hs the first may be called that of a Luminist, or painter
like Rembrandt, whose canvases present great contrasts of light and
shade, while the second is that of the Colorist, such as Titian, whose
work shows great fulness of hues without the violent extremes of white
and black.

+Total balance of the sphere tested by rotation on any desired axis.+

(122) Not only does the mount of the color sphere permit its rotation on
the vertical axis (white-black), but it is so hung that it may be spun
on the ends of any desired axis, as, for instance, that joining our
first color pair, red and blue-green. With this pair as poles of
rotation, a new equator is traced through all the values of purple on
one side and of green-yellow on the other, which the rotation test melts
in a perfect balance of middle gray, proving the correctness of these
values. In the same way it may be hung and tested on successive axes,
until the total balance of the entire spherical series is proved.

(123) But this color system does not cease with the colors spread on the
surface of a globe.[30] The first illustration of an orange filled with
color was chosen for the purpose of stimulating the imagination to
follow a surface color inward to the neutral axis by regular decrease of
chroma. A slice at any level of the solid, as at value 8 (Fig. 10),
shows each hue of that level passing by even steps of increasing
grayness to the neutral gray N8 of the axis. In the case of red at this
level, it is easily described by the notation R 8/3, R 8/2, R 8/1, of
which the initial and upper numerals do not change, but the lower
numeral traces loss of chroma by 3, 2, and 1 to the neutral axis.

[Footnote 30: No color is excluded from this system, but the
excess and inequalities of pigment chroma are traced in the
Color Atlas.]

(124) And there are stronger chromas of red outside the surface, which
can be written R 8/4, R 8/5, R 8/6, etc. Indeed, our color measurements
discover such differences of chroma in the various pigments used, that
the color tree referred to in paragraphs 34, 35, is necessary to bring
before the eye their maximum chromas, most of which are well outside the
spherical shell and at various levels of value. One way to describe the
color sphere is to suggest that a color tree, the intervals between
whose irregular branches are filled with appropriate color, can be
placed in a turning lathe and turned down until the color maxima are
rem