It’s actually “Swift,” not “Smith,” but I’ll check the source of my statements in my “Chimneys” article that appeared in The Mall. However, bear this in mind, there are many “authorities.” For instance, do we want to cite the manufacturer’s specs, the National Fire Protection Association (NFPA) standards, the Chimney Safety Institute of America (CSIA), or should we just use palin old common sense. This is what I can tell you, in the rich oxygen atmosphere of an attic, I would prefere to see a prefabriocated fireplace flue enclosed within a chase sheather with drywall. Regardless, i’ll check my sources and keep you informed. Meanwhile, my advice is that you ere on the side of caution and safety.