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 102 [Transcribers Note: [Plate XXI]].)
Plate XXI.
STUDY IN RED CHALK
Illustrating a treatment of hair in line-work.
To sum up, in the method of line drawing we are trying to explain (the method employed for most of the drawings by the author in this book) the lines of shading are made parallel in a direction that comes easy to the hand, unless some quality in the form suggests their following other directions. So that when you are in doubt as to what direction they should follow, draw them on the parallel principle. This preserves a unity in your work, and allows the lines drawn in other directions for special reasons to tell expressively.