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LETTERS ON NATURAL MAGIC. 



opening might be surrounded with a picture-frame, and a 

 painting which exactly filled it might be so connected 

 with a pulley that it could be either slipped aside, or 

 raised so as to leave the frame empty. A large concave 

 mirror M N is then placed in another apartment, so that 

 when any object is placed at A, a distinct image of it 

 may be formed in the centre of the opening E F . Let us 

 suppose this object to be a plaster cast of any object made 

 as white as possible, and placed in an inverted position at 

 A. A strong light should then be thrown upon it by a 



Fig. 4. 



powerful lamp, the rays of which are prevented from 

 reaching the opening E F. When this is done, a spectator 

 placed at 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. t 



If the opening E F is filled with smoke rising either 

 from a chafing dish, in which incense is burnt, or made to 

 issue in clouds from some opening 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 in the air. The 



