CHAPTER IV.--THE AEROPLANE IN DANGER.

A strong wind came out of the Western Sea at ten o'clock that night and swept the lofty plateau as a woman might have swept it with a new broom. Ned and Frank, pursuing their investigations in the cavern, knew nothing of what was going on at the camp, but Jack and Pat were not long in ignorance of the danger of the situation.

With the first strong rush of wind the boys were on their feet, steadying the aeroplane, driving stakes wherever the nature of the ground permitted, and running bracing cords. The shelter tents went down instantly and were blown against the rocks of the east, where they waved canvas arms in the tearing breeze like sheeted ghosts.

The black clouds which swarmed up from the valley brought no rain, but fitful flashes of lightning and deep-toned thunder made a threatening sky. The roaring of the swirling trees in the canyon and on the slopes came up to the ears of the boys like the boom of a strong surf.

After persistent efforts the boys succeeded in bracing the aeroplane so that there was little danger of its being swept away, though they still remained with their backs to the wind, holding on. As time passed, they crept close together in order that the situation might be discussed.

"Lucky thing we remained here," Pat said, tugging with all his might to steady the monster machine against a particularly vicious dash of wind.

"It would have gone sure, if we hadn't," Jack screamed back. "I wish Ned and Frank would come and help. My back is creaking like a shaft that needs oiling with the strain on it."

"A little help wouldn't go amiss," Pat admitted, shouting at the top of his lungs in order that he might be heard above the whistling of the storm.

"I wonder if we'll ever be able to put the tents up again?" Jack shouted. "They are flapping and snapping like musketry out there on the rocks. I hope they won't blow away entirely."

Pat gazed anxiously in the direction indicated, but could only see pieces of canvas bellying up in the wind, mounting upward like balloons at times, then falling back to earth when a short lull came in the storm.

"Why," he cried, in a moment, "where's Jimmie? I thought I saw him here a moment ago. Have you seen him?"

"Not since the storm," panted Jack.

"He may have been smothered in his tent," Pat shouted. "You hold on here while I go and look him up."

"Be sure that you keep close to the ground," warned Jack. "If you don't you'll be blown away."

It was not at all difficult for the lad to reach the flapping tents, for the wind generously assisted him in the journey. Only that he crept on his hands and knees he would have been tossed against the wall where the tents lay.

Struggling with the tearing canvas, bracing himself against the face of the cliff, the boy looked over the ruined tents but found no indication of the presence of the boy he sought, either dead or alive. Then he felt along the angle of the foot of the rise with no better success.

"He's not there," he reported, crawling back to Jack, now braced tenaciously with his toes and elbows digging into the soil above the rock.

"Did you find his clothes?" asked Jack.

"Not a thing belonging to his outfit," was the reply.

"Well, he went to bed, didn't he?" asked Jack, a sudden suspicion entering his mind.

"He went into his tent," was the reply, "but I did not see him undress."

Then Pat, much to his astonishment, heard Jack laughing as if mightily pleased over something that had taken place.

"You've got your nerve!" he exclaimed. "Laughing at a time like this. I'll bet the kid has been blown off the plateau."

There was now a little lull in the drive of the wind and Jack nudged his companion with his elbow, turning an amused face as he did so.

"Blown off nothing!" he said. "You saw how he acted when Ned went off without him--how sulky he was?"

"I noticed something of the sort."

"Well, Jimmie ducked after him!"

"Why, he was told to remain here."

"He has been told that before," Jack said, "and he's never obeyed orders. He followed Ned from Manila to Yokohama, not long ago, and made a hit in doing it, too. Oh, it is a sure thing that Jimmie is not far from Ned at this minute."

"The little scamp!" grinned Pat.

"He seems to think that Ned can't get along without his constant presence and his pranks," Jack continued. "He generally stirs something up in his immediate vicinity, but he's a pretty good scout at that."

"I hope he is with Ned," Pat said.

The wind now died down a bit, so that it was no longer necessary to hold the aeroplane, and the boys, after seeing that the rope still held, began the work of repairing the tents.

The clouds drifted away and the moon looked down as bravely as if it had not just hidden its face from sight at the threats of the wind! The electric flashlights with which the boys were well provided seemed inadequate and Pat started in to build a fire.

"I don't know about that," Jack said. "If there had been a fire here when that wind came up it would have been roaring in the canyon now. The storm would have swept it down on the trees there, and the whole gully would soon have become a roaring furnace. Better cut out the fire."

"I guess you are right," Pat said, reluctantly laying his dry faggots aside.

While the boys worked, trying to restore the shelter tents to something like form, the wind came up once more and reached out for the aeroplane. Pat and Jack renewed their holding efforts, and thanked their stars that no fire had been built on the plateau, for the forest about was dry as tinder.

Presently a voice which neither recognized came out of the shadows cast by a mass of clouds just then occupying the sky where the moon should have been.

"Hello!" the voice said.

The boys looked at each other in perplexity for a moment and then Jack answered back.

"Hello!" he said.

"Are you all safe up here, safe and sound?" the voice asked, and then the figure of a tall man, roughly dressed, but bearing the manner, as faintly observed in the darkness, of a gentleman, advanced toward the aeroplane, to which the lads were still devoting their whole attention.

"Safe and sound!" repeated Pat.

The stranger sat down by Jack's side and laid hold of the aeroplane.

"Pulls hard, doesn't it?" he asked, as the machine, forced by the wind, drew stoutly on the ropes and the muscles of the boys.

"Pulls like a horse," Jack replied.

"I'm Greer, of the forest service," the stranger said, in a moment. "I saw a fire up here this afternoon, and I was afraid harm might come from it during the gale. One blazing brand down in that canyon, and millions of feet of timber would be destroyed."

"As you see," Jack said, "we have no fire."

"This, I presume," Greer said, still pulling at the machine, "is the aeroplane your friends came in this evening?"

"The same," replied Pat shortly.

The lad was annoyed to think that the forester, as he called himself, had been watching them. If he had taken so much interest in their movements, Pat thought, why hadn't he shown himself before?

Jack's thoughts seemed to be running in the same direction. In fact, both boys were suspicious of this soft-spoken stranger who had come to them out of the storm with questions on his lips.

"Where are your friends?" Greer asked, in a moment. "I hope they are not out in the forest thinking of starting a fire?"

"They've gone to the lake after fish," Jack said, accounting for the absence of the others with the first words that came to his lips.

Greer gave a quick start and leaned over to look into Jack's face.

"Down at the lake?" he repeated. "Not out in a boat in a storm like this?"

"No," replied Jack, gruffly, so gruffly, in fact, that the stranger caught the hostile note and turned away.

"I'm always afraid of fire on a night like this," Greer continued in a moment, "and rarely sleep until morning. My cabin is back on the mountain a short distance, some distance above this plateau. That's how I happened to see what was going on here."

"Rather a lonely life," Pat said, resolved to keep the fellow talking if he could. "Because," he reasoned, "you can tell what's in a man's head if he keeps his mouth open and his tongue moving, but no one can tell the secret locked up behind closed lips."

"Yes, it is rather lonely," Greer replied. "I'm glad you boys are here. Going to remain long?"

"Only a few weeks--just to hunt and fish," was Jack's reply.

"If you don't mind," Greer went on, "I'll come down and visit you now and then."

The statement almost took the form of a question, and Jack gave a grudging answer that the visits would be a pleasure, though he believed that the man was arranging a way of watching their movements.

"I wish this wind would go down," Greer said, presently. "As I said before, I'm always afraid of fire on nights like this. See! The wind blows straight off the distant ocean strong and steady, and a fire started out there to the west would run over this plateau and over the mountain like a wash of tide."

"There's nothing to burn on the plateau," Jack said, glad of an opportunity to contradict the stranger.

"Nothing to burn!" Greer repeated. "I reckon you don't know much about forest fires, young man! Why, it would burn the soil down to bed rock, even evaporate the water in the rock itself and crumble it down to ashes. A forest fire is no joking matter."

The boys remained silent, looking cautiously into each other's faces and both wondering how a forester, a man marooned in a great wilderness should be so exact in his speech, should wear such a shirt--actually a dress shirt--as they saw under his rough coat when the wind blew it aside.

"I rather think there's more company coming," Greer continued, seeing that the boys were not inclined to comment on his warnings. "A moment ago I saw a flash of light at the foot of the rise to the west."

The wind was still blowing fiercely, but both boys turned and looked down the incline. There was a faint light there now, glimmering among the trees.

"It looks like a lantern," Greer said. "And the fellow seems about to climb the hill. Good luck to him, in this gale."

"It seems to me," Pat said, "that the light we see is running along on the ground. If that should be a forest fire, there would be the dickens to pay to-night--and nothing to pay with!"

"That is not the way forest fires start," Greer said, turning indolently in the direction of the divide. "That is a man with a lantern."

The boys watched the glimmer below with interest. The man with the lantern, if there was a man and a lantern, seemed to be moving with the wind. Then, again, he seemed to divide himself, as the lower orders of life at the bottom of the seas divide themselves, appearing on both sides of a dark space at the same moment.

They were satisfied that something unusual was going on, but were for the moment lulled into a half-sense of security by the positive assertions of the alleged forester. Presently they turned away from the scene below and fixed their eyes on the stranger.

He was standing straight up, his tall figure braced against the wind, peering down into the canyon. Notwithstanding the steady wind, the sky was now comparatively free of clouds, and they saw him lift a hand with something bright shining in it.

It appeared to the lads that he was signaling to some one in the canyon. They turned away instantly so that Greer did not note their observation of him, and again fixed their gaze on the slope to the west.

The lantern, if there was a lantern, was growing larger! It was showing itself in half a dozen places now, and was tracing lights far up in the crotches of dead trees. Then the penetrating odor of burning wood and grass came up the slope.

Filled with a fear which could hardly be expressed in words, the boys faced Greer again. He still stood facing the canyon to the south, but his hands were not lifted now. There was no need for that, the boys thought, for the previous signal seemed to have sufficed.

Among the dry faggots on the ground at the bottom of the canyon there was another man with a lantern. He, too, if there was such a man, was moving about among the trees and dividing himself into sections, as the rudimental creatures of the world multiply themselves. Pat sprang to Greer's side and shook him roughly by the arm.

"There's a fire down there!" he cried.

In the uncertain moonlight the boy saw the stranger's face harden.

"You are mistaken," he said, turning away toward the lake.

"Smell the smoke!" Jack shouted. "I tell you the forest is on fire on two sides of us."

"Then your friends have set the fires!" Greer shouted, against the wind. "I have been suspicious of you all along--ever since you failed to satisfactorily account for the absence of your friends. It is all very well for you to come here in an aeroplane and start a conflagration! But how do you think that we, who are not so well provided with means of getting away, are to escape death?"

Pat drew back his hand, as if to strike the fellow, but Jack restrained him.

"You set the fires!" Pat shouted, then. "You set it through your fellow conspirators! I saw you signaling to the canon!"

"You're no more a forester than I am!" Jack added. "You're a scoundrel, and ought to be sent to prison for life."

There was no more talk for a time. Greer stood defiantly against the wall of rock to the east, as if fearful of an attack from behind, his right hand in his bulging pocket. The boys knew that he had a weapon there, and their own hands were not empty.

The aeroplane drew and shivered in the rising gale, but now little attention was paid to it. Pat and Jack were listening for some indication of the return of Ned and Frank. No farther fable of a man with a lantern was necessary, for fire was racing up the western slope, heading directly for the plateau and the priceless aeroplane. Down in the canyon the flames were leaping from tree to tree. A stifling smoke filled the air, always in swift motion, but stifling still.