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."
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.
"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?"
"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.