replied. "The Yale latch-key rather suggests a flat, and a flat with a single occupant, and the probable habits of our absent friend offer a similar suggestion." He ran his eye down the list and presently turned to me with his finger on the page.
"If the facts that we have elicited—the singular series of agreements with the required conditions—are only a string of coincidences, here is another. On the south side of Dockhead, actually next door to the spice-grinders and opposite to Carbutt's rice-mills, is a block of workmen's flats, Hanover Buildings. They fulfil the conditions exactly. A coat hung in a room in those flats, with the windows open (as they would probably be at this time of year), would be exposed to the air containing a composite dust of precisely the character of that which we have found. Of course, the same conditions obtain in other dwellings in this part of Dockhead, but the probability is in favour of the buildings. And that is all that we can say. It is no certainty. There may be some radical fallacy in our reasoning. But, on the face of it, the chances are a thousand to one that the door that that key will open is in some part of Dockhead, and most probably in Hanover Buildings. We must leave the verification to Miller."
"Wouldn't it be as well to look at the tram-ticket?" I asked.
"Dear me!" he exclaimed. "I had forgotten
