is near either a rice-mill or a spice-grinder, with one exception: Seth Taylor's, St. Saviour's Flour Mills, Dockhead."
"This is really becoming interesting," said I.
"It has become interesting," Thorndyke retorted. "You observe that at Dockhead we find the peculiar combination of factories necessary to produce the composite dust in which this coat has hung; and the directory shows us that this particular combination exists nowhere else in London. Then the graphite, the cocoa and the hops tend to confirm the other suggestions. They all appertain to industries of the locality. The trams which pass Dockhead, also, to my knowledge, pass at no great distance from the black-lead works of Pearce Duff & Co. in Rouel Road, and will probably collect a few particles of black-lead on the seats in certain states of the wind. I see, too, that there is a cocoa factory—Payne's—in Goat Street, Horsleydown, which lies to the right of the tram line going west, and I have noticed several hop warehouses on the right side of Southwark Street, going west. But these are mere suggestions; the really important data are the rice and flour mills and the spice-grinders, which seem to point unmistakably to Dockhead."
"Are there any private houses at Dockhead?" I asked.
"We must look up the 'Street' list," he
