."

"You 'fraid, Apple?"

"No, I'm scared, but I'm not afraid. But I don't wonder so much at Matt.
I know how I'd be if I didn't know God had a firm hold of me, right now.
Let's sing a little."

He started a familiar camp song, and from one song they went to another.
When they were singing "Where He leads me I will follow" Chick-chick
held up his hand.

"Matt's asleep," he whispered. "I'll bet his head's made him 'bout half
crazy. Hope he sleeps till morning."

How many hours they slept they could not tell, for there were no
timepieces. They would rouse, turn over, and drop asleep again, for each
one was determined to sleep away as much of the waiting time as
possible. It was probably early morning when at last Glen arose,
stretched himself and carefully lighted a lantern.

"It's going down, boys," he announced. "The opening isn't uncovered yet,
but it's two or three feet lower than it was last night."

They were all wide awake now, and all leaned over the ledge to form
their own opinion.

"The current seems to run differently," said Glen. "It acts as if the
rock we threw in has stopped up the old outlet and it was running back
of the heap we pulled down instead."

"Yes, sir. Strikes me just that way," said Chick-chick.

"I'm going to take the other lantern and explore a little," said Glen.
"You fellows needn't come. I'll holler if I find anything."

He disappeared behind the ruined arch, swimming and wading, but he was
back in a minute, all excitement.

"There's a regular passage out this way, fellows. Seems to go clear
through the Mound. The water's rushing down in a torrent. Come and
see."

They needed no invitation, for they were down before he finished
speaking. Around the crumbled masonry he led them, and pointed to an
opening like a natural tunnel which, seemed to lead far into the bowels
of the earth.

CHAPTER XX

THE TREASURE OF BUFFALO LAKE

The cavernous opening into which the boys swung their lanterns in a vain
attempt to penetrate its gloom seemed indeed to lead into the heart of
Buffalo Mound. A muddy, turbulent stream was rushing down it at a
tremendous rate, but there was room enough left to allow the passage of
an agile boy, willing to bend himself double, and the water was not deep
enough to be an obstacle.

"It may show us a way out," exclaimed Glen. "I'm bound to see where it
goes. Who'll go with me?"

"We'll all go, Brick. You don't leave me behind in this dark cave,