on," the operator informed him.
"Just a moment, please."

Bernt Ahlgren was calling from the Pentagon. The defense expert's voice
was strained.

"Tom, there's just been another attempt to cause an earthquake here in
Washington!"

Tom gasped. "What happened?"

"It failed, thanks to you. But Intelligence believes an attempt will be
made on New York City very soon. We need your help to stop it. How near
completion are the other shock deflectors?"

Before Tom could answer, he heard excited voices at the other end of the
line. Then Ahlgren broke in again abruptly.

"A news flash, Tom! The Walling range-finder plant has been demolished
by an earthquake!"

CHAPTER XIV

AIR-BORNE HIJACKERS

Mr. Swift, hearing Tom's dismayed reaction, rushed to the telephone.

"What's wrong, son?"

Tom clamped his hand over the mouthpiece and quickly gave his father the
news of the destroyed range-finder plant. Then he spoke into the
telephone.

"Bernt, we must prevent another disaster! Let me check with our
construction company on the Quakelizors and I'll call you right back!"

"Right, Tom," Ahlgren agreed.

Both Tom and Mr. Swift were shocked by this latest blow of their
enemies. Tom called Ned Newton at the Swift Construction Company at once
and told him the news.

"How soon will the Quakelizors be ready, Uncle Ned?"

"They're finished, Tom. We're running a final inspection on them right
now. We can have them ready to ship out by one o'clock."

Tom relayed word to the Pentagon. Bernt Ahlgren was greatly relieved.
"By the way," Tom went on, "what about the sites? Have they been chosen
yet?"

"Only tentatively," Ahlgren replied. "We wanted to get your opinion
first."

One of the deflectors, Ahlgren felt, should be based in position to
guard the New York and New England area, in view of Intelligence
warnings about a probable attack on New York City. Another, in the
Cumberland plateau region of Kentucky, could damp out shock waves
threatening either the heavily industrialized Great Lakes area or any
southern city.

As to the other three Quakelizors, Ahlgren suggested that one be
installed on the West Coast, one in the Black Hills of South Dakota, and
the third on the Atlantic island of San Rosario. This would protect both
Latin-American allies and Caribbean defense bases of the United States.

Before deciding, Tom asked that Dr. Miles at the Bureau of Mines be
circuited into the telephone conversation. Mr. Sw