The Magician's Own Book, or, the Whole Art of Conjuring / Being a complete hand-book of parlor magic, and containing over one thousand optical, chemical, mechanical, magnetical, and magical experiments, amusing transmutations, astonishing sleights and subtleties, celebrated card deceptions, ingenious tricks with numbers, curious and entertaining puzzles, together with all the most noted tricks of modern performers.

by George Arnold; Frank Cahill

The prism is a triangular solid of glass, and by it the young optician may decompose a ray of light into its primitive and supplementary colors, for a ray of light is of a compound nature. By the prism the ray A is divided into its three primitive colors, blue, red, and yellow; and their four supplementary ones, violet, indigo, green, and orange. The best way to perform this experiment is to cut a small slit in a window-shutter, on which the sun shines at some period of the day, and directly opposite the hole place a prism P; a beam of light in passing through it will then be decomposed, and if let fall upon a sheet of white paper, or against a white wall, the seven colors of the rainbow will be observed.

TO MAKE A PRISM.

Provide two small pieces of window-glass and a lump of wax; soften and mould the wax, stick the two pieces of glass upon it, so that they meet, as in the cut, where w is the wax, g and g the glasses stuck to it (Fig. 1). The end view (Fig. 2) will show the angle, a, at which the pieces of glass meet; into which angle put a drop of water.

Fig. 1. Fig. 2.

To use the instrument thus made, make a small hole, or a narrow horizontal slit, so that you can see the sky through it, when you stand at some distance from it in the room; or a piece of pasteboard placed in the upper part of the window-sash, with a slit cut in it, will serve the purpose of the hole in the shutter. The slit should be about one tenth of an inch wide, and an inch or two long, with even edges. Then hold the prism in your hand, place it close to your eye, and look through the drop of water, when you will see a beautiful train of colors, called a spectrum; at one end red, at the other violet, and in the middle yellowish green.

Fig. 3.

The annexed Figure 3 will better explain the direction in which we look: here, e is the eye of the spectator, p is the prism, h the hole in the shutter or pasteboard, s the spectrum. By a little practice, you will soon become accustomed to look in the right direction, and will see the colors very bright and distinct.

By means of this simple contrivance white light may be analyzed, and proved to consist of colored rays, and several of its properties be beautifully illustrated.