Jimmie laughed and turned on full speed. Just as the _Louise_ swung over the edge of the cup which formed the round valley below, the boy saw Ben and Carl, doubtless awakened by the starting of the motors, rush out of the shelter-tent and wave toward them. It was evident that the two boys left in camp did not think much of Jimmie’s unannounced excursion into the air, for their greeting seemed to be more of a command to return than anything else. A mile away, Jimmie slowed down and, with a field glass, began a close examination of every gully, canyon, and valley which he passed. Finally the glistening planes of an aeroplane came to view, lying on a level stretch of rock only a short distance from the main ridge. “Here we are, now!” thought the boy. “Here’s the other machine! Now, if I can only coax him out of his nest, and keep him amused through the day, I’d like to know how he’s going to get time to deliver the message sent by the underworld of New York to Phillips and Mendosa?” As the boy slowed down again, he saw a figure running wildly around the aeroplane below. He circled the little shelf, dropping lower at each swing. Presently he darted away, as if satisfied with his scrutiny, and the machine below lifted instantly and gave chase. “And here,” mused Jimmie with a grin, “you’ll see the liveliest game of tag ever pulled off in the air!” CHAPTER XV. A CRIPPLED AEROPLANE. Left together in the camp, astonished and angry at the sudden departure of Jimmie, Ben and Carl saw the _Louise_ disappearing with varying emotions. “Now what did he do that for?” demanded Carl. “He’s always up to some mischief!” growled Ben. “Well, if he’s going sailing around over the mountains in broad daylight,” Carl suggested, “we may as well go up to San Francisco and bring down a band. A brass band wouldn’t give us any more prominence in the community, and it might be more amusing.” “Oh, the boy always has some fairly good reason for what he does,” defended Ben, chuckling inwardly at the daring of his chum, “but I wish he’d tell us a little more about his plans before he makes such breaks. It would take the strain off a little!” he added. From the valley in which the _Bertha_ lay the boys could not, of course, see what was taking place until the _Louise_ was high up above the lower summits, with the third aeroplane in full pursuit. “Now, what do you think of that?” demanded Carl. “That fool boy has found the crook’s machine, and the chances are that he’ll be sorry he did it before the day is over!” “Oh, well,” Ben replied, “we’ll have to wait and see what comes of this absurd trip. Perhaps we’d better be getting something to eat, so as to be ready for a flight if the boy should need assistance.” While the two were eating a hastily prepared meal, an exclamation of astonishment came from the vicinity of the _Bertha_, and they both sprang to their feet and chased off in that direction.