e wheels, or rods or
levers. If we compel them to change their plan they won't have time to
organize a perfect new one."

"The old simile of the watch, I suppose. It'll run a hundred years if
all the works are kept right. But if a single one of them goes wrong
it's done forever."

"It's as you say. Sit steady, now. We're going to take another upward
swoop. I've seen enough of that town and its forts, and I don't want to
linger so close to the earth that they'll see us."

The machine rose like a mighty bird, but shortly after it reached the
top of its flight John felt a slight jerk. It was a sudden movement of
Lannes' hand on the steering rudder that had caused it.

"John," he said, and the voice shook a little, "take the glasses. Look
off there in the northwest, and see if you can't make out a black object
hanging in the sky?"

John took the glasses and put them to his eyes.

CHAPTER V

THE FIGHT IN THE BLUE

John turned his glasses toward the northwest, where cloud wrack hung. At
first he could see nothing, as the dark blue sky was obscured by the
darker mists and vapors, but he presently discovered in the very midst
of them an object that looked jet black. It was moving, and slowly it
took the shape of an aeroplane. He wondered at the keenness of Lannes'
vision, when he was able to pick out so distant an object with the naked
eye.

"What do you make of it?" asked Lannes.

"It's an aeroplane, or some other kind of flying machine."

"And which way do you think it's going?"

"The same way that we are. No, it seems to be nearer now."

"Likely it's running parallel with us in a sense; that is we two are
moving down the sides of a triangle, and if we continue long enough we'd
meet at the point."

"Perhaps it's Castelneau and Mery in the other plane?"

"Impossible! They would certainly stay on the mountains far behind us.
They would never disobey orders. We're back into a bank of fine air now
and the machine almost sails itself. Let me have the glasses a moment."

But he looked many moments. Then he calmly put the glasses away in the
tiny locker and said:

"It's not a French machine, John, and it's not a friend's. It's a German
Taube, and it's flying very fast. I think the man in it has seen us,
which is unfortunate."

"And there's another!" exclaimed John in excitement. "Look! He's been
hidden by that long, trailing sheet of vapor off toward the north. See
it's close to the other one."

"Ay