He found that no one had been near the machine and it was as ready as ever for service. It would have been the height of imprudence for him to bring it forth so long as the return of the Professor was impending. He devoted a few minutes to oiling the moving parts and giving the structure a minute examination, and frequently he stepped into the open space and studied the sky through his field glass, searching for the object that had become familiar to him.

Remembering what Aunty Hep had said, he scrutinized the country a little to the east of north. It was mountainous, wooded, unsettled, and so far as he could judge contained very few or no cabins.

“It is the place where I should think he would hide Bunk, but his prison may be a score of miles beyond the farthest reach of my vision.”

A mass of cumulous, fleecy clouds was drifting across the sky low down, while the firmament above was of a clear soft blue. Just below a stratum of snowy vapor, he saw what looked like a bird with outstretched wings sailing toward him. Its rapid increase in size and the power of the binoculars quickly disclosed the fact that it was a monoplane. Professor Morgan was returning to his workshop near the town of Purvis.

Instead of taking the same course as before, the inventor circled to the east, so that he was a fourth of a mile distant on his nearest approach to where Harvey Hamilton stood on the edge of the cleared space with leveled glass. He was still flying low, and in a few minutes sank from sight.

“I am sure that Detective Pendar would agree with me as to the meaning of what I have seen to-day. Professor Morgan carried food to Bunk, and at the same time gave his machine a test so far as he could. He has not yet accomplished all he has in mind, though he may be close to it, and has gone back to his workshop to continue his experiments. He will stay there for the rest of the day and make another trip to-morrow morning.”

This was drawing it fine, but our young friend was so confident he was right that he acted upon the theory. It will be seen that he was steadily narrowing the circle of search. At daybreak he had established the fact that the place where Bunk was held a prisoner was north of the ridge which the pursuer crossed on his way to the home of Aunty Hephzibah Akers. He had learned later that it was somewhere in the wild region a little to the east of north, which loomed up on the farther limit of his vision. The next visit of the Professor to Bunk ought to locate the spot so nearly that Harvey could, so to speak, put his finger on it.

Aunt Hep had resumed her sewing by the window, and her niece having cleared off the table was chatting with her about the remarkable story told by their youthful caller, when both were startled by a roar and racket which caused them to listen with bated breath. Neither had ever heard anything like it, for it will be remembered that the monoplane to which they were accustomed sailed on its aerial voyages without ripple or noise. Ann sprang up and opened the door.

“O Aunty! here he is! come and look!”

As she called, she sprang off the little porch and ran out to where Harvey Hamilton had just finished volplaning to the earth only a few rods away from the front of the house. Her relative was at her heels, as much amazed as she. They stared at the strange looking thing, and upon the owner’s invitation went forward and listened, absorbed, to his description of the functions of the different parts. Harvey patiently answered questions that belonged more to a child than to an adult.