"We can't get an aim if he keeps on swerving," said Herb.

"Steady, fellows," warned Hawke, for they had moved about, twisting in their seats, to get a sight of the game. The plane was mounting steadily higher, and Hawke had reduced his speed, pursuing the enemy as well as he could, for it had adopted a zigzag course, flying to right and left and dipping up and down.

"I'm going to try a shot anyway," said Herb.

The others unconsciously left the shooting to the southerner, who, it was naturally and rightly supposed, would be glad to bag the animal that had given his father so much trouble.

Young Phipps took aim at the first good opportunity, and shot three times. It seemed to be without result, for the huge shape moved on, though its course became more uncertain than ever, and, although it seemed heading toward the mountain ranges, its flight was uneven and hap-hazard.

"We must be over the mountains now," said Fly, after a time.

"We're about 1,800 feet above level," responded Hawke.

At that moment the bird resumed its swift circles, flying downward.

Pointing the nose of the plane toward the earth, Hawke followed it, making a thrilling spiral descent.

"Why, there's the old tower," cried Fred, when the plane had dropped far enough for its lights to play upon the surface below.

"And he's circling down for it," cried Fly.

"That's his roost, I'll bet," exclaimed Jerry.

"Then it must be the Thunder Bird Carl told about--the one you saw when I tried to take that picture--the one that raised the storm," jabbered Fred disjointedly.

"And the one the old Indian is after," put in Gray.

"Let him roost, and then we'll get him," suggested Herb.

But Hawke had altered his course, and was making swiftly in the direction of home.

"Where you going?" shouted Fly in surprise. It had been necessary for them to raise their voices considerably, for the mountain torrents were distinctly heard below, while the noise of their own machine added made hearing difficult.

"We've got to get right back," responded the aviator, throwing on top speed.

"What--what for?" yelled Gray. "We nearly had him."

"There's a wind rising, and I felt a splash of rain," returned the aviator. "We can't take chances over these peaks in a storm."

As if to corroborate his statement there was a distant rumble.

"Thunder," gasped Jerry breathlessly, for the speed of the machine almost shut off his wind, and like the other boys he was clinging tightly to his seat.

"I felt rain then, too," shouted Herb.

Another rumble, louder than the first, sent thrills down their backs.

"It was the Thunder Bird all right," yelled Fred. "I told you I saw him that day."

"We know where he lives now, though," returned Fly.

But they were dashing through s.p.a.ce at such a terrific pace that speech became impossible. Hawke was bending every energy to beat the storm.

Already the wind had risen considerably, and he was obliged to concentrate his whole thought on the control of the machine.

"Make for the B. P.," requested Herb. "Dad'll be anxious to know how we come out. We can--"

But the rest of his sentence was lost in a deafening roar, while a flash of lightning split the darkness and revealed, below them, the stretches of pasture belonging to the Bread Pudding ranch.

While they had been obliged to give up when victory was within easy reach, the boys were more pleased than otherwise at the adventurous turn things had taken. The flight by night, so eagerly antic.i.p.ated, was becoming more exciting than they had expected.

Before they realized it, they had skidded down and stopped in front of the ranch-house. But they could only pause long enough to allow Herb and Gray to dismount, for it was necessary to reach the Fort as quickly as possible and lodge the plane in its shed before the storm, whose threatening voice was growing constantly louder, broke upon them.

The boys had no chance to exchange words with the rancher before, Carl and Dunk having taken the place of Herb and Gray, they were whisked upward again. And, though anxious to learn the result of their companion's flight, the Indian and his friend were obliged to wait until, just in time, they had shoved the plane back into the hangar and rushed to the Crawford residence. They had scarcely reached the veranda when the fury of the tempest was upon them.

"Whew!" e.j.a.c.u.l.a.t.ed Hawke, breathing a deep sigh of relief. "That was a record run. If I had made that at an aviation meet I'll bet they'd have awarded me some kind of a medal."

He spoke lightly, and the boys never knew how wonderfully well he had made that flight. Not one aviator in a hundred would have been able to accomplish it with such coolness and accuracy as Hawke had displayed.

Perhaps, after they had themselves learned to fly, they realized the precarious condition in which they had been that night and how much they owed their safe return to Hawke.

They were greeted cordially by the captain when they arrived at the Fort, who listened, with unfeigned interest, to their rapid recital of the evening's events.

"But we're goin' back to-morrow," said Fly, "and get him. For we know where he roosts."

"Yes," said Hawke. "We must lose no time. We have the drop on him now, and I'll run you all up there in the morning. You can let Herb and Gray know."

"Telegram for Mr. Hawke," announced Ike, appearing, dripping but smiling, at the screen door.

"Well, what do you think of that!" exclaimed the aviator, his face suddenly growing grave as he read the wire, and handed it to the captain, who was quickly surrounded by the boys.

"'Mexican insurrectos threaten invasion of Texas,'" read Jerry's father.

"'Come immediately. Take charge aviation corps. Urgent.'" The message was dated from Juarez, and was signed by General Marley, commander of the border troops.

CHAPTER XVIII

SUCCESS AT LAST

The next day was a blue one for the boys. Apparently all their plans had been knocked sideways. The hunt, for which they had worked and waited all summer, had been nipped in the bud at the moment of success.

"Let's scout it, anyhow," suggested Fred that evening, as the downcast group huddled together on Jerry's veranda.

"What d'ye mean?" asked Dunk, uninterestedly.

"Well, make a trip up into the mountains and see what we can do,"

continued the easterner.

"How you going to get across that ravine?" disparaged Fly, who had been moping all day. "It's too wide even to throw a rope across."