

CHAPTER XIII. 



DESCRIPTION OF VARIOUS EXPERIMENTS, CHEMICAL, ELECTRICAL, 



ETC., FOR CLASS INSTRUCTION, WHICH ARE POSSIBLE WITH 



THE LANTERN. 



|OB different experiments, various forms of slides 

 must be employed. The galvanometer slide, 

 shown at fig. 45, is an extremely useful 

 one for demonstrations in electricity and magnetism. 

 I need hardly mention that such a slide consists of 

 a magnetised needle, which is surrounded by a coil 



FIG. 45. 



of fine wire. This coil is flattened, and there is just 

 space enough between its convolutions for the needle 

 to move from side to side. It is supported on 



