482 



yields least plankton. The factors of vegetation of the coarser 

 sort and of tributary waters serve here to modify and overbal- 

 ance light as a controlling factor in production. 



From the data of the TJ. S. Weather Bureau at Springfield, 

 Mr. W. G. Burns, Section Director, has kindly furnished me the 

 records of the number of cloudy days per month in 1894-1899 

 observed at Peoria, Havana, and Springfield. These are given 

 in the accompanying table. The records for Havana have also 

 been plotted on Plates VIII.-XIII. in the uppermost row of 

 squares. 



NUMBER OF CLOUDY DAYS. 

















u 



u 



V- 

























0) 





u 



<L) 









%H 



1-1 





xi 



~- 









-4-J 



X! 



<u 



j-> 



£> 



~^ 



j* 





<D 



> 



3 



c 



3 







P- 



< 





cu 

 a 



3 



^ 



3 

 M 

 3 

 < 



S 



P- 

 <L> 

 C/2 





 







s 



> 

 

 2 



E 







CD 



Q 





 H 



a 





1894 



13 



Li] 8 



12 



19 



5 



9 



7 



9 



9 



1 + 



15 



133 



5 





1895 



II 



7 11 



13 



2 



9 



7 



4 



4 



4 



15 



18 



105 



1 



Springfield 



1896 

 1897 



14 

 16 



12 16 



15! 2 ° 



8 

 17 



9 



4 



9 

 10 



7 



5 



2 

 2 



12 

 1 



7 

 4 



18 

 12 



15 

 21 



129 

 127 



4 





3 





1898 



12 



12' 16 



13 



11 



5 



3 



8 



10 



IS 



9 



12 



126 



1 





1899 



16 



14I 21 



12 



17 



7 



13 



7 



6 



8 



47 



16 



84 



10 

 91 



147 

 767 



6 





Total 



82 



73| 92 



75 



62 



45 



44 



30 



42 







1894 



7 



8 | 7 



6 



4 











3 



3 



6 



10 



7 



61 



1 





1895 



6 



3 i° 



9 



3 



4 



4 



3 



4 



2 



13 



1.3 



74 



3 



Havana 



1896 

 1897 



7 

 10 



6 

 ■ 10 



4 

 17 



3 

 13 



5 



6 



b 

 6 



4 

 



2 

 4 



11 



2 



3 

 4 



10 



12 



9 



70 



2 





15 99 



6 





l8g8 



II 



10 



II 



6 



8 



4 



3 



8 



2 



16 



5 



7 



91 



5 





1899 



7 



6 



16 



4 



5 



3 



5 



3 



3 



6 



10 



7 



75 



4 





Total 

 1894 



48 

 11 



43 

 9 



65 

 6 



4i 

 8 



31 



9 



23 

 



16 



3 



23 



S 



25 

 8 



37 

 6 



60 

 12 



58 

 11 



470 

 88 







1 





1895 



10 



8 



10 



8 



4 



S 



6 



5 



4 



2 



18 



19 



99 



2 



Peoria 



1896 

 1897 



17 



13 



10 



14 



8 

 18 



3 

 16 



6 

 S 



8 

 6 



6 

 1 



2 

 4 



10 

 3 



10 



3 



16 

 15 



14 



no 



4 





19 117 



5 





1898 



IS 



14 



14 



10 



13 



6 



2 



8 



4 



16 



11 



I3'i26 



6 





1899 



12 



12 



i lfc 



10 8 



2 



5 



5 



6 



6 



13 



11 106 3 





Total 



78 



6 



1 72 



5S 1 45 



27 



23 



29 



35 



43 



85 



78 646 1 . . . 



The variations in the relative cloudiness in the three local- 

 ities in many months and in the total number of cloudy days 

 in the several years in the three localities render any correla- 

 tion with production largely conjectural and close comparisons 



