616 



THE IRRIGATION AGE. 



forward portion of the fire from the main wings. A part 

 of the crew attacks the forward part and others run down 

 and extinguish the wings. The front of the fire, attacked 

 from the sides, is forced gradually and constantly into a 

 ;.' narrower path. 



Uusually the front can be directed toward some 

 cleared space, road, pond, stream, swamp, or fire line, 

 when it will be checked enough to admit of a direct front 

 attack. Sometimes by this plan the front may be rapidly 

 narrowed by working from the sides, until it is at last en- 

 tirely extinguished. The plan of giving direction to the 

 course of the fire has often been successfully carried out 

 when the fighting crew is too small for a direct attack. 



When fires gain such headway that it is impossible to 

 stop them by direct attack, no matter how numerous and 

 efficient the crew or complete the equipment for fighting, 

 back firing becomes the only means of stopping the fire. 

 It should, however, be used only when it is absolutely 

 necessary. One of the commonest mistakes in fighting 

 fires is to overestimate the rapidity of the fire and the 



wings with the ordinary methods of fighting. It is neces- 

 sary to attack the wings at once, particularly if there is 

 a strong wind, for otherwise each wing of the old fire 

 would soon form an independent fire with a well-developed 

 head. It is necessary, also, that a number of men be sta- 

 tioned where the original fire and the back fire meet in 

 order to extinguish smoldering fires in tops, logs, and 

 other debris. 



Damage by Fires. 



The damage done by forest fires may be discussed 

 under the following heads: 



(1) Death of standing trees, (2) injury to trees that 

 are not killed, (3) injury to the soil, (4) reduction of the 

 rate of growth of the stand, (5) effect on reproduction. 



Crown fires kill outright most of the trees in their 

 paths. In a severe crown fire the foliage of coniferous 

 trees is completely consumed. Hardwood trees in mix- 

 ture are generally so badly scorched that the buds, leaves, 

 and living tissues in other finer parts of the trees are 

 killed, if not consumed, by the heat. Sometimes, however. 



A Favorable Condition for Burning Piled Brush. 



difficulty of putting it out. A forest fire is always a 

 frightening spectacle, particularly if it is sweeping in the 

 direction of one's own property. Men often become ex- 

 cited and start back fires when it is entirely unnecessary. 

 Back firing necessarily involves deliberately burning over 

 property. When this belongs to another person and one's 

 own forest seems in danger, there is a great temptation to 

 sacrifice it. 



If it is found that a back fire is necessary, a favorable 

 point is selected directly in front of the fire, from which 

 to set the new fire. This must be a point where it is safe 

 to start a back fire, such as a road, fire line, stream, or 

 swamp. The leaves are ignited at points five feet to a 

 rod apart for a distance not greater than the estimated 

 width of the head of the fire. These small fires gradually 

 meet and form a continuous line, eating back against the 

 wind. A part of the crew is stationed across the road or 

 other break from which the back fire is started and put out 

 at once the small fires which may result from the sparks 

 blown over from the back fire. 



The meeting of the two fires stops at once the head 

 of the main fire. It is usually possible then to attack the 



where the fire burns somewhat irregularly as, for ex- 

 ample, where there are a good many hardwoods in mixture 

 or the fire is broken by irregularities in topography single 

 trees or groups of trees often escape injury. 



Ground fires, also, usually kill all trees in their way, 

 for although they burn very slowly, they generate a great 

 volume of heat and kill the living tissues of the roots. 

 Sometimes the injury is not apparent above ground, at all, 

 but the trees die and after a time are blown over, because 

 the roots have been killed and weakened. 



Surface fires kill seedlings and young trees with tender 

 bark, but in a great many cases do not kill outright the 

 larger trees. Nevertheless, a very severe surface fire may 

 kill everything in its path, and, not uncommonly, hard- 

 wood forests are entirely destroyed by fires which do not 

 at any time ?ssume the character and proportions of crown 

 fires." 



The presence of dry tops and piles of brush, in the 

 forest constitutes the greatest menace from fires. The 

 severity of a fire, and hence the damage done, is in direct 

 proportion to the amount of dry debris on the ground. 

 Still more serious is the fact that the presence of this 



