r_, the balance
may be preserved by compensations to the intervals that separate the
colors (see paragraphs 109, 110).

+Unequal color quantities compensated by relations of hue, value,
and chroma.+

(165) Small bits of powerful color can be used to balance large fields
of weak chroma. For instance, a spot of strong reddish purple is
balanced and enhanced by a field of gray-green. So an amethyst pin at
the neck of the girl's dress will appear to advantage with the gown, and
also with the Leghorn straw. But a large field of strong color, such as
a cloth jacket of reddish purple, would be fatal to the measured harmony
we seek.

(166) This use of a small point of strong chroma, if repeated at
intervals, sets up a notion of rhythm; but, in order to be rhythmic,
there must be recurrent emphasis, "a succession of similar units,
combining unlike elements." This quality must not be confused with the
unaccented succession, seen in a measured scale of hue, value, or
chroma.

+Paper masks to isolate color intervals.+

(167) A sheet of paper large enough to hide the color sphere may be
perforated with three or more openings in a straight line, and applied
against the surface, so as to isolate the steps of any sequence which we
wish to study. Thus the sequence given in paragraph 160--Y 8/7, G 6/5,
BG 4/3--may be changed to bring it on the surface of the sphere, when it
reads Y 8/3, G 6/5, BG 5/5. A mask with round holes, spaced so as to
uncover these three spots, relieves the eye from the distraction of
other colors. Keeping the centre spot on green, the mask may be moved so
as to study the effect of changing hue or value of the other two steps
in the sequence.

(168) The sequence is lightened by sliding the whole mask upward, and
darkened by dropping it lower. Then the result of using the same
intervals in another field is easily studied by moving the mask to
another part of the solid.

(169) Change of interval immediately modifies the character of a color
sequence. This is readily shown by having an under-mask, with a long,
continuous slit, and an over-mask whose perforations are arranged in
several rows, each row giving different spaces between the perforations.
In the case of the girl's clothing, the same sequence produces quite a
different effect, if two perforations of the over-mask are brought
nearer to select a lighter yellow-green dress, while the ends of the
sequence remain unchanged. To move the middle perfo