Harvey Hamilton was in the middle of an odd dream, in which a big Irishman was swinging a tremendous hammer and bringing it down on the top of his head with every stroke. The sentiment of wonder is always absent in the visions which come to us in sleep, no matter how incongruous they may be, but the youth came very near feeling surprised at the thickness of a skull that could withstand so terrific attacks.

By and by the slumber lifted and Harvey’s senses came back. He was wide awake and conscious that some one was tapping gently outside. He sprang out of bed and turned the key. As if automatically, the door swung inward and revealed Detective Pendar in the dim gaslight. He stepped within and secured the lock behind him.

“Sh!” he whispered; “I don’t think either of those men is in his room, but we cannot be too careful.”

The night was so sultry that Harvey did not dress, but sat down on the edge of the bed, his caller doing the same, near enough to be touched with the outstretched hand. The time had come for the officer to tell more than was his rule in circumstances of a critical nature.

“How did you succeed?” asked the younger.

“It’s a fizzle so far,” was the reply; “I have inspected that cabin in the woods, where you and I thought the little girl was held a prisoner, but she is not there now and never has been there.”

And then he told his story to the astonished and disappointed listener.

“Understand, no blame attaches to you,” the detective hastened to add; “your mistake was natural and I could have made it as readily as you.”

This was not strictly true. The picture which Bunk Johnson viewed from the biplane would have been analyzed to the point of disclosing the truth, had Pendar been the one who saw it.

“Then I suppose, you will give up the hunt?”

“By no means, but it must end one way or another before we are twenty-four hours older.”

This assertion opened the way for the startling revelation that if Grace Hastings was not recovered before the ensuing midnight, the ransom would be paid by the officer, who had it waiting in the safe of the hotel below stairs.

“Although you mistook the place where the gang are holding her,” added the man, “you came near it. Did either you or your colored friend notice any other house in the woods when you were sailing over them?”

“I gave my attention to the management of the aeroplane after observing the cabin, and could easily have passed several dwellings without seeing them. Bunk spoke of no other, though it is possible he saw one.”

“I have information which cannot be questioned that the spot we are looking for is not far from the home of Uncle Tommy Waters the weather prophet. Had my investigation been made by daylight, I should have pushed it farther, but I was helpless at night. You will have to make another search as soon as it is daylight.”

“I am eager to do what I can, but you must tell me how.”

“Is your negro capable of running your aeroplane?”

“He can when the conditions are favorable, as they promise to be to-morrow; I shouldn’t be willing to trust him otherwise.”

“Good! let him handle the levers then, while you occupy the aluminum chair and give your efforts to spying out the land.”

“Shall we follow the same course as before?”

“Substantially so; he will keep the speed just high enough to sustain you at an altitude of say five hundred feet. You understand that the closer you are to the ground, the narrower is your field of vision, so you will keep far enough aloft to gain an extended survey, and yet not so high that you will lose distinctness of view. I notice that you carry a field glass.”

“Yes; it is of German make and the best in the world; our government sells them only to its army and navy officers; mine belongs to one who is a relative, and who has loaned the instrument to me for life, I making a suitable money acknowledgment therefor.”

This pleasant little fictional arrangement explains how it is that some of these fine instruments are in the hands of civilians.

“You are not likely to need the glasses on this trip.”

“Hardly; the heights from which I am to make the search are so moderate that my eyes will require no help.”

“Then will you loan them to me?”

“With pleasure.”

The detective explained the use to which he expected to put the binoculars.

“I shall take a position that will give me an extended survey over the woods without drawing notice to myself, and after you are fairly started on your aerial voyage, I do not intend to lose sight of you.”

“If I discover the place you have in mind, how shall I let you know it?”

“By signal.”

“They will be likely to see it.”

“Not likely but certain; therefore the message must be of a nature that will not rouse suspicion on their part.”

Harvey could not forbear asking an explanation at this point.

“You said that if your visit to the cabin had been made by daylight, you would have gone farther. Why not do so in the morning?”

“I should if time permitted. You understand that without your aid I should have to make a hunt through the woods. This would not only consume time but would surely be discovered by some of the gang on the lookout. That is why I have refrained and waited for an opportunity to present itself. When you locate the exact spot—and I am sure you will do so—I can go straight to it.”

“Will you not be watched?”

“Quite likely, but I can push on in spite of that. Let us get back to the important point of how you are to let me know of your success. The simplest thing is—I’m blessed if I know,” said the detective, after slight hesitation, with a laugh; “help me out.”

That which at first seemed an insignificant matter threatened to become insurmountable. Pendar’s first suggestion was that when Harvey made his discovery he should swing his cap over his head, but such a signal would be instantly noticed by the kidnappers, who would accept it as a menace.

“Suppose I tell Bunk to swoop downward as if about to make a landing.”

“That would be fully as bad, for the scoundrels would think it was meant to gain a clearer view of them.”

“If we sail upward?”

“That’s it! They can give no meaning to such a manoeuver. When you are sure of what you see, direct your servant to go upward at the sharpest angle possible. I shall be the only one who will know what the movement means.”

“It seems to me,” added the youth thoughtfully, “that those two Italians who are stopping at the hotel must begin to suspect you.”

“Not as yet; I count myself fortunate that I have thrown them off the scent completely. There is no doubt of that, though it looks as if there will be a waking up before to-morrow night.”

“You have played your part with skill, Mr. Pendar.”

“I’ll not deny that I feel some pride over my work thus far; but, all the same, I have as yet accomplished nothing, and it is by no means certain that I shall do anything more than pay a set of criminals fifty thousand dollars to give back the child they have stolen.”

At this point Harvey recalled the other matters that had slipped his mind during his previous talk with the detective.

“You know, Mr. Pendar, that since Bunk and I started on our little sail through the upper regions, we have several times run across a curious character called Professor Milo Morgan.”

“I know him well; he is a crank of the first order.”

“He was friendly at first and did me a great favor when I was in danger of being mobbed, but it is hard to forgive one of his acts.”

“What was that?”

“Wrecking my aeroplane, by chopping and battering it to pieces when it was housed under the sheds of this hotel.”

The detective rose from the side of the bed and stood upright in the gloom in front of his young friend.

“What in the name of the seven wonders put that fancy into your head?”

“Why,” replied Harvey hesitatingly, not expecting such an implied contradiction; “it couldn’t have been any one else.”

“Well, it was some one else; Professor Morgan had no more to do with destroying your biplane than King George V.”

The amazed Harvey stared in astonishment.

“Bunk saw him sneaking out of the back of the shed early in the morning, when he went to look at the machine.”

“Did the Professor have an axe or hatchet in his hand?”

“I believe not.”

“Having told you what he did not do, can you now form an idea of what he did do?”

“I suppose he went off in that marvelous monoplane of his.”

“But previous to that?”

“I haven’t the remotest idea.”

“He went to the telegraph office as soon as it was open, and sent your father a long message, giving the particulars of your misfortune. Your father, like the good fellow he is, immediately ordered a new machine, which reached you this morning.”

“I am amazed and gratified,” replied Harvey; “the first chance I have I shall apologize to Professor Morgan.”

“Don’t do that.”

“Why not?”

“He will know that you have been idiot enough to suspect him.”

“But, Mr. Pendar, do you know who did destroy my machine?”

“Don’t you?”

“I have no suspicion.”

“Well, I shall leave you to solve one of the simplest problems that was ever submitted to a ten-year old child. I was so certain you knew the truth at once, that I didn’t think it worth while to make any reference to it when we next spoke together.”