During one of my Colorado camping-trips a 

 high October wind brought me the information 

 that spruce wood was burning near by. While 

 I was searching for the fire in the thick needle 

 carpet of the forest floor, a spark from above 

 settled before me. A fire was sputtering and 

 starting in a tree top about thirty feet above the 

 earth. This fire was starting where a dead lean- 

 ing tree-trunk was rasping and rubbing against 

 an upright one. The bark of the standing tree 

 was powdered and tufted with wood-dust which 

 had been ground by friction from the trunks as 

 they swayed and rotated in the wind. This in- 

 flammable wood-dust, together with accumu- 

 lated bark-bits and needles, had been set on fire 

 from the heat generated by these two big sticks 

 rubbing together. Plainly this was a friction fire. 

 The incessant swaying of treetops in the tire- 

 less wind occasionally causes a smoke from 

 friction at points where overlapping limbs or 

 entangled trees are rubbing. Within a few min- 

 utes after my discovery, this fire was roaring 

 eagerly through the treetops. 



Friction fires are rare, but my old notebooks 



134 



