Introduction.
ALTHOUGH objects can be well represented on a flat surface by means of accurately drawn outlines, we find it impossible to express their solidity and the character of their surfaces without the addition of light and shade.
A circular plane and a sphere may each in some positions be rendered in outline by a circle ; a square plane and a cube by a square ; a cone and a sphere by a circle. Under such conditions the difference between the bodies can be expressed only by shading. These are, it is true, extreme cases ; but a momentâs consideration will convince the student that mere outline can never adequately render the delicate variations of the surface of flowers and fruits.
All art is progressive, and is fostered only by careful and exact observation. To the beginner there is little to choose between a tree drawn in outline by Mr. Alfred Parsons, or a figure by Mr. Henry Holiday, and the characterless production of some amateur friend ; and only after much observation does the difference become apparent.
So the educated eye alone is fully alive to all the wonderful variety of light and shade in Natureââin clouds, hills, waves, fruits, trees, and leaves.
At first the reader will be unable to realise the gradations that he is assured are to be found on an object before him. But by carefully noting the well-defined differences of light and shade on geometrical solids, he will in time be able to distinguish the more delicate ones on casts of ornament or on natural objects.
Lights, Shades, Shadows
Place a whitened india-rubber ball upon a dark book-cover, and in a stream of light falling in a direction from left to right of the spectator. (See Fig. 43.)
The surface of the ball appears to be broadly divided into two parts, of which the darker is said to be in shade, the other in light. Moreover, its opaque body deprives part of the book-cover of light: i.e., it casts a shadow. In the following pages this distinction will be maintained. By shadows we shall always mean cast-shadows, and by shades those parts of the surface turned from the direct light.
Now place the ball upon a sheet of white paper, and you will see light, shade, and shadow as before; but the shade appears considerably lighter in parts than beforeâa change due to light reflected from the paper.
This portion of the shadeâfor it is always most strongly marked in the shadeâis known as the reflected light. It is always present, but is most evident when the reflecting body is light in tone.
Again, that spot on the left side of the egg lying directly opposite the source of light is decidedly brighter than any other part of that side.
This spot is said to be the high light, and the remaining portion is said to be in half tone.
Shadows (A) cast by artificial light.âThe character of the shadows cast by artificial light can be best explained by a few simple experiments.
Take two sheets of cardboard and place them at right angles to one another, and in a flood of light from a single source. Then (as in Fig. 1) hold a smaller piece of cardboard with its faces parallel to the perpendicular sheet, so that its shadow may be caught upon the upright plane.
You will notice that the four points a, b, c, d are obtained by drawing lines from the source of light through the four corners of the rectangle; and this you will find true, no matter at what angle you may turn the card.
We learn then :â(I) The shadow falls immediately behind the object, and along the straight line joining the object with the source of light.
Keeping the light and the sheet of cardboard as before, place the small rectangle nearer the light. The points of the shadow can be found as before ; necessarily the shadow as a whole must be larger (Fig. 3). But you will notice that the tone of the shadow is not so deep as in the last instance, and that its edges are not nearly so distinct.
Hence :â(2) The farther the object from the surface receiving the shadow, the larger and fainter will that shadow appear.
If you now rest the rectangle upon the lower sheet, you will find its shadow cast as in Fig. 4. Here the part of the shadow along the floor, so to speak, gradually decreases in darkness of tone until it reaches the upright, upon which, according to the last experiments, it appears approximately of the same depth throughout.
It will be readily understood why the shadow gets wider along the horizontal plane as it recedes from the object, for the parts receiving the shadow are removed at greater and greater distances from the object. This experiment, therefore, really gives the principles underlying Figs. 1 and 3 in one.
Thus :â(3) The shadows cast on flat surfaces by objects resting on those surfaces appear darkest along the portions nearest the object, whence they gradually decrease in depth.
Lastly, bend the perpendicular sheet into any shape, as in Fig. 2. Place a stick of pencil so that its shadow may be caught, and notice how the sh...