ck," he directed.
"Now then--"

The boys started to obey, but at the first touch the man cried out in
such pain that they were forced to put him down again.

"It's something in here," said the old fellow, while the girls and boys
stood looking helplessly at him, not knowing what to do. He put a hand
over his left side. "Something's broken. I--I was trying to--invent a new
kind of aeroplane," he went on jerkily, and in spite of the tragic
circumstances the young folks felt a thrill of excitement as they
realized that here perhaps was the secret of that strange humming noise
that had so badly frightened and bewildered them.

"The second ghost," murmured Teddy softly, as though to himself, but
Billie, standing close beside him, heard.

"A new kind of aeroplane," Chet prompted, gently but with an unusual
light in his eye.

"Yes. And this was its--trial flight," the old man said with a world of
bitterness in his voice. "The engine exploded. I guess it shows that I'm
pretty much of a failure--in every way."

"I don't see why," cried Billie, her warm heart eager to give him
comfort. "There may have been just some little thing the matter that
you--What's that?"

"That" was the sound of running feet and a crackling of bushes, and the
next minute two men burst out into the clearing. They were red of face
and breathless, and when they saw the old man and the wrecked machine
they stood stock still and stared in consternation.

With a start the girls and boys recognized the men as those whom they
had met in the woods that other day not so long ago--the men who had so
curtly ordered them to "go the other way."

So the corn story was a fish story after all, and the old inventor's
vain attempt to make a new kind of flying machine was the key to all
the mystery!

"Are you very much hurt, Dad?" cried the younger of the two men, leaning
anxiously over the old man. Again the young folks were startled. So one
of the bearded men was the old man's son!

"All in, Son, I guess," answered the old man. With a sigh he laid his
hand over his left side and whispered: "I'm all smashed to pieces. The
engine exploded."

"Well, let's see about that," said the second of the two men, pushing the
younger aside and beginning to rip open the old man's shirt.

Up to that time neither of the men had thrown a glance in the direction
of the wondering boys and girls--in fact they gave every impression of
not having seen them at all.

The older