File:The theory and practice of landscape painting in water-colours. Illustrated by a series of twenty-six drawings and diagrams in colours, and numerous woodcuts (1871) (14780594311).jpg

Identifier: theorypracticeof00barn (find matches)
Title: The theory and practice of landscape painting in water-colours. Illustrated by a series of twenty-six drawings and diagrams in colours, and numerous woodcuts
Year: 1871 (1870s)
Authors: Barnard, George, 1807-1890
Subjects: Landscape painting Watercolor painting
Publisher: London : George Routledge & Sons
Contributing Library: Getty Research Institute
Digitizing Sponsor: Getty Research Institute

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That all the coloured rays proceed from thecard-board is proved by the effect described in the second mode of viewingthe spectrum,—namely, by looking through the prism at a piece of whitepaper on a black ground. But though all the kinds of rays are reflected,far more or less of each ray is extinguished and destroyed as to any powerof producing further illumination or colour; and the rest, or that whichstill remains radiant, is thrown about in all directions. If less light fall on the white surface, its apparent whiteness will bediminished, because less light is reflected from it; diminish the light stillmore, it becomes gray; and with no light incident upon its surface, itappears black, for it sends no rays to the eye. To illustrate this in anothermanner; suppose the illuminated surface to be that of a mixture of plasterof Paris and powdered charcoal; then, though the illuminating power beever so strong, the surface will appear gray; much more of the incident THE PRISMATIC SPECTRUM.
Text Appearing After Image:
LET0I1T0N, BROTHERS. PRISMATIC COLOURS. 13 light being there extinguished, and consequently much less reflected tothe eye than before. If the surface be that of charcoal alone, then nearlyall the incident light is extinguished, and we have, as before, black. But,in all these cases of extinction of light by the object, all the various rayshave been dealt with at once ; and, while any light remained to be reflectedfrom its surface, however deep the gray it may have presented, still suchgray has contained rays of all the colours, and these in due proportions forforming white. Even a surface of the purest white that we can prepare,quenches a considerable proportion of the light falling upon it; and hencearises much of the artists difficulty; for there being nothing but this im-perfectly white surface with which to represent light, his representations ofit must fall infinitely short of the reality; and yet, as regards his trees,buildings, and other objects, his pigments are as bright in co

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