“Good place for spooks!” Bud whispered jokingly.

A steep draw led upward among the rocky slopes.  A hundred feet on, Tom’s group found the black yawning mouth of a cave.  The yellow beams of their flashlights revealed a tunnel leading downward inside.  Tom checked with a pocket detector.  Its gauge needle showed no field force caused by electrical equipment in operation.

“Okay, let’s go in!” Tom murmured.

Cautiously they moved into the tunnel.  Then suddenly ahead of them a powerful dazzling light burst on, nearly blinding the searchers!

CHAPTER XIX

A FIENDISH MACHINE

A chill of fear gripped Tom and his companions as they blinked helplessly in the glare!  Had the enemy detected them the first moment they had set foot on Balala Island?  Had they walked blindly into a trap?

Gradually Tom’s eyes and those of his friends adjusted to the dazzling radiance.  A door, blocking the tunnel just ahead, had slid open and the light was pouring out of a room beyond.

“What happened?” Arv gasped.

Tom pointed downward to a pedallike plunger inserted in the tunnel floor.  “This must be a switch,” he explained.  “When I stepped on it accidentally, it must have opened the door and flashed on the lights.”

Bud whistled.  “Wow!  Let’s be thankful it wasn’t a booby trap!”

“Maybe it is,” murmured Hank grimly.

Steeling their nerves, and with every sense alert, the searchers advanced into the secret room.

Tom suddenly gave a cry of amazement.  “The earthquake machine!”

A huge hydraulic device, with massive steel bed and supporting pillars, looking somewhat like the enormous body presses found in automobile plants, stood embedded in a recess in one wall.

Tom rushed to the machine and examined it in fascination.  A powerful diesel generator stood nearby with banks of complicated electrical equipment, amid a spider-web tangle of wiring.  Tom assumed this gear was for timing and synchronizing the shock waves.  Evidently the whole setup was operated from a single control panel in the wall, studded with knobs and dials.

“What a job of design!” Tom exclaimed in awe.  His eyes roved over every detail of the equipment while he poked here and there with his hands.  He was getting the “feel” of the setup almost as much by touch and handling as by his superb technical intuition.  “Boy, I hate to admire anything those Brungarian rebel scientists do, but this is really masterful!”

“Yes?  Well, don’t go ga-ga over it,” said Bud.  “Let’s do what we came to do and scram out of here.  This place makes me jumpy!”

Tom appeared oblivious.  “It seems like vandalism to wreck such an engineering achievement!  Also, and this may sound strange to you,” he went on in a doubtful tone, “are we really justified in taking the law into our own hands?”