of dark
force, as related to the sky, as that shown in Fig. 4. Plate +25+, while
the sky itself will still, if there are white clouds in it, tell as a
clear dark, throwing out those white clouds in vigorous relief of light;
yet, conduct the experiment of the white paper as already described, and
you will, in all probability, find that the darkest part of the
mountain--its most vigorous nook of almost black-looking shadow--_is
whiter than the paper_.

The figure given represents the _apparent_ color[17] of the top of the
Aiguille Bouchard (the mountain which is seen from the village of
Chamouni, on the other side of the Glacier des Bois), distant, by
Forbes's map, a furlong or two less than four miles in a direct line
from the point of observation. The observation was made on a warm sunny
morning, about eleven o'clock, the sky clear blue; the mountain seen
against it, its shadows grey purple, and its sunlit parts greenish. Then
the darkest part of the mountain was _lighter than pure white paper_,
held upright in full light at the window, parallel to the direction in
which the light entered. And it will thus generally be found impossible
to represent, in any of its _true_ colors, scenery distant more than two
or three miles, in full daylight. The deepest shadows are whiter than
white paper.

Sec. 9. As, however, we pass to nearer objects, true representation
gradually becomes possible;--to what degree is always of course
ascertainable accurately by the same mode of experiment. Bring the edge
of the paper against the thing to be drawn, and on that edge--as
precisely as a lady would match the colors of two pieces of a
dress--match the color of the landscape (with a little opaque white
mixed in the tints you use, so as to render it easy to lighten or darken
them). Take care not to imitate the tint as you believe it to be, but
accurately as it is; so that the colored edge of the paper shall not be
discernible from the color of the landscape. You will then find (if
before inexperienced) that shadows of trees, which you thought were dark
green or black, are pale violets and purples; that lights, which you
thought were green, are intensely yellow, brown, or golden, and most of
them far too bright to be matched at all. When you have got all the
imitable hues truly matched, sketch the masses of the landscape out
completely in those true and ascertained colors; and you will find, to
your amazement, that you have painted it in th