118 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
Table III is so imperfect that it is of but little value, and moreover it is 
formed of the averages of monthly means of the rainfall of all the 
stations, varying from two or three to twelve or fifteen in a State. As 
new stations are added they may very materially change the average 
from what it would otherwise be. Although a combination of tbis kind, 
of the rain-fall records at different stations over a State or Territory, 
may be valuable as showing the average rain-fall over a State for a 
single year, it is of little or no value, as expressing the variation in 
different years, unless from the same stations. It is given, therefore, 
simply as one means of enabling the reader to form a general idea of the 
rain-fall in the Northwest in the years specified. 
Table No. IV, showing the monthly and annual means of the tempera- 
ture, consists of the average means of all the stations in the State, as 
the preceding, but is more complete aud of more value in the discus- 
sion of the question we are now considering. As will be seen by refer- 
ence to the annual averages it corresponds generally with what has 
already been said in reference to the temperature of 18G6, though not in 
a marked degree. 
The year 18G5, according to this table, appears to have been as warm 
as any, if not the warmest, of the five. But the differences are too slight 
to indicate any law bearing upon the locust problem. An examination 
of the monthly averages also fails to reveal anything worthy of notice 
in this connection unless it be that July as a rule was warmer in 1864 
and 1866 than in the other years. The only fact which can be drawn 
from the table which appears to be of any value in this discussion is 
shown by the following exhibit of the extreme variations in the monthly 
means, and this only because it appears to correspond somewhat with 
what will hereafter be shown in reference to the years 1872-'78. 
Table V. — Extreme variations of monthly mean temperature from 1863 to 1867. 
Months. 
s 
o 
m 

a 
- 
§ 
Iowa. 
e 
00 
a 
00 
03 
00 
a 
a 
M 
03 
M 
09 
Bj 
u 
e 
•a 
09 
to 
03 
u 
3 
< 

o 
o 
o 
' o , 
10.4 
13.8 
19.2 
6.5 
13.9 
12.8 
13.5 
12.5 
11.7 
9.4 
7.9 
11.0 
15.7 
19.9 
12.8 
19.0 
20.3 
17.5- 
5.3 
9.2 
8.0 
8.6 
7.9 
7.8 
12.9 
15.2 
10.8 
14.0 
8.1 
12.2 
5.8 
7.4 
3.6 
6.9 
6.4 
CO- 
7.2 
7.3 
3.7 
7.6 
6.6 
6.5- 
5.4 
7.5 
4.7 
6.C 
2.8 
5.4 
1!.C 
13.9 
13.2 
12.9 
13.8 
13.1 
8.9 
10.1 
9.2 
8.3 
15.2 
10. 3 
8.0 
6.0 
6.2 
8.5 
9.8 
7.7 
9.6 
8.4 
11.9 
13.7 
10.9 
10.9 
January . . 
February. 
March 
April 
May , 
June 
July 
August 
September 
October . . . 
November 
December. 
An inspection of the averages shows that the chief variations are in 
the winter or cold months, from December to March. The variations 
in May and September are somewhat remarkable, and, as will be seen 
hereafter, do not correspond with what is shown by the reports of the^ 
Signal Service Bureau. 
