t at all times.

And especially valuable would this qualification become when confronted
by a baffling mystery such as the Hickory Ridge troop was now up
against.

"Those who occupied this shack were four in number," Elmer began.

"How did you find that out?" asked Red.

"By the various tracks. So far as I could see there were just four
separate kinds leading up to this place, and each one different."

"Hurrah! I tell you, fellows, that's the way to learn things. Elmer
knows how to do it," cried Lil Artha.

Without even smiling at the implied compliment Elmer went on:

"Two of them wore shoes with hobnails just as you see on this old
cast-off shoe here. A third one had on American-made brogans, and I
expect they hurt him some, too, because he was limping as he walked. He
is undoubtedly the chap who used to own these old foreign-made
gun-boats."

"Hold on a minute, please, Elmer," pleaded Red.

"All right. You want to ask me something, and I think I know what it
is," remarked the other.

"You say this fellow's new shoes hurt him, and made him limp; please
tell us how in the wide world you ever found that out?" Red continued.

"Well, it might be possible that the fellow was always lame, but his
tracks show plainly that he limped. Something was wrong with his left
leg or foot, because the toe dug deeply into the ground."

"Well, I declare is that dead-sure evidence, Elmer?" demanded the
astounded tenderfoot, Landy, who was listening with all his might to
these intensely interesting facts as brought out by the scout master.

"Try it yourself sometime, Landy," remarked Elmer. "Pick out a nice
piece of ground where the marks will show plainly. Limp as naturally as
you can with the left leg. Then go back and examine the trail. You will
find that not only does the left foot dig deeper at the toe than the
right one, but that same toe drags a little over the ground as you bring
the left foot forward each time."

"Just listen to that, will you!" remarked Red, "but I know Elmer is
right. I can grab the principle of the thing."

"But how about the fourth one, Elmer; seems to me you've been holding
back something there, that you mean to spring on us," said Lil Artha.

"Well, I have," remarked the other, quickly. "This fourth track was
smaller than the others, and the person also wore American-made shoes."

"Ah, a boy, eh?" asked Red.

The scout master shook his head.

"Wrong that time, my boy. You'll have to gu