In monochrome representation the eye has to deal only with one mode of perception—that of form. The perception of colour depends upon the differentiation of the effect upon the optical nerve fibres, that of form on the numbers and relative position of the latter. The latter mode of æsthetic perception is, in our times, more trained and developed, as it is in constant usage. Reproductive processes, the halftone and photography, have made monochrome a vehicle of expression almost as popular as the spoken word.
To former ages only the various processes of engraving were known. With the exception of etching and wood engraving, they were applied largely to popularize the products of painters, and the independent etchers and block-cutters generally adhered to a severe and classical style of art. It was the nineteenth century with its principle of universal education, newspapers, books and manifold publications, that brought about the great change.
Texture constitutes to most collectors the principal charm of the graphic arts. It is a rare and fantastic valuation, an appreciation of preciosity, this occupying oneself with the fascination of the minor arts. Art would be too austere if it were not for the makers of etchings and lithographs, of pastels and water-colours.
Photography, the latest arrival in the ranks of the graphic arts, has the widest range of expression, and its technique is interesting as far as it can express mechanically and with comparative ease gradations of tone that without visible touches, marks, strokes or lines melt imperceptibly into each other. But this smoothness of texture will also be its most formidable drawback. There is no chance for manual expression without destroying the charm of photographic texture. Chemistry is the only legitimate means to accomplish it.
NOCTURNE (LITHOGRAPH).
Copper and steel engravings lack that freedom of expression, and are restricted largely to reproductive purposes. Carried out by cross-hatching, they are limited by the black of the ink and the white of the paper, and the precise character of the line work. Modern reproductive wood engraving, notably of the American school, is the only medium which has conquered the subtleties of tone.
The scale in monochrome painting in colour is so limited that few artists apply it. India ink and sepia, however, are much in favour, and if handled by an artist, fulfil the requirements of painting. The only short-comings are a certain transparency in the middle tints and an artificial look in the texture.
Charcoal and chalk have a great similarity, and also lend themselves to elaborate composition, although the more delicate and lighter greys are frequently muddy. Pen and ink can merely give an impression of line, and next to etching it is the best medium for sketching, only a less pliable one, which is largely due to the unelasticity of the steel pen; all subtler gradations are left out, as the brightest tints are lost in the white and the darkest in the black.