119. Before proceeding, however, to the subject of tones and
tone-relations, I must speak of a peculiar type of area which is
produced by increasing or diminishing the width of a line. I have
postponed the discussion of measures of width in lines until now.
A line may change its width in certain parts or passages. It may
become wider or narrower as the case may be. The wider it is the more
it is like an area. If it is sufficiently wide, the line ceases to be
a line, and becomes an area. The line may change its width abruptly
or gradually. The effect of the line is by these changes indefinitely
varied. The line of Design is not the line of Geometry.
120. Considerable interest may be given to what I have called Linear
Progressions by changing the width of the line at certain points, in
certain passages, and more or less abruptly. The changes will be like
accents in the line, giving variety and, possibly, an added interest.
[Illustration: Fig. 218]
Let us take this line as the motive of a linear progression. We can
give it a different character, perhaps a more interesting character, by
widening all the vertical passages, as follows:—
[Illustration: Fig. 219]
This is what we get for a motive by widening all the vertical passages.
[Illustration: Fig. 220]
This is what we get for a motive by widening all the horizontal
passages.
[Illustration: Fig. 221]
Compare this Progression, in which I have used the motive of Fig.
219, with that of Fig. 77, p. 47. The accents, which in Fig. 221
occur in every repetition of the motive, might occur only in certain
repetitions, at certain intervals.
[Illustration: Fig. 222]
It is not necessary that the changes in the width of the line be
abrupt, as in the examples just given. The width of the line may
increase or diminish gradually, in which case we may have, not only
accents in the line, but movements due to gradations of dimension,
to convergences, or to an increase or gradual crowding together of
attractions in a series of visual angles.
[Illustration: Fig. 223]
In this case we have a gradual increase followed by a diminution of
the width of the line in certain parts, and these changes occur at
equal intervals. A certain amount of rhythmic movement is given to
the progression by such accents, provided the direction of movement
is unmistakable, which it is not in this case. It is not at all clear
whether the movement is down-to-the-right or up-to-the-left. It seems
to me about as easy to move in one direction as in the other.
[Illustration: Fig. 224]
In this case there is less doubt about the movement. It seems to
be down-to-the-right. The eye is pulled through an increase of
width-measures toward a greater extension and crowding together of
contrasting edges.
[Illustration: Fig. 225]
Substituting outlines for areas in the previous illustration, we are
surprised, perhaps, to find that the movement is reversed. We go
up-to-the-left in this case, not down-to-the-right. The pull of a
greater extension of tone-contrast in a given area was, in Fig. 224,
sufficient to overcome the pull of a less evident convergence in the
other direction.
By increasing or diminishing the width of lines, doing it gradually
or abruptly, we are able to control the movement of the eye to an
indefinite extent. This is one of the important resources of the
designer’s art. Its use is not limited to forms of Linear Progression,
but may be extended to all forms of Design in which lines are used.
[Illustration: Fig. 226]
In this case, for example, the eye follows the direction of
convergences, but we can easily force it to turn and move in the
opposite direction, by widening the lines in that direction, thus
increasing the extent of contrasting edge until it more than
outbalances the convergences; as in the following illustration:—
[Illustration: Fig. 227]