e lumber on one of the cars, and
quickly disappear on discovering him. A moment after he had a fleeting
glimpse of the intruder running low along the side of the train toward
the rear.

"Only a hobo," Alex decided on second thought. For numbers of tramps had
come through on the material-trains. And presently Alex returned to the
telegraph-car.

Shortly after midnight the young operator was awakened by someone running
through the car and shouting for Construction Superintendent Finnan. When
he caught the word "Fire!" he scrambled into his clothes and leaped to
the floor, and out.

Over the tops of the cars in the direction of the track-machine was a
dancing glare.

In alarm Alex joined the stream of men dropping to the ground all along
the boarding-cars. Dodging through the intervening trains, he brought up
with an expression of relief beside, not the track-machine, but a car of
bridge material.

Fanned by a brisk wind, flames were spouting from amid the timbers at
several points. Already men were pitching the burning beams over the
side, however; and finding a shovel, Alex joined those who were
smothering them with sand.

"Tramps, sure!" Alex heard another of the shovelers remark angrily.
Immediately then he recalled the man he had seen from the track-machine
tower, and pausing in his work, he counted the cars back.

It was the same car. Yes; undoubtedly the fire was the careless work of
the tramp he had seen running away.

The force of fire fighters was rapidly augmented, and soon, despite the
fresh breeze, the last of the burning beams were smothered, and all
danger of a general conflagration was past.

It was as Alex at last headed back for the boarding-train that a theory
other than the tramp theory of the origin of the fire occurred to him. It
came from a sudden recollection of Division Superintendent Cameron's
prediction of interference from the K. & Z. "Could that be the real
explanation?" he asked himself with some excitement.

The first streak of dawn found Alex again at the scene of the fire, bent
on proving or disproving the theory of incendiarism. Climbing aboard the
scorched car, he dropped to his knees and began carefully brushing aside
the sand with which the burning floor had been covered.

A few minutes' search produced the burned ends of shavings!

"So!--the 'fight' is on!" observed Alex to himself gravely.

With several of the tell-tale fragments in his pocket Alex was about to
leap t