62 LETTi^S ON NATUEAL MAGIC. 



centre of the opening EF. Let us suppose this 

 Fig. 4. 



object to be a plaster cast of any object made as 

 white as possible, and placed in an inverted posi- 

 tion at A. A strong light should then be thrown 

 upon it by a powerful lamp, the rays of which 

 are prevented from reaching the opening EF. 

 When this is done, a spectator placed at O will 

 see an erect image of the statue at B, the centre 

 of the opening, standing in the air, and differing 

 from the real statue only in being a little larger, 

 while the apparition will be wholly invisible to 

 other spectators placed at a little distance on 

 each side of him. 



If the opening EF is rilled with smoke, rising 

 either from a chafing-dish, in which incense is 

 burnt, or made to issue in clouds from some open- 

 ing below, the image will appear in the middle of 

 the smoke depicted upon it as upon a ground, 

 and capable of being seen by those spectators 

 who could not see the image of the air. The 

 rays of light, in place of proceeding without 



