iet
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,