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 60° 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. +Suggestion of a chromatic score.+ [Illustration: Fig. 21.] (132) The last chapter traced a series of steps leading to the construction of a practical color sphere. Each color was tested by appropriate instruments to assure its degree of hue, value, and chroma, before being placed in position. Then the total sphere was tested to detect any lack of balance.