Scott: Lakes of Tippecanoe Basin 



11 



constant. The formula* that I have used is as follows: 



(3A + 21/AB + B) (t^— 1°) 



T = :=z + t°, in which T is average tem- 



(A + l/AB + B) 4 

 perature, V is temperature at upper contour, t° is temperature at 

 lower contour, A is area at upper contour, and B is area at lower 

 contour. As I have stated before, the difference in the results 

 in Birge's method and the one here proposed is slight in lakes with 

 steep slopes and greater in lakes in which the slopes are more 

 gentle. 



The following comparison between Yellow Creek lake and 

 Manitou lake illustrates the point. Yellow Creek has a much 

 steeper slope than Manitou. 



Table II. A Comparison of the Results of Calculating the Average 

 Temperature of Lakes 





Area in 

 Sq.M. 



Average 

 Depth 



Average 

 Temperature 



Wind-distributed 



Heat 



Birge's 

 Method 



Pro- 

 posed 

 Method 



Birge 



Pro- 

 posed 

 Method 



Differ- 

 ence 



Manitou. 



3,265,607 



2.997 



21.48 



21.89 



5238 



5361 



123 



Yellow 

















Creek 



576,785 



10,000 



15.4297 



15.4585 



11429 



11458 



29 



Birge's method is much more rapid and on that account is 

 usually to be preferred. 



The wind-distributed heat of these lakes is very much less 

 than that of the 'Tinger lakes" of New York, where in 1910 

 it varied from 22,800 calories in Keuka to 32,000 calories in Seneca; 

 notwithstanding the fact that more heat per square centimeter 

 strikes the surface of these lakes than is received by the New 

 York lakes. This is due to two factors. First, the spring usually 

 advances more rapidly or rather the changes are likely to be more 

 abrupt in the Indiana lakes than in those of New York, because 

 the climate is more typically continental. This results in an early 



*I am under obligations to Mr. F. G. Tucker for developing this formula for me. 



