ere broken
through. But the horses raced along the smoothed tread-trails. Once a
broken, twisted rail tore at Sergeant Walpole's sleeve. Somehow the last
great plate of a tread had bent it upward. Presently they saw a mass of
something dark off to the left. Flames were licking meditatively at one
of the wrecked cars.

Then they heard explosions far ahead. Flames lighted the sky.

"Our men in action!" said Sergeant Walpole hungrily.

He flogged his mount mercilessly. Then the sky became bright in the
distance. The horses, going down the crushed-smooth trail of the treads,
gained upon the din. Then they saw the cause of it, miles distant. A
train was burning luridly. Its forepart was wreckage, pure and simple.
The rest was going up in flames and detonations. Munitions, of course.
The Wabbly was off at one side, flame-lit and monstrous, sliding
smoothly out of sight.

* * * * *

"Ten miles of railroad," said the 'copter pilot calmly, "mashed out of
existence. That's going to scare our people into fits. They can drop
eggs till the cows come home, and every egg'll smash up a hundred yards
of right-of-way, and we can build it back up again in four hours with
mobile track-layers. But ten miles to be regraded and laid is different.
Half of America will be imagining all our railroads smashed and
starvation ahead."

A piercing light fell upon them.

"Shut it off!" roared Sergeant Walpole. "D'y'want to get us killed?"

He and the 'copter pilot swerved. There was a car there, a huge
two-wheeled car, whose gyroscopes hummed softly while its driver tried
to extract it from something it was tangled in.

"I commandeer this car," said the 'copter pilot. "Military necessity. We
have to trail that Wabbly."

Someone grunted. Lights flashed on within. The 'copter pilot and
Sergeant Walpole stiffened to attention. The stars of a major-general
shone on the collar of the stout man within.

"Beg pardon, sir," said the pilot, and was still.

"Umph," said the major-general. "There seem to be just four of us alive,
who've seen the thing clearly. I hit on it by accident, I'll admit. What
do you know about it?"

"It come on a tramp-steamer--" began Sergeant Walpole.

"Hm. You're Sergeant Walpole. Mentioned in dispatches to-morrow,
Sergeant. You, sir?"

"Its weapon against our planes, sir," said the 'copter man precisely,
"is a radio beam carrying several thousand horsepower of energy. When it
hits i