Color schemes based on Brewster’s mistaken theory.
Runge, of Hamburg (1810), suggested that red, yellow, and blue be placed equidistant around the equator of a sphere, with An image should appear at this position in the text. 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
