310 NATURE OF CAPITAL AND INCOME [Cmar. XVII 
But it is not necessary to have three separate diagrams. 
It is possible to superimpose one of the first two figures 
upon the other, as shown in Figure 21. In this figure, on 
the same axis XY is drawn first F@, corresponding to Fig- 
ure 18 above, and, secondly, at distances above FG corre- 
sponding to the ordinates in Figure 19, is drawn the line 
MN. This line MN contains an apparent tooth or break 
which does not appear in Figure 19, but this is only for 
the purpose of preserving at this point the preseribed dis- 
tance from the line FG. Considered relatively to FG there 
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Fie. 22. 
is no break. Thus the line MN, measured relatively to 
FG, takes the place of the constituent curve of Figure 19, 
and measured relatively to the base line XY it represents 
the combined curve of Figure 20 for both constituents. 
The same method applies where there are any number of 
constituent capital curves. Thus (Fig. 22), let us draw for 
our first capital curve one which has an income item a, 
and superimpose upon it a second capital curve, of which 
the income item is a’, and so on. The capital curve at 
the top will represent the total of the individual capital 
curves beneath it, and each belt between — namely, the 
difference between any two neighboring capital curves — 
will replace a constituent curve. From the manner of 
their construction it is clear that the income item a’ will 
be carried forward successively to each of the curves above 
it, and will be represented by a tooth in the curve at the