ile, and their embarrassment at
their ineptness.

"Sure, Guys," he said, when Professor Maddox called him in. "Let's see
if we can find out what this stuff is. Who knows? Maybe we've got a bear
by the tail."

It was delicate precision work, preparing specimens and obtaining
spectrographs of the lines that represented the elements contained in
them. Time after time, their efforts failed. Something went wrong either
with their sample preparation, or with their manipulation of the
instruments. Ken began to feel as if their hands possessed nothing but
thumbs.

"That's the way it goes," John Vickers consoled them. "Half of this
business of being a scientist is knowing how to screw a nut on a
left-handed bolt in the dark. Unless you're one of these guys who do it
all in their heads, like Einstein."

"We're wasting our samples," Ken said. "It's taken two weeks to collect
this much."

"Then this is the one that does it," said Vickers. "Try it now."

Ken turned the switch that illuminated the spectrum and exposed the
photographic plate. After a moment, he cut it off. "That had better do
it!" he said.

After the plates were developed, they had two successful spectrographs
for comparison. One was taken from the metal of a failed-engine part.
The other was from the atmospheric dust. In the comparator Vickers
brought the corresponding standard comparison lines together. For a long
time he peered through the eyepiece.

"A lot of lines match up," he said. "I can throw out most of them,
though--carbon, oxygen, a faint sodium."

"The stuff that's giving us trouble might be a compound of one of
these," said Ken.

"That's right. If so, we ought to find matching lines of other possible
elements in the compounds concerned. I don't see any reasonable
combination at all." He paused. "Hey, here's something I hadn't
noticed."

He shifted the picture to the heavy end of the spectrum. There, a very
sharp line matched on both pictures. The boys took a look at it through
the viewer. "What is that one?" Ken asked.

"I don't know. I used a carbon standard. I should have used one farther
toward the heavy end. This one looks like it would have to be a
transuranic element, something entirely new, like plutonium."

"Then it could be from the hydrogen bomb tests," said Joe.

"It could be," said Vickers, "but somehow I've got a feeling it isn't."

"Isn't there a quick way to find out?" said Ken.

"How?"

"If we took a spectrograph o