114 THE POLYTECHNIC INSTITUTION. 



back on the table, with its feet toward the glass. The doll 

 will thus appear in an upright position in the glass. 



In these expei-iments which you make with the glass, a 

 common table will be found too low, except for young 

 children whose heads just come up above the level of the 

 upper surface of it ; for the head of the spectator ought to 

 be about on a level with the middle of the glass. A chair 

 placed upon a table a kitchen table, for example will 

 bring the glass, perhaps, at about the right height for 

 young persons from twelve to fifteen years of age. 



In the exhibition which Lawrence and John witnessed 

 at the Polytechnic there were several different perform- 

 ances, in which quite a number and variety of phantasms 

 were made to appear. One was the figure of a statue, 

 which had the appearance of standing back against the 

 wall of a painter's studio. Of course it was produced by 

 some kind of statue in pasteboard, which was lying in a 

 horizontal position beneath the front of the stage. It could 

 be made to appear and disappear at pleasure by throwing 

 a strong light upon it or shutting the light off. Then 

 there were figures also some that represented hobgoblins 

 that ran about upon the wall. One was in the form of a 

 monstrous fat lizard, with four paws and a long tail, that 

 crawled about in a most mysterious manner as he appeared " 

 reflected in the glass. Of course this animal was really a 

 boy, with an artificial shell or coat to represent an uncouth 

 green monster. 



Then there were a number of very pretty and agile lit- 

 tle fairies in gorgeous dresses, that danced about in the 

 most fantastic manner, so much so that it was difficult to 

 follow them, and to tell whether they were upon the wall, 

 in the air, or upon the floor. 



After the exhibition had been continued for some min- 

 utes, and it was time to bring the lecture to a close, Pro- 



