In order to show the power of the instrument, and the extent to which these combinations may be carried, I have sometimes constructed a long object-plate, like the slider of the magic lantern, in which combinations of all the principal harmonic colours followed one another in succession, and presented to the eye a series of brilliant visions no less gratifying to some persons, and to some others even more gratifying, than those successions of musical sounds from which the ear derives such intense delight. We cannot conclude this chapter without noticing the fine effects which are produced by the introduction of carved gems, and figures of all kinds, whether they are drawn or engraved on opaque, or transparent grounds. The particular mode of combining these figures will be pointed out in a subsequent chapter. CHAPTER IX. ON THE ILLUMINATION OF TRANSPARENT OBJECTS IN THE KALEIDOSCOPE. When the Kaleidoscope is directed to the sky, or to a luminous object, such as a gas flame, or the flame of a candle, a uniform tint is seen through the pieces of glass, or other transparent fragments that have flat surfaces, and there is a certain degree of hardness in their outlines. When the instrument is not opposite the flame, but directed to one side of it, the light enters the transparent fragments obliquely, and a much finer effect is produced. The pattern, indeed, changes very considerably by making the Kaleidoscope move round the flame. An excellent effect is obtained, as we have already stated, by directing the tube between two bright lights; and the richness of the symmetrical pattern increases with the number of lights which illuminate the objects. As it would be inconvenient to adopt such a mode of illumination, it becomes of importance to have some contrivance attached to the instrument, by which we can illuminate the objects by light falling upon them in different directions. [Illustration: FIG. 24.]