could see that it was
with the most exhaustive effort that his fireman kept up his nerve and
strength. Fogg was weak and panting the last shovel full of coal he
threw into the furnace, as they sighted Stanley Junction. He was as
limp as a rag, and looked wretched as the train rolled into the
depot.

They ran the locomotive to the roundhouse. Ralph went at once to the
foreman's office, while Fogg attended to the stalling of No. 999. He
found the night watchman asleep there and no orders on the blackboard
for Fogg or himself. This meant that they need not report before
noon.

Ralph looked around for the fireman when he came out of the office,
but the latter had disappeared, probably headed for home. Ralph,
half-across the turntable, halted and went over to No. 999.

"The vest of that mysterious new acquaintance of mine, Clark--Porter,"
said Ralph--"he said he left it in the locomotive."

Ralph did not find the article in question in his own bunker. He threw
back the cover of Fogg's box, to discover the vest neatly folded up at
the bottom of that receptacle. With some curiosity he looked over its
pockets.

"Whew!" whistled Ralph, as he removed and opened the only article it
contained--a check book. The checks were upon a bank at Newton. About
half of what the book had originally contained had been removed.
Examining the stubs, Ralph calculated that over $1,000 had been
deposited at the bank in the name of Marvin Clark, and that fully half
that amount had been checked out.

"This is pretty serious," commented the young engineer. "It looks as
if the impostor has not only stolen Clark's name, but his passes and
his check book as well. I don't like the looks of this. There's
something here I can't figure out."

Ralph placed the check book in his own pocket and returned the vest to
the box. As he did this, he disturbed a piece of cloth used by Fogg to
wipe grease from the cab valves. Something unfamiliar to the touch was
outlined wrapped up in the rag, and Ralph explored.

Two objects came into view as he opened the piece of cloth. With a
great gasp the young engineer stared at these. Then he rolled up the
rag and placed it and its contents in his pocket.

His face grew grave, and Ralph uttered a deep sigh, startled and
sorrowful.

The young engineer of No. 999 had made a discovery so strange, so
unexpected, that it fairly took his breath away.

The mystery of the collision on the siding at Plympton was disclose