240 



FOREST PRODUCTS 



the form may vary from a regular cone to an obtuse cone or a truncated 

 cone. Opem'ngs are left at the base to serve as a draft, together with a 

 central shaft to carry off the smoke rurming vertically through the middle 

 of the pile. 



The sticks of wood are piled compactly together. The pile is first 

 covered with grass, leaves, moss, branches, or needles, etc., depending 

 upon the best available material, to a depth of from 3 to 5 in., and then 

 with soil and turf to a depth of from 2 to ^ in. in addition. It is then 



Fig. 64. — A charcoal pit in the process of burning. An " explosion " has occurred and the 

 burners are determining the extent of the cavity. The latter is filled with small pieces 

 of wood which are held in readiness for this purpose. The framework in the exterior 

 is used to hold the dirt in place. Photograph taken in Deerlodge National Forest, 

 Montana. The wood used is lodgepole pine [Pinus niurrayana.) 



ignited by means of a torch at the base of the central flue, and the whole 

 pile gradually chars upward and outward, great care being exercised not 

 to burn the pile too rapidly, or to permit flames to burst out. The 

 admission of only sufficient air to cause partial combustion is a most 

 important feature of the burning process. The time required for burning 

 depends upon the kind of wood and its size and dryness, the method of 

 piling, size of pile, the temperature and weather, and the character of 

 the ground, etc. 



In Montana the average-sized charcoal pit is about 40 ft. in diameter 



