152 LETTERS ON NATURAL MAGIC. 



stood Latin.' He redoubled his persuasions, assuring me 

 that the knowledge of the Latin language was by no 

 means material. He added, that he could have Latin 

 scholars enough, if he had thought it worth while to look 

 out for them, but that he could never have met with a 

 partner of resolution and intrepidity equal to mine, and 

 that I should by all means follow his advice. Whilst we 

 were engaged in this conversation, we arrived at our re- 

 spective houses, and all that night dreamt of nothing but 

 devils." 



It is impossible to peruse the preceding description 

 without being satisfied that the legions of devils were not 

 produced by any influence upon the imaginations of the 

 spectators, but were actual optical phantasms, or the 

 images of pictures or objects produced by one or more 

 concave mirrors or lenses. A fire is lighted, and perfumes 

 and incense are burnt, in order to create a ground for the 

 images, and the beholders are rigidly confined within the 

 pale of the magic circle. The concave mirror and the 

 objects presented to it having been so placed that the 

 persons within the circle could not see the aerial image 

 of the objects by the rays directly reflected from the 

 mirror, the work of deception was ready to begin. The 

 attendance of the magician upon his mirror was by no 

 means necessary. He took his place along with the spec- 

 tators within the magic circle. The images of the devils 

 were all distinctly formed in the air immediately above 

 the fire, but none of them could be seen by those within 

 the circle. The moment, however, that perfumes were 

 thrown into the fire to produce smoke, the first wreath of 

 smoke that rose through the place of one or more of the 

 images would reflect them to the eyes of the spectator, 

 and they could again disappear if the wreath was not 

 followed by another. More and more images would be 

 rendered visible as new wreaths of smoke arose, and the 



