Climate of Middle Illinois. 



25 



How great the influence of insolation must be upon the growth of 

 plants is shown by the difference of the thermometer in the shade and 

 exposed to the sun, which, in June, often exceeds 20 degrees and more yet 

 in winter. 



December 



January 



February 



March 



April 



May 



June 



J uly 



August 



September 



October 



November 



Winter 



Spring 



Summer 



Fall 



Year 



peK cent, of covering. 



7 A.M. 



59 

 57 

 52 

 53 

 51 

 45 

 44 

 87 

 37 

 44 

 47 

 55 



56 

 4!) 

 39 



48 



48 



54 

 56 

 55 

 56 

 57 

 50 

 48 

 47 

 45 

 45 

 46 

 56 



55 

 54 

 47 

 49 



51 



9p.«. 



53 

 48 

 49 

 49 

 45 

 35 

 32 

 29 

 27 

 31 

 35 

 49 



50 

 43 

 29 

 39 



40 



Mean. 



55 

 54 

 52 

 52 

 51 

 43 

 41 

 38 

 35 

 40 

 43 

 53 



54 

 49 

 38 

 45 



47 



NUMBMR OF DAYS 



Cloud- 

 less. 



4 

 4 

 3 

 3 

 2 

 3 

 2 

 2 



4 

 4 

 6 

 8 



11 



8 



7 



13 



39 



Moder- 

 ately 

 cloudy. 



10 

 10 

 11 

 12 

 11 

 13 

 16 

 18 

 18 

 14 

 12 

 10 



31 

 87 

 52 

 36 



156 



Very 

 cloudy. 



17 

 17 

 14 

 16 

 16 

 15 

 12 



n 



10 

 12 

 13 

 17 



48 

 47 

 33 

 42 



170 



With- 

 out sun 

 shine. 



10 

 9 

 7 

 6 

 5 

 3 

 1 

 1 

 1 

 2 

 5 



26 



14 



3 



16 



59 



SUNSHINE. 



Hours. 



129 

 133 

 149 

 182 

 192 

 269 

 315 

 314 

 299 

 216 

 202 

 148 



411 

 643 

 929 

 566 



2550 



per ct. 



45 

 46 

 51 

 50 

 49 

 61 

 71 

 69 

 71 

 58 

 59 

 51 



48 

 53 

 70 

 56 



58 



WIND. 



West winds are prevalent from October to April. South winds dur- 

 ing the summer; only in August east equals the south. About 12 p. m. 

 of all the observations are marked as high winds, gales or hurricanes, but 

 the force of winds were not measured by the anemometer but only esti- 

 mated, and the dates are not quite reliable. 



The windiest months are March and April; the calroest, August and 

 September. 



Wind and temperature, wind and cloudiness, wind and precipitation 

 are, in a certain degree, correlative. The warmest winds are south, south- 

 west and east; the coldest, northwest, north and northeast. The difference 

 between the coldest and warmest winds is about 15, in spring even 20 de- 

 grees. Above the average is the temperature with south and southwest 

 in all the months, with east only in spring and fall. Southeast wind is 

 too scarce, so that no reliable mean could be abstracted. The temperature 

 of north is always below. Northeast is only in November, December and 

 January above, and that may be accounted for by the great quantity of 

 cloudiness that always accompanies these winds, preventing radiation. 

 Northwest has only, in August, a temperature above average. The region 

 from which this wind come is naturally a cold one, only during the sum- 

 4 



