The arrangement of the theatre requires in addition to the ordinary stage a second stage at a lower level than the ordinary one, hidden from the audience as far as direct vision is concerned; this hidden stage is to be strongly illuminated by artificial light, and is capable of being rendered dark instantaneously whilst the ordinary stage and the theatre remain illuminated by ordinary lighting. A large glass screen is placed on the ordinary stage and in front of the hidden one. The spectators will not observe the glass screen, but will see the actors on the ordinary stage through it as if it were not there; nevertheless the glass will serve to reflect to them an image of the actors on the hidden stage when these are illuminated, but this image will be made immediately to disappear by darkening the hidden stage. The glass screen is set in a frame so that it can readily be moved to the place required, and it is to be set at an inclination to enable the spectators, whether in the pit, boxes, or gallery, to see the reflected image. The glass is adjustable and it is readily adjusted to the proper inclination by having a person in the pit, and another in the gallery, to inform the party who is adjusting the glass when they see the image correctly. Having thus stated the nature of our Invention, we will proceed more fully to describe the manner of performing the same. * * * * * DESCRIPTION OF THE DRAWINGS.—Fig. 1. (_Frontispiece_). Figure 1 of the annexed Drawings illustrates the arrangement of a theatre for carrying our Invention into effect; the Figure shows a section taken through the stage, the orchestra, the pit, and gallery.