The Mystery of Cloomber

Quote, "At this moment he fell back upon his pillow as if he had been shot, while the same look of horror came over his face which I had observed when I first entered the room. At the same instant there came, apparently from the air immediately above his bed, a sharp, ringing, tinkling sound, which I can only compare with the noise made by a bicycle alarm, though it differed from this in having a distinctly throbbing character. I have never, before or since, heard any sound which could be confounded with it."