A LIMNOLOGICAL STUDY OF THE FINGER LAKES. 569 
smallest of the former year (5,000 calories in Cayuga Lake). This distribution illus- 
trates several principles. 
1. The amount of heat received by the hypolimnion depended on the vicissitudes 
of weather during the early part of the warming period. (See p. 553.) 
2. The lakes of the district were all similarly affected in each year. 
3. In spite of this general similarity there are great individual differences, and 
neither the size nor the depth of the lake seem to be decisive in influencing the amount 
of heat given to the hypolimnion. In 1910 Skaneateles Lake, with a hypolimnion 
72 meters in maximum thickness and 29 meters in mean thickness, received 7,600 
calories. Seneca Lake, with a hypolimnion 168 meters in maximum thickness and 
71 meters in mean thickness, received only 8,800 calories. This was true in spite of 
the fact that Seneca Lake is far larger and its hypolimnion began only 2 meters farther 
from the surface. In 1911 Seneca Lake received less heat in its hypolimnion than 
Skaneateles Lake (3,250 calories and 4,800 calories, respectively); less than Cayuga 
Lake (4,400 calories); and practically the same as Owasco Lake (3,150 calories), the 
smallest and shallowest of the lakes. 
Distribution to the several lo-meter strata . — It will be of interest to consider the 
distribution of heat by the wind to different depths below the surface, as well as its 
distribution to the different thermal regions. This distribution may be expressed in 
two ways: 
1. The heat absorbed by each square centimeter of the surface may be followed 
through the lake and the amount determined which is absorbed by or passed through 
each successive stratum, and the result may be expressed in calories per square centi- 
meter of the surface of the lake. 
2. The boundary planes of the successive strata of the lake become smaller in 
proportion to their distance from the surface. It is possible, therefore, to state not 
merely the number of calories per square centimeter of the lake’s surface which pass 
through any given plane, but also the number of calories which pass through each 
centimeter of the plane itself. 
An example will make this clear. The water of Cayuga Lake absorbed 28,600 
gram-calories through each square centimeter of the surface in 1910; 12,800 calories 
were left in the o-io meter stratum. Thus there remained at 10 meters 15,800 calories 
of those received by each square centimeter of the surface, and this amount was dis- 
tributed to the water below the depth of 10 meters. But the area of the lake at 10 
meters is 72.5 per cent of the surface area, and the number of calories which passed 
through each square centimeter of this plane is correspondingly greater. Through each 
square centimeter of the lo-me ter plane there passed 21,800 calories, or 
