The lack of definiteness which is at present so general in color nomenclature, is due in large measure to the failure to appreciate the fundamental characteristics on which color differences depend. For the physicist, the expression of the wave length of any particular light is in most cases sufficient, but in the great majority of instances where colors are referred to, something more than this and something easier of realization is essential.
The attempt to express color relations by using merely two dimensions, or two definite characteristics, can never lead to a successful system. For this reason alone the system proposed by Mr. Munsell, with its three dimensions of hue, value, and chroma, is a decided step in advance over any previous proposition. By means of these three dimensions it is possible to completely express any particular color, and to differentiate it from colors ordinarily classed as of the same general character.
The expression of the essential characteristics of a color is, however, not all that is necessary. There must be some accurate and not too complicated system for duplicating these characteristics, one which shall not alter with time or place, and which shall be susceptible of easy and accurate redetermination. From the teaching standpoint also a logical and sequential development is absolutely essential. This Mr. Munsell seems to have most successfully accomplished.
In the determination of his relationships he has made use of distinctly scientific methods, and there seems no reason why his suggestions should not lead to an exact and definite system of color essentials. The Munsell photometer, which is briefly referred to, is an instrument of wide range, high precision, and great sensitiveness, and permits the valuations which are necessary in his system to be accurately made. We all appreciate the necessity for some improvement in our ideas of color, and the natural inference is that the training should be begun in early youth. The present system in its modified form possesses elements of simplicity and attractiveness which should appeal to children, and give them almost unconsciously a power of discrimination which would prove of immense value in later life. The possibilities in this system are very great, and it has been a privilege to be allowed during the past few years to keep in touch with its development. Icannot but feel that we have here not only a rational color nomenclature, but also a system of scientific importance and of practical value.
H. E. Clifford.
Massachusetts Institute of Technology,
February, 1905.
Writing from Samoa to Sidney Colvin in London, Stevenson1 says: “Perhaps in the same way it might amuse you to send us any pattern of wall paper that might strike you as cheap, pretty, and suitable for a room in a hot and extremely bright climate. It should be borne in mind that our climate can be extremely dark, too. Our sitting-room is to be in varnished wood. The room I have particularly in mind is a sort of bed and sitting room, pretty large, lit on three sides, and the colour in favour of its proprietor at present is a topazy yellow. But then with what colour to relieve it? For a little work-room of my own at the back I should rather like to see some patterns of unglossy—well, I’ll be hanged if I can describe this red. It’s not Turkish, and it’s not Roman, and it’s not Indian; but it seems to partake of the last two, and yet it can’t be either of them, because it ought to be able to go with vermilion. Ah, what a tangled web we weave! Anyway, with what brains you have left choose me and send me some—many—patterns of the exact shade.”
(1) Where could be found a more delightful cry for some rational way to describe color? He wants “a topazy yellow” and a red that is not Turkish nor Roman nor Indian, but that “seems to partake of the last two, and yet it can’t be either of them.” As a cap to the climax comes his demand for “patterns of the exact shade.” Thus one of the clearest and most forceful writers of English finds himself unable to describe the color he wants. And why? Simply because popular language does not clearly state a single one of the three qualities united in every color, and which must be known before one may even hope to convey his color conceptions to another.
(2) The incongruous and bizarre nature of our present color names must appear to any thoughtful person. Baby blue, peacock blue, Nile green, apple green, lemon yellow, straw yellow, rose pink, heliotrope, royal purple, Magenta, Solferino, plum, and automobile are popular terms, conveying different ideas to different persons and utterly failing to define colors. The terms used for a single hue, such as pea green, sea green, olive green, grass green, sage green, evergreen, invisible green, are not to be trusted in ordering a piece of cloth. They invite mistakes and disappointment. Not only are they inaccurate: they are inappropriate. Can we imagine musical tones called lark, canary, cockatoo, crow, cat, dog, or mouse, because they bear some distant resemblance to the cries of those animals? See paragraph 131.
(3) Music is equipped with a system by which it defines each sound in terms of its pitch, intensify, and duration, without dragging in loose allusions to the endlessly varying sounds of nature. So should color be supplied with an appropriate system, based on the hue, value, and chroma2 of our sensations, and not attempting to describe them by the indefinite and varying colors of natural objects. The system now to be considered portrays the three dimensions of color, and measures each by an appropriate scale. It does not rest upon the whim of an individual, but upon physical measurements made possible by special color apparatus. The results may be tested by any one who comes to the problem with “a clear mind, agood eye, and a fair supply of patience.”
(4) The child gathers flowers, hoards colored beads, chases butterflies, and begs for the gaudiest painted toys. At first his strong color sensations are sufficiently described by the simple terms of red, yellow, green, blue, and purple. But he soon sees that some are light, while others are dark, and later comes to perceive that each hue has many grayer degrees. Now, if he wants to describe a particular red,—such as that of his faded cap,—he is not content to merely call it red, since he is aware of other red objects which are very unlike it. So he gropes for means to define this particular red; and, having no standard of comparison,—no scale by which to estimate,—he hesitatingly says it is a “sort of dull red.”
(5) Thus early is he cramped by the poverty of color language. He has never been given an appropriate word for this color quality, and has to borrow one signifying the opposite of sharp, which belongs to edge tools rather than to colors.
(6) When his older sister refers to the “tone” of her green dress, or speaks of the “key of color” in a picture, he is naturally confused, because tone and key are terms associated in his mind with music. It may not be long before he will hear that “a color note has been pitched too high,” or that a certain artist “paints in a minor key.” All these terms lead to mixed and indefinite ideas, and leave him unequipped for the clear expression of color qualities.
(7) Musical art is not so handicapped. It has an established scale with measured intervals and definite terms. Likewise, coloristic art must establish a scale, measure its intervals, and name its qualities in unmistakable fashion.
(8) It may sound strange to say that color has three dimensions, but it is easily proved by the fact that each of them can be measured. Thus in the case of the boy’s faded cap its redness or HUE3 is determined by one instrument; the amount of light in the red, which is its VALUE,3 is found by another instrument; while still a third instrument determines the purity or CHROMA3 of the red.
The omission of any one of these three qualities leaves us in doubt as to the character of a color, just as truly as the character of this studio would remain undefined if the length were omitted and we described it as 22 feet wide by 14 feet high. The imagination would be free to ascribe any length it chose, from 25 to 100 feet. This length might be differently conceived by every individual who tried to supply the missing factor.
(9) 
To illustrate the tri-dimensional nature of colors. Suppose we peel an orange and divide it in five parts, leaving the sections slightly connected below (Fig.4). Then let us say that all the reds we have ever seen are gathered in one of the sections, all yellows in another, all greens in the third, blues in the fourth, and purples in the fifth. Next we will assort these HUES in each section so that the lightest are near the top, and grade regularly to the darkest near the bottom. Awhite wafer connects all the sections at the top, and a black wafer may be added beneath. See PlateI.
(10) The fruit is then filled with assorted colors, graded from white to black, according to their VALUES, and disposed by their HUES in the five sections. Aslice near the top will uncover light values in all hues, and a slice near the bottom will find dark values in the same hues. Aslice across the middle discloses a circuit of hues all of MIDDLE VALUE; that is, midway between the extremes of white and black.
(11) Two color dimensions are thus shown in the orange, and it remains to exhibit the third, which is called CHROMA, or strength of color. To do this, we have only to take each section in turn, and, without disturbing the values already assorted, shove the grayest in toward the narrow edge, and grade outward to the purest on the surface. Each slice across the fruit still shows the circuit of hues in one uniform value; but the strong chromas are at the outside, while grayer and grayer chromas make a gradation inward to neutral gray at the centre, where all trace of color disappears. The thin edges of all sections unite in a scale of gray from black to white, no matter what hue each contains.
The curved outside of each section shows its particular hue graded from black to white; and, should the section be cut at right angles to the thin edge, it would show the third dimension,—chroma,—for the color is graded evenly from the surface to neutral gray. Apin stuck in at any point traces the third dimension.
(12) 
Having used the familiar structure of the orange as a help in classifying colors, let us substitute a geometric solid, like a sphere,4 and make use of geographical terms. The north pole is white. The south pole is black. The equator is a circuit of middle reds, yellows, greens, blues, and purples. Parallels above the equator describe this circuit in lighter values, and parallels below trace it in darker values. The vertical axis joining black and white is a neutral scale of gray values, while perpendiculars to it (like a pin thrust into the orange) are scales of chroma. Thus our color notions may be brought into an orderly relation by the color sphere. Any color describes its light and strength by its location in the solid or on the surface, and is named by its place in the combined scales of hue, value, and chroma.
(13) Much of the popular misunderstanding of color is caused by ignorance of these three dimensions or by an attempt to make two dimensions do the work of three.
(14) Flat diagrams showing hues and values, but omitting to define chromas, are as incomplete as would be a map of Switzerland with the mountains left out, or a harbor chart without indications of the depth of water. We find by aid of the measuring instruments that pigments are very unequal in this third dimension,—chroma,—producing mountains and valleys on the color sphere, so that, when the color system is worked out in pigments and charted, some colors must be traced well out beyond the spherical surface (paragraphs 125–127). Indeed, aCOLOR TREE5 is needed to display by the unequal levels and lengths of its branches the individuality of pigment colors. But, whatever solid or figure is used to illustrate color relations, it must combine the three scales of hue, value, and chroma, and these definite scales furnish a name for every color based upon its intrinsic qualities, and free from terms purloined in other sensations, or caught from the fluctuating colors of natural objects.
(15) The solar spectrum and rainbow are the most stimulating color experiences with which we are acquainted. Can they be described by this solid system?
(16) The lightest part of the spectrum is a narrow field of greenish yellow, grading into darker red on one side and into darker green upon the other, followed by still darker blue and purple. Upon the sphere the values of these spectral colors trace a path high up on the yellow section, near white, and slanting downward across the red and green sections, which are traversed near the level of the equator, it goes on to cross the blue and purple well down toward black.
(17) This forms an inclined circuit, crossing the equator at opposite points, and suggests the ecliptic or the rings of Saturn (see outside cover). Apale rainbow would describe a slanting circuit nearer white, and a dimmer one would fall within the sphere, while an intensely brilliant spectrum projects far beyond the surface of the sphere, so greatly is the chroma of its hues in excess of the common pigments with which we work out our problems.
(18) At the outset it is well to recognize the place of the spectrum in this system, not only because it is the established basis of scientific study, but especially because the invariable order assumed by its hues is the only stable hint which Nature affords us in her infinite color play.
(19) All our color sensations are included in the color solid. None are left out by its scales of hue, value, and chroma. Indeed, the imagination is led to conceive and locate still purer colors than any we now possess. Such increased degrees of color sensation can be named, and clearly conveyed by symbols to another person as soon as the system is comprehended.
1. Vailima Letters, Oct. 8, 1902.
2. See color variables in Glossary.
3. For definitions of Hue, Value, and Chroma, see paragraphs 20–23.
4. See frontispiece.
5. For description of the Color Tree see paragraphs 33 and34.
The Century Dictionary helps an intelligent study of color by its clear definitions and cross-references to HUE, VALUE, and CHROMA,—leaving no excuse for those who would confuse these three qualities or treat a degree of any quality as the quality itself.
Obscure statements were frequent in text-books before these new definitions appeared. Thus the term “shade” should be applied only to darkened values, and not to hues or chromas. Yet one writer says, “This yellow shades into green,” which is certainly a change of hue, and then speaks of “a brighter shade” in spite of his evident intention to suggest a stronger chroma, which is neither a shade nor brighter luminosity.
Valuevalue-scale