_a_, _a_, is an opening which is formed in the ordinary stage. In the front part of the stage, but at a lower level, is the hidden stage _b_. The opening _a_ is capable of being closed at the top by trap doors, a plan of which is shewn at Figure 2. When the trap doors are closed, actors on the ordinary or visible stage can pass freely to and fro above the lower or hidden stage. The ordinary stage and trap doors are covered with green baize or other dark material, so that when the trap doors are opened, the audience, even those in the gallery, will not readily be able to perceive the opening. The actors or objects corresponding with the phantom images, which it is desired to represent to the audience, are on the lower or hidden stage _b_, and are strongly illuminated by the lime light or the electric light, or other powerful illuminating means may be employed. This light must accompany the actor in any movement he has to make. The hidden stage _b_, and the lanterns _c_, may be mounted on a carriage on rails (a plan of which is shown at Figure 3), so that when it is necessary for the phantom actor or object on the lower stage to be moved, the lanterns may be caused to move also, or the lanterns may remain stationary whilst the actor moves, provided the whole space through which he moves is sufficiently illuminated. The lanterns are to be provided with means for instantaneously extinguishing or masking the light, and for reproducing it so that the phantom may be made to disappear and reappear at pleasure, whilst the audience and the ordinary stage will be more or less lighted in the ordinary manner according to the effects desired to be obtained. For this purpose a board _b_¹ is employed, which is capable of being raised into the position shewn by dotted lines so as entirely to cut off the light from the hidden stage when desired, or an ordinary opaque shade attached to each lantern may be used for the purpose, or when using the lime light the desired effects are caused by gradually or instantaneously (as the case may require) cutting off the supply of gases, and the phantom image may by any of these means be caused gradually or instantaneously to fade away. When the trap doors over the hidden stage are open, the part _d_ thereof assists in hiding the lanterns and the opening from the audience. The part _e_ is raised into the position shown in the Drawing and acts (together with the part _d_) to screen the lanterns from the audience, and also to insure that any actor or object on the hidden stage shall not accidentally appear above the level of the visible stage. The phantom actor, when standing on the stage _b_, leans against the screen _k_, which is inclined so as to be parallel with the glass screen, and is covered with black velvet or other dark material, as is also the stage _b_, in order that no image of either the screen _k_ or the stage _b_ may be seen in the reflection. _f_ (the glass screen) is a large sheet of plate glass on