n. The earth had vanished. Vast clouds of gray and
black floated between, and to John's startled eyes they took on all the
aspects of the sea. Here the great swells rolled and tumbled, and off
far in the north stretched a vast smooth surface of tranquility. But
beneath him he saw flashes of light, and heard the heavy mutter as of
giant guns. High above, the air was thin, cold and motionless.

A troubled world rolled directly under them, and the scene that he
beheld was indescribably grand and awful. The clouds were in
conjunction, and thunder and lightning played as if monstrous armies had
crashed together. But here they sailed steadily on a motionless sea of
air. He shared the keen pleasure that Lannes so often felt. The _Arrow_
suddenly became a haven of safety, a peaceful haven away from strife.

"Aren't you glad you're not down there?" asked Lannes.

"Aye, truly."

"The winds that blow about the world, and the clouds that float where
the winds take them appear to be having a terrible commotion, but we are
safe spectators. Monsieur Jean the Scott, I wonder if the time will ever
come when we'll have a flying machine that can manufacture its own air
to sail in. Then it could rise to any height."

"Phil, you're dreaming!"

"I know I am but I'm not dreaming any more than you were just now when
you saw Napoleon and his army crossing the Alps. Besides who can
forecast the achievements of science? Why, man who was nothing but a
savage yesterday is just getting a start in the world! Who can tell what
he'll be doing a million years from now? Think of going on, and on in
the void, and maybe arriving on Venus or Mars!"

"In that case we'll find out whether that Mars canal story is true or
not."

Lannes laughed.

"I come back to earth," he said, "or rather I come back to a point a
safe distance above it. How's our storm making out?"

"It seems to be moving westward."

"And we're flying fast toward the north. We'll soon part company with
the storm, and then we'll drop lower. But John, you must take the
glasses and watch the skies all the time."

"Which means that we'll fly near the French border, and that I've got to
be on the lookout for the Taubes and the dirigibles."

"And he guessed right the very first time. That's more of your American
slang. Yes, John, the hosts of the air are abroad, and we must not have
another encounter with the Germans. Before night we'll be approaching
the battle lines, and the air wil