The evening train was feeling its way down over the wireless line and was half-way to Brewster before the three men sitting in the otherwise unoccupied smoking-compartment of the sleeper broke the silence which the sudden tragedy had laid upon them. But at the lighting of his third cigar Maxwell could contain himself no longer.
“It’s another of your miracles, Calvin,” he said. “By this time I’m so well used to them that nothing you do fazes me any more. But I’m sure Billy will sleep better to-night if you tell him how you did it.”
The big man grunted softly.
“I think both of you have put the broken bits of the puzzle together before this,” he returned. “The motive was the chief thing; what I call the ‘nucleus thought,’ and we had that all ready-made. We knew that this ‘Big Nine,’ as Ford names it, was out after your scalp; and as soon as you told me about the tunnel and the Grafton Brothers’ contract the probable point of attack was no longer in doubt. You see, I happen to know that the Graftons have always been hand-in-glove with your principal competitor—had installed all the block signals for it, cutting a fine melon for themselves in the process, too.”
“Still,” said Maxwell, “it’s a long way from that to this.”
“It was only taking one step after another, and Benson gave me three or four of them. The details of Stribling’s exceedingly simple plot became very plain after Benson had told us about the train-stopping, the empty dynamite boxes, the safety switch—which could have been just as easily and effectively placed at either end of the tunnel as in that hole in the middle of it—and finally about the pouring of the sirupy stuff into the oil-tank. There was a bit of fine work on Stribling’s part. Benson doubtless knows nitro-glycerine when he sees it; but under the circumstances he would be completely disarmed—as he was.”
“But how did you know that there would be a false cover on the tank?” queried Starbuck.
“A bit of pure reasoning. The specific gravity of glycerine is greater than that of the heaviest of the earth oils; hence the explosive would sink to the bottom of the tank and mix with the oil to some extent. I reasoned that Stribling would not take the risk of the mixture.”
“He didn’t,” said the mine owner; “the pan was there and it was packed in ice.”
“But the laboratory experiment?” put in Maxwell.