There was, however, one circumstance which Captain Duncombe never mentioned to Harker. That circumstance was the apparition of old Screwton's ghost. Joe Duncombe was, to tell the truth, a little ashamed of his credulity on that occasion. He entertained no doubt that he had been victimized by a clever practical joke, and while he chuckled over the recollection that it had been an expensive jest to the perpetrator, who had lost a valuable gold coin by the transaction, he had no fancy for exposing himself to any further ridicule on the occasion. So the bluff, imperious, soft-hearted captain issued an ukase commanding silence on the subject; and silence was observed, not in the least because Rosamond Duncombe or Susan Trott were afraid of him, but because Rosamond loved her father, and Susan Trott respected her master too much to disobey his lightest wish. There was also one circumstance which Joyce Harker never mentioned to Captain Duncombe. This circumstance was the identity of the former occupant of the cottage with the man whom he believed to be the murderer of Valentine Jernam. "It is bad enough to live in a place that's said to be haunted," said Harker to himself, when he visited the cottage for the first time; "without my telling him that he comes after a man who is certainly a convict, and probably a murderer." * * * * * CHAPTER XVII. DOUBTFUL SOCIETY. Victor Carrington still lived in the little cottage on the outskirts of London. Here, with his mother for his only companion, he led a simple, studious life, which, to any one ignorant of his character, would have seemed the life of a good and honourable man. The few neighbours who passed to and fro beneath the wall which surrounded the cottage, knew nothing of the inner life of its occupants. They knew only that of all the houses in the neighbourhood this was the quietest. Yet those who happened to pass the house late at night always saw a glimmer of light in an upper chamber, and the blue vapour of smoke rising from one particular chimney. Those who had occasion to pass the house frequently after dark perceived that the smoke from this chimney was different from the common smoke of common chimneys. Sometimes vivid sparks glittered and flashed upon the darkness. At other times a semi-luminous, green vapour was seen to issue from the mouth of the chimney. These facts were spoken about by the neighbours; and by and by people discovered that the smoke issued from the chimney of Victor Carrington's laboratory, where the surgeon was frequently employed, long after midnight, making experiments in the science of chemistry.