12 THE BOOK OF THE LANTERN. 



form of lantern may be dispensed with in the instrument 

 designed for the lecture or school room. Indeed, in an- 

 other chapter I point out how a very simple arrangement 



FIG. 



of lamp and lenses can be made serviceable for educational 

 work. One of the most important additions to an instru- 

 ment used for teaching is what is known as the 

 vertical attachment. The object of this arrangement 



