But all this time we have been allowing our party to travel on without bestowing any attention upon them. As the afternoon wore on, Coyote Pete began to feel real apprehension about reaching their destination that evening. Walt Phelps' fear about the water had been verified. The supply was getting low. Provided they could "pick up" the mesa they were in search of before sundown, however, this was not so serious a matter as might have been supposed. Coyote Peter knew that there was a well at the mesa, the handiwork of the ancient desert-dwellers. The really serious thing was, that although they had apparently been traveling in the right direction, they had not yet sighted it. The cow-puncher knew, though he did not tell his young companions so, that they should long since have spied its outlines. Of the real seriousness which their position might shortly assume, the boys had as yet, little idea. Coyote Pete was not the one to alarm them unless he was convinced it was really necessary. Suddenly, Jack, who had been riding a little in advance of the rest, gave an exclamation and pointed upward at the sun. "Say, what's the matter with the sun?" he exclaimed. "Sun spots, I suppose," put in Ralph Stetson jokingly. "I see what you mean," spoke up the professor; "it has turned quite red, and there seems to be a haze overcasting the sky." "It's getting oppressive, too," put in Walt Phelps. "What's up, Pete?" The cow-puncher had, indeed, for some time been noticing the same phenomenon which had just attracted their notice, but he had hesitated to draw their attention to it. Now, however, he spoke, and his voice sounded grave for one of Pete's usually lively temperament. "It means that ole Mar'm Desert is gettin' inter a tantrum," he grunted, "and that we're in an almighty fix," he added to himself. "Is it going to rain?" inquired Ralph Stetson, as it grew rapidly darker. "Rain?" grunted Pete. "Son, it don't rain here enough to cover the back uv a dime, even if you collect all the water that fell in a year. No, siree, what's comin' is a heap worse than rain." "An electric storm?" queried the professor. "No, sir--a sand storm," rejoined the cow-puncher bluntly. CHAPTER II. THE SAND STORM. As he spoke, a queer, moaning sort of sound, something like the low, distant bellow of a steer in pain, could be heard. The air seemed filled with it. Coming from no definite direction, it yet impregnated the atmosphere. The air, too, began noticeably to thicken, until the sun, from a pallid disc--a mere ghost of its former blazing self--was blotted out altogether. A hot wind sprang up and swept witheringly about the travelers. "Ouch!" exclaimed Ralph Stetson suddenly. "Something stung me!" "That's the sand, son," said Coyote Pete. "The wind's commencin' ter drive it." "Is it going to get any worse?" inquired the professor anxiously. "A whole lot, afore it gits any better," was the disconcerting reply.