She went to sleep, and I watched. I lay till half past eleven with my eyes staring at the dark, wide awake and undisturbed and triumphant. At half past eleven I must confess that I heard a singular sound. Something whistled at the keyhole. It could not have been the wind, by the way, for there was no wind that night. Something else than the wind whistled in at the keyhole, sighed through into the room as much like a long-drawn breath as anything, and fell with a slight clink upon the floor. I lighted my candle and got up. I searched the floor of the room, and opened the door and searched the entry. Nothing was visible or audible, and I went back to bed. For about ten minutes I heard no further disturbance, and was concluding myself to be in some undefined manner the victim of my own imagination, when there suddenly fell upon the headboard of my bed a blow so distinct and loud that I involuntarily sprang at the sound of it. It wakened Alison, and I had the satisfaction of hearing her sleepily inquire if I had caught that rat yet? By way of reply I relighted the candle, and gave the bed a shove which sent it rolling half across the room. I examined the wall; I examined the floor; I examined the headboard; I made Alison get up, so that I could shake the mattresses. Meantime the pounding had recommenced, in rapid, irregular, blows, like the blows of a man's fist. The room adjoining ours was the nursery. I went in with my light. It was empty and silent. Bridget, with Tip and the baby, slept soundly in the large chamber across the hall. While I was searching the room my wife called loudly to me, and I ran back. "It is on the mantel now," she said. "It struck the mantel just after you left; then the ceiling, three times, very loud; then the mantel again,--don't you hear?" I heard distinctly; moreover, the mantel shook a little with the concussion. I took out the fire-board and looked up the chimney; I took out the register and looked down the furnace-pipe; I ransacked the garret and the halls; finally, I examined Miss Fellows's door,--it was locked as I had left it, upon the outside; and that locked door was the only means of egress from the room, unless the occupant fancied that of jumping from a two-story window upon a broad flight of stone steps. I came thoughtfully back across the hall; an invisible trip-hammer appeared to hit the floor beside me at every step; I attempted to step aside from it, over it, away from it; but it followed me, pounding into my room. "Wind?" suggested Allis. "Plaster cracking? Fancies? Dreams? Blind headaches?--I should like to know which you have decided upon?" Quiet fell upon the house after that for an hour, and I was dropping into my first nap, when there came a light tap upon the door. Before I could reach it, it had grown into a thundering blow.