The lighting of the exposition can barely be touched upon in a few paragraphs and it would be difficult to describe in words even if space were unlimited. It represented the power of light to beautify and to awe. It showed the feebleness of the decorator's media in comparison with light pulsating with life. It consisted of a great variety of direct, masked, concealed, and projected effects, but these were blended harmoniously with one another and with the decorative and architectural details of the structures. It was a crowning achievement of a century of public lighting which began with Murdock's initial display of a hundred flickering gas-jets. It demonstrated the powers of science in the production of light and of genius and imagination in the utilization of light. It was a silent but pulsating display of grandeur dwarfing into insignificance the aurora borealis in its most resplendent moments.
XXIII
THE EXPRESSIVENESS OF LIGHT
From an esthetic or, more broadly, a psychological point of view no medium rivals light in expressiveness. Not only is light allied with man's most important sense but throughout long ages of associations and uses mankind has bestowed upon it many attributes. In fact, it is possible that light, color, and darkness possess certain fundamentally innate powers; at least, they have acquired expressive and impressive powers through the many associations in mythology, religion, nature, and common usage. Besides these attributes, light possesses a great advantage over the media of decoration in obtaining brightness and color effects. For example, the landscape artist cannot reproduce the range of values or brightnesses in most of nature's scenes, for if black is used to represent a deep shadow, white is not bright enough to represent the value of the sky. In fact, the range of brightnesses represented by the deep shadow and the sky extends far beyond the range represented by black and white pigments. The extreme contrast ordinarily available by means of artist's colors is about thirty to one, but the sky is a thousand times brighter than a shadow, a sunlit cloud is thousands of times brighter than the deep shadows of woods, and the sun is millions of times brighter than the shadows in a landscape.
The range of brightnesses obtainable by means of light extends from darkness or black throughout the range represented by pigments under equal illumination and beyond these through the enormous range obtainable by unequal illumination of surfaces to the brightnesses of the light-sources themselves. In the matter of purity of colors, light surpasses reflecting media, for it is easy to obtain approximately pure hues by means of light and to obtain pure spectral hues by resorting to the spectrum of light. It is impossible to obtain pure hues by means of pigments or of other reflecting media. These advantages of light are very evident on turning to spectacular lighting effects, and even the lighting of interiors illustrates a potentiality in light superior to other media. For example, in a modern interior in which concealed lighting produces brilliantly illuminated areas above a cornice and dark shadows on the under side, the range in values is often much greater than that represented by black and white, and still there remains the possibility of employing the light-sources themselves in extending the scale of brightness. Superposing color upon the whole it is obvious that the combination of "primary" light with reflected light possesses much greater potentiality than the latter alone. This potentiality of light is best realized if lighting is regarded as "painting with light" in a manner analogous to the decorator's painting with pigments, etc.
The expressive possibilities of lighting find extensive applications in relation to painting, sculpture, and architecture. A painting is an expression of light and the sculptor's product finally depends upon lighting for its effectiveness. Lighting is the master painter and sculptor. It may affect the values of a painting to some extent and it is a great influence upon the colors. It molds the model from which the sculptor works and it molds the completed work. The direction, distribution, and quality of light influence the appearance of all objects and groups of them. Aside from the modeling of ornament, the light and shade effects of relatively large areas in an interior such as walls and ceiling, the contrasts in the brightnesses of alcoves with that of the main interior, and the shadows under cornices, beams, and arches are expressions of light.
The decorator is able to produce a certain mood in a given interior by varying the distribution of values and the choice of colors and the lighting artist is able to do likewise, but the latter is even able to alter the mood produced by the decorator. For example, a large interior flooded with light from concealed sources has the airiness and extensiveness of outdoors. If lighted solely by means of sources concealed in an upper cornice, the ceiling may be bright and the walls may be relatively dark by contrast. Such a lighting effect may produce a feeling of being hemmed in by the walls without a roof. If the room is lighted by means of chandeliers hung low and equipped with shades in such a manner that the lower portions of the walls may be light while the upper portions of the interior may be ill defined, the feeling produced may be that of being hemmed in by crowding darkness. Thus lighting is productive of moods and illusions ranging from the mystery of crowding darkness to the extensiveness of outdoors.
Future lighting of interiors doubtless will provide an adequacy of lighting effects which will meet the respective requirements of various occasions. A decorative scheme in which light and medium grays are employed produces an interior which is very sensitive to lighting effects. To these light-and-shade effects colored light may add its charming effectiveness. Not only are colored lighting effects able to add much to the beauty of the setting but they possess certain other powers. Blue tints produce a "cold" effect and the yellow and orange tints a "warm" effect. For example, a room will appear cooler in the summer when illuminated by means of bluish light and a practical application of this effect is in the theater which must attract audiences in the summer. How tinted illuminants fit the spirit of an occasion or the mood of a room may be fully appreciated only through experiments, but these are so effective that the future of lighting will witness the application of the idea of "painting with light" to its fullest extent. Color is demanded in other fields, and, considering its effectiveness and superiority in lighting, it will certainly be demanded in lighting when its potentiality becomes appreciated and readily utilized.
The expressiveness of light is always evident in a landscape. On a sunny day the mood of a scene varies throughout the day and it grows more enticing and agreeable as the shadows lengthen toward evening. The artist in painting a desert scene employs short harsh shadows if he desires to suggest the excessive heat. These shadows suggest the relentless noonday sun. The overcast sky is universally depressing and it has been found that on a sunny day most persons experience a slight depression when a cloud obscures the sun. Nature's lighting varies from moment to moment, from day to day, and from season to season. It presents the extremes of variation in distributions of light from overcast to sunny days and in the latter cases the shadows are continually shifting with the sun's altitude. They are harshest at noon and gradually fade as they lengthen, until at sunset they disappear. The colors of sunlit surfaces and of shadows vary from sunrise to sunset. These are the fundamental variations in the lighting, but in the various scenes the lighting effects are further modified by clouds and by local conditions or environment. The vast outdoors provides a fruitful field for the study of the expressiveness of light.