Thirty- fourth Annual Convention. ^^^ 



90.5 



25.0 



143.1 



24.9 



78.3 



6.7 



85.3 



14.9 



84.2 



12.0 



47.2 



13.3 



508.3 



62.4 



72.0 



20.0 



204.0 



30.0 



51.6 



6.0 



117.0 



18.0 



140.0 



20.0 



43.0 



8.0 



Lawrence 362 



McDonough 574 



McLean 1166 



Marion 570 



Montgomery 702 



Moultrie 354 



Pike 815 



Richland 360 



St. Clair 680 



Sangamon 860 



Tazewell 650 



Whiteside 700 



Winnebago 540 



In twenty-eight Illinois counties in which the detail soil sur- 

 vey has been made 22.6 per cent of the land, as an average, is of 

 such a character that it is subject to serious damage from surface 

 washing. 



Rainfall. 



Illinois lies in the belt of prevailing westerly winds, and 

 much of our rainfall comes in moderate or gentle rains, but dur- 

 ing the summer we occasionally have torrential rains, when a 

 large amount of rain falls in a very short time. During the mod- 

 erate showers or long gentle rains a large proportion of the water 

 that falls soaks into the ground, but in the torrential rains, the 

 soil is unable to absorb so much water in such a short time, and 

 much of it runs off the sloping land. It is not an unusual thing 

 to have two inches or more of rain fall in a few hours. 



The average annual rainfall recorded for the state up to 1902 

 was 37.39 inches. In the northern district the average is 33.48 

 inches, a quarterly distribution of 5.8 inches in winter, 9.4 inches 

 in spring, 10.7 inches in summer and 7.6 inches in autumn. The 

 average rainfall for the central district is 38 inches, the winter 

 rainfall being 7.1 inches, the spring 11.3, the summer 11, and the 

 autumn 8.6 inches. The southern section has an average of 42.19 

 inches, of which 9.1 inches falls in winter, 12.9 in spring, 11 in 

 summer, and 9.2 in the autumn quarter. From this we see that 

 the greatest rainfall is in the spring and summer months, when 

 the soil is in the best condition to absorb water, but in spite of 

 this there is an enormous run-off from the rolling land of the 

 state. 



