Nearly a week went by. The lead capsule containing the stolen
radioisotope had not been found. In fact, as far as Eddie knew, there
had been no worthwhile clues on which to base a search. Curious as he
was, Eddie still managed to keep from asking his father a lot of
questions. Around home, Mr. Taylor had been thoughtfully silent. Eddie
knew that his father must be very worried.
Eddie gathered enough from the conversations between his parents to know
that the search for the stolen isotope was still going on. In fact, it
was pretty well known that FBI agents had arrived in Oceanview to lend a
hand. Eddie hadn’t seen them, but several of his friends had. It was
hard to keep secrets in a college town like Oceanview.
The newspapers had temporarily dropped the story. After all, when the
radioisotope had been stolen it had made a big story, but nothing more
had happened, so there was nothing more to write about.
There were still articles in the newspapers about the Acme Aircraft
Company problem of the missing blueprints. Actually, it seemed to Eddie
that the newspapers were making more of a mystery out of the missing
blueprints than of the stolen radioisotopes. Perhaps that was because it
had not yet been decided whether the blueprints had been stolen,
destroyed by accident, or simply lost. In an aircraft plant, where
thousands and thousands of plans are being used at all times, some
carelessness is apt to occur. Eddie found it hard to believe that anyone
could get careless with top-secret blueprints, yet such things did
happen.
Maybe the reason people remained curious about the missing blueprints
was that everyone knew what a blueprint was. Even the word
“radioisotope” meant very little to most readers. What they were and
what they did were even less well known.
Friday morning Teena came whistling up to the back door at Eddie’s house
to see if he wanted to do anything.
“Mom’s gone shopping,” Eddie said. “She’ll be back in a few minutes.
Then maybe we could take the Geiger counter and—”
His words were interrupted by the telephone ringing inside.
“Be right back,” he said, hurrying into the house.
His father was on the other end of the line.
“Eddie,” he said, “there’s a dark-green notebook on my desk in the
study. I forgot it this morning. Can’t get away from here, and I need
it.”
“I’ll bring it over, Dad,” Eddie volunteered quickly.
“Good. I’ll be outside the botany building. Know where that is?”
“Botany? Where they raise all the plants and stuff?” Eddie asked.
“That’s right.”
“I know where it is,” Eddie said. “Be there in five minutes.”
He went into the study, got the notebook off the desk, and went back
outside.
“I’ve got to tear over to school with this notebook,” he explained to
Teena. “That was my dad.”
“I’ll go with you,” Teena said.
“O.K.”
It was only a few blocks to the college campus. Reaching the grounds,
they took a short cut past the men’s gymnasium, crossed the athletic
field, and arrived at the Botany Building.
“I see Dad over there,” Eddie said, pointing. There were several men
standing in a group in the small cultivated field which the botany
department used to grow test plants of various kinds. Eddie and Teena
picked their way carefully between the rows.
“You made good time, Eddie,” his father said, taking the notebook.
“Morning, Teena. Hope I didn’t interrupt any big plans.”
“Oh, no, Mr. Taylor,” Teena said. “We weren’t doing anything special.”
Eddie was about to turn and leave, when he noticed that several of the
young men—students, no doubt—were wearing strange-looking, long, heavy
gloves.
“Why the gloves, Dad?” he asked.
Mr. Taylor glanced up from the notebook. “We’re experimenting with
radioactive tracers,” he said. “They’re weak—certainly not dangerous—but
there’s no harm in taking a little extra precaution. The gloves are
lead-lined and absorb any of the rays which might possibly be picked up
from handling the plants.”
“What are tracers, Mr. Taylor?” Teena asked.
Eddie shot her a quick scowl. He doubted that his father wanted to be
bothered with questions at the moment. Then Eddie noticed one of the
students holding the wandlike probe—or diode—of a Geiger counter down
close to the leaves of one plant. It seemed a strange thing to be doing.
Who would prospect for uranium in plants.
“That’s a good question, Teena,” Mr. Taylor said. “Glad to see you’re
interested.” He turned and spoke to the student with the Geiger counter.
“Jim, you want to explain to this young lady, and my son here, what
tracers are?”
Eddie smiled to himself. His father was the kind of a professor who
believed his students should have the chance to use their knowledge
whenever possible.
“Maybe we should all listen to this,” Eddie’s father said to the others.
They gathered around as the dark-haired student switched off the Geiger
counter, swallowed a bit uncomfortably, and turned to face the outdoor
classroom which Teena’s question had formed on the spot.
“Well, er—” Jim began, addressing Teena, “a tracer is a radioactive
isotope which we—well, send out on a journey, then follow it with a
Geiger counter.”
“I’m afraid that’s not too clear, Jim,” Mr. Taylor said. “Teena’s not an
atomic scientist. Can you simplify it for her?”
“Oh, I know what a radioactive isotope is, Mr. Taylor,” Teena said
proudly.
“You do?” Eddie’s father said in surprise.
“It’s something—I think you call it an element—which they put in an
atomic reactor, and—and cook it until it becomes radioactive. Kind of
like a sponge soaking up water.”
“Very good,” Mr. Taylor nodded, obviously impressed.
“Eddie explained it to me,” Teena said, smiling, “but he didn’t say
anything about tracers.” She turned her attention back to Jim, the
student.
“All right,” Jim said, seeming more at ease, “let’s look at it this way.
Any radioisotope keeps shooting out rays. Of course, you can’t see the
rays with your eyes. They’re almost too small to think about. But you
can follow them with a Geiger counter.” He indicated the black metal
instrument which he still held in his hand.
“Well,” Jim went on, “say, for instance, that you wanted to know how
fast a stream of water flows. You might toss in a rubber ball and time
how long it takes to float a mile downstream. That would give you its
speed. Or say you wanted to know which way its currents twist and turn.
You might dump in a gallon of ink and watch it follow the currents. In a
way, the ball and the ink are tracers. Not radioactive tracers, of
course, but by watching how they act, you learn what you want to know.”
“Let’s talk about radioactive tracers,” Eddie said eagerly.
“You’re crowding me, bub,” Jim said, smiling. Everyone laughed.
“How are we using tracers here, Jim?” Mr. Taylor prompted.
“We’re testing the use of phosphate in plant growth,” the student
explained. “We want to know what the plant does with it. Does a
phosphate fertilizer merely feed the plant’s roots, or is it pulled up
into the stems and leaves? And we want to know how quickly the plant
absorbs it, if at all. Of course, we can’t see it, but if we make the
phosphate slightly radioactive, then we have what we call a tracer. By
using a Geiger counter, we can follow or trace its movement.”
“Can you explain our method, Jim?” Mr. Taylor said.
“Well, we spread a little of the radioactive phosphate around the
plant,” the student said. “Soon the roots start taking it in.”
“How do you know that, Jim?” Mr. Taylor asked.
“We hold the Geiger counter to the root. If it starts clicking faster
than usual, we know the root has absorbed some of the phosphate tracer.
We also hold the Geiger counter over the stems and leaves. As the tracer
works upward into the plant, the Geiger counter reacts to it. Here, let
me show you how it works on this cotton plant.”
Eddie and Teena moved over closer to the two-foot-high plant. Jim
switched on the Geiger counter. Eddie saw the needle on the gauge
flutter slightly, indicating the normal cosmic-ray background count.
“Teena,” Jim said, handing her the earphones which were attached by a
long wire to the Geiger counter, “you take these earphones. Now, I’ll
pass the probe down close to the base of the cotton bush.”
“What does the stick do?” Teena asked. Although Eddie had explained it
to her, she seemed to feel that, as a pupil, she should ask some
questions to help Jim out.
“Stick? Oh, you mean the probe. Actually, it’s called a diode, but
probe’s easier to remember. Anyway, the probe is a vacuum tube filled
with a special kind of gas. Whenever invisible radioactive particles
shoot through the probe and into the gas, the Geiger counter clicks, and
the needle on the dial moves forward. The more rays shooting through the
probe, the more clicks; the more clicks, the more radioactivity. That’s
why Geiger counters are so useful in hunting for uranium. Uranium is
very, very radioactive. If you happen onto some uranium ore, the Geiger
counter really goes wild.”
“We have a Geiger counter at home,” Eddie said eagerly. “Teena and I
have gone uranium prospecting several times.”
“Haven’t found any uranium,” Teena said, “but we’ve had fun trying.
Whoops. There’s some clicking!” She put her hands up to the earphones.
Jim had moved the probe down close to the stem of the cotton plant.
“Good,” he said. “We mixed a little radioactive phosphate into the
ground around the roots this morning. See, the Geiger counter shows that
the phosphate tracer has already started moving up into the plant. Helps
show how important phosphate is to plant growth, and how eagerly the
plants absorb it.”
“The plant sure looks healthy enough, all right,” Eddie said.
“Right,” Jim said. “Now let’s see how far up into the plant the tracer
has gone.”
He moved the probe upward over the smaller twigs and leaves. On the
lower leaves the Geiger counter kept clicking rapidly. Eddie watched the
needle stay forward on the gauge.
“See, the leaves have taken a lot of it in already,” Jim explained.
Then, as he moved the probe farther up toward the top of the plant, the
clicking diminished until only the familiar slow background count
remained.
“It quit,” Teena said.
“Shows that the phosphate has only reached about half of the plant so
far,” Jim said. “You see, with the tracer and the Geiger counter we can
tell just how far it has gone and how long it has taken. We can even
tell how much has been absorbed by comparing the amount of radioactivity
in the leaves and stems of the plant to what we know was contained in
the original tracer.”
“Boy, that’s something!” Eddie exclaimed.
“By adding tracers to some fertilizers,” Jim went on, “we found that the
plant made no use of the fertilizer. The Geiger counter didn’t pick up
any radioactivity in the plant. Meant wasted money to any farmer or
gardener who used it. Now do you see what we mean by a tracer? See how
radioactive tracers can be helpful?”
“Oh, yes,” Teena said. “I do.”
“I’ll bet if I had some of that tracer I wouldn’t lose so many things,”
Eddie said. “I could paint a little on my marbles or sling-shot. Then I
could always find them with a Geiger counter.”
“You could, at that,” his father said. “And I wouldn’t be stepping on
the marbles in my bare feet. But, of course, great care must be taken in
handling radioisotopes, which is what tracers are.”
Jim had warmed up to the subject, and wasn’t quite ready to drop it.
“Tracers are used in many ways,” he went on. “They are used in medicine
to locate diseased tissue which attracts and absorbs certain isotopes. A
radiation-sensitive instrument, similar to a super Geiger counter,
sniffs out the isotope and locates the damaged tissue. Then the doctor
knows what to treat, or where to operate. Radioisotopes are used in
various food tests. By watching the tracer with electronic gadgets, they
can tell whether the food is a muscle builder, a bone builder, or what.”
“You can make machine parts radioactive,” Mr. Taylor said. “Then by
seeing how many radioactive particles are in the oil after the machine
has been run, you can tell how much wear the machine has taken. Oh,
there are hundreds of ways to use radioactive tracers. You might call
them atomic signposts. Using a Geiger counter to read the signs, you are
directed along the paths that lead to the answers of nature’s
mysteries.”
“Wow!” Eddie exclaimed.
“Pretty flowery, at that, I guess,” his father said, smiling. “Well,
anyway, Jim, you did a nice job of explaining it. Now, I think we’d
better get back to our work. Thanks for bringing the notebook over,
Eddie—and Teena.”
The two young people turned and started back toward Eddie’s house.
“Let’s go across the mall,” Teena suggested. “I haven’t been over here
for a long time.”
The mall, as it was always called, was a broad ribbon of lawn which
stretched for more than a block down the center of the college campus.
It was bordered on both sides by the many buildings which made up
Oceanview College. Sidewalks laced back and forth across the mall.
During class changes, the area swarmed with students. Now, as Eddie and
Teena walked along the mall, only a few students sauntered around or sat
loafing in front of the buildings waiting for their next class.
Teena and Eddie walked past the library, the assembly hall, and the
nuclear-science building. They were starting past the chemistry
building, when Eddie tugged at Teena’s sleeve.
“Look,” he said, pointing to the back of a man walking about fifty yards
ahead of them. “Who’s that?”
“Who’s who?” Teena asked. “You mean that man? Am I supposed to know
him?”
“I think I do,” Eddie said. “He sure looks familiar.”
“How can you tell? All we can see is his back. Lots of backs look alike.
He’s tall. Maybe he’s a basketball player. He looks older than most
students, though. Why, his hair’s even a little gray, and—”
“I’ve got it now,” Eddie interrupted. “The tall and kind of gray part.
You know who? Simms. That fellow we ran into down at the cove last
week.”
“Well-ll, maybe,” Teena admitted thoughtfully. “We could tell for sure
if he’d turn around. Anyway, I don’t see what difference it makes. Maybe
he’s a student here. There are a lot of older students. Maybe he’s even
a teacher. Lots of teachers fish on week ends. No reason to get
excited.”
“Who’s excited?” Eddie challenged. “Can’t a fellow ask—”
“O.K., O.K.,” Teena said. “Anyway, there he goes into the chemistry
building, so we’ll never know just who it was. And that’s the end of
your mystery.”
Eddie didn’t say anything. He walked along, busy with his own thoughts.
Probably Teena was right. Why make a mystery of it? Even if the man were
Simms, what difference would it make?
Yet, why had Simms acted so strange and unfriendly that day. And for no
reason Eddie could think of. There was also the memory of the strange
metal tube which had been in the rowboat when the two men went fishing,
and wasn’t there when they returned.
There was no point in even mentioning it to Teena, but Eddie had a
strangely uncomfortable feeling on seeing the man right there on the
campus from which the secret radioisotope had been stolen recently.
No, it really couldn’t mean a thing, Eddie told himself.
Then, again, maybe it could.