stitious; but he couldn't help, as he limped along, connecting
these disasters, remotely at least, with general order No. 13.

In time the "unseen signal" came to be talked of by the officials as
well as by train and enginemen. It came up finally at the annual
convention of General Passenger Agents at Chicago and was discussed by
the engineers at Atlanta, but was always ridiculed by the eastern
element.

"I helped build the U.P.," said a Buffalo man, "and I want to tell you
high-liners you can't drink squirrel-whiskey at timber-line without
seein' things nights."

That ended the discussion.

Probably no road in the country suffered from the evil effects of the
mysterious signal as did the Inter-Mountain Air Line.

The regular spotters failed to find out, and the management sent to
Chicago for a real live detective who would not be predisposed to accept
the "mystery" as such, but would do his utmost to find the cause of a
phenomenon that was not only interrupting traffic but demoralizing the
whole service.

As the express trains were almost invariably stopped at night, the
expert travelled at night and slept by day. Months passed with only two
or three "signals." These happened to be on the train opposed to the
one in which the detective was travelling at that moment. They brought
out another man, and on his first trip, taken merely to "learn the
road," the train was stopped in broad daylight. This time the stop
proved to be a lucky one; for, as the engineer let off the air and
slipped round a curve in a canon, he found a rock as big as a box car
resting on the track.

The detective was unable to say who sounded the signal. The train crew
were overawed. They would not even discuss the matter.

With a watchman, unknown to the trainmen, on every train, the officials
hoped now to solve the mystery in a very short time.

The old engineer, McNally, who had found the rock in the canon, had
boasted in the lodge-room, in the round-house and out, that if ever he
got the "ghost-sign," he'd let her go. Of course he was off his guard
this time. He had not expected the "spook-stop" in open day. And right
glad he was, too, that he stopped _that_ day.

A fortnight later McNally, on the night run, was going down Crooked
Creek Canon watching the fireworks in the heavens. A black cloud hung
on a high peak, and where its sable skirts trailed along the range the
lightning leaped and flashed in sheets and chains. Above the roar o