A MYSTIC MAZE.
We present an [engraving] of a very interesting optical illusion produced with only three mirrors. By multiplying the mirrors the large number of different effects can be obtained.
Let us imagine that three perfectly plain and very clear mirror glasses, as large as possible, form a prism whose base is an equilateral triangle. A person placed in the interior of this prism will see his image reflected a very large number of times. A very simple geometrical construction, and one which we recommend our young readers to carry out as an exercise in optics, by the simple application of the principle that the angle of incidence is equal to the angle of reflection, allows us to see that the image of any point whatever placed in the center of this triangle of glass plates will be reproduced indefinitely by groups of six images distributed symmetrically around points regularly spaced in the prolongations of the planes of the three glasses.
A person, therefore, sees his image reproduced indefinitely in groups of six until, the successive reflections attenuating the intensity of the images, the latter cease to be visible. Three or four persons massed in one of the angles present the illusion of a compact and mixed crowd standing upon a sidewalk and awaiting the passage of a procession. The hats waving in the air convert the peaceful waiting into an enthusiastic manifestation, which is so much the more surprising in that it is made by but half a dozen persons at the maximum.
The accompanying [figure] gives an idea of this remarkable effect, and the three persons, whose images reflected ad infinitum produce the curious result that we call attention to, would have much trouble to believe that they were the subject of an illusion.
Upon the whole, the experiment is nothing more than an application of the principle of the old kaleidoscope enlarged and revived, in the sense that the observer has before his eyes the successive reflections of his own image, and that the objects are replaced with living beings movable at will.
Five or six persons may occupy, at the same time, the triangular prism, of which the sides are about six feet wide, and which they enter through a trap in the floor. When these five or six persons are walking about in all directions, they present the aspect of a tumultuous and agitated crowd commenting upon grave events.