Although the coloring media which are permanent under the action of light, heat, and moisture are relatively few, by a knowledge of their spectral characteristics and other principles of color the expert is able to produce many permanent colors for lighting effects. The additive and subtractive methods are chiefly involved, but there is another method which is an "averaging" additive one. For example, if a warm tint of yellow is desired and only a dense yellow glass is available, the yellow glass may be cut into small pieces and arranged upon a colorless glass in checker-board fashion. Thus a great deal of uncolored light which is transmitted by the filter is slightly tinted by the yellow light passing through the pieces of yellow glass. If this light is properly mixed by a diffusing glass the effect is satisfactory. These are the principal means of obtaining colored light by means of filters and by mixing colored lights. By using these in conjunction with the array of light-sources available it is possible to meet most of the growing demands. Of course, the ideal solution is to make the colored light directly at the light-source, and doubtless future developments which now appear remote or even impossible will supply such colored illuminants. In the meantime, much is being accomplished with the means available. XXII SPECTACULAR LIGHTING Artificial light is a natural agency for producing spectacular effects. It is readily controlled and altered in color and the brightness which it lends to displays outdoors at night renders them extremely conspicuous against the darkness of the sky. It surpasses other decorative media by the extreme range of values which may be obtained. The decorator and painter are limited by a range of values from black to white pigments, which ordinarily represents an extreme contrast of about one to thirty. The brightnesses due to light may vary from darkness to those of the light-sources themselves. The decorator deals with secondary light--that is, light reflected by more or less diffusely reflecting objects. The lighting expert has at his command not only this secondary light but the primary light of the sources. Lighting effects everywhere attract attention and even the modern merchant testifies that adequate lighting in his store is of advertising value. In all the field of spectacular lighting the superiority of artificial light over natural light is demonstrated.