566 
BULLETIN OP THE BUREAU OF FISHERIES. 
rise from 4° to its summer temperature. In what proportion is this heat so received 
distributed to the three main thermal regions? 
In order to answer this question the mean temperature of each region must be 
known, and to determine this the reduced thickness of each region must be ascertained. 
Fig. 8. — Distribution of wind-distributed heat in 1910, in Canadice (Cn), Owasco (O), Cayuga (Cy), and Seneca (S) Lakes. 
Depth in meters; heat in gram-calories per square centimeter of surface of the lakes. Diagram extends to 100 meters. The 
curves of Seneca and Cayuga Lakes, from 50 meters to 100 meters, are repeated on a more open scale. (See p. 572.) 
In table xii the column marked “Extent” shows the thickness of each thermal region 
as measured in meters below the surface of the lake; the column marked “R. T.” 
(reduced thickness), shows its thickness as referred to the area of the surface of the lake. 
