“Sure thing,” Adrian told him, and then almost immediately he went on to say in a different tone of voice, that had a vein of new anxiety in it, Billie thought: “I wonder why Donald is rubbering so much for toward the southwest. Perhaps he feels the hot breeze that’s beginning to blow from there. I hope it doesn’t mean we’re going to have a sand storm.” Billie pricked up his ears, so to speak; that is, he showed considerable interest, and himself turned to watch Donald. “He does look like he had got on the track of something out of the usual run, for a fact,” he muttered, uneasily. Then he sneezed several times in quick succession, at which Adrian looked as if even this simple event had its significance. “Beginning to be dust in the air, and I always sneeze when it tickles my nose,” Billie started to say, as if in apology for his explosion. “Yes, the breeze is picking up, and already the air is starting to get full of the fine sand,” Adrian told him. “Does that mean we’re bound to run up against a real sand storm?” Billie wanted to know at once, scenting trouble. “Donald’s coming this way, and we’ll soon hear what he thinks,” was all Adrian would say. “Looks to me as if we’re going to get caught out here in a lovely mess,” Donald told them, as he came up. “Sand storm, is it?” demanded Billie, trying not to show any apprehension, for he never wanted others to know when his heart was beating faster than its wont. “Yes, and coming down on us like two-forty,” the other declared. “Watch the nags, and you’ll see that they know what they’re in for. Here’s _Wireless_ been looking over that way every little while for ten minutes past. The wind’s rising, and all around us the sand is stirring, so that the air’s getting thicker all the while. Before half an hour we’ll have the worst of it around us. It’s about noon now, and let’s hope that we get to the hills before night sets in.” “What’s the programme?” asked Billie, undaunted Billie, carelessly enough. “Keep as close together as we can travel, and go straight ahead,” answered Donald; “there’ll be all sorts of queer noises around us, so pay no attention to them. Be sure and keep your mouth shut all the time; and have water along with you, every fellow, so that in case one of us did stray away, he wouldn’t die of thirst before he could be found. Now, let’s push on again.” His words were more than verified, for presently the wind grew to the proportions of a gale, and the way that fine sand whirled through the air was something that Billie had never expected to experience in all his life. It was a terrible task to press on, but luckily the prevailing wind was from the southwest now, and so they had the worst of the sand storm to their backs. Only for that they could not have ventured to attempt any progress whatever; but must have camped where they were, to wait for the whirlwind of sand to cease.