Page:A color notation (Munsell).djvu/26

 the initial for both value and vertical. Vertical movement through color may thus be thought of as a change of value, but

not as a change of hue or of chroma. Hues of color are spread around the equator of the sphere. This is a horizontal scale, memorized as H, the initial for both hue and horizontal. Horizontal movement around the color solid is thus thought of as a change of hue, but not of value or of chroma. A line inward from the strong surface hues to the neutral gray axis, traces the graying of each color, which is loss of chroma, and conversely a line beginning with neutral gray at the vertical axis, and becoming more and more colored until it passes outside the sphere, is a scale of chroma, which is memorized as C, the initial both for chroma and centre. Thus the sphere lends its three dimensions to color description, and a color applied anywhere within, without, or on its surface is located and named by its degree of hue, of value, and of chroma.

(26) Color education begins with ability to recognize and name certain hues, such as red, yellow, green, blue, and purple (see paragraphs 182 and 183). Nature presents these hues in union with such varieties of value and chroma that, unless there be some standard of comparison, it is impossible for one person to describe them intelligently to another.

(27) The solar spectrum forms a basis for scientific color analysis, taught in technical schools; but it is quite beyond the comprehension of a child. He needs something more tangible and constantly in view to train his color notions. He needs to handle colors, place them side by side for comparison, imitate them with