Tom
Swift's invention safeguard the threatened area?_

As the deadline approached, Tom pushed a button. The mighty hydraulic
drivers throbbed into action, sending out their pulse waves across the
continent!

CHAPTER XVIII

EARTHQUAKE ISLAND

Now came the hardest part of all for Tom and his companions--waiting to
learn if the shock deflectors had succeeded in blotting out the enemy
quake wave.

No one spoke. As the silence deepened inside the cave, the suspense
became almost unbearable. Minutes passed.

"When will we know, skipper?" a crewman ventured at last.

"Soon, I hope," Tom replied tersely.

But the waiting seemed endless. Bud's eyes met Tom's. The flier grinned
and held up crossed fingers, just as Tom had done to Mike Burrows the
previous evening. Tom managed a feeble grin in response.

Suddenly the telephone shrilled, shattering the silence of the cave. Tom
snatched it from the radioman's hands.

"Tom Swift here!... Yes?... Thank heavens! I guess we can all be
grateful, Dr. Miles!"

"Providence protected us, I'm sure, Tom," the seismologist replied at
the other end of the line. "But in this instance it worked through Tom
Swift's Quakelizors! The Bona Fide plant and the surrounding area never
even felt the tremor--your quake deflectors worked perfectly!"

There was no need to tell the others. Tom's words on the telephone and
the grin on his face told the story. A spontaneous volley of cheers
echoed through the cave as he hung up. Then the crew crowded around to
slap Tom on the back and shake his hand.

"I hope the whole country learns what you've done, Tom," Mike Burrows
said. "If it doesn't, I'll be the first to spread the word as soon as
the secrecy lid's taken off!"

"Shucks, I knew all along Tom's contraption would do the trick!" Chow
boasted, glowing with pride over his young boss's achievement.

Tom could only smile happily. "Guess we can go home now," he said to Bud
and Chow.

They were preparing to leave when another flash from Washington came
over the radiotelephone. A ship's captain, five hundred miles out on the
Pacific, had just reported sighting a great waterspout, accompanied by
considerable wave turbulence.

"It could have been the spot where the enemy shock waves and our
deflector waves met and damped out," Tom commented.

"Dr. Miles thinks so, too," the caller said.

Soon the sleek Swift jet was arrowing back across the continent. En
route, Tom radioed word of h