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.

“Whatever it is I’ll have it now!” I whispered, turned the latch without noise, and flung the door wide into the hall.  It was silent, dark, and cold.  A little glimmer of moonlight fell in and showed me the figures upon the carpet, outlined in a frosty bar.  No hand or hammer, human or superhuman, was there.

Determined to investigate matters a little more thoroughly, I asked my wife to stand upon the inside of the doorway while I kept watch upon the outside.  We took our position, and I closed the door between us.  Instantly a series of furious blows struck the door; the sound was such as would be made by a stick of oaken wood.  The solid door quivered under it.