nd, to
assist him in going down.

The smaller boy looked rather wistfully into the hole as Dick went down,
and Jack, breaking another stout stick, asked:

"Do you want to go down there, young fellow, and follow Dick Percival on a
fool's errand?"

"It might not be that," said the other, "and I would like to go."

"All right, then, come along. Here is a staff for you. I can do without
one, I think. Keep close to me. Can you walk upright, Dick?"

"Yes, generally," came back the answer in a muffled voice. "My! but the
place is filled with echoes, Jack. It goes down quite a distance I should
say. The light is a big help. Funny, but there seems to be a light down
here, although where it comes from I can't say."

The boys kept going down and at length Jack said, pausing and trying to
pierce the darkness, the light that Percival had spoken of not being
visible at that moment:

"I think we would better get a light, Dick. We don't know where we are
going, and it is dark. It is never safe to go anywhere in the dark unless
one is familiar with his surroundings."

"That's true enough, Jack. Have you any matches? The next time we come
this way, if we do, we had better take a flashlight along."

"I have matches," said Jack, and in a moment a tiny blaze shot up,
increasing till it enabled them to see to some extent where they were.

They were still descending, but in a short time were on more level ground
or rock, whatever it was, proceeding till the match went out, and a few
steps farther when Dick suddenly brought up against something and
exclaimed in surprise:

"Hello! we cannot go any farther, Jack. Strike another match, and let us
see where we are."

Jack lighted two or three matches at once, and held them just above his
head so as to obtain a good view of his surroundings.

"Hello! what is this?" exclaimed Percival. "A cave, or what?"

Just before them was a jagged opening into some region beyond, but whether
it was a cave or not puzzled them.

Jack went closer, and held his light in the jagged opening.

"It's a hole in the side of a vessel, Dick!" he cried in amazement.

CHAPTER VI

A WALK UNDER WATER

"That's what it is, Jack," said Dick, after the first sensation of
astonishment had passed. "It is more in the bow than on the side, however.
You can see how she narrows a little farther on. This hole is pretty well
forward. I tell you what! This is the vessel we saw under water, or the
one that stu