“Hug the rocks!  She’s going down!” shouted the guide.

Go down it did, with a crash that seemed to shake the mountain.  Rolling to the edge of the shelf, it had toppled over, taking a large strip of shelving rock with it.

“Wow!” howled Chunky;

The other boys uttered no sound, though their faces were a little more pale than usual.

Kris Kringle stepped to the edge, peering over.

“No one will get that up here again, right away,” he said.

“The cave, the cave!” shouted Walter.

Everyone turned, gazing half in awe at the dark opening that the removal of the stone had revealed—­ an opening that had been closed for probably more than two centuries.

CHAPTER XVIII

 Facing the enemy’s guns

“Do we go in?” asked the Professor.

“Wait, I’ll get some light inside first,” answered the prudent guide.  “Can’t tell whether we shall want to go in or not.”

He built up a small fire within, then called to the others that they might enter.  They crowded in hastily, finding themselves in a fairly large chamber, at the far end of which was a sort of natural alcove in the rocks.

The remnants of a fire still lay at one side, where the last meal of the ancient dweller had probably been cooked.  Several crude looking utensils lay about, together with a number of pieces of ancient pottery.

“This is, indeed, a rare find!” exclaimed the Professor, carrying the precious jars out into the light for closer examination.

Chunky, about that time, pounced upon an object which proved to be a copper hatchet.

“Hurray for George Washington!” he shouted, brandishing the crude tool.  “The man who never told—­”

“We’ve heard that before,” objected Ned.  “Give us something new, Chunky, if you’ve got to talk.”

The Professor came in, searching for other curios just as Stacy went out to examine his “little axe,” as he was pleased to call it.  He tried the edge of it on the ledge to find out if the stone would dull it, but it did not.

“I’ll use that to cut nails and wire with when I get back home,” decided the boy.  “Guess I’ll chop my name in the side of the mountain here.”  Stacy proceeded to do so, the others being too much engrossed in their explorations to know or care what he was about.  He succeeded very well, both in making letters on the wall and in putting several nicks in the edge of his new-found hatchet.

He was thus engaged when all at once something struck the axe hurling it from his hand.  At the same instant a rifle crashed off somewhere below and to the southeast of him.

“Ouch!” exclaimed the fat boy holding his hand.  “Wonder who did that?” His mind had not coupled the shot with the blow on the hatchet.

Bang!

A bullet flattened itself close to his head, against the rock.