380 Wisconsin Academy of Sciences , Arts, and Letters. 
Plate VI. Diagram of work, lake Mendota, Aug. 1910. This 
diagram corresponds to the calories and loss of density shown in 
pi. V and table 1. In this diagram the horizontal lines represent 
the meters, and the distances between them represent the values of 
RTXZ. The scale is placed beside the diagram and lines for it 
are not drawn, so as to avoid confusion. In a working diagram 
coordinate paper would be used. One space on the vertical scale 
equals 50,000 g. cm. One space on the horizontal scale equals 
0.0004. The values of 1-D are platted on the meter-lines. The 
area enclosed by the density curve may be measured with a plani- 
meter, and the value of W ascertained. The result will be given in 
g. cm. per sq. cm. of the surface of the lake. By similar measure¬ 
ment the value of W for any single meter may be ascertained. 
The broken line representing 1 -D may be replaced by a smooth 
curve if this is thought advisable. 
