THE GREATEST ENEMY OF THE FORESTFIRE 57 



will run into the wind, it can be put out more 

 easily. Fires that have. the wind back of them 

 and plenty of dry fuel ahead, speed on their way 

 of destruction at a velocity of 5 to 10 miles an 

 hour, or more. They usually destroy everything 

 in their course that will burn, and waste great 

 amounts of valuable timber. Wild animals, in 

 panic, run together before the flames. Settlers 

 and farmers with their families flee. Many are 

 overtaken in the mad flight and perish. The 

 fierce fires of this type can be stopped only by 

 heavy rain, a change of wind, or by barriers 

 which provide no fuel and thus choke out 

 the flames. 



Large fires are sometimes controlled by back- 

 firing. A back-fire is a second fire built and so 

 directed as to run against the wind and toward 

 the main fire. When the- two fires meet, both will 

 go out on account of lack of fuel. When prop- 

 erly used by experienced persons, back-fires are 

 very effectual. In inexperienced hands they are 

 dangerous, as the wind may change suddenly or 

 they may be lighted too soon. In such cases they 

 often become as great a menace as the main fire. 

 Another practical system of fighting fires is to 

 make fire lines around the burning area. These 



