So far I have only given the simplest plan of the line that I might get the basis of the affair as clear as possible. That plan is not quite complete, for though there was only this one line joining the stations A and B there was a short side-line, H I, which led to a sand-pit which had supplied a glass-factory. But since the glass-factory had failed, they no longer worked the sand-pit; and the side-line was practically abandoned. Here is the complete plan:
It will naturally be supposed that this side-line leading to the sand-pit is going to provide the explanation, the quite simple explanation of the disappearance of the express. But if the matter had been as simple as the side-line would appear to make it, I should hardly have omitted it from the first map. I could have said at once: "It is quite clear that, owing to a train of circumstances which it remains to determine, the express, instead of continuing to follow the line B A, must have turned off up the side-line H I, and buried itself in the vast mass of loose sand at the sand-pit I. Rushing along at a speed of over sixty miles an hour, it evidently plunged into the mass of sand, which covered it up; and that is the stupid but actual reason of its disappearance."
But, to say nothing of the fact that this does not explain the presence, at the point D, of the guard's-van and railway-carriage, out of the window of which Signor Petito had stuck his head, this explanation could not have failed to occur to the alert intelligence of the engineers of the company. Moreover, there were points and a switch at the point H; this switch, in accordance with the rules, was padlocked; and the key had been taken away.
I indeed attached no importance to the fact that the padlock was locked; for, it seemed to me quite probable that the key had been left in the padlock, which had actually been the case, and that Theophrastus, who had good reasons for stopping the train in order to join Signor Petito, had profited by the presence of that key, to shift the points. It was only a matter of thrusting over the lever of the switch; and that would explain why the train was not seen by the signal-man at A, since, instead of continuing along the line B A, it had turned off up H I towards the sand-pit. I told myself all this; and if it had explained anything, I should have stated it at once, and instead of giving two maps I should have given merely the latter with the side-line H I on it.
That I have not done so is owing to the fact that the side-line H I explains nothing. I also believed at first that it was going to make the disappearance of the express clear to us, but as a matter of fact it complicates the catastrophe instead of explaining it; for here is the story, the true story; and that too continues to explain nothing at all.
Wandering along the road which runs beside the railway, Theophrastus had noticed the little side-line, and seen that the key had been left in the padlock of the switch. This fact, which had been of no importance to him before his brief but stormy interview with Signora Petito, assumed an enormous importance when he resolved to join, at any cost, Signor Petito, who was in the train which was about to pass under his nose. M. Longuet said to himself: "I cannot board the express, rushing between the two stations A and B, in the usual way. But there is a little side-line H I, the key is in the padlock of the switch; I have only to turn the lever, and the express will dash up H I. Since it is broad daylight the engine-driver will see what has happened, he will stop the train, and I shall take advantage of its stopping to board it."
Nothing could be more simple; and Theophrastus did it. He dragged over the lever of the switch, walked up the side-line, and waited for the express.
Theophrastus, hidden behind a tree that none of the officials on the express might see him, awaited its coming at the point K, that is to say, rather more than half-way up the side-line, that is to say, on this side of the sand-pit I. He waited for the express coming from H, with his eyes on the track. If, as everyone must have been supposing ever since I mentioned the sand-pit, the train coming from H had buried itself in the sand at I, Theophrastus, who was at K, between H and I, must have seen it. But Theophrastus waited for the train and waited for the train and waited for the train. He waited for it as the signal-man at station A had waited for it; and he no more saw the express than did the signal-man at A and the rest of the officials of the line.
The express had disappeared for M. Longuet as it had disappeared for the rest of the world.