920 JOURNAL OF FORESTRY 



The relative average sizes of all fires on the various aspects vary 

 greatly, south slops having the largest and level the lowest. 



In Table 2 is also given the average size of all fires on degree of 

 slope alone. Roughly, those on gentle slopes are 2^/4 times as large as 

 on level land; on medium slopes nearly twice as great as on gentle; 

 on steep, twice as great as on medium. The data for precipitous slopes 

 are very fragmentary and unsatisfactory, only a few fires having been 

 recorded as on such situations. 



If the data in Table 2 be platted on degree of slope corresponding to 

 the percentages used, and curved, it will be found that the curves 

 have a slight upward trend, in the same ratio that percentage of slope 

 per degree increases with increase in steepness of slope. 



The relations so far discussed are, obviously, very general, and if 

 the data were available it would certainly be profitable to express rate 

 of spread on the basis of forest type instead of aspect. That unques- 

 tionably is the manner in which rate of spread will finally be worked 

 out, but at present our data on occurrence of fires are not sufficiently 

 well tied in to timber type to permit of such a division. All that this 

 study claims is an expression of the general relations between aspect 

 and degree of slope and rate of spread. 



It is clear enough that on a north slope at low elevatioii, yellow 

 pine type, rate of spread will be greater than on a south slope, high 

 elevation, in red fir type. At present, however, with no further 

 apologies, the data are presented for what they may be worth. 



Work at present under way will establish relative rates of spread in 

 the different timber types in the State. 



SEASONABLE DIFFERENCES IN OCCURENCE OF FIRES 



Table 3 shows the relative seasonal importance of fires on diflferent 

 aspects. In deriving these figures the total number of fires in a given 

 month is taken as 100 per cent, and the percentage occurring on each 

 aspect was compiled with this as a basis. It is seen that the figures 

 for south slopes are high in May and June, low in July and August 

 and rise again through September, October and November. The 

 figures for east and west slopes are, generally speaking, practically 

 constant throughout the season, while those for the level land show 

 a general tendency to be high in the early part of the season and 

 low at the end. Relative percentage on north slopes rises from May 

 to August and then drops to end of season. 



