the bedstead, I looked over the headboard minutely at the second casement. Passing my hand down behind the board, I readily discovered and pressed the spring, which was, as I had supposed, identical in character with its neighbor. I now looked at the nail. It was as stout as the other, and apparently fitted in the same manner—driven in nearly up to the head.
"You will say that I was puzzled; but, if you think so, you must have misunderstood the nature of the inductions. To use a sporting phrase, I had not been once 'at fault.' The scent had never for an instant been lost. There was no flaw in any link of the chain. I had traced the secret to its ultimate result,—and that result was the nail . It had, I say, in every respect, the appearance of its fellow in the other window; but this fact was an absolute nullity (conclusive as it might seem to be) when compared with the consideration that here, at this point, terminated the clew. 'There must be something wrong,' I said, 'about the nail.' I touched it; and the head, with about a quarter of an inch of the shank, came off in my fingers. The rest of the shank was in the gimlet-hole, where it had been broken off. The fracture was an old one (for its edges were incrusted with rust), and had apparently been accomplished by the blow of a hammer, which had partially imbedded, in the top of the bottom sash, the head portion of the nail. I now carefully replaced this head portion in the indentation whence I had taken it, and the re-semblance to a perfect nail was complete—the fissure was invisible. Pressing the spring, I gently raised the sash for a few inches; the head went up with it, remaining firm in its bed. I closed the window, and the semblance of the whole nail was again perfect.
"This riddle, so far, was now unriddled. The assassin had escaped through the window which looked upon the bed. Dropping of its own accord upon his exit (or perhaps purposely closed), it had become fastened by the spring; and it was the retention of this spring which had been mistaken by the police for that of the nail,— farther inquiry being thus considered unnecessary.
"The next question is that of the mode of descent. Upon this point I had been satisfied in my walk with you around the building. About five feet and a half from the casement in question there runs a lightning-rod. From this rod it would have been impossible for any one to reach the window itself, to say nothing of entering it. I observed, however, that the shutters of the fourth story were of the peculiar kind called by Parisian carpenters ferrades —the kind rarely employed at the present day, but frequently seen upon very old mansions at Lyons and Bordeaux. They are in the form of an ordinary door (a single, not a folding door), except that the lower half is latticed or worked in open trellis—thus affording an excellent hold for the hands. In the present instance these shutters are fully three feet and a half broad. When we saw them from the rear of the house, they were both about half open—that is to say they stood off at right angles from the wall. It is probable that the police, as well as myself, examined the back of the tenement; but, if so, in looking at these ferrades in the line of their breadth (as they must have done), they did not perceive this great breadth itself, or, at all events, failed to take it into due consideration. In fact, having once satisfied themselves that no egress could have been made in this quarter, they would naturally bestow here a very cursory examination. It was clear to me, however, that the shutter belonging to the window at the head of the bed, would, if swung fully back to the wall, reach to within two feet of the lightning-rod. It was also evident that, by exertion of a very unusual degree of activity and courage, an entrance into the window, from the rod, might have been thus effected. By reaching to the distance of two feet and a half (we now suppose the shutter open to its whole