n on the sand in the position their antagonist
might have taken when he fired at them.

"Here I am with a view of the water hole, and in a good place to shoot
from without being shot. Now I want to get away quick. What do I do?
If I roll to the left, I expose myself to fire. If I roll to the
right, I--" there was a little clump of mesquite by his right elbow.
Bud pulled himself toward this. "That would afford protection, but
once I get in here how can I get out? Now--" The boy was rolling to
the center.

With a "Hold it, bronc!" he released the reins and his hand slid off
the clump. Suddenly a queer thing happened. Bud felt the ground below
him give way, and the next moment he found himself in a hole just large
enough to admit his body, and about four feet deep. Above him the
bushes had closed again, effectively screening him from the view of
anyone above ground. He had accidentally solved the mystery of the
gunman's strange disappearance.

For a few seconds Bud lay still, so sudden was the shock of the fall.
He was not really stunned, however, and as soon as he recovered from
his surprise he struggled to his feet and parted the brush above him.
His horse was near by, moving slowly and cropping grass.

Then he saw how easily it would be to escape observation by falling
into the small pit. The bush was certainly not large enough to conceal
a man, and for this reason no one would imagine it could serve to
screen a hole. It afforded a perfect hiding place. On either side was
flat prairie, and no one would suspect the presence of a hidden person
in that country.

"So that's how it all happened!" Bud gave a low whistle. "No wonder
we missed the fellow. Say, this is one bird of a hiding place! All a
man has to do is to roll in it, like I did. Anyone who can tell this
hole is here without being in it is a better detective than I am.

"But what a crazy spot for a hiding place! Surely whoever dug it
didn't know he'd use it to fire on us and then escape. Must have been
some other reason for making it, and then it came in handy when whoever
shot at us wanted to get away. He must have just lain quiet while we
looked around, then, when we left, he just came out and walked away.
Clever, all right. Now who'd think of a stunt like that?"

He looked more closely at the hole. It was well walled up, and had
evidently been dug some time ago. By parting the bushes and kneeling
on a mound of earth at the botto