6. Orange and red-violet give dull mixtures, but redder or less blue than the preceding. ON THE PRINCIPLE OF CONTRAST IN CONNEXION WITH THE PRODUCTION OF TAPESTRY. 351. The tapestry-weaver should therefore thoroughly understand the effects of contrast, to know the influence which the part of the copy he proposes to imitate receives from the colours surrounding it, and so judge what coloured threads 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. _First Example._ 352. If there be two coloured stripes in a picture, one red the other blue, touching each other, the phenomenon of contrast between two contiguous colours would have arisen, had not the painter sustained the red by blue, and the blue stripe by making it red or violet next to the red stripe (320). 353. Suppose a weaver wishing to imitate these two stripes, but ignorant of the law of contrast of colours, after choosing the wools or silks, he is sure to make two stripes, which will produce the phenomenon of contrast; for he will select his wools or silks of only one blue or one red, to imitate two stripes of different colours, each of which appears homogeneous throughout, but which the painter has only succeeded in making so by neutralizing the phenomenon of contrast, which would undoubtedly have resulted had each been painted of a uniform colour. 354. 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 come in contact. Hence the contrast will be more exaggerated than if he had worked the two stripes with homogeneous colours. 355. Suppose a weaver has to copy the series of ten grey stripes in flat tints (fig. 3, Plate 1) described (11), it is evident that if he is ignorant of such effects 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 graduated conformably to what he sees; he will probably also have recourse to lighter and darker tones than those which correspond exactly to the model, and thus he will require a greater number of tones than would have been necessary had he been aware of contrast, rendering the copy an exaggeration of the model.