630. A work executed in small prisms of transparent coloured glass, in imitation of painting in chiaro-’scuro, would be a true transparent mosaic. I do not know that such an imitation has ever been executed. All the coloured glass windows which I have spoken of as decorations of Gothic churches, are composed exclusively of small pieces of glass of uniform colour, united by strips of lead or of iron; or altogether of these small pieces of glass, and of glass upon which we have applied with a pencil materials which afterwards have been vitrified: we can only entertain the question of the latter in this article. We may propose two different objects in the production of these windows: either the coloured pieces are altogether secondary in the work, that is to say, occupying a much smaller extent of surface than the others, they do not attain to the perfection of painting,—such is the case with the greater part of the windows of large Gothic churches,—or else these pieces are the principal parts, which, predominating over the others, we attach great importance to the design and to the gradation of tints; such are several windows executed at the Royal Manufactory at Sèvres. The more such works resemble the preceding windows by the effect of their variety, brilliancy, and apposition of colours, the more they attain the object they must essentially fulfil. _Tapestries, Carpets, Mosaics, and Coloured Glass Windows, corresponding to Painting in Flat Tints.—Tapestries with Human Figures._ 631. Although I have advised for tapestry models executed on the system of painting in chiaro-’scuro to resemble painting in flat tints, yet I shall not recommend taking the models entirely according to this latter system. _Tapestry for Furniture._ It is quite otherwise with patterns of tapestry for furniture. I believe that we can make some very beautiful works by copying patterns in flat tints; and that, in the decoration of large apartments, we may obtain an excellent effect from this kind of tapestry. I believe, also, that it would be more suitable for forming part of a general system of decoration, than the kind of tapestry of which I have spoken in the preceding article. Moreover, it is more favourable than the latter to the splendour of the colours. The preceding observations are entirely applicable to the production of carpets. _Mosaics._ 632. Mosaics being composed of more rigid and coherent coloured materials than are employed in the arts which combine coloured materials, I believe that it will be requisite, in judging works of this sort, to consider the power of the materials to resist the effects of friction, water, and atmospheric agents as essential qualities; the colour will follow. _Windows of Coloured Glass._