y systematic color description.

APPENDIX TO CHAPTER V.

+Color schemes based on Brewster's mistaken theory.+

[Illustration]

Runge, of Hamburg (1810), suggested that red, yellow, and blue be placed
equidistant around the equator of a sphere, with white and black at
opposite poles. As the yellow was very light and the blue very dark, any
coherency in the value scales of red, yellow, and blue was impossible.

Chevreul, of Paris (1861), seeking uniform color scales for his workmen
at the Gobelins, devised a hollow cylinder built up of ten color
circles. The upper circle had red, yellow, and blue spaced equidistant,
and, as in Runge's solid, yellow was very light and blue very dark. Each
circle was then made "one-tenth" darker than the next above, until black
was reached at the base. Although each circle was supposed to lie
horizontally, only the black lowest circle presents a level of uniform
values.

Yellow values increase their luminosity thrice as fast as purple values,
so that each circle should tilt at an increasing angle, and the upper
circle of strongest colors be inclined at 60deg. to the black base.
Besides this fault shared with Runge's sphere, it falls into another
by not diminishing the size of the lower circles where added black
diminishes the chroma.

Desire to make colors fit a chosen contour, and the absence of measuring
instruments, cause these schemes to ignore the facts of color relation.
Like ancient maps made to satisfy a conqueror, they amuse by their
distortion.

Brewster's mistaken theory underlies these schemes, as is also the case
with Froebel's gifts, whose color balls continue to give wrong notions
at the very threshold of color education. As pointed out in the Appendix
to Chapter III., the "red-yellow-blue" theory inevitably spreads the
warm field of yellow-red too far, and contracts the blue field, so that
balance of color is rendered impossible, as illustrated in the gaudy
chromo and flaming bill-board.

These schemes are criticised by Rood as "not only in the main arbitrary,
but also vague"; and, although Chevreul's charts were published by the
government in most elaborate form, their usefulness is small. Interest
in the growth of the present system, because of its measured character,
led Professor Rood to give assistance in the tests, and at his request a
color sphere was made for the Physical Cabinet at Columbia.

CHAPTER VI.

COLOR NOTATION.

+Suggestio