HOW THE FOREST IS GUARDED 93 



shown that fires caused by lightning or set by Indian 

 hunters to drive out game swept over the mountains 

 again and again long before white men settled on the 

 Atlantic Coast. In fact, the vast stretches of lodgepole 

 pine in northern Colorado are believed to be the result 

 of these early fires, as this species finds ideal conditions 

 for germination and growth after the forest soil has 

 been heavily burned. 



It is only within the past few years that an organized 

 effort has been made to prevent and check forest fires. 

 Formerly they were regarded as an act of Providence 

 and the advancing flames were fought only when they 

 approached a village. Otherwise the fires were gener- 

 ally allowed to burn until the wind changed or a general 

 rain made the forest too wet to burn. "Within late years 

 and largely as the result of fire-fighting experience 

 by the foresters of the country, lumbermen have learned 

 that forest fires are largely preventable, and under 

 ordinary circumstances can be extinguished if attacked 

 at once. As a consequence in addition to the fire- 

 fighting force of patrolmen, forest guards, and look- 

 out men, maintained by the National Forest Ser- 

 vice and many of the States, protective associations are 

 now being formed by lumbermen to reduce their fire 

 risk. 



Forest fires may be divided into three classes : First, 

 those that burn along the surface of the ground, called 

 surface fires; second, those that burn in the duff or 

 layer of vegetable mold on top of the mineral soil 

 ground fires; and third, the crown fire which burns 

 from tree to tree with the head of the fire up in the 

 treetops and the widespread wings trailing down upon 

 the ground. 



Surface fires are the most common and least danger- 



