Birge—Heat Budgets of American and European Lakes . 179 
The results of Table A may be summarized as follows: 
TABLE 3 
ANNUAL HEAT BUDGETS OF EUROPEAN AND AMERICAN LAKES 
Calories 
European 
American 
Budgets 
Lakes 
Budgets 
Lakes 
Below 20,000 . 
2 
2 
0 
0 
20,000-25,000 . 
18 
10 
0 
0 
25,000-30,000 .. 
22 
14 
0 
0 
30,000-35,000 .. 
17 
8 
9 
2 
35,000-40,000 ... 
10 
6 
12 
5 
40,000-45,000 . 
4 
3 
1 
1 
Above 45,000 . 
3 
3 
0 
0 
76 
23 
22 
6 
This table discloses the following facts: 
1. The European heat budgets are on the whole smaller than 
the American. More than one-third of the whole number are 
below any American budget. Green lake (see Table A) has a 
larger average budget than any European lake except three of 
the giants—Geneva, Ness, and Mjosen. 0wasco lake exceeds 
Green and is only slightly behind the other three. This is espe¬ 
cially significant when we note that these two American lakes 
are shallower, both as regards maximum and mean depth, than 
any European lake recorded in Table A. and that their area is 
much below the average. Only five of the twenty-live European 
lakes are decidedly smaller than Owasco. Yet only three lakes 
besides those already named—lago di Como, Traun-See, Zuger 
See—have even single budgets that exceed Owasco’s largest, or 
indeed, its mean budget. 
It must also be noted that the small average size of the Euro¬ 
pean budgets is due in great measure to the numerous mid- 
European lakes, whose budgets are in general very small. If 
only those lakes were considered which lie south of the Alps or 
north of latitude 55°, the difference in favor of America would 
be much less. 
The larger amount of heat in the American lakes is due chiefly 
