_Behavior of Forest Fires._ Fires behave differently, once they get started, depending upon the character of the timber, the amount of wind, and the degree of inflammability of the forest cover. Ground fires burn the inflammable dry grass, needles, dead twigs, etc., on the ground; crown fires are much more severe and, being usually fanned by a heavy wind, run through the tops or crowns of the trees; brush fires burn the bushes and dry shrubs from 5 to 10 feet high; timber fires consume the entire forest--crown, stem, ground cover, and undergrowth--and usually occur in timber that stands close together. _Losses by Forest Fires on the National Forests._ The results of forest fires naturally vary with the kind and intensity of the fire. Crown and timber fires do the most damage, and ground and brush fires do less. While the ground fires and brush fires seem to do very little damage to the valuable timber, still they may greatly reduce the productive power of the soil and destroy the watershed cover. Severe ground fires may kill valuable timber by girdling the trees. The great fires of August, 1910, which swept northern Idaho and western Montana destroyed millions of dollars' worth of timber and 85 human lives, and cost the United States $839,000 for fire fighting. These were timber fires and they occurred for the most part in valuable stands of dense timber. The forest fire losses on the National Forests for the last 9 years show a very great and gradual reduction of losses due to forest fires. In 1908, the total loss through fires was $451,188 and in 1909 it was $297,275. In 1910, the year of the great fires in Montana and Idaho, there were very heavy losses in timber and human lives, due to an unusual combination of dry weather and high winds. But in that year the fire organization was not complete; it had never really been tried out. In this year the organization received its first severe test, and while it did the best it could with the available men and equipment, the situation in Idaho pointed out conclusively the weak points and the short-comings. The proof of these statements is found in the statistics of the next 5 years, when the average total loss for 1911 to 1915, inclusive, was $293,000, and, it must be remembered, several of these years were equally as unfavorable, so far as dry weather and high winds were concerned, as the year 1910. During these years, however, the fire fighting organization had a good chance to be tried out thoroughly; for, as is quite evident, experience is the greatest teacher in this kind of work. During the calendar year 1916 the fire losses reached a new low level, compared to other years, the losses amounting to only $198,599. In 1917 they were higher. [Illustration: Figure 35. A forest fire lookout station on the summit of Brokeoff Mountain, elevation 9,500 feet. Lassen National Forest, California. Photo by the author.]