Two miles up the road the light engine, screaming through a cut, encountered a flock of sheep, wallowed through them, left the track, and slammed the four men on board up against the side of the cut.

Not a bone was broken, though all of them were sore shaken, the engineer being unconscious when picked up.

“Go back and report,” said the old man to the conductor.  “You look after the engineer,” to the fireman.

“Will you flag west, sir?” asked the conductor.

“Yes,—­I’ll flag into Pee-Wee,” said the old man, limping down the line.

To be sure, the superintendent was an intelligent man and not the least bit superstitious; 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 of wheels he could hear the splash, and once in a while he could feel the spray, of new-made cataracts as the water rushed down the mountain side, choking the culverts.