Page:Journal of the Optical Society of America, volume 30, number 12.pdf/6

 576 all appreciate the necessity for improvement in our ideas of color, and “the natural inference is that the training should begin in early youth.” The subtitle of A Color Notation, as published by A. H. Munsell in the “fourth edition, revised and enlarged,” 1916, is “an illustrated system defining all colors and their relations by measured scales of hue, value, and chroma made in solid paint for the accompanying Color Atlas”, the Atlas having been published in full in 1915.

Because they may help in understanding Mr. Munsell's exposition of his system and notation, the following definitions which he gave in A Color Notation are listed. These definitions appear in a glossary which accompanied the first seven editions of the book. This glossary is omitted in the 1936 edition (the definitions that still seemed applicable being incorporated in the text). In his book Mr. Munsell refers all discussion of hue, value, and chroma to these definitions.

Color.—Objectively that quality of a thing or appearance which is perceived by the eye alone, independently of the form of the thing; subjectively, a sensation peculiar to the organ of view, and arising from the optic nerve (p. 108).

Hue.—Specifically and technically, distinctive quality of coloring in an object or on a surface; the respect in which red, yellow, green, blue, etc., differ one from another; that in which colors of equal luminosity and chroma may differ (p. 109).

Value.—In painting and the allied arts, relation of one object, part, or atmospheric plane of a picture to the others, with reference to light and shade, the idea of hue being abstracted (p. 112).

Chroma.—The degree of departure of a color sensation from that of white or gray; the intensity of distinctive hue, color intensity.

Scale.—A graded system, by reference to which the degree, intensity, or quality of a sense perception may be estimated.

The first entry in the A. H. Munsell color diary goes back to 1879: “Studied Rood's —made twirling model of two triangular pyramids. . . .” There is an entry dated 1892 when he and were sketching together in Venice. It says they talked over a "systematic color scheme for painters, so as to determine mentally on some sequence before laying the palette." In 1898 Munsell worked with rotary color mixture, having bought a child's globe for that purpose. It was about this time that the Munsell daylight photometer was built, a cat's eye shutter being used to cut down the amount of light entering the standard side of the instrument. Several of these instruments were built in 1900-1902. From the diary, it is evident that Munsell was quite familiar with the, for there are many references to it during this period. The names of Rood, Bailey, Pickering, Cross (A. K. and C. R.), Clifford, Dolbeare, Ross, Pritchard, Abney, and Bowditch appear during this time, and with most of them he discussed his ideas and to most of them showed his sphere. It was in this early period that asked to have the sphere shown to the Shopkeepers' Association in Boston.

In 1901 Munsell was still wondering whether to base his hue circuit on ten or on three colors. The decimal system was finally decided upon, and five principal hues were then determined by selecting colors which, when they appeared to have equal chroma, with values equal as determined by luminosity readings on the photometer, would spin together in equal proportions to give a neutral gray. As early as 1901 (April 11) he quotes Mr. Filene as saying "The retailers want a standard system fixed at all times—charts with numbers." In 1901 (April 29) appears the first mention of contact with the ; Mr. Munsell wrote to "tasking about color."

By January of 1902 A Color Notation and a Color Atlas were already being discussed and described. In 1903, on November 7, he describes the spinning of disks in the photometer, with value equalized by adjustments in illumination, in order to measure chroma. However, this method was dropped as unsatisfactory, for chroma scales were not finally decided upon until 1912, although charts were painted by visual estimates as early as 1901-02 in his studio by a Mr. Lyon who (evidently) prepared the original charts under Mr. Munsell's direction.

In 1904 Mr. Munsell met and talked with Jay Hambidge and notes that he was struck with points common to investigators of color and design. He lectured before many audiences, a number of them at the Massachusetts Institute of Technology, where during this early period he kept in close touch with Professor C. R. Cross