But Skinny had seen Dave's danger, and with a yell he took after the second steer. An instant later his lasso had settled over the animal's head, and as the pony stopped short, and braced back, the steer fell, his feet kicking in the air. Dave himself was not aware of what had happened, so intent was he on driving back the brute he was after. And it was not until he had done this, and looked back, seeing the prostrate creature, that our hero was aware of what had happened. Then he understood at once. "Thanks, Skinny," he said, pantingly. "Don't mention it," replied the other. He shook free his rope, and the steer, now subdued, and tractable, rose to his feet and went back to the herd. It needed every effort and attention on the part of the cowboys to keep the cattle from stampeding, but they managed to do it. The fire came on, halted at the burned strip, hesitated as if considering a leap across, and then divided, rolling down either side of the bare strip. "That does the trick," said Mr. Carson. "I guess we've saved our stock." "And we didn't need the plowed strip after all," Dave said, for, so far, the blaze had not approached within danger-distance of the herd. "Well, it isn't over yet," said the ranch owner. "That fire still has plenty of ginger in it, and the wind may shift any minute. Dave, you worked well!" "Oh, no better than any of the others." "Yes you did! You worked well, and I shan't forget it But I'd like to know how this fire started. No cowman would be so careless with matches when he knows how dry it's been. And I don't believe lightning set it. I'd like to know how it started." "So would I," said Dave, "and I think I'll investigate." "How? Where?" asked the cattleman. "Why, I'll go over there where the fire started. I may be able to learn something." "Better take one of the boys with you," Mr. Carson cautioned him. "That's in the direction of Molick's ranch, and they may be in a bad humor. Take some one with you." When Dave's intention was made known Pocus Pete and Mr. Bellmore offered to accompany him. Dave was glad to have them. They rode over the blackened, scarcely-cooled area, there being light enough from the distant flames to enable them to see well. But there was nothing to observe--that is at first. Finally, however, as they went on, Dave gave a sudden exclamation. "What is it?" asked the engineer. "Hush! Not so loud!" was Dave's caution. "Don't you see some one crouched down in the grass there, lighting matches?" The other two looked to where he pointed. They did indeed see a dark figure. Suddenly it became plain, and the three saw some one stooping over in the dry grass, setting fire to it with matches. "The scoundrel!" cried Mr. Bellmore. "Who is he?" "I don't know, but we'll soon find out," said Pocus Pete, grimly. "Come on, boys!"