PRISMATIC COLOR.
+Pure color is seen in the spectrum of sunlight.+
(87) The strongest sensation of color is gained in a darkened room, with
a prism used to split a beam of sunlight into its various wave lengths.
Through a narrow slit there enters a straight pencil of light which we
are accustomed to think of as _white_, although it is a bundle of
variously colored rays (or waves of ether) whose union and balance is so
perfect that no single ray predominates.
[Illustration: Fig. 13.]
(88) Cover the narrow slit, and we are plunged in darkness. Admit the
beam, and the eye feels a powerful contrast between the spot of light on
the floor and its surrounding darkness. Place a triangular glass prism
near the slit to intercept the beam of white light, and suddenly there
appears on the opposite wall a band of brilliant colors. This delightful
experiment rivets the eye by the beauty and purity of its hues. All
other colors seem weak by comparison.
Their weakness is due to impurity, for all pigments and dyes reflect
portions of hues other than their dominant one, which tend to "gray" and
diminish their chroma.
(89) But prismatic color is pure, or very nearly so, because the shape
of the glass refracts each hue, and separates it by the length of its
ether wave. These waves have been measured, and science can name each
hue by its wave length. Thus a certain red is known as M. 6867, and a
certain green sensation is M. 5269.[21] Without attempting any
scientific analysis of color, let it be said that Sir Isaac Newton made
his series of experiments in 1687, and was privileged to name this color
sequence by seven steps which he called red, orange, yellow, green,
blue, violet, and indigo. Later a scientist named Fraunhofer discovered
fine black lines crossing the solar spectrum, and marked them with
letters of the alphabet from a to h. These with the wave length serve to
locate every hue and define every step in the sequence. Since Newton's
time it has been proved that only three of the spectral hues are
_primary_; viz., a red, a green, and a violet-blue, while their mixture
produces all other gradations. By receiving the spectrum on an opaque
screen with fine slits that fit the red and green waves, so that they
alone pass through, these two primary hues can be received on mirrors
inclined at such an angle as to unite on another screen, where, instead
of red or green, the eye sees only yellow.[22]
[Footnote 21: See Micron in Glossary.]
[Footnote 22: The fact that the spectral union of red and green
makes yellow is a matter of surprise to practical workers in
color who are familiar with the action of pigments, but
unfamiliar with spectrum analysis. Yellow seems to them a
primary and indispensable color, because it cannot be made by
the union of red and green pigments. Another surprise is
awaiting them when they hear that the yellow and blue of the
spectrum make _white_, for all their experience with paints goes
to prove that yellow and blue unite to form green. Attention is
called to this difference between the mixture of colored light
and of colored pigments, not with the idea of explaining it
here, but to emphasize their difference; for in the next chapter
we shall describe the practical making of a color sphere with
pigments, which would be quite impractical, could we have only
the colors of the spectrum to work with. See Appendix to
preceding chapter.]
(90) A similar arrangement of slits and mirrors for the green and
violet-blue proves that they unite to make blue, while a third
experiment shows that the red and violet-blue can unite to make purple.
So yellow, blue-green, and purple are called secondary hues because they
result from the mixture of the three primaries, red, green, and
violet-blue.
In comparing these two color lists, we see that the "indigo" and
"orange" of Sir Isaac Newton have been discarded. Both are indefinite,
and refer to variable products of the vegetable kingdom. Violet is also
borrowed from the same kingdom; and, in order to describe a violet, we
say it is a purple violet or blue violet, as the case may be, just as we
describe an orange as a red orange or a yellow orange. Their color
difference is not expressed by the terms "orange" or "violet," but by
the words "red," "yellow," "blue," or "purple," all of which are true
color names and arouse an unmixed color image.
(91) In the nursery a child learns to use the simple color names red,
yellow, green, blue, and purple. When familiarity with the color sphere
makes him relate them to each other and place them between black and
white by their degree of light and strength, there will be no occasion
to revert to vegetables, animals, minerals, or the ever-varying hues of
sea and sky to express his color sensations.
(92) Another experiment accentuates the difference between spectral and
pigment color. When the spectrum is spread on the screen by the use of a
prism, and a second prism is placed inverted beyond the first, it
regathers the dispersed rays back into their original beam, making a
white spot on the floor. This proves that all the colored rays of light
combine to balance each other in whiteness. But if pigments which are
the closest possible imitation of these hues are united on a painter's
palette, either by the brush or the knife, they _make gray, and not
white_.
(93) This is another illustration of the behavior of pigments, for,
instead of uniting to form white, they form gray, which is a darkened or
impure form of white; and, lest this should be attributed to a chemical
reaction between the various matters that serve as pigments, the
experiment can be carried out without allowing one pigment to touch
another by using Maxwell discs, as will be shown in the next chapter.
(94) Before leaving these prismatic colors, let us study them in the
light of what has already been learned of color dimensions. Not only do
they present different values, but also different chromas. Their values
range from darkness at each end, where red and purple become visible, to
a brightness in the greenish yellow, which is almost white. So on the
color tree described in Chapter II., paragraph 34, yellow has the
highest branch, green is lower, red is below the middle, with blue and
purple lower down, near black.
[Illustration: Fig. 15.]
(95) Then in chroma they range from the powerful stimulation of the red
to the soothing purple, with green occupying an intermediate step. This
is also given on the color tree by the length of its branches.
(96) In Fig. 15 the vertical curve describes the values of the spectrum
as they grade from red through yellow, green, blue, and purple. The
horizontal curve describes the chromas of the spectrum in the same
sequence; while the third curve leaning outward is obtained by uniting
the first two by two planes at right angles to one another, and sums up
the three qualities by a single descriptive line. Now the red and purple
ends are far apart, and science forbids their junction because of their
great difference in wave length. But the mind is prone to unite them in
order to produce the red-purples which we see in clouds at sunset, in
flowers and grapes and the amethyst. Indeed, it has been done
unhesitatingly in most color schemes in order to supply the opposite of
green.
(97) This gives a slanting circuit joining all the branch ends of the
color tree, and has been likened to the rings of Saturn in Chapter I.,
paragraph 17.
+A prismatic color sphere.+
(98) With a little effort of the imagination we can picture a prismatic
color sphere, using only the colors of light. In a cylindrical chamber
is hung a diaphanous ball similar to a huge soap bubble, which can
display color on its surface without obscuring its interior. Then, at
the proper points of the surrounding wall, three pure beams of colored
light are admitted,--one red, another green, and the third violet-blue.
(99) They fall at proper levels on three sides of the sphere, while
their intermediate gradations encircle the sphere with a complete
spectrum plus the needed purple. As they penetrate the sphere, they
unite to balance each other in neutrality. Pure whiteness is at the top,
and, by some imaginary means their light gradually diminishes until they
disappear in darkness below.
(100) This ideal color system is impossible in the present state of our
knowledge and implements. Even were it possible, its immaterial hues
could not serve to dye materials or paint pictures. Pigments are, and
will in all probability continue to be, the practical agents of
coloristic productions, however reluctant the scientist may be to accept
them as the basis of a color system. It is true that they are chemically
impure and imperfectly represent the colors of light. Some of them fade
rapidly and undergo chemical change, as in the notable case of a green
pigment tested by this measured system, which in a few weeks lost four
steps of chroma, gained two steps of value, and swung into a bluer hue.
(101) But the color sphere to be next described is worked out with a few
reliable pigments, mostly natural earths, whose fading is a matter of
years and so slight as to be almost imperceptible. Besides, its
principal hues are preserved in safe keeping by imperishable enamels,
which can be used to correct any tendency of the pigments to distort the
measured intervals of the color sphere.
This meets the most serious objection to a pigment system. Without it a
child has nothing tangible which he can keep in constant view to imitate
and memorize. With it he builds up a mental image of measured relations
that describe every color in nature, including the fleeting hues of the
rainbow, although they appear but for a moment at rare intervals.
Finally, it furnishes a simple notation which records every color
sensation by a letter and two numerals. With the enlargement of his
mental power he will unite these in a comprehensive grasp of the larger
relations of color.
APPENDIX TO CHAPTER IV.
+Children's Color Studies.+
These reproductions of children's work are given as proof that color
charm and good taste may be cultivated from the start.
FIVE MIDDLE HUES are first taught by the use of special crayons, and
later with water colors. They represent the equator of the color sphere
(see Plate I.),--a circle midway between the extremes of color-light and
color-strength,--and are known as MIDDLE RED, MIDDLE YELLOW, MIDDLE
GREEN, MIDDLE BLUE, and MIDDLE PURPLE.
These are starting-points for training the eye to measure regular scales
of Value and Chroma.[23] Only with such a trained judgment is it safe to
undertake the use of strong colors.[24]
[Footnote 23: See Century Dictionary for definition of chroma.
Under the word "color" will be found definitions of Primary,
Complementary, Constants (chroma, luminosity, and hue), and the
Young-Helmholtz theory of color-sensation.]
[Footnote 24: It must not be assumed because so much stress is
laid upon quiet and harmonious color that this system excludes
the more powerful degrees. To do so would forfeit its claim to
completeness. A Color Atlas in preparation displays all known
degrees of pigment color arranged in measured scales of Hue,
Value, and Chroma.]
_Beginners should avoid Strong Color._ Extreme red, yellow, and blue are
discordant. (They "shriek" and "swear." Mark Twain calls Roxana's gown
"a volcanic eruption of infernal splendors.") Yet there are some who
claim that the child craves them, and must have them to produce a
thrill. So also does he crave candies, matches, and the carving-knife.
He covets the trumpet, fire-gong, and bass-drum for their "thrill"; but
who would think them necessary to the musical training of the ear? Like
the blazing bill-board and the circus wagon, they may be suffered
out-of-doors; but such boisterous sounds and color sprees are unfit for
the school-room.
_Quiet Color is the Mark of Good Taste._ Refinement in dress and the
furnishings of the home is attractive, but we shrink from those who are
"loud" in their speech or their clothing. If we wish our children to
become well-bred, is it logical to begin by encouraging barbarous
tastes? Their young minds are very open to suggestion. They quickly
adopt our standards, and the blame must fall upon us if they acquire
crude color habits. Yellow journalism and rag-time tunes will not help
their taste in speech or song, nor will violent hues improve their taste
in matters of color.
_Balance of Color is to be sought._ Artists and decorators are well
aware of a fact that slowly dawns upon the student; namely, that color
harmony is due to the preservation of a subtle balance and impossible by
the use of extremes. This balance of color resides more _within_ the
spherical surface of this system than in the excessive chromas which
project beyond. It is futile to encourage children in efforts to rival
the poppy or buttercup, even with the strongest pigments obtainable.
Their sunlit points give pleasure because they are surrounded and
balanced by blue ether and wide green fields. Were these conditions
reversed, so that the flowers appeared as little spots of blue or green
in great fields of blazing red, orange, and yellow, our pained eyes
would be shut in disgust.
The painter knows that pigments _cannot_ rival the brilliancy of the
buttercup and poppy, enhanced by their surroundings. What is more, he
does not care to attempt it. Nor does the musician wish to imitate the
screech of a siren or the explosion of a gun. These are not subjects for
art. Harmonious sounds are the study of the musician, and tuned colors
are the materials of the colorist. Corot in landscape, and Titian,
Velasquez, and Whistler in figure painting, show us that Nature's
richest effects and most beautiful color are enveloped in an atmosphere
of gray.
_Beauty of Color lies in Tempered Relations._ Music rarely touches the
extreme range of sound, and harmonious color rarely uses the extremes of
color-light or color-strength. Regular scales in the middle register are
first given to train the ear, and so should the eye be first
familiarized with medium degrees of color.
This system provides measured scales, established by special
instruments, and is able to select the middle points of red, yellow,
green, blue, and purple as a basis for comparing and relating all
colors. These five middle colors form a Chromatic Tuning Fork. (See page
70.) It is far better that children should first become familiar with
these tuned color intervals which are harmonious in themselves rather
than begin by blundering among unrelated degrees of harsh and violent
color. Who would think of teaching the musical scale with a piano out
of tune?
_The Tuning of Color cannot be left to Personal Whim._ The wide
discrepancies of red, yellow, and blue, which have been falsely taught
as primary colors, can no more be tuned by a child than the musical
novice can tune his instrument. Each of these hues has three variable
factors (see page 14, paragraph 14), and scientific tests are necessary
to measure and relate their uneven degrees of Hue, Value, and Chroma.
Visual estimates of color, without the help of any standard for
comparison, are continually distorted by doubt, guess-work, and the
fatigue of the eye. Hardly two persons can agree in the intelligible
description of color. Not only do individuals differ, but the same eye
will vary in its estimates from day to day. A frequent assumption that
all strong pigments are equal in chroma, is far from the truth, and
involves beginners in many mishaps. Thus the strongest blue-green,
chromium sesquioxide, is but half the chroma of its red complement, the
sulphuret of mercury. Yet ignorance is constantly leading to their
unbalanced use. Indeed, some are still unaware that they are the
complements of each other.[25]
[Footnote 25: See Appendix to Chapter III.]
It is evident that the fundamental scales of Hue, Value, and Chroma must
be established by scientific measures, not by personal bias. This system
is unique in the possession of such scales, made possible by the
devising of special instruments for the measurement of color, and can
therefore be trusted as a permanent basis for training the color sense.
The examples in Plates II. and III. show how successfully the tuned
crayons, cards, and water colors of this system lead a child to fine
appreciations of color harmony.
PLATE II.
COLOR STUDIES WITH TUNED CRAYONS IN THE LOWER GRADES.
Children have made every example on this plate, with no other material
than the five crayons of middle hue, tempered with gray and black.
A Color Sphere is always kept in the room for reference, and five color
balls to match the five middle hues are placed in the hands of the
youngest pupils. Starting with these middle points in the scales of
Value and Chroma, they learn to estimate rightly all lighter and darker
values, all weaker and stronger chromas, and gradually build up a
disciplined judgment of color.
Each study can be made the basis of many variations by a simple change
of one color element, as suggested in the text.
1. Butterfly. Yellow and black crayon. Vary by using any single
crayon with black.
2. Dish. Red crayon, blue and green crayons for back and foreground.
Vary by using the two opposites of any color chosen for the dish and
omitting the two neighboring colors. See No. 4.
3. Hiawatha's canoe. Yellow crayon, with rim and name in green. Vary
color of canoe, keeping the rim a neighboring color. See No. 4.
4. Color-circle. Gray crayon for centre, and five crayons spaced
equidistant. This gives the invariable order, red, yellow, green,
blue, purple. _Never use all five in a single design._ Either use
a color and its two neighbors or a color and its two opposites. By
mingling touches of any two neighbors, the intermediates are made
and named yellow-red (orange), green-yellow, blue-green, purple-blue
(violet), and red-purple. Abbreviated, the circle reads R, YR, Y,
GY, G, BG, B, PB, P, RP.
5. Rosette. Red cross in centre, green leaves: blue field, black
outline. Vary as in No. 2.
6. Rosette. Green centre and edge of leaves, purple field and black
accents. Vary color of centre, keeping field two colors distant.
7. Plaid. Use any three crayons with black. Vary the trio.
8. Folding screen. Yellow field (lightly applied), green and black
edge. Make lighter and darker values of each color, and arrange in
scales graded from black to white.
9. Rug. Light red field with solid red centre, border pattern and
edges of gray. This is called self-color. Change to each of the
crayons.
10. Rug. Light yellow field and solid centre, with purple and black
in border design. Vary by change of ground, keeping design two
colors distant and darkened with black.
11. Lattice. Yellow with black: alternate green and blue lozenges.
Vary by keeping the lozenges of two neighboring colors, but one
color removed from that of the lattice.
For principles involved in these color groups, see Chapter III.
PLATE III.
COLOR STUDIES WITH TUNED WATER COLORS IN THE UPPER GRADES.
Previous work with measured scales, made by the tuned crayons and tested
by reference to the color sphere, have so trained the color judgment
that children may now be trusted with more flexible material. They have
memorized the equable degrees of color on the equator of the sphere, and
found how lighter colors may balance darker colors, how small areas of
stronger chroma may be balanced by larger masses of weaker chroma, and
in general gained a disciplined color sense. Definite impressions and
clear thinking have taken the place of guess-work and blundering.
Thus, before reaching the secondary school, they are put in possession
of the color faculty by a system and notation similar to that which was
devised centuries ago for the musical sense. No system, however logical,
will produce the artist, but every artist needs some systematic training
at the outset, and this simple method by measured scales is believed to
be the best yet devised.
[Illustration: PLATE 2.
Copyright 1907 by A. H. Munsell]
[Illustration: PLATE 3.
Copyright 1907 by A. H. Munsell]
Each example on this plate may be made the basis of many variants, by
small changes in the color steps, as suggested in the text, and further
elaborated in Chapter VI. Indeed, the studies reproduced on Plates II.
and III. are but a handful among hundreds of pleasing results produced
in a single school.[26]
1. Pattern. Purple and green: the two united and thinned with water
will give the ground. Vary with any other color pair.
2. Pattern. Figure in middle red, with darker blue-green accent.
Ground of middle yellow, grayed with slight addition of the red and
green. Vary with purple in place of blue-green.
3. Japanese teapot. Middle red, with background of lighter yellow
and foreground of grayed middle yellow.
4. Variant on No. 3. Middle yellow, with slight addition of green.
Foreground the same, with more red, and background of middle gray.
5. Group. Background of yellow-red, lighter vase in yellow-green,
and darker vase of green, with slight addition of black. Vary by
inversion of the colors in ground and darker vase.
6. Wall decoration. Frieze pattern made of cat-tails and
leaves,--the leaves of blue-green with black, tails of yellow-red
with black, and ground of the two colors united and thinned with
water. Wall of blue-green, slightly grayed by additions of the two
colors in the frieze. Dado could be a match of the cat-tails
slightly grayer. _See Fig. 23, page 82._
7. Group. Foreground in purple-blue, grayed with black. Vase of
purple-red, and background in lighter yellow-red, grayed.
For analysis of the groups and means of recording them, see Chapter III.
[Footnote 26: The Pope School, Somerville, Mass.]