I've been doing some insulation work in the attic of our late-1800's Edwardian, and I finally found out why the chimney chase is so narrow: it uses metal pipe. What I found was white asbestos-covered, 4" single-wall steel pipe coming up the chase, which was cut off below the roof sheathing when the new roof was put on ten years ago (before us). The fireplaces were also removed at that time, so I don't know what type they were; my best guess is coal (shallow firebox). The interior of the pipe is rusty but clean. Does anybody know when this type of pipe was generally used, and whether it's wood or coal pipe? I'm trying to figure out if this was the original chimney arrangement, or if it was retrofitted.