230 LETTKRS ON NATURAL MAGIC. 



going on in the exhibition room, and communications 

 were no doubt made to her by signals from the person 

 who attended the machine. When one of the spectators 

 asked a question by speaking into one of the trumpets T, 

 the sound was reflected from the mouth of the trumpet 

 back to the aperture at A, in the horizontal rail, Fig. 38, 



Fig. 39. 



and was distinctly conveyed along the closed tube into 

 the apartment N. In like manner the answer issued 

 from the aperture A, and being reflected back to 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 increased by 

 the circumstance, that an answer was returned to ques- 

 tions put in a whisper, and also by the conviction that 

 nobody but a person in the middle of the audience could 

 observe the circumstances to which the invisible figure 

 frequently adverted. 



Although the performances of speaking heads were 

 generally effected by the methods now described, yet 

 there is reason to think that the ventriloquist sometimes 

 presided at the exhibition, and deceived the audience 



