164 LETTERS ON NATURAL MAGIC. 



tinctly conveyed along the closed tube into the 



apartment N. In like manner the answer issued 



from the aperture A, and being reflected back to 



Fig. 39. 



the ear of the spectator by the trumpet, he heard 

 the sounds with that change of character which 

 they receive when transmitted through a tube 

 and then reflected to the ear. 



The surprise of the auditors was greatly in- 

 creased by the circumstance, that an answer was 

 returned to questions put in a whisper, and also 

 by the conviction that nobody but a person in the 

 middle of the audience could observe the circum- 

 stances to which the invisible figure frequently 

 adverted. 



Although the performances of speaking heads 

 were generally effected by the methods now de- 

 scribed, yet there is reason to think that the 

 ventriloquist sometimes presided at the exhibition, 

 and deceived the audience by his extraordinary 

 powers of illusion. There is no species of decep- 

 tion more irresistible in its effects than that which 

 arises from the uncertainty with which we judge 



