ing drawn in every direction, crossing each other and resolving
themselves into tone effects, suggest atmosphere and the absence of
surface form. This is more often used in the backgrounds of pen and ink
work and is seldom necessary in pencil or chalk drawing, as they are
more concerned with form than atmosphere. Pen and ink is more often used
for elaborate pictorial effects in illustration work, owing to the ease
with which it can be reproduced and printed; and it is here that one
more often finds this muddled quality of line spots being used to fill
up interstices and make the tone even.

Speaking generally, #lines of shading drawn across the forms suggest
softness, lines drawn in curves fulness of form, lines drawn down the
forms hardness, and lines crossing in all directions so that only a
mystery of tone results, atmosphere#. And if these four qualities of
line be used judiciously, a great deal of expressive power is added to
your shading. And, as will be explained in the next chapter, somewhat
the same principle applies to the direction of the swing of the brush in
painting.

Shading lines should never be drawn backwards and forwards from left to
right (scribbled), except possibly where a mystery of shadow is wanted
and the lines are being crossed in every direction; but never when lines
are being used to express form. They are not sufficiently under control,
and also the little extra thickness that occurs at the turn is a
nuisance.

The crossing of lines in shading gives a more opaque look. This is
useful to suggest the opaque appearance of the darker passage that
occurs in that part of a shadow nearest the lights; and it is sometimes
used in the half tones also.

Draughtsmen vary very much in their treatment of hair, and different
qualities of hair require different treatment. The particular beauty of
it that belongs to point drawing is the swing and flow of its lines.
These are especially apparent in the lights. In the shadows the flow of
line often stops, to be replaced by a mystery of shadow. So that a play
of swinging lines alternating with shadow passages, drawn like all the
other shadows with parallel lines not following the form, is often
effective, and suggests the quality of hair in nature. The swinging
lines should vary in thickness along their course, getting darker as
they pass certain parts, and gradating into lighter lines at other parts
according to the effect desired. (See illustration, page