The evening was perfect. As the great, clean-cut disk of the sun dropped slowly below the far-off edge of the prairie, the breeze that had been busy all day rustling the prairie-grass died away, and the silence was so complete that they all stopped involuntarily "to listen to it." They had ridden until they were three or four miles from the ranch, when they paused again, this time to hear the crooning of far-away cow-boys. They were between two great herds of cattle. One, on the left, was half a mile away; and the moon, which now shed a great white light over the prairie showed it only as a black mass. Those cattle had been "bedded" for the night--that is, two cow-boys had ridden around and around them driving them closer together so that they would be easy to watch, and much less likely to be restless. The other herd was a little nearer, and the cow-boys were bedding it as the trio from the ranch approached. The camp-fire flickered between the riders and the herd, and its flaring light seemed to make the cow-boys and cattle nearest it lurch back and forward in and out of the gloom while their changing shadows danced fantastically over the prairie. Here the three riders paused again to listen. Closer by, the cow-boys' crooning would have sounded harsh and unmusical, but at this distance it shaped itself into a plaintive, minor melody that was very pleasing. For many moments they waited and enjoyed it in silence. Then suddenly a quick gust of wind and a low, muttering rumble of thunder made them turn quickly and look at the sky behind them. A bank of dead black clouds was rising on the eastern horizon. John stopped, gazed at it ruefully for a moment, and said: "There's a big thunder-storm coming; but we can get home all right before it strikes us. You girls ride slowly back. I'll rush to the camp and tell the boys to stop in in the morning. I'll overtake you before you've gone far." With that he was off at a brisk canter toward the herd. Martha and Scylla did as he told them. The rising but still distant clouds, lighted on their edges by the moon, added greatly to the beauty of the night, and both the girls appreciated the sight. They walked their horses and talked girlish nonsense. John had promised to take Martha to the North the next winter, and she told Scylla some of the wonderful things she had heard about the great cities and the curious things to be seen up there. Suddenly Scylla interrupted her with: "Martha, I believe there's something the matter with Texas--he's trembling all over." "Oh, I guess not," said Martha; "he's just tired. Texas has had a pretty hard day of it. But yet, he doesn't often get tired." She rode up close to Scylla and put her hand on Texas's neck. It was wet with sweat, although he had hardly gone faster than a walk since he had left the ranch. And, sure enough, he _was_ trembling slightly. "There is something the matter with him, I know," said Scylla.