The remaining stones were quickly laid in place.  Tad motioned for Chunky to descend.  The fat boy leaped down.  The tree top remained on the ground leaving a wide opening in the rocks.

“Now, Chunky, keep your nerve.  You may need it.”

“What are you going to do?”

“I’m going in there.  I think perhaps it might be the wiser plan for you to remain out here and keep watch.”

“No, sir, I guess not!  I’ve helped discover that hole and I’m going to reap my reward by exploring the inside.”

“Come along then.  It is taking long chances, but I guess the tree is safe unless some one should come along and trip the stones.  Then we would be in a fine fix, shouldn’t we?”

“I reckon we would.  We wouldn’t be getting out of that hole, right smart, should we, Tad?”

“I guess not.  We should be buried alive.”

“Still, there may be some other opening to the place.  We will take a chance.  Got your matches?”

“Yes.”

“Then you light a match when we get inside.  I’ll have my revolver ready in case there is anything in there.”

Taking a final glance about, Tad moved toward the opening in the rocks with brisk step.  Chunky was trotting along behind him, the fat boy full of importance over the discovery they had made.  At the opening they paused, glancing apprehensively at the great roots towering above them.  Were the butt of that giant tree to settle down now, it would crush them.

The boys stepped inside.  They could see but a few feet ahead of them, but saw that they were in a huge crevice in the rocks, a sort of cave formed by the splitting apart of the rocks themselves, perhaps from some long past earthquake disturbance.

“Light a match, Stacy.”

The fat boy did so.

“There have been horses in here,” announced Tad.

“Yes, I guess there have, but there aren’t any here now.”

“Fortunately for us.”

The air was cool, though a little damp in the cave.  To this the boys gave no heed.  They had more important matters on hand than observing the atmosphere of the place.  The cave they found was much larger than they had had any idea of.  In places the roof was all of ten feet high.  But as they penetrated further in, moving cautiously, lighting the way with every step, the walls sloped toward the back, approaching nearer to the floor.

Except for the light from the matches, the boys were in darkness, so that they were not able to observe that the opening to the cave had closed.  A strong breeze, swaying the upper limbs of the tree, had dislodged the stones and allowed the roots to slip quietly into place again.  The boys, without knowing it, were prisoners.

“You aren’t throwing your matches on the floor, are you?” demanded Tad turning sharply.

“Yes, why not?”

“Show me a light here,” commanded Tad going down on his knees and gathering up all the burnt matches he could find.  “That is a fine trail you are leaving.  Why, were any one to come in here, he would discover instantly that strangers had been here.”