and innumerable manikins moved
over the hills and valleys.

Above the thunder of this battle rose a mighty crash that sent the air
rolling in circular waves. The _Arrow_ quivered and then Lannes dropped
it down several hundred yards, in order that they might get a better
view.

"It's one of their giant guns, a 42 centimeter," he said, "and it's
posted on that hill over to our right. I didn't think they could bring
so big a gun in the pursuit, but it seems that they have been able to do
so."

"And it's plumping shells more than a ton in weight, right into the
middle of the Franco-British army."

"It would seem so, and doubtless they're doing terrible destruction."

John was silent for a moment or two. He had felt an inspiration. It was
a terrible and dangerous impulse, but he meant to act upon it.

"Philip," he said, "have you any bombs with you?"

"A good supply, John. But why?"

"I propose that you and I fly over the mammoth gun and blow it up."

Lannes turned a little in his seat, and stared at his comrade.

"I hold that against you," he said.

"Why?"

"Because I didn't think of it first. I'm considered reckless, and it's
the sort of enterprise that ought to have occurred to me. Instead the
idea comes to you, a reserved and conservative sort of a fellow. But
John, you and I will try it. We'll either blow up that gun or die for
France. Search the heavens with the glasses, and see if any of the
German flyers are near."

"There are some dots far off toward the east, but I don't think they're
near enough to interfere with us."

"Then well try for the gun at once. We've got to sink low to be sure of
our aim, and for that reason, John, I'm going to ask you to drop the
bombs, while I steer. But don't do it, until I say ready because I mean
to go pretty close to the 'Busy Bertha.'"

"Good enough," said John, as Lannes passed him the bombs. His hand was
perfectly steady and so was that of Lannes on the steering rudder, as
they made a gentle curve toward the point, from which the mighty crash
had come. John knew that the bombs would not make a destructive
impression upon those vast tubes of steel, but he hoped to strike the
caisson or ammunition supply behind, and blow up one or two of the
shells themselves, involving everything in a common ruin. But to do so
he knew that they must fly very low, exposing themselves to the danger
of return fire from the Germans.

"I can see the gun now," said Lannes. "The g