324 THE UTILISATION OF WOODLAND PRODUCE. 



is fixed in the centre, and two bits of wood set at right angles 

 through the clefts ; and in each of the right angles thus forme4 

 a billet of wood is laid thick end down against the centre 

 post, while large straight billets are laid radially on the ground 

 like the spokes of a wheel to form a floor, the spaces between 

 being filled with small branches or brushwood. These flooring 

 billets are held in position 'by "pegs driven into the ground 

 round the circumference of the stack, and about a foot apart. 

 On this ground-floor, the first stage of the kiln is built up with 

 the largest billets set thin end up and inclining slightly inwards 

 towards the central stake ; then another storey of shorter 

 billets is laid similarly above this ; then an upper layer of 

 smaller stuff; and the top is rounded off with small wood to 

 form a paraboloid cone. The stack is then covered with turf 

 and surfaced with mixed earth and sand, and the kiln is lighted 

 by drawing out the central billet in the upper layer, and filling 

 and lighting pieces of dry wood. The burning usually takes 4 

 or 5 days, according to the size of the kiln and the state of the 

 weather; and great attention has to be paid, both day and night, 

 to regulate the course of the firing, by closing openings where 

 flames appear, showing unnecessary combustion ; but vents are 

 opened with a sharp stick to equalise the rate of carbonisation 

 all round the stack, being closed, when no longer required, with 

 earth and sand (as shown by colour of smoke). When the 

 firing is complete right down to the circumference, all vents are 

 stopped, more earth is ihrown on, and the kiln is allowed to 

 cool before being opened to remove the charcoal. 



The contents of such a stack are known from the amount of 

 cordwood used, but can also be reckoned by multiplying the 

 square of the circumfeTence into the height and dividing by 

 OTT (28*25) ; because, the contents of a true cone being J (basal 

 area x height), and of a paraboloid cone being - (basal area 

 x height), the actual contents of such a stack will be about 

 i- (basal area x height). 



