On a day in the preceding month, a man who answered to the description of Rochdale given by the first driver and the bric-à-brac seller, being fair-haired, pale, tall, and broad-shouldered, came to his shop to order a wig and a beard; these were to be so well constructed that no one could recognise him, and were intended, he said, to be worn at a fancy ball. The unknown person was accordingly supplied with a black wig and a black beard, and he provided himself with all the necessary ingredients for disguising himself as a native of South America, purchasing kohl for blackening his eyebrows, and a composition of Sienna earth for colouring his complexion. He applied these so skilfully, that when he returned to the hairdresser's shop, Jullien did not recognise him. The unusualness of a fancy ball given in the middle of summer, and the perfection to which his customer carried the art of disguise, astonished the hairdresser so much that his attention was immediately attracted by the newspaper articles upon "The Mystery of the Imperial Hotel," as the affair was called. At my father's house two letters were found; both bore the signature of Rochdale, and were dated from London, but without envelopes, and were written in a reversed hand, pronounced by experts to be disguised. He would have had to forward a certain document on receipt of these letters; probably that document was in the letter-case which the assassin carried off after his crime. The firm of Crawford had a real existence at San Francisco, but had never formed the project of making a railroad in Cochin China. The authorities were confronted by one of those criminal problems which set imagination at defiance. It was probably not for the purpose of theft that the assassin had resorted to such numerous and clever devices; he would hardly have led a man of business into so skilfully laid a trap merely to rob him of a few thousand francs and a watch. Was the murder committed for revenge? A search into the record of my father revealed nothing whatever that could render such a theory tenable. Every suspicion, every supposition, was routed by the indisputable and inexplicable fact that Rochdale was a reality whose existence could not be contested, that he had been at the Imperial Hotel from seven o'clock in the evening of one day until two o'clock in the afternoon of the next, and that he had then vanished, like a phantom, leaving one only trace behind--_one only_. This man had come there, other men had spoken to him; the manner in which he had passed the night and the morning before the crime was known. He had done his deed of murder, and then--nothing. "All Paris" was full of this affair, and when I made a collection, long afterwards, of newspapers which referred to it, I found that for six whole weeks it occupied a place in the chronicle of every day. At length the fatal heading, "The Mystery of the Imperial Hotel," disappeared from the columns of the