“How do you know?”

“I bet it is!”

“Do you think he’s comin’ here?”

Questions and exclamations such as these came in rapid succession following the announcement from Hal that the object flying toward them high in the air was Johnson Miles’ new airship. It was approaching rapidly and seemed to be headed right for the top of Flathead.

“Maybe he knows we’re here.”

Pickles made the suggestion, and nobody seemed disposed to take it as a joke. However Hal replied:

“I don’t believe he does. How could he, unless somebody found one of our arrows? We didn’t see anybody pick any of ’em up.”

“Maybe he’s just hunting for us,” suggested Fes.

“It’s more likely he’s just taking his first flight,” said Hal. “I’d feel more hopeful if I knew that was true.”

“So would I,” said Byron. “He’d probably fly up here the first place. If he’s hunting for us, he won’t come here at all unless he knows we’re here.”

“Well he’s surely makin’ for this mountain,” Hal declared after a few moments of silence.

It certainly seemed true. The biplane was flying at an elevation slightly above that of the plateau, and did not waver in its course.

“We’ve got to get busy and make sure that he sees us,” Hal suddenly exclaimed. “He might fly right over this mountain without stopping unless we attract his attention. Take off your coats and wave ’em and make all the noise you can when he gets near.”

Hal set the example and the others followed. Soon the five mountain-top Crusoes were cutting the wildest capers imaginable and creating a noise with their throats that surely was loud enough to be heard within a hundred yards by the aviator in spite of the vibrations of his propellers.

The airship was making remarkable speed and in less than five minutes from the time it was first sighted, Johnson Miles glided gently down to a level spot not far from where the truant Scouts were capering about. They had forgotten their hunger, their tired condition, and their despair.

Such a jumble of excited questions as followed the alighting of the airship could hardly be represented without a phonographic record. The boys were eager to know how the aviator discovered them—did he know they were on the mountain?—and Mr. Miles was equally curious to learn how they had come there. Finally he said:

“Boys, I’ve brought you some food and water. You said you were hungry.”

That settled it. Mr. Miles had read one of the notes on the whistle-arrows. Naturally, they marveled at this, but Hal satisfied himself by concluding that one of the arrows had fallen into one of the vehicles at which he had directed his aim.

From the cabin of the airship, the aviator produced a large jug of water and a basket filled with sandwiches and other edibles. Eagerly the boys poured the cool liquid down their throats and then pounced upon the contents of the basket. For a while they did nothing but eat and drink, but at last Pickles inquired:

“How did you know we was here?”

“He found one of the arrows,” laughed Bad.

“No, I didn’t,” replied the aviator.

“There! there!” Pickles jeered, pointing his finger at Frank. “You will know it all, will you?”

Frank was a little crestfallen, and awaited developments, hoping for an opportunity to vindicate himself.

“I didn’t find an arrow, but somebody else did,” explained the rescuer.

“A-ha! What did I tell you?” cried Frank.

“He didn’t find it,” Walter replied stoutly.

“Well, what’s the difference? I suppose if I said the top of this mountain’s flat, you’d say it isn’t ’cause there’s hills on it.”

“My, what silly things you boys quarrel over,” exclaimed Mr. Miles. “You’re as bad as rival politicians. If you’ve settled the question I’ll proceed. The arrow hit Dr. Edwards’ horse as he was driving through the caÑon.”

“I bet that was the horse that ran away,” interrupted Byron.

“Yes, it was,” replied Mr. Miles. “He tipped over the carriage, broke loose and ran back to town. There he was caught and the arrow found sticking in his back. The person who found it took your note to Dr. Byrd.”

“Was Dr. Edwards hurt?” inquired Hal.

“Not much. Somebody overtook him just outside the caÑon and gave him a lift, so he didn’t have to walk all the way home.”

Hal’s note tied to the arrow contained brief information of their predicament and also that they were hungry and thirsty. It did not, however, contain any details as to how they had been trapped over the waterfall cave and later reached the top of the mountain. Hence, they found it necessary to relate their experiences as soon as Mr. Miles had finished his story. Incidentally, the man discovered that Hal was running away, but he made no comment on the subject. Neither did he refer to the nugget episode, which he suspected to have something to do with the boys’ escapade.

Finally all the food was eaten, all the water was gone, and all the stories were told, and then Mr. Miles suggested that it was time to return to Lakefarm.

“How we going to go?” asked Ferdinand. “In the airship?”

“Sure. You boys all wanted a ride in it. Now you’ll have a chance to prove your nerve.”

“We can’t all ride at once,” objected Frank.

“Oh, come now, Bad, don’t back down,” admonished the aviator mischievously. “You know you cried out the loudest that you wouldn’t be afraid.”

“I ain’t afraid,” protested Frank angrily, “but you know there isn’t room enough for all of us.”

“No. I agree with, you, Frank. I’ll take only one with me on the first trip, and that’ll be you.”

“Why me? I don’t want to ride alone with you. You’ll be busy all the time. I want somebody else to talk with. Let Pickles go the first trip.”

“All right. I don’t care; only I want to try the ship with one passenger before I take two. Pickles, you’re not afraid to go first, are you?”

“No, I ain’t afraid,” replied Walter, smiling. He seldom became excited or disturbed. Doubtless he would have watched the moon shoot across the heavens with no more fear than the average boy feels over a burning house or a runaway horse.

“I ain’t afraid either,” insisted Frank, but he did not offer to make the first trip with Mr. Miles.

“All right, you’ll have a chance to prove your bravery next time,” assured the latter. “Come on, Pickles, we must hurry, for it’s getting late and I’ve got to make two more trips before sundown. It’s after four o’clock now.”

“You can make ’em all in half an hour, can’t you?” inquired Hal.

“Pretty nearly, if everything goes well. But something might happen to delay me.”

Walter and the aviator now got aboard the aeroplane and Mr. Miles started the engine. The two big propellers turned faster and faster, and the biplane gave a few jerks and tugs, then leaped and bounded forward violently over the uneven ground until the wheels no longer touched the earth. Rapidly now she arose in the air, circling around towards the north.

In order to insure safety for Walter while giving his entire attention to the management of the vessel, Miles had closed the front and rear slides, so that they were enclosed in a room, or cabin, twelve feet long, including the tapering forequarter, and five feet wide. The aviator sat at the wheel in the narrow prow, while Walter was free to move about as he wished.

The four boys left behind gazed eagerly and admiringly at the airship with her invisible occupants for several minutes, not a word escaping the lips of any of them. Suddenly Frank broke the silence by saying:

“Say, fellows, maybe we’ll never have a chance to come up here again. Dr. Byrd won’t let us come up in the airship, and the passage through the cave’s closed. Let’s explore this mountain top some before Mr. Miles gets back.”

“There isn’t much to explore,” replied Ferd. “We can see pretty near everything standing right here.”

“We can’t see the other side of those big rocks and cliffs over there,” Byron answered, pointing to the south through the thin belt of timber: “That’s what we were lookin’ at through the field-glasses from Uncle Sam’s mountain, you know.”

“Yes, let’s go and have a look at it,” proposed Hal.

There was no need of further urging, and the four boys started off at a brisk rate. Through the timber they ran and then southward along the high ridge of rocks and mounds, until they came to a passage through the rocks. Into this passage they entered and hastened on until near the middle a new discovery brought them to a halt.

“My goodness! Look at that!”

Hal exclaimed thus as he stopped suddenly and pointed toward something very remarkable fifteen feet ahead. It was the opening of a cave in the clay and stone wall, and slightly ajar was a wooden door of rough-hewn tree trunks.

“Why, somebody lives up here!” cried Ferdinand in excited tones. “Let’s go and see who it is.”

“No,” Hal cautioned. “We’ve got to be careful. If anybody does live here, he’s probably crazy. Let’s pick up some stones to throw at him if he comes at us.”

The boys all accepted this suggestion and soon they were armed. Then they advanced cautiously past the opening in the left wall.

They reached the western end of the passage and turned to the right. Here they found a much more satisfactory view of the rocky and bluff-lined elevation they had observed through the field-glasses from the top of Porcupine Hill. In places the elevation rose two hundred feet above the level of the plateau. Perhaps at no place was it more than one hundred feet in thickness, but it was seven or eight hundred feet long, constituting by far the biggest mole on the pate of Flathead.

Near the pass the line of cliffs presented an almost perpendicular face to the south, scooped out here and there in the form of overhanging shelters. And in these shelters, twenty or thirty feet from the Flathead level were a number of openings, cave-like and fronted with ruined outer structures, that thrilled Hal with a realization of an important discovery.

But this thrill was quickly replaced by another more intense and immediately important. It was occasioned by the appearance of a live, cat-like form, with burning eyes and crouching, hungry attitude in one of the openings—a panther—and it was looking right down on the boys.