226 THE PRINCIPLES OF HANDLING WOODLANDS 



are inadequately protected from fire. It is probable that 

 in fully 75 per cent, of the private forests there is no 

 attempt whatever at systematic protection. 



Character of Forest Fires 



It is customary to distinguish three classes of forest 

 fires, as follows: 



1. Surface fires, which burn the surface layer of dry 

 leaves and other litter, dry grass, brush, and small trees. 



2. Ground fires, which occur where the mineral soil is 

 covered with a deep accumulation of vegetable mold, and 

 which, on account of the peaty character of the material, 

 burn much more slowly than surface fires. 



3. Crown fires, which burn through the crowns of the 

 trees. 



Surface Fires 



Nearly all forest fires start as surface fires. The dry 

 litter on the surface of the ground is ignited by a spark, 

 perhaps from a locomotive or a camp-fire. At first the 

 fire burns in a small circle, gradually eating out in all di- 

 rections. If there is a wind, the fire burns with greatest 

 intensity on the leeward side, and quickly assumes an 

 oval form. If the wind is very strong, the fire may die 

 out entirely on the windward side, but it burns intensely 

 on the other side, soon developing a distinct front or 

 head, with side wings running diagonally with the wind. 

 At first the front of the fire is very narrow, but it gradu- 

 ally widens and takes the form of a broad, irregular line. 

 The front may reach indefinite proportions, from a few 



