The trackman was listening with the greatest interest.

“Just how do you know that, Miss Warfield?” he said.

“Why,” replied Marion, “don’t you see, from the mark on the ties, that the engine wheels left the rail almost at the moment they struck it.  The marks of the wheels commence on the second tie ahead of the beginning of the rail.  Therefore, this rail, for some reason, was more easily pushed out of alignment than it should have been.  What was the reason?”

The track boss reflected.

“You see, Miss Warfield, this place is the beginning of an up-grade, the engine was coming down a long grade toward it, so when this train struck the first rails of the up-grade it struck it just like you’d drive in a wedge, and the hundred-ton brute of an engine jammed this rail out of alignment.  That’s all there is to it.  When the rail sprung the wheels went down on the ties on that side and the train was ditched.”

“It was a clean accident, then, you think?” said Marion.

“Sure, Miss Warfield,” replied the man.  “If anybody had tried to move that rail out of alignment, he would have to disconnect it at the other end, that is, take off the plate that joins it to the next rail.  That would leave the end of the rail clean, with no broken plate.  But the end of the rail is bent and the plate is twisted off.  We looked at that the first thing.  Nobody could twist that plate off.  The engine did it when it left the track.

“You see, Miss Warfield, the weight of the engine, like a wedge, simply forced one of these rails out of alignment.  Don’t you understand how a hundred ton wedge driven against the track, at the start of an upgrade, could do it?”

The old peasant woman stood behind the track boss.  The thing was a sort of awful game.  She did not speak, but the vicissitudes of the inquiry advanced her, or retired her, with the effect of points, won or lost.

“I understand perfectly,” replied Marion, “how the impact of the heavy engine might drive both rails out of alignment, if they offered an equal resistance, or one of them out if it offered a less resistance.  This is straight track.  The wedge would go in even.  It should have spread the rails equally.  That’s the probable thing.  But instead it did the improbable thing; it spread one.  I hold the improbable thing always in question.  Human knowledge is built up on that postulate.

“True, a certain factor of difference in conditions must be allowed, as I have said, but an excessive factor cannot be allowed.  We have got to find it, or discard human reason as an implement for getting at the truth.”

Again the big track boss smashed through the niceties of logic.

“These things happen all the time, Miss Warfield.  You can’t figure it out.”

“One ought to be able to determine it,"’ replied the girl.

The track boss shook his head.