AS WE are unable to fully and exactly reproduce by means of pencil drawings, all of nature's intricate form, her complicated light and shade, and her varied coloring, we are forced to adopt certain conventional methods for their suggestion and indication.
Of the numerous conventions thus employed outline is perhaps the one most commonly used. Natural forms, it should be understood, have no definite outlines. We are able to distinguish objects one from the other only because of their contrasts of light or shade or shadow or color. To demonstrate the truth of this, study the objects about you, and you will see that each is visible only because it is light against dark or dark against light or because one color is contrasted with a different one, but never because it has an outline. It may by chance have a border of some strong color or tone which at first glance seems to be an outline, but closer inspection will prove it to be merely a narrow tone of light or dark or of color, so small as to appear as a line. Cracks between floorboards, for instance, often seem to be the outlines of the boards themselves, but in reality we see these cracks only because they form shadows or because they are filled with dirt or other materials of a color or tone different from that of the wood itself. Streaks of highlight along the edges of objects frequently appear to be outlines, too, unless the source of light causing them is hidden or moved, when they either disappear or change their positions.
Granting, then, that nature employs no real outline, it is remarkable that her forms can be so quickly and accurately suggested by its use. Even a child, as a rule, is able to so indicate objects by a few simple profiles that we can recognize them easily, and primitive peoples, ages ago, made outline drawings which we are able to read and understand with little effort. Because such drawings do indicate form simply and directly, it is important for the student to learn to make them well and he should frequently practice this form of work. By varying the lines used, the textures and materials represented can be more accurately and artistically suggested than at first seems possible. Shadow, too, can be indicated by darkening such edges as are turned away from the light. Outline drawing has, at the same time, so many limitations that for architectural purposes it is mainly valuable for the suggestion of form. Therefore whenever we wish to do more than simply indicate the light and shade or color we are forced to either supplement the outline by the addition of tones of gray or black, or to do away with it entirely, representing the object wholly by values of light and shade, approximating as closely as is possible those tones found in nature itself.
At "A," Figure 21, is a sketch of an old chimney done in outline only, but this outline is so accented as to suggest the textures of the various surfaces and a few tiny lines are added also as an indication of the shade and shadow. At "B" the same chimney is shown in full tone of light and shade but with the outline omitted. This drawing is much like a photograph of the same subject, in that the stone and brick and other materials have been given tones as similar as is possible to those appearing in nature. Though this type of drawing is used to some extent, it is not as popular as that shown at "C" in which much of the white of the paper is left. Drawing "C" not only has more character than "B" but the method used is a more economical one. In this particular instance the outline was drawn exactly as at "A" and then enough tone added to suggest the values of light and shade as found at "B." For architectural work this method is quite satisfactory, for much of the form can be represented by the accented outline; the white of the paper answers for the lighter values and the darker tones can be drawn with the gray and black of the pencil. Color cannot, of course, be more than suggested in any pencil drawing. A dark red brick wall can be shown dark, and light green shutters can be shown light, but unless explanatory notes are added or some color employed there is no way of making it clear that the brickwork is red and the shutters are green. Because of these limitations, tints of water color are frequently washed over a pencil drawing and the results obtained in this way are often very effective, especially if the tints are light and delicate. Colored pencils are sometimes used, too, with considerable success.
Figure 22 is one sketch in which the effect is gained by the use of values representing the color and tone of the various building materials and accessories, little attempt being made to show the shadows. It is sometimes possible to obtain a very pleasing result by this means and it would be well for the student to try a few such drawings, but the average subject demands some suggestion of the shadow tones as well. Many drawings can, in fact, be entirely made by the use of the shade and shadow tones only, the color of the building materials being largely disregarded, and the lower sketch, Figure 22, is shown to illustrate this point. This method proves especially useful when drawing objects made of light colored materials such as carved white marble, ornamental terra-cotta, white clapboarded or stucco walls, etc.
Although the natural tone and color of materials in buildings and their surroundings is of great importance, so much of the effect of a structure, both as a whole and in detail, depends on its shadows that the study of light and shade deserves special attention. When a sketch is in outline only, the light is either indicated in a simple manner or entirely disregarded, but when a drawing is to be done in full values it is especially important to determine both the source of the light and the direction in which it is coming before starting to render. Students have been known to cast the shadows on a building in one direction and to indicate the shade on the trees as though the light were coming at a different angle. Such inconsistencies are amusing, but warning should be given that they are almost sure to occur when students attempt to copy and combine parts of several drawings by other men or even make original drawings of their own unless the matter of lighting is carefully thought out before the pencil rendering is begun. Such mistakes show that the student cannot give too much study to this subject if he is to avoid many similar errors. There are, however, so many separate influences affecting the lighting of all objects, such as the condition of the atmosphere, the reflective or absorbing powers of different surfaces and materials, the constant shifting and moving of clouds and foliage, that it seems unwise to attempt here to give the student more than a few hints to point the way for his further individual study. Even in interiors the light often comes from so many sources and is reflected from so many surfaces that nothing but constant observation and sketching will teach the student what he should know of such conditions. The opening or closing of a door may be sufficient to entirely change the appearance of an interior and in the same way the shifting of a cloud may cause windows viewed from without to appear very light one minute and almost black the next. Sometimes the lighting varies to such an extent that an entire building may appear dark against light at one time and light against dark at another, as was illustrated in the example of the lighthouse in Figure 19. Such an extreme change as this, though by no means unusual, generally takes place at morning or in the evening or under exceptional lighting conditions, but even the average building under normal conditions will vary greatly in appearance from hour to hour. Because of these constant changes most buildings appear to better advantage at certain time of day than at others, and so if drawings of them are to be made it is naturally best to make them during these favorable moments. Buildings and foliage usually get the most satisfactory light during the late afternoon when the sun's rays are so slanted as to cause an interesting variety of shade and shadow, but there are of course exceptions to this, a great deal depending on the location of the building in relation to the points of the compass. Many architects fail when designing buildings to give sufficient attention to the fact that a design which will appear well when turned at a certain angle with the sun or other source of illumination, may be much less effective placed in some other position. It is not enough to make instrumental studies of buildings, with shadows cast in the usual 45 degree manner, but in addition the designer should consider how the structure will appear under the vertical rays of the sun at midday or the slanting rays of early morning or late afternoon, and should, in many cases, make special studies with the shadows shown as they would exist in the completed building. The author has in mind one particular public building which was most attractive in the preliminary drawings, with its shadows cast in the conventional manner. Unfortunately the building is so situated that for months at a time the sun seldom shines on the main facade and in the evening this facade is especially uninteresting when the bright light from the street lamps entirely eliminates the cornice shadows. Obviously it is impossible to foresee and prevent all such unpleasant appearances, but the student who has learned to study and observe light effects and has drawn much from nature will find the knowledge gained from this work of great assistance to him if he is called upon to do original work in design, both in avoiding such unpleasant results as we have mentioned and in making the greatest use of the lighting conditions as they exist. Such knowledge is of great importance, too, when one is called upon to make renderings of proposed buildings or sketches from memory or the imagination.