down. A fire is more all-consuming in going up, 

 and even after years have passed, the remains 

 left on a slope will often enable one to deter- 

 mine whether a fire swept up or crept down. 

 One peculiarity of flames in young growths on 

 steep slopes is that they sometimes dart up the 

 heights in tongues, leaving narrow ragged 

 stretches of unburned trees! Usually these 

 fiery tongues sweep in a straight line up the 

 slope. 



The intense heat of a passing fire-front is 

 withering at long distances. I have known a 

 fire to blister aspen clumps that were seven or 

 eight hundred feet from the nearest burned 

 trees. The passing flames may have been pushed 

 much closer than this by slow heavy air-swells 

 or by the brief blasts of wild wind rushes. 



The habits of forest fires are largely deter- 

 mined by slope-inclination, wind-speed, and the 

 quantity and quality of the fuel. In places the 

 fire slips quietly along with low whispering, then 

 suddenly it goes leaping, whirling, and roaring. 

 A fire may travel less than one mile or farther 

 than one hundred miles in a day. The ever 



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