Colour-Music: The Art of Mobile Color/Chapter 4
CHAPTER IV
THE COLOUR SCALE AND MOBILE COLOUR
COLOUR, like music, is both precious for its own sake and as an educative influence. It also can stimulate the imagination and develop other mental faculties; can give pleasure and refreshment to the mind, and increase the responsiveness of the sense to which it appeals.
Let us, then, begin to clear our path through the jungle of untried possibilities, which prevents our seeing clearly how to use these attributes of colour in a mobile colour art somewhat resembling music.
They are so striking and so significant that, in devising any form of such an art, we can hardly escape from them.
As most of us know, according to generally accepted scientific theory all colours are produced by varying frequencies of vibration of the ether acting upon the retina of the eye, and all musical sounds by varying frequencies of air vibration acting upon the ear. Both colour and sound, as we perceive them, are due to vibrations which stimulate the optic and aural nerves respectively.
This in itself is remarkable as showing the similarity of the action of sound and colour upon us, for within the variations of frequency of these two sets of vibrations are contained all, or nearly all, the impressions we receive of pleasure and pain, beauty or ugliness, interest or dullness, both in colour and sound.
If we go a little farther we shall find a second, and perhaps almost equally remarkable, point of resemblance, though I have no wish to lay undue weight upon it, and if it could be successfully disputed, it would not in the least weaken the position of colour-music as an independent art.
All music is built upon the octave. Western nations have mostly divided it into twelve intervals or notes, and Eastern ones into more; but the octave is and must be the foundation of the division. And it is so because our ears demand it; because we cannot escape from it; and because for some reason of which we have no certain explanation it is in itself an inexorable psychological necessity. No sound with-out vibrations; no musical notes without selection of certain definite rates of vibration carefully related to each other; no such selection possible without reference to the octave. What, then, is the octave, looked at from the musical standpoint?
Take any audible rate of regular air vibrations and you have a musical note. Consider it as the first note of your octave. Double the speed of its vibrations and you have the first note of the next octave above it.
Turning now from sound to colour, what do we find?
If we experiment upon colour with suitable scientific instruments and split up colours of all kinds into their components, we arrive at the fact that all visible colours can be resolved into proportionate mixtures of those we see in the spectrum-band or the rainbow, both of which contain all the primary colours.
White light can be divided into its constituents, as we all know, by passing it through a prism. If we allow a ray of sun-light, or a beam of light obtained from an arc-lamp, to traverse a prism, after passing it through a lens and a narrow slit, and arrange the prism at a proper angle, we shall obtain a series of colours which, if received upon a white screen, spread themselves out into a long band, and range from a deep red to a very tender violet. This is the spectrum-band.
Below the red and beyond the violet are other rays, or other colours, which our eyes cannot see; but confining ourselves to those which are visible, and comparing this band of colours with the musical octave, we shall find at least one very remarkable point of resemblance.
If we get the physicist to measure the speed of the vibrations of the ether at the red and violet end of the band respectively, we shall find that, as in the case of the last note of the musical octave, the latter has approximately double the number of vibrations. The octave of colour is in fact practically complete, and a counterpart of the musical octave as regards the range of vibrations which produce it. It does not extend to the first note of the octave above it, but it constitutes one nearly complete octave in itself.
To make this quite clear let us place the two scales one above the other.[1]
Of course the selection of the note C as a starting-point of comparison is purely arbitrary. All that it is wished to show is that, recognizing the musical octave as the physio-logical basis of music, there is a corresponding octave of colour with its lowest and highest points also separated by a proportionate increase of speed of vibrations.
This is a very remarkable fact, and would seem to point to some common foundation or organic basis in nerve structure, or in mental constitution for receiving both colour and musical impressions. Its significance may, however, easily be exaggerated, and too much stress should not be laid upon it.
It is possible that it is a coincidence, and nothing more, but it suggests, as I have said, that there may be laws connected with the 
Chromatic scale in Music and Colour.
Shewing correspondence of intervals when C = lowest spectrum red.
There is, however, a remarkable and significant point to be noted which tends to carry the analogy a step farther.
Taking the last note of the colour-octave from the spectrum-band, namely, violet, if we examine it carefully we shall see that as it approaches the dark spaces beyond it into which our eyes cannot penetrate, it tends more and more towards becoming purplish before it finally fades into a dark neutral tint. In other words, purple being a mixture of blue and red, it has more and more red in its composition. This suggests as a possibility that if our eyes could see more of the dark rays falling on the screen beyond the blue and violet, we should again receive the impression of red. If so, this would be a repetition of similar notes in a succeeding octave as in music. Sir J. Herschel remarked upon this in the following passage: "I cannot persuade myself that they could fail to recognize a certain redness in the colour of the violet, which Newton appears to have had in view when he regarded the spectrum as a sort of octave of colour, tracing in the repetition of redness in the extreme refrangible rays the commencement of a higher octave too feeble to affect the sight in its inferior tones."
An examination of the red end of the spectrum also, I think, reveals a tendency towards carmine before it fades away into darkness, which means the presence of a small proportion of blue in the red, and perhaps suggests a return to the violet of an invisible octave.
It is of course evident that in the case of the musical scale there are many octaves, but in that of colour we have only one, and one which is not quite complete as to part of its last note. This is, however, from the mobile colour point of view, compensated for by the far greater variety of combinations possible in colour than in sound, and the immensely greater sensitiveness of the eye to minute differences of "pitch" as compared to the ear, as I shall show later.
This brings us to a further resemblance.
As with colour, so with sound; there is a long range of vibrations below and above the first and last visible colour and first and last audible note, of which we are unconscious.
The invisible rays beyond each end of the spectrum-band can be photographed and made evident in other ways, and it is extremely probable that various animals and insects are visually affected by them, though we are not consciously so. Similarly, there are many air vibrations which we cannot hear, but which other creatures are sensitive to, though to us they are beyond each end of the audible musical scale. In both cases it is only a limited range of vibrations that can act upon our senses, which have, as it were, selected this range for their own purposes.
The question now arises as to whether there are discords and harmonies in colour as in music, and what points, if any, of resemblance there are between the action of these respectively upon our senses. This is an important point, because if an art of mobile colour is to be developed and we are to obtain any assistance from the example of the methods of the older art of music, harmony and discord and intermediate stages between them must play a great part in its construction.
All musical compositions depend largely upon the approach to, or the divergence from, what is thoroughly pleasant, namely, harmony or concord, or what is thoroughly painful, namely discord, and even the lightest music is more or less dependent upon this undercurrent of pleasure and pain based upon concord and discord.
Turning from sound to colour, there can of course be no question as to the broad fact of the existence of discords and harmonies of great power and wide range. Everyone realizes this more or less. Most people are pleased by the decoration and furnishing of a room if it is harmonious, and displeased by a glaring discord in a picture or a wall-paper, a dress or an advertisement-board.
Those who have a highly developed colour faculty feel these discords acutely, and those whose colour sense is weak somewhat less, but few are quite unconscious of them.
To appreciate subtle harmonies in colour as in music requires a trained sense, and to reproduce or create any series of refined and beautiful harmonies in either requires an educated and sensitive eye and an artistic mind. In fact, we all admit the existence of discords in speaking of crude colours and vulgar contrasts, and there are certain juxtapositions of colours which almost everyone feels to be painful. And, in referring to contrast, it should, of course, be added that it plays so great a part in the relative pleasantness and unpleasantness of colours, that as soon as any individual colour is placed side by side with another its beauty is either diminished or increased, or altogether destroyed.
Here, then, we again have a characteristic of colour which is extremely like what we find in music, when the simultaneous sounding of two notes each pleasant in itself may produce a discord.
Elaborate experiments have been carried out in Austria and Germany with the object of finding a basis for determining upon scientific grounds which colours should be regarded as beautiful and which as ugly. It has been found that with single and isolated colours there is a certain unanimity of opinion as to the beauty of certain tints, amongst several hundred persons taken at random from all classes and submitted to the same tests; and physiological theories have been put forward by Professor Exner and others to account for this. But he and other investigators all admit that the influence of contrast, both as to tint and as to intensity, overrides all these calculations when they are put into practice.
In other words, all decorative arrangements of colour are dependent for their effect and their beauty upon properly adjusted contrasts and harmonies as in music.
In the latter art, as just pointed out, if we sound a single note, beautiful in timbre and pure in quality, we can instantly make it intolerable by another, also beautiful and pure in itself but discordant when sounded at the same time. And exactly in the same way, a colour exquisite in itself can be made painful to the educated and sensitive eye by placing another beautiful but discordant colour side by side with it. Every artist learns this with the a b c of his professional work.
It cannot, further, for a moment be denied that the ranges of beautiful harmonies in colour, as in music, are almost infinite. Even if we take the harmonies producible by admixture of the various colours of the spectrum in one degree of depth or luminosity, millions of such harmonies are possible. And, when we consider that the eye is capable of appreciating a vast variety of degrees of luminosity of each colour, we see how difficult it is to assign any limits to harmonious sequences of colour; and this applies of course also to discords and partial discords.
We have, therefore, in colour, as in music, both discord and harmony, wide in their scope and mutually dependent. We can in both produce series and sequences of harmonies differing in their degree of pleasantness. We can change them into discords and resolve them again into harmonies, we can, in fact, use colour as we use musical sounds, and we know that, although the physiological laws which govern the effects of both upon us may be obscure, they exist, and in some respects are common to eye and ear.
In music, after centuries of experiment, we have ascertained much more about them than we have as yet succeeded in doing in the case of colour, but the art of colour-music is now enabling us to pursue the subject much farther than has ever been possible before, as will be shown later on.
Passing on from this broad statement as to the general analogy, the next question may well be whether there is any close resemblance in detail between the musical scale and the spectrum-band in respect of harmony and discord—whether we can divide the range of visible colour into intervals like those of the notes of the octave, and whether, having done so, we shall find the same relative discords and harmonies.
There are great difficulties in making this comparison, as we shall see, but we may begin by pointing out one remarkable and perhaps significant resemblance.
If we strike the first note of the musical octave—say the middle C of the pianoforte, and also the last note, the seventh—we have a peculiarly disagreeable combination of sounds, a discord in the strongest sense of the word.
If we take a patch of red from the red end of the spectrum and place it side by side with a patch of blue-violet, we also have for most people a most unpleasant and crude contrast—a discord in colour for the educated eye—and if we combine the red and the blue, we obtain a compound colour which, by fairly general consent, is a disagreeable one—namely magenta.
This, again, seems to point to some underlying physiological law of sensation common to the organs of seeing and hearing, or to some laws governing the mental impressions received through them; but when we try to go farther we are met by various difficulties, some of them so considerable as to lead many to doubt whether there is any parallel here.
Let us go into these difficulties a little more carefully.
In the first place, as has already been said, the construction of the musical octave is somewhat arbitrary. An octave has been generally agreed upon as consisting of seven whole tones and five half-tones—seven white keys and five black keys on the pianoforte.[2]
All modern European music has been composed in conformity to this scale or to others very closely resembling it, but we must not forget that it is an arbitrary one. The Greeks had a different division in classic times, and some of the Oriental nations have another very divergent one to this day.
From time to time new and more accurately divided scales have also been introduced, but as they would have rendered obsolete all previously written music, none of them, so far, have found favour with the modern musical world. Amongst these may be mentioned the harmonic scale of Baillie-Hamilton.
If, then, we were to apply the ordinary division of tones to the colour-band, dividing it into similar intervals according to rates of vibration, we should be applying an arbitrarily constructed scale. We should have, moreover, to decide what musical note to take as the first note of our scale to correspond with the lowest tint of red of the spectrum-band.
Let us suppose that we take the middle C. We have then introduced two arbitrary conditions. First, the method of division of our octave; secondly, its starting-point.
In drawing any deductions as to the extent of the direct analogy between the two scales of sound and colour, we must bear this in mind and remember that it can scarcely be positively asserted that an analogy holds good or that it fails.
Further than this the colour sense has been so little educated as an æsthetic faculty as compared with the high cultivation of the musical one through past centuries that, although there is, perhaps, a general agreement as to certain pronounced discords, in colour though even that is open to question—there is not the same general sensitiveness amongst most people as to lesser ones. Hence, although there may be a general agreement as to the discord between the juxtaposition of the colours at the beginning and end of the spectrum-band, there will be less unanimity as to whether intermediate combinations are discordant, even supposing we have divided our colour scale correctly and started it from the right point. Opinion as to what constitutes a discord in music is, moreover, undergoing a change and becoming less definite in its pronouncement, as is evidenced by some advanced modern music.
This portion of the general analogy is purely a question of opinion or of psychological investigation, and it is of little importance as affecting the main theory and practice of colour-music. In the earlier days of my experimental work, I was perhaps inclined to think it of more value as a working hypothesis in the construction of some of my instruments than I do at present, and there is, no doubt, a certain fascination about its mysterious possibilities; but I cannot too clearly guard myself from being understood to lay any great stress upon the probability of its existence. Some physicists consider that there is no evidence to support the contention, others are in favour of it; but it is really a question for the psychologist.
If it could be shown without possibility of dispute that similarly divided scales of colour and musical sounds have insufficient features in common to establish any emotional analogy whatever based upon numerical division, the general theory and the main advantages of colour-music as an art and as a mode of experimental research would remain unaffected, and the force of the chief arguments, which can be advanced in support of it as a separate and distinct art, would not be weakened in the least. The question of a possible analogy between the two scales is an interesting one, but how far it holds good is relatively not of very much importance.