hat Fran had made and tried at Navajo Dam.

"Which," said Soames, frowning, "proved not to work. You didn't realize
the local resources. This thing works, obviously, because a terrifically
strong electric field is cut off abruptly and collapses instantly. The
original apparatus--the one I burnt--no doubt had a very fine gimmick to
break a heavy current flow without making an arc. The trouble at Navajo
Dam was that it did arc--and how! That was a mess!"

He paused, considering. Since Soames was not looking at him, Fran
regarded him with infinite respect.

"The problem," said Soames, thinking hard, "is a glorified job of
turning off an electric light without making a spark at the switch.
That's all. It doesn't matter how long the current flows. The thing is
that it must stop instantly. So we turn the whole business inside out.

"Instead of making a terrific steady current and cutting it off, I'm
going to start with it not flowing and use a strobe-light pack. Every
amateur photographer has one. They give a current of eight hundred
amperes and twenty-five hundred volts for the forty-thousandth of a
second. The juice doesn't flow long enough to burn anything out. It cuts
itself off. There's nothing to maintain an arc.

"The really tricky part," he said uncomfortably, "may be the stealing of
a helicopter. But I guess I can manage it."

* * * * *

He left Fran fishing and went down to the nearest town again to buy
eccentric items of equipment. Copper foil. Strobe-light packs, two of
them. He could use foil instead of large-area heat-dissipating units,
because the current would flow so briefly. He would get a terrific
current, of course. Two strobe-light packs in series would give him four
million watts of power for part of the wink of an eyelid.

When he got back to the camp, Soames called to Fran. "We've got to get
to work. I don't think we've got much time. I had hopes of a
castaway-gadget coming up, but it hasn't."

He began to assemble the device which would substitute for the larger,
heavier, much more massive apparatus he'd destroyed on the Antarctic
ice-sheet. The work went swiftly. Soames had re-designed the outfit, and
a man can always build a thing of his own design more easily than
something from another man's drawings.

Before sunset the thing was done. Fran was very respectful. This
apparatus was less than a quarter the size of the one his own people had
prepared for the s