Rushing out in the direction of the cries, the boys found Billy struggling in the grasp of Fred Reade, Luther Barr, and Slade, while the red-headed mechanic was striking at the aeroplane with a big wrench.

“There! If we can’t fly any more, no more can you,” he exclaimed viciously, making a savage smash at the engine. There was a sound of splintering metal.

“Consarn ’em, they’re trying to bust up our aeroplane,” yelled Bart Witherbee, making a dash at the group.

As they saw the boys and their companions coming the men took to their heels, Reade alone looking back to shout out:

“Now you can’t fly, either. You’re out of the race.”

This the boys construed to mean that the Slade aeroplane was too badly crippled to fly. And so they afterwards learned. The engine had developed a serious flaw, and one of the cylinders was cracked from top to bottom. In the part of the country in which they were it would, of course, have taken weeks to get a new engine.

“Shall we chase them?” asked Harry.

“No, it would be useless. Hark! they’re in their auto now, and would be away ahead of us by the time we got after them,” rejoined Frank.

The sound of an auto’s exhaust rapidly growing fainter reached their ears. It was the last they saw of Luther Barr and his gang, for that night they left Calabazos and making their way to the railroad took a train east. The skeleton of Slade’s unlucky aeroplane still remains in the little settlement, and greatly puzzles visitors there, some of whom think it is the framework of some extinct animal.

Billy Barnes soon told how, while shooting in the woods, he had heard an auto coming up the trail, and suspecting some mischief had hastened to the spot where the aeroplane had been left. He found his surmise correct when Barr and his companions suddenly emerged from the woods and began their attempt to wreck the craft. Before Billy, who indignantly sprang forward, could seize the arm of the vandal with the wrench, he had been seized. Luckily he had time to cry out before they thought of stopping him, and so the aeroplane was saved from serious damage. It was found, in fact, that the blow aimed at it had done no worse harm than to splinter a spark plug, which was soon replaced.

That afternoon the boys, leaving Bart Witherbee and the sheriff to make an inventory of the dead miner’s effects and to explore the tunnel, which was found to be a wonderful piece of work, the boys motored down to the settlement and sent out telegrams seeking information of the whereabouts of the dirigible. It was not till late evening that they received from Doolittle, a small town about forty miles from Calabazos, information that the big gas-lifted craft had laid up there for repairs, but was ready to start early the next day.

To the boys who had feared that the rival must have been almost in San Francisco by that time this was cheering news, and the Golden Eagle’s planes were hurriedly readjusted, as she was put in shape for a continuation of her trip. Early the next day the start was made. Bart Witherbee was left behind at his mine, in which he had insisted on the boys, much against their will, each taking a share. Old Mr. Joyce also received a large enough portion of the general good luck to secure him from want and give him ample leisure to work out his queer inventions. The Witherbee mine—he calls it the Aeroplane—is now one of the most famous in the west.

The boys had determined to shape their course by Doolittle, as it was on their direct path westward, and they wished also to get out of the mountainous region of the foothills. As Doolittle came in sight they had an opportunity to view their rival for the first time in many days. Her big red gas bag showed like a bright crimson flower above the sober gray of the prairie town. That their rivals had sighted them was soon made evident by the fact that a flag was run up on the single staff the town possessed and the citizens wheeled out a rusty old cannon and began firing it like mad. When the boys were within a mile of the town they made ready to drop messages which, as they sailed above, they cast down. They could see the people scrambling furiously for them.

“I hope they leave enough of them to send back home,” laughed Harry as they saw the wild struggle.

That day was to be a memorable one for the town of Doolittle. As the aeroplane passed above it, the faithful escorting auto not far behind, the big dirigible also was shot into the air.

Mr. McArthur from his deck waved a greeting to the boys and hailed them through a megaphone.

“Glad to see you,” he hailed. “Hurray, for ’Frisco!”

All that afternoon the two ships sailed along in company, the boys’ aeroplane slightly in the lead. As the sun sank lower a big bank of clouds arose toward the north and the sun glowed with a peculiar red light.

A light breeze also sprang up, but instead of being cooling it was as hot as if it had blown from an oven door.

“We’re in for a storm,” remarked Frank, “or I’m very much mistaken.”

“What, a regular rain and wind storm?” asked Harry. “I thought they only had those in the hills in this part of the country.”

“They have a worse thing than that,” said Frank apprehensively, “a sand storm, and that’s what may be coming.”

“McArthur doesn’t seem to be worrying,” remarked Harry, glancing up at the dirigible, which was sailing slightly above them.

“No,” said Frank, “that’s a fact. Maybe I am mistaken, after all. Anyhow, we’ll keep on as long as he does.”

But half an hour later the boys wished they had alighted. The wind came in sharp, hot puffs from the north, and had it not been for the Joyce gyroscopic balancer they carried, the ship would have been in hard straits. As it was, when Frank wished to make a landing he dared not risk it. The air, too, grew so thick that he could not see the earth beneath them.

Stinging particles of sand drove into their eyes, blinding them and gritting between their teeth. The wind grew stronger, and as it did so the air grew black as night with the sand with which it was impregnated.

So dark was it, in fact, that when night came and found them still in the air, unable to make a landing, there did not seem to be any perceptible difference.

The aeroplane drove rigidly before the howling wind. Her speed was terrific. Neither boy spoke after their first expressions of alarm, but devoted their entire attentions to keeping the aeroplane from capsizing.

“Keep cool, Harry,” said Frank at length. “We may come out of it all right.”

“Where are we being driven?” asked the other lad.

“To the south at a terrific pace, too. If the gasolene holds out we may manage to live out the storm, but I don’t know where we will be driven to.”

“What lies to the south of us?” asked Harry, after another long pause, during which the storm-stressed aeroplane made several sickening lurches, always recovering herself in time, however, thanks to the gyroscope.

“Why, about as desolate a country as can be imagined. Nothing but arid wastes and cactus.”

“It will be a bad lookout, then, if we have to land there.”

“It certainly will,” was the laconic response.

On and on through the darkness drove the storm-tossed aeroplane, carrying her two young navigators into the unknown.