The second requisite is Variety of Line,--not merely variety of
size and direction, but, since each line ought to exhibit a feeling
for the particular texture which it is contributing to express,
variety of character. Mr. Gibson's manner of placing very delicate
gray lines against a series of heavy black strokes exemplifies
some of the possibilities of such variety. Observe, in Fig. 6,
what significance is imparted to the heavy lines on the roof of
the little foreground building by the foil of delicate gray lines
in the sky and surrounding roofs. This conjunction was employed
early by Mr. Herbert Railton, who has made a beautiful use of it
in his quaint architectural subjects. Mr. Railton's technique is
remarkable also for the varied direction of line and its expression
of texture. Note this characteristic in his drawing of buttresses,
Fig. 7.

[Illustration: FIG. 8 B. G. GOODHUE]

[Illustration: FIG. 9 C. D. M.]

[Illustration: FIG. 10 C. D. M.]

[Side note: _Economy of Method_]

The third element of good technique is Economy and Directness of
Method. A tone should not be built up of a lot of meaningless strokes.
Each line ought, sensibly and directly, to contribute to the ultimate
result. The old mechanical process of constructing tones by
cross-hatching is now almost obsolete. It is still employed by
modern pen draughtsmen, but it is only one of many resources, and