I was on Brattle Street, which seemed quite deserted, thought it was daylight. I was walking slowly by the closed doors of the buildings opposite M's. Suddenly I heard a series of rapping noises, which seemed to come from within. I was impelled to open the nearest door, and saw before me a bare entryway in half darkness, with a flight of uncarpeted stairs leading to the floor above. Looking up, I beheld with chilling horror a simple walking stick standing on end on an upper stair, and while I gazed, saw it rise, move forward and descend with a sharp tap on the next step below, precisely as if in the hand of an invisible person! I thought that I fell to the floor overcome with terror. Then, of course, I awoke.