“Good night!” Bud gasped in a stunned voice.  “Don’t tell me that’s just a coincidence!”

Tom shrugged.  “We can certainly rule out the possibility that anything was wrong with the radio itself.  Every set is checked before it leaves the electronics department.”

“So where does that leave us?” Bud persisted.

Tom shook his head worriedly as he took off the goggles.  “Both times it seemed to happen just as the reply was coming through from the space station.  There is no possibility that their signal was too strong—­in other words, that the explosion was caused by overloading the receiving circuits.”

“Are you implying that an enemy intercepted the message and sent some sort of ray that caused the set to explode?” Bud demanded.

Tom’s face showed clearly that Bud had pinpointed the suspicion in the young inventor’s mind.  “Could be.”

Bud was worried by this latest development.  “Skipper, suppose I hop up to the space wheel and talk it over with your dad.  He may be able to help us detect any enemy moves.”

“Good idea, pal,” Tom agreed.  “The sooner the better, I’d say.”

The boys exchanged a quick handshake and affectionate shoulder slaps.  Then Bud hurried out to one of the Enterprises hangars to ready a helijet for the flight to Fearing Island.  This was the Swifts’ rocket base, just off the Atlantic coast.  From there, Bud would board one of the regular cargo shuttle rockets operating between the space station and Fearing.

Tom, meanwhile, plunged back to work on his shock-wave deflector.

At ten the next morning he called in Hank Sterling and showed him a set of completed drawings.

“Hank, you did a fast job on the container for the brain,” Tom began apologetically, “but you’ll really have to burn out a bearing on this one!”

Hank grinned.  “I’m geared to action.  Say, what do we call it, anyhow?” he asked.

Tom grinned.  “Chow told me last night this gadget looked like a fireplug under a rose trellis and I ought to call it Fireplug Rose!  But I’ve given it a more dignified name—­the Quakelizor, which stands for an underground quake wave deflector.”

Briefly, Tom explained the various parts of his latest invention, which consisted of a hydrant-sized cylinder to be inserted into the ground, with magnetic coils near the top.  A smaller hydraulic cylinder, mounted above this, was wired to a metal framework and radio transmitter.

“This setup will detect any incoming enemy shock waves,” Tom said.  “We’ll need fifty of ’em, so turn the job over to Swift Construction.  And have Uncle Ned put on extra shifts.”

The Swift Construction Company, managed by Ned Newton, was the commercial division which mass-produced Tom Jr.’s and Tom Sr.’s inventions.

Information from the detector-transmitters, Tom went on, would be fed into an electronic computer at the Bureau of Mines in Washington.