CH. XII] 



POSITION OF PROJECTION APPARATUS 



453 



Occasionally when the seats are on a steep incline there is left a 

 space through which the projection objective can send its beam to 

 the curtain, the apparatus and operator being under the seats of 

 the amphitheater. 



618. Apparatus on one side of the room. Occasionally the 

 apparatus is put on one side of the room and instead of projecting 

 directly in front of the audience the projection is on one side of the 

 room. The auditors simply turn in their seats to face the screen. 



L T 



FIG. 245. SECTIONAL VIEW OF A LECTURE ROOM SHOWING THE POSITION OF 

 THE PROJECTION APPARATUS WITH A TRANSLUCENT SCREEN. 



Ml Magic lantern or other projection apparatus on its table (T) and 

 raised platform (PI) in a room outside the lecture room. 



L T Lecturer's table. 



Tr Sc Translucent screen. The audience does not see the apparatus; 

 only the screen image is visible. 



Lantern slides must be inserted in the holder facing the objective, not the 

 light, or the image will have the rights and lefts changed like fig. 213. 



This is not so satisfactory as when the screen is directly in front 

 (fig. 243). 



619. Apparatus wholly without the room. Regardless of the 

 form of the room, the apparatus may be placed in a room just back 

 of the lecture table in front of the audience and a translucent screen 

 employed. This arrangement has decided advantages, but a 

 translucent screen is not so satisfactory as a white opaque screen 

 (see fig. 245). 



620. Special operating room. With the ordinary magic 

 lantern and projection microscope the apparatus and operator are 



