Apr. 15, 1925 
Use of Liability Ratings in Forest Fire Protection 
703 
respectively. Curves were then drawn 
on the basis of these points, showing the 
average size that fires may be expected 
to attain for different elapsed periods. 
(See figs. 4 to 18.) 
RELATION BETWEEN SIZE OF FIRES 
AND COSTS OF SUPPRESSION 
In organizing the suppression work, 
it is important to know the relation 
between the speed of attack, which is 
determined by the intensity of the 
protective organization, and the cost of 
putting out fires that may occur. The 
cost of suppression depends more 
directly on the size of the fire than on 
the speed of attack, though the latter 
has much to do with determining the 
size of fire. Accordingly, the fires were 
grouped by area classes—less than one 
acre, one to two acres, etc.—and the 
average areas and average suppression 
costs of fires within each group were 
then plotted on cross-section paper, as 
abscissae and ordinates, respectively. 
From the curves based on these points 
it is possible to determine the probable 
average suppression cost for fires of 
any given size, and from these curves 
and those of size based on elapsed time, 
the suppression cost according to speed 
of attack can be ascertained (Table VI 
and figs. 19 to 36). 
© Lodge pol e (l50 f i res) 
xDouglas fir (47 i» ) Fig. 4— Northern Rocky Mountains (Regions 1, 9, and 10): 
t Alpine (20 ) Relation of size of fire to time elapsed between discovery and 
* Grass ^Sage(i79n ) attack 
0Spruce ill ” ) 
• Brush (l4 ” ) 
