Once across the Colorado the horses cantered off briskly, snorting and whickering with good spirits. They had been filled up with all the water they could hold and it was yet early morning, keen and cool. The steep climb up the red buttes that led over the divide to the flat country north of the mesas began. Then came sand, valleys and valleys of it, with scant vegetation, dry, arid and desolate. That loose sand was particularly hard on the dogs. Lee had been left behind in camp, for he was too long-coupled to have the needful endurance, but Pepper and Bourbon, they had felt, would be worth taking. Ruler seemed made of iron, as he rambled right along through it. He evidently appreciated his responsibilities, for if either Pepper or Bourbon attempted to lag he was behind them with ready snarl and snapping teeth that drove them flying onward. At noon the party halted and doled out their first water. It worried the boys to see how greedily the horses sucked down their allotments of half a canvas pail each and then whickered and bit for more. The dogs nearly came to a fight over theirs, and each had to be held by his collar to prevent him from flying at the drinking one. By evening the horses had slowed to an exasperating walk and the dogs limped painfully. Down into a hideous gulch Big John led the party. It was out of the wind, but dry as the Sahara. Here they made their first dry camp. The first water bag had gone flat and the second was already alarmingly lean. Sid shook his canteen. There was but a drop or two in the one on the off hook, and again he felt the cork of the other to make sure that it had not come out. He had gotten through the day on schedule. They were all right, _provided_---- That night he woke up with the cold. That was unusual, in itself, for that bag was good down to below freezing. Sid uncovered the flap and looked out. The stars were obscured, and a steady stinging sift, sift, sift of sand went on all around him. He could hear that faint, continuous hiss and ticking, and, attempting to move in his bag he was surprised to note it heavy as lead and immovable. “Sounds like the beginning of a sandstorm to me,” he murmured to himself. “I’d better wake John, so we can all turn out and look after the horses.” He crawled out of his bag and punched Big John awake. The keen wind blew steady and strong, chilling him to the bone, while blown sand gritted in his teeth. It did not take the big plainsman more than one sniff to bounce out of his mess of blankets, wide awake. “Shore it’s a reg’lar night-bloomin’ swozzle a-comin’, Sid! Let Scotty lie. We’ll git the hosses in under the shelter of the buttes.” Out in the cold gloom they found the animals, standing patiently with their sides to the wind. Pulling up their picket pins, they herded them into a sort of shelf where a great rock wall jutted out in a weird, wind-scoured formation, like a vast top on end.