s a force-field which caused particles
charged with positive electricity to attempt to move in a right-hand
direction about the source of the field, and particles charged with
negative electricity to attempt to move in a left-hand direction. The
result was that any effort to thrust an external object into the field
of force was an attempt to tear the negatively charged electrons of
every atom of that substance, free from the positively charged protons
of nuclei. An object could only be passed through the field of force
if it ceased to exist as matter--which was not an especially helpful
discovery. And--Thorn Hard and Sylva were still hunted fugitives
inside the inner dome.

* * * * *

The sun was an hour high when the helicopter appeared to hunt for them
by day. After the first time they had never dared light a fire,
because Kreynborg in the helicopter searched the hills for a glow of
light. But this day he came searching for them by day. Thorn had
speared a fish for Sylva with a stick he had sharpened by rubbing it
on a crumbling rock. He was working discouragedly on a little
contrivance made out of a forked stick and the elastic from his
parachute-pack. He was haggard and worn and desperate. Sylva was
beginning to look like a hunted wild thing.

Two hundred yards from them the most formidable fighting force the
world had ever seen littered the earth with gossamer-seeming cellate
wings and streamlined bodies at all angles to each other. And it was
completely useless. The least of the weapons of the air-fleet would
have been a godsend to Thorn and Sylva. To have had one ship, even the
smallest, where they were would have been a godsend to the fleet. But
two hundred yards, with the dome of force between, made the fleet just
exactly as much protection for Sylva as if it had been a million miles
away.

The droning hum of the helicopter came across the broken ground. Now
louder, now momentarily muted, its moments of loudness grew steadily
more strong. It was coming nearer. Thorn gripped his spear in an
instinctive, utterly futile gesture of defense. Sylva touched his
hand.

"We'd better hide."

They hid. Thick brush concealed them utterly. The helicopter went
slowly overhead, and they saw Kreynborg gazing down at the earth below
him. Nearly overhead he paused. And suddenly Thorn groaned under his
breath.

"It's the flagship!" he whispered hoarsely to Sylva. "Oh, what fools
we were!