A strong cross-current of wind suddenly wobbled the planes, causing the aillerons to flop anew. The broad prairie had been left behind; they were flying over a chain of rugged foot-hills. The aviator could see, far below, deep gorges, masses of reddish rock, and green forests passing by in kaleidoscopic fashion.
The mountain ahead, forming a stern and forbidding-looking barrier, rose high above them; and it was now apparent that the snow-capped peak, which glistened strangely white in the darkening atmosphere, reared itself immediately beyond.
“Ah ha!” muttered Bob. “Major Carroll is throwing out ballast.”
Quantities of sand, as bags were emptied, could be seen falling—curious misty patches of a lightish color that streaked downward in showers, to speedily spread out and fade from view.
As patch after patch appeared, and melted away, the “Border City” rose perceptibly. The aeronauts had evidently decided to cross the mountains.
“If Major Carroll can’t rise high enough to clear those summits, they’ll be in awful danger.” Bob Somers spoke his thoughts aloud. “Crickets!” His face paled slightly under its coat of tan. “I guess this is adventure enough for even Cranny Beaumont.”
The latter’s eyes were sparkling with excitement; his gaze constantly shifted from the “Border City” to the eagle below, then toward the mountain peaks, which every instant seemed to present a more threatening aspect.
The proportions of the runaway dirigible were looming up in all their hugeness; but a few minutes more, at the present rate of speed, and the “Ogden II” would be shooting past.
The brief interval of time passed, the roar of the engine lessened, and the biplane drew abreast of its monster rival.
The boys were too eager, now, to pay any further attention to the feathered form flying below. Strange thrills coursed through them, as they looked at the air-ship and its occupants scarcely a hundred feet away. Willie Sloan was waving his hands vigorously.