The most peculiar occurrences, however, were the antics of certain keys belonging to doors in the house. "The door of the front bedroom was often found locked, and the key would disappear." The doctor kept his eye on the key and presently saw it move round, locking the door, and then "he saw the last of the key disappearing through the hole." At another time the lady of the house, her children, and the maid were locked in for some hours. "The key would be kept away for days; then it would suddenly appear. One day it was found in Mrs Macdonald's lap; once it was quietly laid on the doctor's head," and so forth. On one occasion when the key was not given up the doctor called out: "Won't you send us down the key before we go?" They were passing down the stairs and, before they reached the bottom, the key was gently dropped on the doctor's head. The most careful observations failed to discover the known means by which the feats could be accomplished. The evidence of the intelligence and of the mischievous disposition of these uncanny tricksters was borne out by sounds of dancing being heard outside the door just afterwards. "The possible non-ghostly explanations," says Mrs Sidgwick, "of what pass as ghostly phenomena may be conveniently classed with reference to the various sorts of error by which the evidence to such phenomena is liable to be affected. I should state these as (1) hoaxing, (2) exaggeration or inadequate description, (3) illusion, (4) mistaken identity, (5) hallucination.... I think, however, that anyone who has read the evidence will at once discard the first of these alternatives so far as the great mass of the first-hand narratives is concerned." There are not a few cases, however, where the ghostly manifestations have been found to be due to human agency. The following instance was brought to my notice by a well-known firm of estate agents at Tunbridge Wells:--