450 POSITION OF PROJECTION APPARATUS [Cn. XII 



The lantern should be fastened to a hinged board when it is 

 elevated considerably (fig. 118, 242). 



615. Magic lantern on the lecture table. Occasionally it is 

 an advantage to have the magic lantern on the lecture table ; then 

 the lecturer can manipulate it himself. 



There are three arrangements possible: (i) The lantern is 

 pointed toward a screen at the side of the room (fig. 243). (2) It 

 is pointed obliquely upward toward the screen in front of the 

 audience. In this case the screen must be inclined toward the 

 lantern as indicated above (614). (3) Occasionally, for ease of 

 manipulation, the lantern is pointed obliquely upward toward the 

 audience and a plane mirror reflects the image-forming rays back- 

 ward to the screen (fig. 244). If a mirror is used, the lantern slides 

 must be inserted with their faces toward the objective. 



FIG. 242. MAGIC LANTERN TABLE WITH HINGED BASEBOARD. 

 Hinges connect the baseboard to the table at the left. By putting a block 

 under the board at the right, it can be elevated to bring the screen picture 

 higher up (fig. 118). 



