378 
Wisconsin Academy of Sciences , Arts, and Letters. 
Plate V. Quantitative curves of heat and density, Mendota. 
The scale of abscissas is the same as in fig. 2. The vertical divisions 
correspond to the RT scale shown in fig. 1. One horizontal space 
equals two calories or 200 density points. One vertical space on 
the scale equals 100. The horizontal lines for this scale are not 
drawn for fear of confusion with the meter lines, which are neces¬ 
sary for platting and measuring. In practice the diagram would 
be drawn on coordinate paper. The area between the line for 4° 
and the curve of temperature or density respectively may be 
measured with a planimeter. The total gain of heat and loss of 
density can be thus determined, and from these results the mean 
temperature and the mean density. 
The area bounded by any two meter-lines, the 4° line, and the 
curve, will give the amount of heat or loss of density in any given 
meter. 
The points are marked on the curves which correspond to mean 
temperature and mean density. 
So far as the temperature curve is concerned, pi. V. corresponds 
to figs. 2 and 3, in my paper on heat budgets. (Birge *15, p. 22, 
23.) 
