ould be obtained at once by drawing line _fD_, or 50 feet,
to 16th distance. The other measurements obtained by 8th distance serve
for nearer buildings.

XXXVIII

HOW TO MEASURE LONG DISTANCES SUCH AS A MILE OR UPWARDS

The wonderful effect of distance in Turner's pictures is not to be
achieved by mere measurement, and indeed can only be properly done by
studying Nature and drawing her perspective as she presents it to us. At
the same time it is useful to be able to test and to set out distances
in arranging a composition. This latter, if neglected, often leads to
great difficulties and sometimes to repainting.

To show the method of measuring very long distances we have to work with
a very small scale to the foot, and in Fig. 94 I have divided the base
_AB_ into eleven parts, each part representing 10 feet. First draw _AS_
and _BS_ to point of sight. From _A_ draw _AD_ to 1/4 distance, and we
obtain at 440 on line _BS_ four times the length of _AB_, or 110 feet
x 4 = 440 feet. Again, taking the whole base and drawing a line from _S_
to 8th distance we obtain eight times 110 feet or 880 feet. If now we
use the 16th distance we get sixteen times 110 feet, or 1,760 feet,
one-third of a mile; by repeating this process, but by using the base at
1,760, which is the same length in perspective as _AB_, we obtain 3,520
feet, and then again using the base at 3,520 and proceeding in the same
way we obtain 5,280 feet, or one mile to the archway. The flags show
their heights at their respective distances from the base. By the scale
at the side of the picture, _BO_, we can measure any height above or any
depth below the perspective plane.

[Illustration: Fig. 94.]

_Note_.--This figure (here much reduced) should be drawn large by the
student, so that the numbering, &c., may be made more distinct. Indeed,
many of the other figures should be copied large, and worked out with
care, as lessons in perspective.

XXXIX

FURTHER ILLUSTRATION OF LONG DISTANCES AND EXTENDED VIEWS

An extended view is generally taken from an elevated position, so that
the principal part of the landscape lies beneath the perspective plane,
as already noted, and we shall presently treat of objects and figures on
uneven ground. In the previous figure is shown how we can measure
heights and depths to any extent. But when we turn to a drawing by
Turner, such as the 'View from Richmond Hill', we feel that the only way
to accomplish such