London, deducting half the length of the train, as this carriage is in
the middle, you will find the pistol."

"Wonderful!" I exclaimed.

"Commonplace," he murmured.

At this moment the whistle sounded shrilly, and we felt the grind of
the air-brakes.

"The Pegram signal again," cried Kombs, with something almost like
enthusiasm. "This is indeed luck. We will get out here, Whatson, and
test the matter."

As the train stopped, we got out on the right-hand side of the line.
The engine stood panting impatiently under the red light, which changed
to green as I looked at it. As the train moved on with increasing
speed, the detective counted the carriages, and noted down the number.
It was now dark, with the thin crescent of the moon hanging in the
western sky throwing a weird half-light on the shining metals. The rear
lamps of the train disappeared around a curve, and the signal stood at
baleful red again. The black magic of the lonesome night in that
strange place impressed me, but the detective was a most practical man.
He placed his back against the signal-post, and paced up the line with
even strides, counting his steps. I walked along the permanent way
beside him silently. At last he stopped, and took a tapeline from his
pocket. He ran it out until the ten feet six inches were unrolled,
scanning the figures in the wan light of the new moon. Giving me the
end, he placed his knuckles on the metals, motioning me to proceed down
the embankment. I stretched out the line, and then sank my hand in the