The trackman was a person accustomed to the reality and not the theory of things.

“I don’t see how the accident would have been any different,” he said, “if somebody had put that tree in the right spot to catch the coach; or timed the minute with a stop-watch to kill that brakeman; or piled that wreck on the man so it wouldn’t hurt him.  The result would have been just the same.”

“The result would have been the same,” replied Marion, “but the arrangement of events would have been different.”

“Just what way different, Miss Warfield?” said the man.

“We cannot formulate an iron rule about that,” replied Marion, “but as a general thing catastrophes in nature seem to lack a motive, and their contributing events are not forced.”

The big trackman was a person of sound practical sense.  He knew what Marion was after, but he was confused by the unfamiliar terms in which the idea was stated.

“It’s mighty hard to figure out,” he said.  “Of course, when you find an obstruction on the track or a crowbar under a rail, or some plain thing, you know.”

Then he added: 

“You’ve got to figure out a wreck from what seems likely.”

“There you have it exactly,” said Marion.  “You must begin your investigation from what your common experience indicates is likely to happen.  Now, your experience indicates that the rails of a track sometimes spread under these heavy engines.”

“Yes, Miss Warfield.”

“And your experience indicates that this is more likely to happen at the first rise of the synclinal on a grade than anywhere on a straight track.”

“Yes, Miss Warfield.”

“Good!” said Marion, “so far.  But does not your experience also indicate that such an accident usually happens when the train is running at a high rate of speed?”

“Yes, Miss Warfield,” said the man.  “It’s far more likely to happen then, because the engine strikes the rails at the first rise of the grade with more force.  Naturally a thing hits harder when it’s going . . .  But it might happen with a slow train.”

Marion made a gesture as of one rejecting the man’s final sentence.

“When you turn that way,” she said, “you at once leave the lines of greatest probability.  Why should you follow the preponderance of common experience on two features here, and turn aside from it on the third feature?”

“Because the thing happened,” replied the man, with the directness of those practical persons who drive through to the fact.

“That is to say an unlikely thing happened!” Marion made a decisive gesture with her clenched fingers.  “Thus, the inquiry, beginning with two consistent elements, now comes up against one that is inconsistent.”

“But not impossible,” said the man.

“Possible,” said Marion, “but not likely.  Not to be expected, not in line with the preponderance of common experience; therefore, not to be passed.  We have got to stop here and try to find out why this track spread under a slow train.”