440 PROJECTION ROOM [Cn. XII 



(4) Each seat should have a good view of the stage and the 

 screen. 



(5) There should be enough diffuse light in the room so that 

 people can find their way around easily and after gaining twilight 

 vision, be able to take notes. 



603. Form of the room. In general that shape of room which 

 has been found most satisfactory for churches and theaters and for 

 science lecture rooms in colleges and universities is well adapted for 

 projection. As, however, the entire attention must be given to 

 the images on the screen in the middle of the stage there is a ten- 

 dency to make the rooms used especially for projection longer than 

 they are wide. In a room which is approximately square, the 

 spectators who sit at the sides of the room near the front do not 

 have so good a view of the screen as those in the middle of the room 

 and farther back. 



With a long narrow room either the picture must be magnified 

 excessively to enable those on the back seats to see the details, 

 while for those on the front seats the pictures seem very coarse, or 

 there must be a compromise so that only for those in the middle of 

 the hall are the screen pictures of the most favorable size. 



We strongly advise any person having the responsibility of 

 planning a lecture hall for educational purposes or for exhibitions, 

 to take advantage of human experience and see a considerable 

 number of halls in various places, and get hints of what not to do 

 as well as of what to do from those who have had experience. 

 Then he can combine excellencies and avoid mistakes in planning 

 his own building or room. 



604. Tint and decoration of the room. In order to get the 

 best possible results in projection, no light whatsoever should reach 

 the eyes of the spectators except that reflected from the screen. 

 With the moderate light available for the earliest users of the magic 

 lantern it was advised that the walls and ceiling be made black so 

 that, as they put it, "the room would be as sombre as possible." 

 For some experiments in projection with polarized light, the 

 spectroscope, and the highest power micro-projection such a room 



