5G 5/5 is their centre of mutual balance. A central plane separates all colors into two contrasted fields. To the right are all warm colors, to the left are all cool colors. Each of these fields is again divided by the plane of the equator into lighter colors above and darker colors below. These four color fields are again subdivided by a transverse plane through 5G5/5 into strong colors in front and weak colors beyond or behind it.
[(142)] Any color group, whose record must all be written to the right of the centre, is warm, because red and yellow are dominant. One to the left of the centre must be cool, because it is dominated by blue. A group written all above the centre must have light in excess, while one written entirely below is dark to excess. Finally, a score written all in front of the centre represents only strong chromas, while one written behind it contains only weak chromas. From this we gather that a balanced composition of color preserves some sort of equilibrium, uniting degrees of warm and cool, of light and dark, and of weak and strong, which is made at once apparent by the dots on the score.
[(143)] A single color, like that of a violet, a rose, or a buttercup, appears as a dot on the score, with a numeral added for its chroma. A parti-colored flower, such as a nasturtium, is shown by two dots with their chromas, and a bunch of red and yellow flowers will give by their dots a color passage, or “silhouette,” whose warmth and lightness is unmistakable.
The chroma of each flower written with the silhouette completes the record. The hues of a beautiful Persian rug, with dark red predominating, or a verdure tapestry, in which green is dominant, or a Japanese print, with blue dominant, will trace upon the score a pattern descriptive of its color qualities. These records, with practice, become as significant to the eye as the musical score. The general character of a color combination is apparent at a glance, while its degrees of chroma are readily joined to fill out the mental image.
[(144)] Such a plan of color notation grows naturally from the spherical system of measured colors. It is hardly to be hoped, in devising a color score, that it should not seem crude at first. But the measures forming the basis of this record can be verified by impartial instruments, and have a permanent value in the general study of color. They also afford some definite data as to personal bias in color estimates.
[(145)] This makes it possible to collect in a convenient form two contrasting and valuable records, one preserving such effects of color as are generally called pleasing, and another of such groups as are found unpleasant to the eye. Out of such material something may be gained, more reliable than the shifting, personal, and contradictory statements about color harmony now prevalent.
[31.] To put this in terms of the spectrum wave lengths, long waves at the red end of the spectrum give the sensation of warmth, while short waves at the violet end cause the sensation of coolness. Midway between these extremes is the wave length of green.