tackled it, missed, and called for help.
The Siberians rallied round. Kinnison loaded and tested mines. So did
Paul and Tug and Blondie. Kinnison was testing, out in the Firing Area,
when he was called to Administration to attend a Staff Meeting. Hinton
relieved him. He had not reached the gate, however, when a guard car
flagged him down.

"Sorry, sir, but there has been an accident at Pit Five and you are
needed out there."

"Accident! Fred Hinton! Is he...?"

"I'm afraid so, sir."

It is a harrowing thing to have to help gather up what fragments can be
found of one of your best friends. Kinnison was white and sick as he got
back to the firing station, just in time to hear the Chief Safety
Officer say:

"Must have been carelessness--rank carelessness. I warned this man
Hinton myself, on one occasion."

"Carelessness, hell!" Kinnison blazed. "You had the guts to warn _me_
once, too, and I've forgotten more about safety in explosives than you
ever will know. Fred Hinton was _not_ careless--if I hadn't been called
in, that would have been me."

"What is it, then?"

"I don't know--yet. I tell you now, though, Major Moulton, that I _will_
know, and the minute I find out I'll talk to you again."

He went back to Siberia, where he found Tug and Paul, faces still
tear-streaked, staring at something that looked like a small piece of
wire.

"This is it, Uncle Ralph," Tug said, brokenly. "Don't see how it could
be, but it is."

"What is what?" Kinnison demanded.

"Firing pin. Brittle. When you pull the safety, the force of the spring
must break it off at this constricted section here."

"But damn it, Tug, it doesn't make sense. It's tension ... but
wait--there'd be some horizontal component, at that. But they'd have to
be brittle as glass."

"I know it. It doesn't seem to make much sense. But we were there, you
know--and I assembled every one of those God damned mines myself.
Nothing else could possibly have made that mine go off just when it
did."

"O.K., Tug. We'll test 'em. Call Bart in--he can have the scale-lab boys
rig us up a gadget by the time we can get some more of those pins in off
the line."

They tested a hundred, under the normal tension of the spring, and three
of them broke. They tested another hundred. Five broke. They stared at
each other.

"That's it." Kinnison declared. "But this will stink to high
Heaven--have Inspection break out a new lot and we'll test a thousand."

Of that thou