<h4>AN URGENT WARNING</h4>
<p><span class = "firstword">Mr. Swift</span>
looked on eagerly as Tom explained and demonstrated his touch apparatus.
By moving a pantograph control, Tom was able to manipulate the claws
like a hand with fingers. Whenever they touched any material, the brain
gauges instantly registered an electrical reaction inside the
sphere.</p>
<p>The swing of a voltmeter needle showed how firmly the substance
resisted the claw's touch, thus indicating its hardness or softness.</p>
<p>"With a computer device, such as we planted in Exman," Tom went on,
"the brain would also be able to assimilate the textural pattern of any
substance."</p>
<p>"Wonderful, son!" Mr. Swift exclaimed. "I hope I can do as well
with this artificial sense of sight I'm working on."</p>
<p><span class = "pagenum">146</span>
<SPAN name="page146"> </SPAN>
Another hour went by before Mr. Swift was ready to test his own
arrangement.</p>
<p>"You've probably heard of the experiments conducted with blind
persons," he told Tom. "By stimulating the right part of their brain
with a lead from a cathode-ray-tube device, an awareness of light and
dark can be restored."</p>
<p>Tom nodded.</p>
<p>"Well, I'm using the same principle," Mr. Swift went on, "but with a
sort of television camera scanning setup."</p>
<p>He asked Tom to draw the drapes and shut off the room lights,
throwing the laboratory into complete darkness, except for the weirdly
glowing "brain" in the glass sphere. Then Mr. Swift shone a flashlight
at the scanner. The brain responded by glowing more brightly itself!</p>
<p>Next, after the drapes were opened again and the overhead fluorescent
lights switched on, Mr. Swift painted a pattern of black-and-white
stripes on a large piece of cardboard. He held this up to the
scanner.</p>
<p>Visible ripples of brightness and less-brightness passed through the
glowing ball of energy inside the sphere. It was reproducing the striped
pattern!</p>
<p>"Dad, that's amazing!" Tom said with real admiration.</p>
<p>Mr. Swift shook his head. "Pretty crude, I'm afraid. The brain energy by
itself can't take the
<span class = "pagenum">147</span>
<SPAN name="page147"> </SPAN>
place of a picture tube in a TV receiver. What we need is an analog
computer to sum up the scanning pattern picked up by the camera tube and
then pass this information along in code form."</p>
<p>Before Tom could comment, the alarm bell rang on the electronic
brain. The Swifts dropped everything and rushed to the machine.</p>
<p>"Wonder if it's Exman?" Tom exclaimed.</p>
<p>The answer was quickly revealed as the keys began punching out the
incoming message on tape. At the same time, a flow of strange
mathematical symbols flashed, one after another, on the lighted
oscilloscope screen mounted above the keyboard.</p>
<p>Tom and his father read the tape as it unreeled.</p>
<blockquote>
SPACE BEINGS TO SWIFTS. REQUEST INFORMATION ON PROGRESS AND RESULTS OF
ENERGY SENT TO YOUR PLANET.
</blockquote>
<p class = "space">
After a quick consultation with his father, Tom beamed out the
reply:</p>
<blockquote>
WE ARE PLEASED WITH RESULTS SO FAR. FURTHER EXPERIMENTS NOW GOING ON.
REQUEST VISIT TO CONTINUE LONGER THAN TWENTY-ONE DAYS AS PLANNED.
</blockquote>
<p class = "space">
Hopefully the Swifts stood by the machine. Would their space friends
agree? As the minutes went by without a response coming through, father
and son exchanged anxious glances.</p>
<p><span class = "pagenum">148</span>
<SPAN name="page148"> </SPAN>
"They've <i>got</i> to let Exman stay, Dad!" Tom said.</p>
<p>Mr. Swift nodded. "I'm afraid, though, the space beings have decided
otherwise. They—"</p>
<p>He was interrupted by the ringing of the alarm bell. "Message, Dad!"
Tom said tersely.</p>
<p>A moment later they were overjoyed to see three words appear on the
tape:</p>
<blockquote>
VISIT EXTENSION GRANTED.
</blockquote>
<p class = "space">
Relieved, the two scientists went back to work on their sensing
experiments. Twenty minutes later the signal bell rang again on the
electronic brain.</p>
<p>"This time it <i>must</i> be Exman!" Tom cried.</p>
<p>The unreeling tape quickly bore out his guess.</p>
<blockquote>
EXMAN TO SWIFTS. TWENTY-FOUR-HOUR EARTHQUAKE UNDER HIGH LOYALTY.
</blockquote>
<p class = "space">
"What!" Tom stared at the tape, his brow creased in a puzzled frown.
"That 'twenty-four-hour earthquake' bit must mean he's warning us that a
quake will occur in twenty-four hours. But what about the rest
of it?"</p>
<p>"Hmm... 'Under high loyalty.'" Mr. Swift was as baffled as Tom. He
studied the message for several minutes. It seemed highly unlikely that
the electronic brain had made an error in decoding. Any new or
untranslatable symbol caused a red light to flash on the machine.</p>
<p><span class = "pagenum">149</span>
<SPAN name="page149"> </SPAN>
"I think the only thing we can do is signal Exman and ask for a
clarification, Tom," Mr. Swift decided at last.</p>
<p>Tom agreed. He beamed out a hasty code signal:</p>
<blockquote>
EXPLAIN MESSAGE.
</blockquote>
<p class = "space">
Seconds later came Exman's reply. It was identical with the first
message:</p>
<blockquote>
TWENTY-FOUR-HOUR EARTHQUAKE UNDER HIGH LOYALTY.
</blockquote>
<p><span class = "picture">
<ANTIMG src = "images/pic149.jpg" width = "337" height = "349" alt = "(Tom Jr. and Tom Sr. read a message from Exman)"></span>
<span class = "pagenum">150</span>
<SPAN name="page150"> </SPAN>
Tom and Mr. Swift stared at each other anxiously.</p>
<p>"Good night, Dad! This is horrible!" Tom exclaimed. "Exman sends us
ample warning of a disaster and we're stymied!"</p>
<p>"Hi! What's going on, you two?" asked a merry voice. "More heavy
thinking?"</p>
<p>Sandy Swift stood smiling in the doorway. The smile gave way to a
look of concern as Tom explained the crisis.</p>
<p>"How dreadful!" Sandy gasped. "We <i>must</i> figure out what it
means!... Wait a minute!"</p>
<p>Tom looked at her expectantly. "Got an idea, Sis?"</p>
<p>"Well..." The pretty, blond teen-ager hesitated. "You don't suppose
Exman might have been translating some foreign words with a meaning
similar to 'high loyalty'? For instance, high loyalty could mean 'good
faith.' I know that in Latin 'good faith' would be <i>bona
fide</i>."</p>
<p>"Sandy! You've guessed it!" Tom crossed the room in a single bound,
gave his sister a quick hug, and whirled her around. "Exman must mean
the Bona Fide Submarine Building Corporation! He didn't dare risk
telling us the exact translation."</p>
<p>"Of course!" Mr. Swift was equally jubilant. But his face was grave as
he added, "The company's located on the West Coast close to the
<span class = "pagenum">151</span>
<SPAN name="page151"> </SPAN>
San Andreas fault. Tom, a quake in that area could be devastating!"</p>
<p>"You're right, Dad," the young inventor replied. "I'll call Dr. Miles
and Bernt Ahlgren at once!"</p>
<p>The telephone conversation that followed was grim with tension. Both
government men begged Tom to take personal charge of the
quake-deflection measures. Dr. Miles pointed out that tremors along the
fault might trigger off a chain of quakes amounting to a national
disaster.</p>
<p>After a hasty discussion, Tom agreed that he should station himself
at the Colorado site, rather than at the West Coast Quakelizor
installation. This would give him broader scope for damping out shock
waves across the continent.</p>
<p>"I'll fly out immediately!" the young inventor promised.</p>
<p>Ahlgren, meanwhile, would flash orders to the Bona Fide Company and
to civilian officials to have the entire area evacuated as soon as
possible.</p>
<p>Hasty preparations were made for Tom's departure. He telephoned the
airfield to have a jet plane with lifters readied for take-off. He also
had Bud paged over the plant intercom. The copilot came on the run. When
he heard the news, he was eager to accompany his pal.</p>
<p>"Listen, you two! I insist you have something to eat before you
leave!" Sandy declared.</p>
<p><span class = "pagenum">152</span>
<SPAN name="page152"> </SPAN>
Tom was impatient over any delay. When Sandy proceeded to call Chow, the
old Texan solved the problem by volunteering to go along as cook.</p>
<p>A short time later Chow came jouncing out to the airfield astride a
motor scooter, hauling a cart loaded with supplies.</p>
<p>"Good grief!" Tom said, unable to suppress a grin. "We'll be back
tomorrow, unless something goes wrong!"</p>
<p>"Bring food—that's my motto," Chow retorted, "like any good
cook."</p>
<p>Minutes later, after a parting handshake from his father and a
worried kiss from Sandy, Tom sent the sleek jet racing down the runway
for take-off. Soon they were air-borne and heading westward. Chow served
a tasty meal en route.</p>
<p>It was still daylight when the jet landed vertically in the Colorado
canyon. The government crew manning the installation, and the Swift
technician who had relieved Art Wiltessa as trouble shooter on the
setup, greeted them eagerly.</p>
<p>"Looks as if we're in for a real test, Tom," said Mike Burrows, the
engineer in charge.</p>
<p>"Let's hope we pass!" said Tom, holding up crossed fingers.</p>
<p>He checked every detail of the Quakelizor, power plant, and the
communications gear. He opened an inspection panel in each of the
dual-control
<span class = "pagenum">153</span>
<SPAN name="page153"> </SPAN>
spheres and tuned the kinetic-hydraulic units so as to step up the
working pressure of the four powerful drivers.</p>
<p>"Well, all we can do now is wait," the young inventor muttered,
wiping his arm across his forehead.</p>
<p>Tom passed the night in a fitful sleep, half expecting to be wakened
at any moment by the stand-by crew on watch. No alarm occurred,
however.</p>
<p>Dawn broke, and Chow delighted all hands with a hearty breakfast of
bacon, eggs, and corn fritters. More hours of waiting
dragged by.</p>
<p>"What time do you think the attack will occur?" Bud asked.</p>
<p>Tom shrugged. "The 'twenty-four-hour' business may have been
approximate. But I'd say from two o'clock on is the danger period."</p>
<p>The young inventor checked frequently with Washington and the other
crews stationed around the country. Suddenly the radiotelephone operator
gave a yell.</p>
<p>"Your father is on the line, skipper!"</p>
<p>The scientist was calling from the receiver-computer headquarters at
Enterprises. "Exman has reported a quake pulse will be sent in seven
minutes—at 21.36 G.M.T."</p>
<p>"I'm ready, Dad," Tom said, then asked for various technical details
before hanging up.</p>
<p>He passed the word to the crew and glanced
<span class = "pagenum">154</span>
<SPAN name="page154"> </SPAN>
at his watch. A hasty, last-moment inspection was carried out, every man
checking certain details of the setup.</p>
<p>Soon the pulsemakers began ticking inside the dual-control spheres as
they picked up the frequency signal by radio. Tom studied the gauge
dials.</p>
<p>Tension mounted rapidly among the waiting group. The same thought was
throbbing through every mind:</p>
<p><i>Was the nation on the brink of a terrible disaster? Or would Tom
Swift's invention safeguard the threatened area?</i></p>
<p>As the deadline approached, Tom pushed a button. The mighty hydraulic
drivers throbbed into action, sending out their pulse waves across the
continent!</p>
<span class = "pagenum">155</span>
<SPAN name="page155"> </SPAN>
<h5 class = "left chapter"><SPAN name="chap_18">CHAPTER XVIII</SPAN></h5>
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