WHY AND HOW SOME FOREST FIRES OCCUR 



THE tremendous forest fires which swept the forests 

 of the northwest during July and August, costing 

 niilhons of dollars to fight and causing damages 

 amounting to many millions of dollars more were due 

 to what ? 



This interesting question is well answered in a letter 

 dated August 2, to American Forestry, by R. II. Rut- 

 ledge, acting district forester of District No. i, which 

 includes the national forest area of northern Idaho and 

 Montana. The fires were due to a dry year, the third in 

 succession. Lightning, railroads, campers and brush burn- 

 ing started most of the 909 discovered on this forest 

 area in July. Almost one-fourth were due to unknown 

 causes, and twenty-seven were incendiary. 



A terrific thunderstorm on July 31 resulted in fifty 

 fires being started by lightning. 



"This is the third dry year in succession for District 



I," says Forester Rutledge. "The snowfall last winter 

 was far below normal and in many localities spring pre- 

 cipitation was insufficient, many places having been with- 

 out rain for over three months. High winds have pre- 

 vailed quite generally for some sixty days and the atmos- 

 phere has been charged with electricity to such an extent 

 that dry electrical storms have been constantly occurring. 

 As a result the forest floor is as dry as a powder-hcuse 

 and because of excessive transpiration the leaves of conif- 

 erous trees have become so combustible as to be almost 

 explosive when subject to ignition. 



"While human agencies have been responsible for 

 some of the fires this season, lightning has been by far 

 the most prolific source of trouble. Dry electrical storms 

 have started a great many fires in the most inaccessible 

 parts of the forests where it has been impossible to get 

 men and equipment on the ground quickly. In numerous 



TWO UNUSUAL FIRE PICTURES SHOWING TREE STRUCK BY LIGHTNING AND ITS SPEEDY DESTRUCTION. 



Live ycHow pine tree. 125 feet high in the Selway National forest, struck 

 by liRhtning about 2.30 in the afternoon. Bolt struck at point indi- 

 cated, followed down tree to a large limb on right hand side of tree at 

 upper edge of flame showing in picture. At that point it entered body of 

 tree, followed down inside, splitting it through and through but did not 

 break it off. 15 or 16 feet below bolt emerged, and continued .down on out- 

 side of tree to ground in 3 distinct paths. Smoke was seen coming out 

 of the split portion of tree shortly alter bolt struck. 



1354 



The second picture shows the split portion of the tree more throughly 

 burned, and at one point will be observed a hole burned through the tree. 

 The tree fell, completely destroyed by fire, twenty-four hours after it 

 was struck. There now remains only a blackened fire scarred trunk 20 

 feet high. Picture presented by Supervisor Fenn, of the Selway National 

 Forest, Montana. 



