Eagerly the adventurers looked through
the opening at the end of the passage into the larger
cave. The men opened the small oven in which
the balls of white chemicals and carbon mixed, had
been baked, and a pile of things, that looked like
irregularly-shaped marbles, were placed in the steel
box.
This box, which was about the size
of a trunk, was of massive metal. It was placed
in a recess in the solid rock, and all about were
layers of asbestos and other substances that were nonconductors
of heat.
“That box becomes red hot,”
exclaimed Mr. Jenks, in a whisper. “When
things are in readiness, that lever is pulled and the
diamonds are made. I pulled it once, but I did
not then know the process involved. I supposed
that the lightning had nothing to do with making the
diamonds.”
“It has—a most important
part,” said Mr. Parker. The hidden adventurers
could talk in perfect safety now, for the men in the
large cave were too excited to pay much attention to
them. The muttering of the thunder grew louder,
and at times a particularly loud crash told that a
bolt had struck somewhere in the vicinity of the cave.
“But, bless my watch-charm!”
exclaimed Mr. Damon, “I didn’t know lightning
made diamonds.”
“It does not—always,”
went on the scientist. “But great heat
and pressure are necessary to create the gems.
In nature this was probably obtained by prehistoric
volcanic fires, and by the terrific pressure of immense
rocks. It is possible to make diamonds in the
laboratory of the chemist, but they are so minute
as to be practically valueless.
“However, these men seem to
have hit upon a new plan. They utilize the terrific
heat of lightning, and the pressure which is instantaneously
obtained when the bolt strikes. I am anxious to
see how it is done. Look, I think they are getting
ready to make the gems.”
Indeed there seemed to be an air of
expectancy among the diamond makers. The mixing
machine had now been stopped, and, as it was more
quiet in the cave, our friends, in their hiding-place,
had to speak in mere whispers. All the men were
now gathered about the great steel box.
This receptacle had been closed by
a solid metal door, which was screwed and clamped
tight. Then one of the men examined a number
of heavily insulated electric wires that extended from
the box off into the darkness where Tom and his companions
could not discern them.
“That’s Folwell—the
man I befriended, and who got me into this game,”
whispered Mr. Jenks. “He was also one of
the first to turn against me. I think he’s
one of the leaders.”
Folwell came back, after having gone
into a dark part of the cave. He went over to
an electrical switch on one of the stone walls.
“It’s almost time,”
Tom heard him say to his confederates. “The
storm is coming up rapidly.”
“Will it be severe enough?”
asked one of the helpers. “We had all our
work for nothing last time. The flashes weren’t
heavy enough.”
“These will be,” asserted
Folwell. “The indicator shows nearly a
million volts now, and it’s increasing.”
“A million volts!” exclaimed
Tom. “I hope it doesn’t strike anywhere
around here.”
“Oh, it will probably be harmlessly
conducted down on the heavy wires,” said Mr.
Parker. “We are in no danger, at present,
though ultimately I expect to see the whole mountain
shattered by a lightning bolt.”
“Cheerful prospect,” murmured Tom.
There was a terrific crash outside.
The rocky floor of the cave trembled.
“Here she comes!” cried
Folwell. “Get back, everybody! I’m
going to throw over the switch now!”
The men retreated well away from the
steel box. Folwell threw over the lever—the
same one Mr. Jenks remembered pulling. Then the
man ran to the electric switch on the wall, and snapped
that into place, establishing a connection.
There was a moment’s pause,
as Folwell ran to join the others in their place of
safety. Then from without there came a most nerve-racking
and terrifying crash. It seemed as if the very
mountain would be rent into fragments.
Watching with eager eyes, the adventurers
saw sparks flash from the steel box. Instantly
it became red hot, and then glowed white and incandescent.
It was almost at the melting point.
Then came comparative quiet, as the
echoes of the thunder died away amid the mountain
peaks.
“I guess that did the trick!”
cried Folwell. “It was a terrific crash
all right!”
He and the others ran forward.
The steel box was now a cherry red, for it was cooling.
Folwell threw back the lever, and another man disconnected
the switch. There was a period of waiting until
the box was cool enough to open. Then the heavy
door was swung back.
With a long iron rod Folwell drew
something from the retort. It was the tray which
had held the white balls. But they were white
no longer, for they had been turned into diamonds.
From their hiding-place Tom and the others could see
the flashing gems, for, in spite of the fact that
the diamonds were uncut, some of them sparkled most
brilliantly, due to the peculiar manner in which they
were made.
“We have the secret of the diamonds!”
whispered Mr. Jenks. “There must be a quart
of the gems there!”
The men gathered about Folwell, uttering
exclamations of delight. The diamonds were too
hot to handle yet.
“That’s going some!”
exclaimed the chief of the diamond makers. “We
have a small fortune here.”
The was a sudden commotion at one
end of the cave. A man rushed in. At the
sight of him Tom stared and uttered an exclamation.
“Munson—the stowaway!” he whispered.
“Hello!” cried Folwell,
as he saw his confederate. “I thought you
were East, keeping Jenks away from here.”
“He got the best of me!”
cried Munson, “he and that Tom Swift! I
stowed away on their airship, but they found me out
by a wireless message, and marooned me in the woods.
I’ve been trying to get here ever since!
Didn’t you get my messages of warning?”
“No—what warnings ?” cried
Folwell.
“About Jenks, Tom Swift and
the others. They’re here—they
must be on Phantom Mountain now. In fact, I shouldn’t
be surprised if they were in this cave. I traced
them to their camp, but they’re gone. They
may be among us now—in some of the secret
recesses!”
For an instant Folwell stared at the
bearer of these tidings. Then he cried out:
“Scatter men, and find these
fellows! We must get them before they discover
our secret!”
“It’s too late—we
know it!” exulted Tom Swift. Then he whispered
to the others to hurry to the part of the cave where
Bill Renshaw had first hidden them.