AS I advanced, it seemed to me the stair grew airier and a thought more lightsome; and I was wondering what might be the cause of this change, when a second blink of the summer lightning came and went. It was not only that the flash shone in on every side through breaches in the wall, so that I seemed to be clambering aloft upon an open scaffold, but the same passing brightness showed me the steps were of unequal length, and that one of my feet rested that moment within two inches of the well.

The tower, I should have said, was square; and in every corner the step was made of a great stone of a different shape to join the flights. Well, I had come close to one of these turns, when, feeling forward as usual, my hand slipped upon an edge and found nothing but emptiness beyond it. The stair had been carried no higher; to set a stranger mounting it in the darkness was to send him straight to his death.