Journal of Agricultural Research 
Vol. XXX, No. 8 
,746 
Total general and special lia¬ 
bility.— Having found the general 
and the special liabilities for the unit 
in the manner described, the total 
liability from all causes is their sum, 
or in the illustration given, $1,528 
plus $2,581.45, or $4,109.45. It will 
be noticed that nowhere in this method 
of rating has any allowance been made 
for variations in the factor of efficiency. 
This appears to be justified for at least 
two reasons. The grouping together 
of the fires on several of the national 
forests and for periods of several 
years in studying the past records 
should have evened out differences in 
efficiency as far as past performance is 
concerned, and in figuring on future 
organizations we should assume these 
differences to grow no greater, and 
probably less. 
LENGTH OF FIRE SEASON 
The cost of maintaining a protective 
organization will be governed partly 
by the length of the period during 
which it must be effective. This of 
course depends upon the length of the 
danger period in the different units. 
The occurrence of general risk fires 
per unit of area (per 1,000,000 acres) 
in the different types and subregions, 
by 10-day periods, is shown in Table 
XIII. If it be assumed that the fire 
season, the period during which the 
protective organization should be effec¬ 
tive, is marked by the period during 
which more than one fire per million 
acres occurs in each 10-day period, 
the fire seasons for the different types 
and regions will be found indicated 
under “Fire danger A” in each section 
of the table. A smaller number of fires 
per 10-day period ought to be handled 
effectively by the regular administrative 
organization, without seriously interfer¬ 
ing with their other work. If the stand¬ 
ard is set at some point greater than one 
per 10 days, it will cut down the fire 
seasons accordingly. (See “Fire dan¬ 
ger B,” Table XIII.) 
Table XIII.— Average number of general risk fires per year , per million acres, by 
10-day periods ° 
REGION 2—WESTERN MONTANA 
Number of fires, by forest types 
Period 
Western 
yellow pine 
Douglas fir 
and larch 
Western 
white pine 
Lodgepole 
pine 
Spruce 
and fir 
Subalpine 
Grass and 
brush 
Anr. 21-30_ 
0 . 2 
Mav 1-10_L _ 
0.1 
| 0.6 
11-20 _ 
0.2 
i .... Y. 
! 
21-31_ 
. 1 
. , ' . ,Ol 
i 
June 1-10_ 
.2 
. 1 
1 
1 
11-20 _ 
.5 
. 2 1 
0.1 
0 . 2 
21-30_ 
1.4 
.8 
. 5 
.2 
.6 
July 1-10_ 
.2 
. 1 
. 2 
.3 
. 6 
11-20 _ 
2. 5 
. 5 
. 3 
0 . 6 
. 2 
1. 3 
21-31__ 
4.1 
2. 5 
. i 
2. 5 
. 6 
. 6 
Aug. 1-10_ 
6.0 
3.1 
3.0 
2.1 
1.3 
1.0 
1.3 
11-20 _ 
8.3 
2.3 
1.2 
1.8 
3. 2 
21-31_ 
6.9 
3.3 
1 . 6 
1. 3 
1.3 
3.2 
Sept. 1-1Q_ 
1 . 6 
. 4 
. 8 
1. 3 
. 6 
11-20 _ 
.9 
. 1 
. 1 
. 6 
21-30_ 
1 . 2 
. 1 
. 6 
Oct. 1-10_ 
. 1 i 
11-20 _ 
. 1 
r ' 
21-31_ 
j 
1 
Nov. l-io._ 
i 
i 1 
11-20 _* 
i i 
21-30_ 
. 1 
1 
Danger periods 
June 21-30; 
July 21- 
Aug. 1-10. 
Aug. 1-31. 
July 21- 
Aug. 1-31. 
July 11-20; 
A b 
July 11- 
Aug. 31. 
Sept. 10. 
Aug. 1-31. 
Sept. 30. 
Danger periods 
July 21- 
Aug. 1-31. 
Aug. 1-10. 
None. 
None. 
None. 
Aug. 11-31. 
B.b 
Aug. 31. 
1 
i 
a Tables were prepared also for Regions 1, 5, 7, 9, 10,11,13,14,15,18, and 20, but are omitted because of 
the rather inadequate data on which they were based. 
b Danger periods A are the periods during which one or more than one fire occurs in 10 days. Danger 
periods B are the periods within which three or more fires occur in 10 days, or two fires or more a week. 
