t the invisible dome drew aside to leave a
quadrant clear, and Combat-Squadron Seven merged with the rest, making
the pattern of dancing specks markedly denser.

"With a fire," said Thorn desperately, "they'll come! Of course! But
Kreynborg took my lighter!"

Sylva said hopefully:

"Don't you know some way? Rubbing sticks together?"

"I don't," admitted Thorn grimly, "but I've got to try to invent one.
While I'm at it, you watch for fliers."

He searched for dry wood. He rubbed sticks together. They grew warm,
but not enough to smoke, much less to catch. He muttered, "A drill,
that's the idea. All the friction in one spot." He tugged at the ring
under his lapel and the parachute fastened into his uniform collar
shot out in a billowing mass of gossamer silk, flung out by the
powerful elastics designed to make its opening certain. Savagely, he
tore at the shrouds and had a stout cord. He made a drill and revolved
it as fast as he could with the cord....

A second dark cloud swept forward in the gathering dusk and merged
into the mass of fliers about the dome. Five minutes later, a third.
Dense as the air-traffic was, riding-lights were necessary. They began
to appear in the deepening twilight. It seemed as if all the sky were
alight with fireflies, whirling and swirling and fluttering here and
there. But then the fire-drill began to emit a tiny wisp of smoke.
Thorn worked furiously. Then a tiny flickering flame appeared, which
he nursed with a desperate solicitude. Then a larger flame. Then a
roaring blaze! It could not be missed! A fire within the dome could
not fail to be noted and examined instantly!

* * * * *

A searchlight beam fell upon them, illuminating him in a pitiless
glare. Thorn waved his arms frantically. He had nothing with which to
signal save his body. He flung his arms wide, and up, and wide again,
in an improvised adaption of the telegraphic alphabet to
gesticulation. He sent the watch call over and over again....

A little cloud of riding-lights swept toward the dome from an infinite
distance away. Darkness was falling so swiftly that they were still
merely specks of light as they swept up to and seemed to melt into the
swirling, swooping mass of fliers about the dome....

Cold sweat was standing out on Thorn's face, despite the violence of
his exertions. He was even praying a little.... And suddenly the
searchlight beam flickered a welcome answer:

"W-e u-