lems we have drawn figures on level planes, which is
easy enough. We have now to represent some above and some below the
perspective plane.

[Illustration: Fig. 98.]

Form scale _bS_, _cS_; mark off distances 20 feet, 40 feet, &c. Suppose
figure _K_ to be 60 feet off. From point at his feet draw horizontal to
meet vertical _On_, which is 60 feet distant. At the point _m_ where
this line meets the vertical, measure height _mn_ equal to width of
scale at that distance, transfer this to _K_, and you have the required
height of the figure in black.

For the figures under the cliff 20 feet below the perspective plane,
form scale _FS_, _GS_, making it the same width as the other, namely
5 feet, and proceed in the usual way to find the height of the figures
on the sands, which are here supposed to be nearly on a level with the
sea, of course making allowance for different heights and various other
things.

XLIII

FURTHER ILLUSTRATION OF THE SIZE OF FIGURES AT DIFFERENT DISTANCES
AND ON UNEVEN GROUND

[Illustration: Fig. 99.]

Let _ab_ be the height of a figure, say 6 feet. First form scale _aS_,
_bS_, the lower line of which, _aS_, is on a level with the base or on
the perspective plane. The figure marked _C_ is close to base, the group
of three is farther off (24 feet), and 6 feet higher up, so we measure
the height on the vanishing scale and also above it. The two girls
carrying fish are still farther off, and about 12 feet below. To tell
how far a figure is away, refer its measurements to the vanishing scale
(see Fig. 96).

XLIV

FIGURES ON A DESCENDING PLANE

In this case (Fig. 100) the same rule applies as in the previous
problem, but as the road on the left is going down hill, the vanishing
point of the inclined plane is below the horizon at point _S'_; _AS_,
_BS_ is the vanishing scale on the level plane; and _A'S'_, _B'S'_, that
on the incline.

Fig. 101. This is an outline of above figure to show the working more
plainly.

Note the wall to the left marked _W_ and the manner in which it appears
to drop at certain intervals, its base corresponding with the inclined
plane, but the upper lines of each division being made level are drawn
to the point of sight, or to their vanishing point on the horizon; it is
important to observe this, as it aids greatly in drawing a road going
down hill.

[Illustration: Fig. 100.]

[Illustration: Fig. 101.]

[Illustration: Fig. 102.]