% 
The Climate of Peoria. 39 
in June and July each with 4 inches in 10 and 9 days. The precipitation in 
winter is 6.1 in spring 9.7, in summer 11.2, in fall 8.6. This would be favor- 
able when distributed in that way every year; but the single years differ very 
much. In 1856 it was only 22.8, in 1856 51.4. There are some times long 
droughts. From the 29th of August to the 8th of October 1871 there was 
only one rainy day in the middle of September with 0.65 of an inch of rain. 
The longest period without any rain was in 1861 in October and November, 
which lasted 28 days. There was one of 21 days in April and May I[868, of 
20 days in July 1873, of 19 days andthe same in July and August 1869. 
Some times there are long periods of too much rain, for instance in 1858 
from the 29th of April to the 10th of June 15.7 inches in 27 rainy days. 
The quantity of rain is of less importance than the number of rainy days 
and their distribution. The highest number for one month was 18 in May 
1858 and in July 1865; the lowest in September 1871 and February 1877, each 
with qne rainy day. Suppose that 11 inches of rain in 26 days of the three 
summer months be the most beneficial, and that a plus or minus of 2 inches 
and 2 rainy days be of no importance, then we had in the summers of 1862, 
1869 and 1872:a great excess in quantity, viz: 9.1, 7.8 and 10.8 inches surplus, 
and an excess in the number of rainy days in 1865 and 1866, viz: 18 and 7 
surplus. A deficiency in quantity show the years 1870, 1868 and 1865 with 
6.6, 5.8 and 5.6 minus, and in rainy days 1863 and 1856, viz: 12 and 8 minus. 
The most normal summers (in regard to rain) were 1857 and 1871. The great- 
est quantity of rain for one month was measured in May 1858 =10.64; then 
in June 1872 =9.73, and in September 1875 =9.6. 
The mean precipitation of the single months are: December 2.5; January 
1.6; February 2; March 2.7; April-3.2; May 3.8; June4; July 4; Agust 3.2; 
September 3.5; October 2.7; November 2.4. 
HUMIDITY OF THE ATMOSPHERE. 
The relative humidity of the air was computed from the difference of the 
wet and dry thermometer by means of Guyot’s tables. When there is no dif- 
ference, the atmosphere is saturated with moisture and that is noted by 100, 
the greater the difference the lower is the percentage; 20 means very dry and 
there is scarcely ever noted a lower figure. The means of the year is at 7 A. 
M. =81; at 2 P.M. =58; at9 P.M. =—75. The highest mean in January at 
7 A.M. is 89; the lowest in May 2 p.m. 50. | 
The pressure of vapor is the highest in July 9 P.M. =0.669 of an inch; the 
lowest in January 7 A.M. =0.114. The means for the year are 0.316 at 7 A.M., 
0.8388 at 2 P.M. and 0.3840 at 9 P.M. 
CLOUDINESS. 
The cloudiness of the sky is expressed by figures, which mean the percent- 
age of covering, 100 was noted when the sky was entirely covered, 50 when 
half, and so on, and 0 when cloudless. The sky is most covered in December 
in the morning and least in August in the evening. The mean for the year is 
46; the highest for a month has December —55; the lowest August =35. 
SUNSHINE. 
From the amount of cloudiness cannot be deduced the time of sunshine 
during a period; for the sky may be half covered, yet the sun may shine dur- 
ing the whole day. It is necessary to note the time of sunshine every day. 
This was done from December 1859 to November 1868 and the result was that 
we had sunshine 58 per cent. of the time from sunrise to sunset. The sun- 
niest months are June and August, each with 71 per cent. 
