498 SCIENCE OF HOME AND COMMUNITY 



showing any signs of life and then may break out in an un- 

 expected place even after a heavy rain. 



Causes of fires. The most common cause of forest fires 

 is the railroad locomotive which sends out sparks that 

 readily ignite the dry leaves and grass along the railroad. 

 Other forest fires are caused by burning brush, by lightning, 

 by fires which are started purposely to improve grazing or 

 for other purposes, and by careless campers who fail to com- 

 pletely extinguish a camp fire when leaving it. 



Prevention and control of fires. Most fires are due to care- 

 lessness and can be prevented if proper precautions are 

 taken. In lumbering, proper disposal should be made of 

 the small branches either by piling and burning them or by 

 lopping and scattering the brush, which soon rots. Spark 

 arresters may be placed on locomotives to prevent the sparks 

 from being thrown out, or oil or electricity may be used in 

 place of coal. Fire lanes from which inflammable material 

 has been cleared may be constructed to prevent the spread 

 of fires. In the national forests trails are made so that the 

 rangers may patrol the forests ; lookout points and observa- 

 tion towers are constructed, connected by telephone with the 

 nearest town. 



Putting out fires. Small fires may be controlled by throw- 

 ing dirt on them. In fighting ground fires, a trench must 

 be dug through the forest floor down to the soil. Severe 

 fires may be controlled by back-firing. A second fire is 

 started some distance ahead and allowed to burn against 

 the wind to meet the chief fire. Great care must be taken 

 that the back-fire itself does not spread. This is prevented 

 by starting it to the windward of a road or fire line, or other 

 barrier which the fire can be kept from crossing. 



Destructive lumbering. One oi the chief causes for the 

 decrease of our forests has been the wasteful method of lum- 

 bering. The general policy followed has been to cut down 

 all the growth at one time, securing just one crop and making 



