A LIMNOLOGICAL STUDY OF THE FINGER LAKES. 
561 
The table shows a surprising agreement of the heat budgets of the four lakes com- 
pared in 1910. The difference between the highest and the lowest result is only 1,000 
calories, or less than the heat which may be furnished to the surface of the lake on a 
bright summer’s day. The agreement in 1911 is nearly as cLse, with the exception of 
Skaneateles Lake, and the temperature of that lake was taken at some distance to the 
north of the center and may possibly be too high, though this result does not appear 
in the comparisons for 1912. (See also p. 565.) It would be expected that individual 
variations much greater than 1,000 calories would occur, since both the maximum and 
minimum temperatures must vary, and if in any individual case a high maximum and 
a low minimum came in the same season very considerable differences in the heat 
budget might be present. 
The table also shows that the heat budget of successive years is strikingly similar 
in the case of the same lake. This is especially noticeable in the case of Owasco Lake. 
It also appears that the heat budget is independent of the depths of the lakes, and also 
of their other dimensions within the limits of the lakes compared. 
The table seems, therefore, to warrant the following conclusions: 
1. The annual heat budget of the major New York lakes lies, in general, between 
35,000 and 40,000 gram-calories per square centimeter of surface. It may fall below 
the minimum or rise above the maximum stated, but in general the figures will fall 
between these numbers. 
2. For lakes of the form and size of these the heat budget is apparently independent 
of surface dimensions between the limits of 16 and 60 kilometers of length, and is inde- 
pendent of depth between the limits of 30 and 90 meters mean depth. It is probable 
that a lake much shallower than 30 meters would have a smaller heat budget, but a 
greater depth than 90 meters would produce no effect. 
3. Green Lake, Wis., shows results constantly lower than the New York lakes. 
This is due rather to a high winter minimum than to a low summer maximum. It 
seems right, therefore, to place this lake in the same general class as the others and to 
state the following law: 
Inland lakes of the first class include those whose area and depth are such as to 
permit the maximum annual heat budget possible under the weather conditions of the 
season. Such a budget for lakes in the climatic and topographical conditions of the 
eastern United States ordinarily equals or exceeds 30,000 gram-calories per square 
centimeter of the lake’s surface, and ordinarily lies between 30,000 and 40,000 gram- 
calories. Such lakes, under the conditions stated, will be 10 kilometers or more in 
length and will have a mean depth of 30 meters or more. 
This statement applies to lakes of simple outline whose length is five or more times 
their mean breadth. Lakes of irregular outline can not be compared with those of simple 
shape, and lakes whose proportions are essentially different from those given are not 
present in this region in sufficient numbers for study. 
4. It is obvious that for more accurate results a careful study of the temperatures 
of these lakes must be made, so that a mean temperature curve can be determined for 
each lake and compared with the temperature of the air and with the heat derived from 
