Balusters, columns, archways, round towers and all sorts of similar architectural objects and details require a certain amount of graded shading. At "12" and "13," Figure 27, a baluster and a capital are shown. Even though drawn in elevation the rounded effect is very evident. Had they been done in perspective less care would have been needed in the shading to express roundness, but for architectural purposes it is often necessary to work in elevation and therefore these sketches have been done in that manner to prove that it is not essential to show objects in perspective when a feeling of projection and curvature is required.
In order to illustrate the points under discussion in the clearest possible manner the drawings on Figure 27 have been done with very evenly graded tones, for by this means the values as found on the objects themselves could be more accurately represented than by the use of tones built up of separate lines. As a general rule, however, such smooth tones are not needed, for much the same effect can be arrived at by forming them of lines just touching, in the usual manner, and the result is less mechanical or photographical and hence more desirable. At "14" a few suggestions are offered for the formation of graded tones by individual strokes. (It is suggested that the student make a few drawings similar to these on this plate, trying some with the smooth tone and others with a more sketchy handling.)
It should be remembered that although the exact form which the gradation of a tone takes depends largely on the curve of the surface, it really owes its effect to the light which causes it to be visible. If we had no light the most perfect mouldings would be lost in darkness- - if we have too much light their beauty is often destroyed. The author has in mind a certain coffered ceiling of unusual beauty. After this ceiling had been in existence a number of years and had been much admired, it was decided to install a new indirect lighting system in the room, and this was done. The system was so arranged that the light was uniformly distributed over the ceiling in such a way that nearly all of the shade and shadow was destroyed. The lighting engineers pronounced the job a perfect one, but from an artistic standpoint the effect of the ceiling was ruined; the mouldings and detail were barely visible while the few shadows that remained took weird and grotesque shapes of a most bewildering nature. In this case too much light, or rather light distributed in too uniform a manner, destroyed the effect. This all goes to prove that even a beautiful curve may lose much of its value through unfavorable lighting, and it shows also that the gradation of tone on any given moulding or curve varies with changes in light. Spheres and cylinders, for example, do not appear the same at all times and hence cannot always be represented in the same way. It should be remembered, too, that the gradation of tone on any given form, take a cylinder for example, depends not a little on the nature of the material of which the object is made. A study of a number of cylinders of equal size and of various materials such as wood, plaster, polished white marble, sandstone, red granite, brass, silver, etc., will reveal, even under the same conditions, a surprising difference in the values and the method of gradation of the tones. Those cylinders with highly polished surfaces will show a greater complication of values and much sharper and more sudden contrasts, as a rule, mainly because their surfaces serve as curved mirrors to reflect distorted images of other objects. Such surfaces usually have brilliant highlights in spots while those of the wood or plaster or other dull appearing objects will not only lack these highlights but will show throughout a more simple and gradual change in tone. It is because of such conditions as these that there can be no definite rules given as to just how such objects should be represented. Observation and study will give the student the desired knowledge.
We have, up to this point, spoken mainly of graded tones as found on curved surfaces, yet it should be realized that smooth flat surfaces often appear to grade from one part to another. Prove this to yourself by observing objects around you. It is especially true that on surfaces indoors, where the light is frequently coming from a number of sources and is all more or less diffused, we find many tones which are graded. A ceiling, for instance, often appears light at one side and dark at the other, but it is in the shadow tones especially that we find a great amount of gradation. As a rule the shadows of objects indoors seem the darkest and have the sharpest edges near the object casting them. A chair leg, for example, usually casts a dark shadow where it touches the floor, but this shadow softens as it gets farther from the leg and soon disappears. The little sketch of the pencil touching the paper at "1," Figure 28, was made to illustrate this point, the shadow being the darkest at "A," softening as the light becomes more diffused towards "B." In brilliant light, such as bright sunshine, the opposite effect is often found. Let an object project from the wall like the little cornice shown at "4" and the lower edge of the shadow as at "B" frequently seems sharper and darker than the edge nearer the object as at "A." Such an effect is as a rule only an optical illusion for unless there is something to cause a strong reflection of light into the upper portion of the shadow the tone is usually of equal value throughout. The effect of darkness towards the lower edge is due to the fact that sunlight is so extremely brilliant that when it falls on a light wall or similar surface it produces a value so bright that it is impossible for us to correctly represent it on paper, and so when a shadow tone cast by some object similar to the cornice at "4" falls on this bright surface the tone appears, in its relation to the bright surface, darker than it really is. A shadow may be a medium gray if compared with black but if its lower edge is thrown into sudden and sharp contrast with extremely brilliant light it often seems actually black. In drawing shadows, therefore, there is a legitimate reason for such a gradation as we have shown in the sketch "4," as this method causes the white of the paper to appear brighter than it otherwise would, and therefore to more correctly represent the sunlit surface. The lighter shadow tone above also gains, by this gradation, a quality of depth and transparency.