e". 3 Orange threads with 3 Blue threads present a remarkable phenomenon according to the intensity of the light and the position from which they are viewed. The tapestry being placed in a vertical plane opposite incident light, when the warp is horizontal, we perceive blue and orange stripes; but if the warp be vertical, we may then see the upper part of each blue band violet, and its under part, as well as the upper part of each orange band, green, while the rest of each of these latter bands will appear red, bordered on the lower part with yellow. We may also see the upper part of each blue band violet, and its under part, as well as the upper part of each orange band, green, and the rest of each of these bands red, bordered in the lower part with green, and in the upper part with yellow. We say that they may be seen in this manner, because if the light were strong enough for distinct vision, we should not see the horizontal blue and orange bands.

F. Yellow and Violet.

3 Yellow threads with 1 Violet, give a Greyish-Yellow.
2 Yellow threads with 1 Violet, give a Yellow-Grey.
1 Yellow thread with 1 Violet, give a Grey, much
normal grey than the preceding.

nearer

3 Violet threads and 1 Yellow, give a Greyish-Violet.
2 Violet threads and 1 Yellow, give a dull Violet, greyer
than the preceding.

It is remarkable that in observing the mixture of a yellow with a violet thread, at a greater distance than that at which their colours appear neutralised, the yellow is so much weakened in proportion to the violet, that the mixture appears of a dull violet.

Yellow and Blue exhibit an analogous result.

III. RULE.-CONCERNING THE MIXTURE OF THE THREE PRIMARY COLOURS, IN SUCH PROPORTIONS THAT THEY DO NOT BECOME NEUTRALISED, BECAUSE ONE OR THE OTHER OF THEM IS IN EXCESS.

When we unite Blue, Red, and Yellow in such proportions that they do not neutralise each other, the result is a colour much greyer or more broken than if the proportion of Complementary Colours was more equal.

This rule is the result of the first two; but it was indispensable to enounce it, to comprehend all those cases which may be presented in a mixture of coloured threads, relatively to the point of view which occupies us.

For, as Red mixed with a Greenish-Yellow has given a Carmelite mixture, as above mentioned (380. d"), I shall add the following:

(1.) Crimson-Red and Greenish-Yellow, give much duller mixtures, the nearer these colours are being neutralised. A mixture of 1 crimson-red thread with 1 greenish-yellow thread, produces a brick or copper-orange, the tone of which is higher than that of the colours mixed.

(2.) Scarlet-Red and Greenish-Blue, give mixtures which are without vigour or purity, relatively to the corresponding mixtures made with crimson-red and violet-blue.

(3.) Red worked with Blue-Grey, gives Violet mixtures, which are not so dull as the preceding, because the colours contain no yellow.

(4.) The Red of the mixture (3), worked with a GreenGrey, gives mixtures much duller than the preceding, as might have been expected on account of the yellow contained in the green-grey.

(5.) Orange and Blue-Violet, give very dull mixtures.

(6.) Orange and Red-Violet, give dull mixtures; but redder or less blue than the preceding.

CHAPTER III.

ON THE PRINCIPLE OF CONTRAST, IN CONNECTION WITH THE PRODUCTION OF GOBELINS TAPESTRY.

(381) IF it is important to understand the law of contrast when we wish to imitate a given coloured object by painting, as I have previously stated (323. and fol.), it is much more so when we proceed to imitate a model picture in tapestry; for if the picture does not faithfully represent the colours of the model, the artist has on his palette the means of correcting any defect he perceives, since he can without much inconvenience frequently efface and reproduce the same part of his picture. The weaver has not this resource; it is impossible for him to alter his colours without undoing his work, and doing over again entirely the defective part. Now this requires more or less time, always considerable; for tapestry-weaving is exceedingly slow work.

What, then, must the Gobelins weaver do to avoid the defect I have pointed out? Why, he must thoroughly understand the effect of contrast to know the influence which the part of the сору he proposes to imitate receives from the colours surrounding it, and so judge what coloured threads it will be proper for him to choose. The following examples will explain, better than the most profound reasoning, the necessity for the tapestry-worker to possess a knowledge of the law of contrast.

1st EXAMPLE.

(382.) A painter has delineated two coloured stripes in a picture, one red, the other blue. They are in contact, and, consequently, the phenomenon of contrast between two contiguous colours would have arisen, if the painter had not sustained the red contiguous to the blue stripe by blue, and if he had not sustained the blue stripe by making it red or violet next to the red stripe (330.).

A weaver wishes to imitate these two stripes: if he is ignorant of the law of contrast of colours, after choosing the wools or silks for imitating the pattern before him, he is sure to make two stripes which will produce the phenomenon of contrast, because he will have selected his wools or silks of only one blue and one red, to imitate two stripes of different colours, each of which appears to the eye as homogeneous throughout, but which the painter has only succeeded in making so by neutralising the phenomenon of contrast which the stripes would undoubtedly have presented if they had each been painted of a uniform colour.

2nd EXAMPLE.

(383.) Suppose the painter has painted the stripes with uniform colours, then contrast will arise, so that the red contiguous to the blue will appear orange, and the blue contiguous to the red will appear greenish.

If the weaver be ignorant of the law of contrast, in attempting to imitate his model, he will be sure to mix yellow or orange with his red, and yellow or green with his blue, in those parts of the stripes which are in contact. Hence the resulting contrast will be more or less exaggerated than if he had obtained the effect of the painting by working the two stripes with homogeneous colours.

3rd EXAMPLE.

(384.) Suppose a weaver has to copy the series of ten grey bands in flat tints (fig 3. bis.) which was described in our First Part (13.), it is evident that, if he is ignorant of the effect of contrast of contiguous bands, he will exaggerate it in the imitation; for, instead of working ten tints of the same scale, so as to produce ten bands in flat tints, he will make ten bands, each of which will be graduated conformably to what he sees; and it is extremely probable that he will have recourse to lighter and darker tones than those which correspond exactly to the model; consequently, it is very probable that he will want a greater number of tones than would have been necessary had he known of contrast, and it is certain that the copy will be an exaggeration of the model.

4th EXAMPLE.

(385.) When we attentively observe the rosy flesh-tints of a great many pictures, we perceive in the shadows a green tint more or less apparent, resulting from the contrast of rose with grey. (I presume that the painter has made his shadows without using green, and that he has not corrected the effect of contrast by using red.) Now a weaver ignorant of the effect of rose upon grey, in imitating the shaded part will have recourse to a green-grey, which will exaggerate an effect that would have been produced naturally by employing a scale of pure grey (without green).

This example serves to demonstrate that if a painter has himself exaggerated the effects of contrast in his imitation, these effects will be still more exaggerated in the copy made in tapestry if we do not guard against the illusions produced by the causes now mentioned.

(386.) Beside these examples, I shall cite, as a new application of the law of simultaneous contrast of colours to the art of the Gobelins weaver, the explanation of a fact mentioned in the Introduction.

For seventy years, to my knowledge, they have complained at the Gobelins of a want of vigour in the black dyes of the workshops of the royal manufactories, when they were used in making the shadows of draperies, particularly those of blue, indigo, and violet; the facts cited concerning the juxtaposition of black with blue, indigo, and violet (60., 61., 62.), and explained conformably to the law, of the extremely bril liant complementaries of these three colours, modifying the black, in making known the true cause of the phenomenon, have proved that the reproach addressed to the dyer was unfounded, and that the inconvenience of these juxtapositions could only be made to disappear or diminish by the art of the

weaver.

The following observations were made by M. Deyrolle :

From a pattern of a piece of drapery representing a very deep fold, he executed two pieces of tapestry, differing in this-that the one (No. 1) was worked with single tones of the violet scale of wool, while the other (No. 2) was worked with these same tones, but the depth of the fold was made exclusively with black instead of violet-brown wool.