108 



Irrigation and Drainage 



Table showing the number of periods, and the mean length of these periods, in each 

 year when the amount of rain is not greater than that given at the head of the 

 respective columns 



1887 



1890 

 1891 



Rainfall 

 of .05 in. 



Rainfall 

 of .1 in. 



Rainfall Rainfall Rainfall Rainfall Rainfall 

 of .5 in. of 1 in. of 1.5 in. of 2 in. of 2.5 in. 





s * 1 * s * 1 * s ' 



22 

 



2.2 o 



P* 



20 7 22 6 



18 



27 5 



21 7 



28 4 

 20 8 



25 6 22 8 15 12 11 15 8 21 6 



20 



16 11 



20 8 



15 12 11 15 



13 15 10 18 



26 



17 10 16 10 H 13 12 

 22 7 26 5 



I' 3 



12 13 11 14 10 18 8 24 



Studying this table, it will be seen that during the eleven 

 years there have been on the average in the growing season 23 

 periods of 5.82 days' duration when the rainfall has not exceeded 

 .05 inches ; there have been 23 periods 6 days long, with a rain- 

 fall of .1 inch ; 19 periods on the average 9 days long, with a 

 rainfall of .5 inch ; 15 periods each year 12 days long, with 1 

 inch ; 12 periods 16 days each, with but 1.5 inches ; 10 periods 

 each season 19 days long, with 2 inches, and 8 periods each 

 season of 25 days each, when the mean rainfall did not exceed 

 2.5 inches. 



If we will now compare the field yields which are produced 

 under these conditions of rainfall, we shall be better able to see 

 how important are the quantity and time distribution of rain. It 



