SCIOPTICONMANUAL. 59 



A large plate of glass leans forward on the front of the 

 stage, but its edges are so hidden by the curtains that its 

 presence is not suspected. A "woman in white" stands 

 down in front, concealed from the spectators by the usual 

 board near the orchestra, and is highly illuminated by 

 the light from a magic lantern. The spectators, in the 

 darkness and distance, see the actors upon the stage 

 through the glass, and also the ghost reflected from the 

 glass so as to appear on the stage with the rest. The 

 actors do not see the spectre, but they put on the ap- 

 pearance of fright for the benefit of the spectators. 



The apparition vanishes as the light is withdrawn from 

 " the woman in white." The lantern is used because it 

 illuminates an object without diffusing light in other 

 directions. 



On this principle we may see people in a room through 

 a window, with the reflected images of parties outside 

 standing among them. It seems not a little surprising 

 to sec one person cutting through the space occupied by 

 another. 



THE TANK. 



An excellent and cheap tank (similar to the one shown 

 in Fig. 26), but with permanent clamps without screws, 

 is now shaped so us to slide into the Sciopticon stage 

 without drawing forward the extension front. As the 

 space at the top is unobstructed, all sorts of experiments 

 with it are easily managed. Living creatures encaged 

 in it, in air or water, tigure upon the screen in huge pro- 

 portions, and with wonderful activity. Some fish and 

 parts of many insects are so transparent as to show in- 

 ternal structure. Even opaque objects, when their out- 

 lines arc sharply focused, appear in relief unlike a mere 

 -Jiadow. With almost every object thus shown, except 



