the sky.

"Don't see it," he said grimly, "and it probably doesn't see us. We're
all right, I suppose."

But he was uneasy. The droning noise grew to a maximum and slowly died
away again. It diminished to a distant muttering.

"What say," said Bell suddenly, "we get aloft now? We'll follow that
damned thing home. It's going from Asuncion to that place we want to
find. This is on that route. Whoever's in it won't be looking behind,
and it's close to darkness."

* * * * *

Paula stood up.

"I am ready, Charles."

Bell swung out on the floats and tugged at the prop. The motor caught
and roared steadily. While it was warming up, he stripped off the rest
of his shirt and tore it into wide strips, and tied the rags in the
handles of the gasoline tins in the two cockpits.

"For our bombs," he explained, smiling faintly. "You'll want to wear
your chute pack, Paula. You know how to work it? And we'll divide the
guns and what shells we have, and stick them in the flying suit
pockets."

He made her show him a dozen times that she knew how to pull out the
ring that would cause the parachute to open. She climbed into the
front cockpit and smiled down at him. He throttled down the motor to
its lowest speed and shoved off from the mud bank. Clambering up,
while the plane moved slowly over the water under the gentle pull of
the slow-moving propeller, he bent over and kissed her.

"For luck," he said in her ear.

The next instant he settled down at the controls, glanced a last time
at the instruments, and gave the motor the gun.

* * * * *

The plane lifted soggily but steadily and swept up-stream toward the
rolling water of the _raudal_, which tumbled furiously about an
obstacle half of stones and shallows, and half of caught and rotting
tree trunks. It rose steadily until the trees dropped away on either
side and the jungle spread out on every hand. It rose to a thousand
feet and went roaring through the air to northward, while Bell
strained his eyes for the plane on ahead.

It was ten minutes or more before he sighted it, winging its way
steadily into the misty distance above the jungle. Bell settled down
to follow. The engine roared valorously. For half an hour Bell watched
it anxiously, but it remained cool and had always ample power. Paula's
head showed above the cockpit combing. Mostly she looked confidently
ahead, but once or twice she turned about