THE ENGRAVING EXPLAINED. 103 



But even then the illusion would not be complete, for the 

 real ghost, and the light shining upon him, and also the 

 glass of the window in which he was reflected, would all 

 be seen. In the contrivances for producing these illusions 

 on the stage, all these things are concealed." 



So saying, Lawrence took a book out of his trunk and 

 opened to an engraving in which the arrangements usually 

 made for producing such illusions on the stage were repre- 

 sented and fully explained. 



You see here a copy of this engraving. The glass is a 

 lai-ge piece of plate-glass, like a very large looking-glass 

 without any silvering on the back, and it covers the whole 

 front of the stage. In the engraving the edges of the glass 

 are seen, but in the actual performance these edges are 

 concealed by the curtains coming close to them on each 

 side. Of course the glass must be extremely large. It is 

 placed, too, in an inclined position,, so that all the light 

 shining upon it from the side toward the audience is re- 

 flected downward, and thus it produces no "glare." 



The figure which is to form the image of the ghost in 

 the glass is in front of the stage, and is placed low enough 

 to be entirely concealed from the view of the spectators. 

 It is strongly illuminated by a very bright light, which is 

 also concealed under the stage. The light, of course, radi- 

 ates in every direcfion from the figure, and spreads over 

 the whole surface of the glass, whence it is reflected all 

 over the theatre ; and a certain portion of it, sufficient to 

 form an image upon the retina, reaches every spectator, 

 and such an image, moreover, as if the light, instead of 

 coming up from beneath the stage, and being reflected by 

 the glass, had really come from an equal distance behind 

 the stage that is, from the place where the image seems 

 to stand, near the man who is pointing a pistol at it. 



This man would, however, not see any image at all near 



