Camping and woodcraft - Scoutmastercg.com

246 CAMPING AND WOODCRAFTrow within and flaring outward, so as to help throw,the heat out into the room. This is well enoughwhere fuel must be economized ; but in the big forest,where there is abundance, it is best to buildthe fireplace with straight sides, so that backlogs ofnearly 4-foot length can beused. This saves a lot ofchopping.If the back of the fireplaceis built up straightinto the flue, the chinmeyis very likely to bmokewhenever the air is heavyor the winds contrary.To insure a good draught,build the upper part ofthe fireback with a forwardslope, as shown in Fig.76, forming a "throat" {a)about 5 inches above thefront of arch or lintelsand only 3 or 4 inchesdeep. The top of thisthroat forms a ledge (b)Fig. 76.—Fireplace that checks wind from(vertical section) rushing down the flue.To support the rocks over the fireplace, insteadof building an arch (which is likely to crack or giveway from settling of chimney) set in two flat steelbars, 2^ X 34 inch, as lintels (c).Build the wing walls of the fireplace out Into thecabin far enough to protect the ends of abuttinglogs, and to support a plank or puncheon for mantelshelf(e). The upper part of the chimney goesquite outside the cabin, and so requires no flashings.In backwoods cabins the chimneys generally arebuilt up without mortar, clay being used instead.As clay shrinks and loosens in drying, such a structuremust be chinked over again at Intervals. Itis more satisfactory to take in with you a sack ofI