584 AUXILIARY FOREST INDUSTRIES. 



rest, so as to secure a level surface to the lower tier. This 

 passage should be exposed always to windward, but is not 

 required if the kiln is kindled from above. 



When the two tiers of billets are piled the top of the kiln 

 is filled in, as shown in Fig. 311. For this, the wood, which 

 should be composed of small dry pieces, is laid very obliquely 

 or horizontally. When the kiln is kindled from below, its 

 whole top, including the flue, is thus covered ; but when the 

 kindling is effected from above, the flue runs through the top 

 of the kiln. 



Although the burners endeavour in piling the billets to 

 place them as vertically as possible, as they are piled with 

 their thick ends downwards they become gradually inclined 

 outwards, so that eventually the outside of the kiln acquires 

 a slope of 60 degrees or 70 degrees. This slope is necessary 

 to support the covering of the kiln, being greater or less 

 according to the state of the weather : during summer, in 

 dry weather, it cannot be so great as in damp weather, 

 whenever the covering does not dry very rapidly, a steeper 

 slope is permissible. 



The charging of the kiln is completed by carefully stopping 

 all openings and crevices with small split pieces of wood, in 

 order to prevent too great a draught and save the covering 

 from collapsing. 



v. Supporting and Covering the Kiln. 



The next step is to apply the covering, which should be as 

 air-tight and fire-proof as possible. Two coverings are applied, 

 termed the inner and outer coverings ; in order that they 

 may not collapse they are supported by pieces of wood, termed 

 the upper and lower supports. Every kiln requires at least 

 the latter, which are formed of stout, short, forked pieces of 

 wood driven into the ground all round the edge of the kiln ; 

 they may be replaced by a row of stones as big as one's licml, 

 on which split billets ;in> phiccd contiguously in :i circle a few 

 inches from the ground for the covering to rest on and to 

 admit air to the kiln. In some districts iron supports are 

 used, shaped like circular segments with a prop at one end of 



