n to 5 
Cayuga, | 
Owascol 
SHaneatjjles 
Green 
Bolsenaj 
Orte. J 
Como J 
Geneva j 
Thun | 
Zu a ! 
Zurich | 
Mil I shaft 
Bo urftefj 
Annecy 
Traun 
Tefiei 
Ness 
Morar 
Lochy 
Katrine J 
Wetterrj 
Ladoga 
40 45 TO 55 60 65 70 75 80 65 90 
-H— 
I i i I • ! 
of th^ * 1 ' -J 11 * * * 8 dia ? r . am shows the annual heat budgets of American and European lakes, expressed in gram calories per square centimeter of the surface 
Thpnin % Each division of the diagram indicates 5,000 cal. per sq. cm. The length of the line for any lake indicates the amount of its annual heat budget. 
Btifi .t the line on the diagram indicates the position of the lake as tropical or temperate. The zero line is drawn at the temperature of 4°. The bud- 
s tr °P lcai lake is shown by a line wholly to the right of the zero line. That of a polar lake, if one were present, would lie wholly to the left of the 
-‘Me lme; that of a temperate lake crosses the line. 
ine win*! htoken line extending the budget lines of Millstatter See and Ammer-See to the left indicates the supposed loss of heat below 4° in these lakes dur- 
eintnncTi r Vv ™ nter observations have been made on them. The broken line extending the budget line of Miosen to the right shows the effect of in- 
dueling in the budgets of that Jake the budget of 1901. See p. 43. 
remraTa S tu era ’ whflre tllere are more than two budgets for a lake, the mean is taken. In those tropical lakes for which several winter temperatures are 
eoraed, the mean is taken for the starting point of the lake line. 
