190 Wisconsin Academy of Sciences, Arts, and Letters. 
in the stratum between 10 m. and 20 m. and therefore in the 
thermocline region. The following zones down to 40 m. more 
than make up the rest, while the wind-distributed heat in Wiirm- 
See between 40 m. and 80 m. is greater than in Cayuga lake 
at the same depths. (See Table 5.) 
These facts show (1). That the agents for distributing heat 
are substantially as effective in /Wurm-See as in Cayuga lake; 
and that the smaller heat budget of the European lake is not 
to be attributed to its smaller size or to less efficient agents for 
the distribution of heat. (2). That the gains of heat in early 
spring are not essentially different in the two lakes. (3). That 
the possibilities of gaining heat become less for the European 
lake as the season advances. (4). That the main difference in 
the temperature and in gain of heat lies in the epilimnion and 
the thermocline. 
