and that behind the mirror, the audience will observe no change in appearance when the mirror is passed across.
"The front of the chamber is partially closed at cx by a shield or short partition-wall, either permanently or whenever required. This is done in order to hide from direct view any object, which may be at or about the position c.
"The illusions may be performed in various ways—as, for example, an object may, in the sight of the audience, be passed from the stage to the position c², near the rear short wall or counterpart shield f, diagonally opposite to and corresponding with the front corner shield cx, and there be changed for some other. This is done by providing beforehand a dummy at c′, closely resembling the object at c². Then when the object is in its place, the mirror is passed across without causing any apparent change. The object, when hidden, is changed for another object externally resembling the first, the mirror is withdrawn, and the audience may then be shown in any convenient way that the object now before them differs from that which their eyesight would lead them to suppose it to be.
"We prefer, in many cases, not to use an ordi-
