” Bill opined. Abington calmly knocked the dottle from his pipe and began to refill it, ready for another long, meditative smoke. “For every problem in the universe there is a correct answer,” he said quietly. “It is only our ignorance that makes mysteries of things simple enough in themselves. A peculiar arrangement of details has given this ‘gosh-awful’ animal of yours an air of mystery, but the explanation is simple enough, I’ll guarantee.” “Yeah, but how are you going to find this explanation--that you think is so darned simple?” Bill stifled a yawn.