"The 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_—a kind rarely employed at the present day,
but frequently seen upon very old mansions at Lyons and Bordeaux.
