uted at the top of their voices.

There was no reply, and, indeed, Jack and Dick did not hear them, being
at some distance from the mouth of the cave at this moment.

The boys presently shouted again, but still there was no response, and
Harry said in great disgust:

"We are only wasting our breath. They can't hear through all this
rubbish, and they may be a good way off. I should not wonder if the cave
was a big one. There are some such in the mountains along the Hudson
valley, especially in these counties. Nobody bothers with them very
much, but they're here all the same."

The boys kept hard at work removing the debris that had fallen into the
entrance of the cave, but some of this consisted of great rocks, which
were impossible to get rid of with the means at their disposal, and
Harry presently growled, as he wiped his perspiring forehead with one
hand while he leaned against the ledge with the other:

"We'll have to blow this stuff up. If it were only earth and gravel we
could do something, but there are rocks as big as a house in the hole,
and we can never get rid of them."

Several of these boulders had been uncovered by throwing aside the
earth, so that Harry's statement was seen not to be an exaggerated one,
and Arthur replied:

"We have nothing to blow it up with. Would prying do any good, do you
think? We have no bars, but we can get plenty of stout poles from the
trees, and they will help us."

"I shouldn't wonder. It is clear enough that we cannot do much with the
shovels alone."

"Hark!" cried young Sawyer, who was too little to do a great amount of
the kind of work the boys were doing at the moment, but who seemed to be
on the alert; "don't you hear something?"

"Keep still, boys," said Billy Manners. "Sawyer has heard something.
There is not much of him, but it is all good stuff."

"Keep still!" said the smaller boy impatiently, and there was silence.

In a few moments there was an unmistakable shout heard, distant, it was
true, but still a well-defined shout.

"That's Percival!" cried young Sawyer.

"Hello!" shouted Harry. "Keep her up, boys! Give a good shout all of us.
Now then!"

All of the boys shouted at the same time, and then kept quiet to hear
the answering shout.

"All right, we are coming!" they heard Jack shout in a clear, shrill
tone, which had great carrying power.

"Where are they?" asked Billy. "That does not sound from the cave.
Hello! Are you in the cave, you fello