32 



40 



30 



20 



10 



10 



20 



30 



D 



J 



M 



M 



J 



J 



O 



N 



Fig. I. Temperature curves for Dubuque, Beloit, Keokuk, and Springfield, 

 from December to November, expressed in degrees Fahrenbeit (left) and Centi- 

 grade (right) : A, absolute maximum for Keokuk and Springfield, B, for Du- 

 buque and Beloit ; C, mean maximum for Keokuk and Springfield, D, for Du- 

 buque and Beloit ; E, mean minimum for Keokuk and Springfield, F, for 

 Dubuque and Beloit; G, absolute minimum for Keokuk and Springfield, H, for 

 Dubuque and Beloit. 



