y must come in through these passages above. Some holes probably let
out onto the side of the hill, and the bats go in and out through them
at night."

"I think," said Tom, as they made their way back to the entrance, "that
taking all together, that was the worst scare I ever had."

"Shake on that, Tom," said Jo.

A further search through the cave was fruitless of results, so far as
looked for treasure was concerned, and their original plan of
investigating the smoke signal was taken up.

A walk of another mile brought them to the spot they sought. They had
thus far encountered no one, or any indication of the presence of
inhabitants on the island. They gained finally the summit of the hill
from which the column of smoke was ascending. They found that this had
been made by building a fire in a small chimney of stones and covering
it with wet leaves. There was an opening below which gave just
sufficient draft to keep the fire smouldering.

But little could be seen of the land from the top of the hill on account
of the thick woods, but by climbing one of the taller trees, which they
did in turn while the others kept guard, they were enabled to make out
that they were on an island of many miles extent, and that another
island lay some five or six miles to the southwest. Most unexpected of
all their discoveries, they saw in the distance far out upon the ocean a
steamer which was apparently approaching the island. The distance was
too great to determine with any definiteness anything about her
character or probable intentions, and further information on that point
would have to be sought at a later time.

"I can't understand that smoke business," said Tom, once more examining
the chimney-like arrangement curiously. "It was certainly made by
someone, yet there doesn't seem to be anyone about."

"They may be on the other side of the island," suggested Jim, "or they
may have come from the other island and gone back again."

"But why should they have come over here and made the fire?" persisted
Tom.

"You will have to ask them," laughed Jim. "I am sure I don't know, or
why they should have lighted it at all. But some of us had better return
to the ship or I am afraid that the professor will be getting anxious."

Arriving at the landing place, Tom elected to go on board. He felt that
he had had enough of excitement and adventure for one day. Jim
accompanied him, while Jo and Juarez, the spirit of investigation
awakene