as then considered that the most
important thing would be to utilize the time of two for the purpose of
making the shells. This was the most laborious process, as every step
had to be done by hand, the dies being in the form of separate punches,
held and driven by hand, as they had no such thing as a press for
manipulating the dies.

One morning Harry said: "I know it isn't the proper thing to suggest it
while we are all so busy making the preparations for the expedition, but
I think we ought to make a trip to the cave before we start."

Neither of them objected to the proposal, and George went to the
Professor, and told him that he and Harry had conferred on the subject
of the cave, and with his permission they would take the boys there.

The Professor's assent was given with a smile of pleasure, and several
lamps were put into condition for the event. All was excitement now with
the young spirits, and the Professor assisted them in the preparations.

It did not take long to reach the mouth of the cavern, and lighting the
lamps, descended slowly. Neither George nor Harry had informed the boys
of the treasure within the cave, nor of the skeletons which were
discovered, although, when the boys had asked the source of the
skeletons in the laboratory enough of an evasive answer was given to
make them suspect the source, and this was confirmed when Harry told
them, days before, that they had also discovered a cave.

They descended the steps, and made their way along the passage leading
to the first recess. As the chamber came into view the boys were
entranced at the sight. It was a novelty to them. It was the first time
they had ever witnessed such a thing.

To Harry and George it was no longer a thing to marvel at. They were
veterans in the exploring field.

"This makes a fellow feel queer in here," exclaimed Tom, as he glanced
around at the magnificent stalactites.

"Did we tell you," replied George, "about the mysterious thing that
happened to us the second time we came in?"

"No; what was it?"

"We entered from the other opening by the sea."

"Another opening? Do you mean that this cave has two openings just like
the one John spoke about?"

"Yes; but this is a mighty long one, and it had a lot of water in it
twice when we visited it, but I don't think we shall find any here now."

"Why not?"

"Because we have not had much rain for the past month."

"But you forgot about the mystery."

"That's so; we