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note, the mind expects to hear one of the harmonics of that note. He was unquestionably right; and if he had said that the mind actually does, in certain cases, hear in imagination the expected note, and is all the more shocked when a wrong note comes, he would have been still more correct. In optics, as we have seen, this mental process is most apparent, any given colour never failing to excite on the retina, and suggest to the mind, a colour which is the harmonious complementary of the one beheld. Thus, in Colour, we have the Law of Sympathy or Harmony made visible in its operation on the mind, while in Sound we have it made most perceptible in the outer world; but I entertain no doubt that its operation in both cases is at once physical and metaphysical, influencing alike the nature without and the nature within. That pressure upon the eye produces spectral colours, and that a sharp blow upon it makes us fancy we see a flash of light, is a fact known to everybody—but, like many another everyday phenomenon, its explanation has a good deal puzzled philosophers. Goethe attempted to explain it by the hypothesis that light resided in the eye, and came forth when thus strikingly appealed to; and Mr Field, taking fundamentally the same view, alleged that the eye secreted light, and thus gave it off. The real solution, as it appears to us, is much simpler than the conjectured ones. All sense of light and colour, as we have said, is produced by ethereal vibrations upon the nerve of the eye; and the explanation of the above phenomenon is, that by pressure or concussion, the optic nerve is set a-vibrating, occasioning a sense of sight in the sensorium and mind. The brain is carefully protected by the hard covering of the skull, but if its particles happen to be set a-vibrating by a sharp dingling blow, the same sense of sight follows, as was recorded, for instance, in the case of the present Emperor of Austria, when violently struck with a poniard in the back part of the head by the Hungarian assassin at Vienna. In truth, all our sensations are produced by a vibratory motion in their respective nerves. The nerves peculiar to each organ, indeed, are susceptible of only one class of impressions—those of the eye, light and colours; those of the ear, sounds; those of the palate and nose, taste and smell. But this is simply owing to the fact that each requires a peculiar kind of matter to set it a-vibrating; and if any one substance sufficed to set all of these various sets of nerves a-vibrating, it would at once produce all their varied phenomena. There is one substance, and but one only, which has this power—namely, electricity; and its action, as is well known, actually does produce in all the organs of sense sensations peculiar to each: in the eye, a flash of light; in the ear, sounds; in the nose, an odour; in the palate, a taste; in the skin, a pricking feeling—all in the same person and at the same moment of time. Several attempts have of late years been made to construct a true science of colour—an important task, which has been long impeded by the unfortunate prevalence of the false theory of Beauty, of which Lord Jeffrey was the cleverest expounder. The most elaborate of those inquirers into the nature of colour are Mr D. R. Hay—the appearance of whose Laws of Harmonious Colouring, more than a quarter of a century ago, first gained public attention to this subject, and who has continued to develop his views in later and more costly works,—and M. Chevreul, Member of the Institute of France, who has likewise directed his able and painstaking mind to this subject. This latter gentleman, who is favourably known for his discoveries in chemical science, was induced to devote his attention to Colour in consequence of his being appointed by his Government to superintend the dyeing department of the royal manufactories at the Gobelins. His work, accordingly, is purely scientific in its character, and by no means inviting to the general reader; but it contains a great deal of valuable matter for those who are employed in work which requires taste in colouring. M. Chevreul's book, in fact, is an account of his researches on what he calls the Simultaneous Contrast of Colours. In his preface he says:—“In endeavouring to discover the cause of the complaints made of the quality of certain pigments prepared in the dyeing laboratory of the Gobelins, I soon satisfied myself that if the complaints of the want of permanence in the light blues, violets, greys, and browns, were well founded, there were others—particularly those of the want of vigour in the blacks employed in making shades in blue and violet draperies —which had no foundation; for, after procuring black-dyed wools from the most celebrated French and other workshops, and perceiving that they had no superiority over those dyed at the Gobelins, I saw that the want of vigour complained of in the blacks was owing to the colour next to them, and was due to the phenomena of the contrast of colours.” What, then, is this law of simultaneous contrast of colours? It is, that when we regard attentively two coloured objects at the same time, neither of them appears of the colour proper to it (that is to say, such as it would appear if viewed separately), but of a tint resulting from the proper colour being tinged by the complementary of the colour of the other object; and that, if the colours of the juxtaposed objects are not of the same tone, the lightest tone will be lowered, and the darkest tone will be heightened.

To explain. We know, from the phenomena of the spectral or “accidental” colours described above, that a red spot tends to diffuse over the surrounding space its complementary colour, green—

That Green tends to diffuse Red

. Orange --- Blue
... Blue --- Orange
... Greenish-yellow Violet
... Violet --- Greenish-yellow
... Indigo --- Orange-yellow
Orange-yellow Indigo.

Accordingly, if we place Red and Yellow side by side, we find that the red, losing yellow, appears bluer; and the yellow, losing red, appears bluer: in other words, the red inclines to purple, and the yellow to green. If we take Red and Blue, the red will incline to orange, and the blue to green. If we take Yellow and Blue, the former will incline to orange, and the latter to violet. The fundamental reason of this phenomenon is, that each colour tends to diffuse its complementary hue over the colour or colours placed next to it. But this tendency is intensified by the physiological fact, that if any of our senses receives a double impression, one of which is vivid and strong but the other feeble, we do not perceive the latter; and that this is particularly the case when they are both of the same kind. For instance, if two knocks are given simultaneously at the opposite ends of a room, one very loud and the other weak, we only hear the strong one. Now, when red and blue are presented to the eye, the strength of the blue renders us insensible to any tinge of that colour which may be in the red, making the red yellower; and so with other colours. Nevertheless, the influence of this law in modifying juxtaposed colours must, we think, be little more than theoretical when compared with the far stronger influence exercised in this matter by the law of complementary colouring.

Having given some examples of the changes of tone produced by the juxtaposition of opposite colours, let us examine the effects of juxtaposition upon colours which are analogous.

1. Take Red, and place it in contact with orange-red, and the former will appear purple, and the latter become more yellow. But if we put the Red in contact with a purple-red, the latter will appear bluer, and the former yellower or orange. So that the same Red will appear purple in the one case, and orange in the other.

2. Take Yellow, and place it beside an orange-yellow-the former will appear greenish, and the latter redder. But if we put the Yellow in contact with a greenish-yellow, the latter will appear greener, and the former more orange. So that the same Yellow will incline to green in the one case, and to orange in the other.

3. Take Blue, and put it in contact with a greenish-blue, L the first will incline to violet, and the second will appear yellower. But put the Blue beside a violet–blue, and the former will incline to green, and the latter will appear redder. So that the same Blue will in one case appear violet, and in the other greenish.

Thus, as M. Chevreul remarks, “the colours which painters term simple or primary—namely, Red, Yellow, and Blue—do, when placed in juxtaposition, pass insensibly to the state of secondary or compound colours. For the same Red becomes either purple or orange according to the colour placed beside it, the same Yellow becomes either orange or green, and the same Blue either green or violet.”

Ignorance of this law of contrast has given rise to many a dispute between drapers and manufacturers. M. Chevreul had several instances of this in his own experience. Certain drapers, he tells us, having given to a calico-printer some cloths of a single colour—red, violet, and blue—upon which they wished black figures to be printed, complained that upon the red cloths he had put green patterns, upon the violet cloths greenish-yellow ones, and upon the blue orange-brown or copper-coloured ones, instead of the black figures which had been ordered. To convince them that they had no ground for complaint, M. Chevreul took the cloths, and surrounded the patterns in such a way as to conceal the ground; upon which the designs appeared as black as could be desired. And still further to convince the malcontent drapers, he placed some cuttings of black cloth upon stuffs coloured red, violet, and blue; whereupon the cuttings appeared of the same hue as the printed designs—i.e., of the colour complementary to the ground; although the same cuttings, when placed upon a white ground, were of a beautiful black. In the models of tapestries for furniture we often err in the same way as these drapers did—namely, by neglecting to preserve a contrast between the ground and the dominant colour of the subjects placed upon it. For instance, if it is a crimson ground,

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