F. H. Richardson's bluebook of projection (1935)

THE PROJECTION ROOM 265 sound passing through them will annoy any in the audience except perhaps the few who sit close to the ports. The method of reduction is illustrated in Fig. 69. To make sure, sit in the seats nearest the open ports during performances. If there is not enough noise to annoy you, it will not bother anyone else. (89) Keep the lens ports open if possible — you will eliminate loss of light through reflection from both surfaces of the glass cover, and glass can never be perfectly cleaned — a faint finger mark may spoil an otherwise splendid projection. Lens ports can always be open during relatively small matinee performances. Projection Room Entrance Entrance to the projection room should be comfortable and convenient. If a stairway is necessary it should be of normal grade and safety. The day of mounting a perpendicular ladder, or climbing into the projection room through a hole in the floor is decidedly past and local building safety regulations should be invoked to force a change. (90) The door should be of ordinary height and never less than twenty-four inches clear width when it is open. (91) If the main entrance of the projection room leads directly into the auditorium then there should be two doors, with not less than three feet between them to form a hallway.' Among other advantages this hallway is one more protective factor, in the event of fire, to keep the audience in blissful ignorance of the trouble until it has filed out. (92) All projection room doors must be fireproof ed. There is a door approved by the Underwriters for such use. It is known as the "Kalamein," of which there are two kinds. Use only the one bearing the Underwriters' label, as it influences insurance rates. This door is made of layers of white pine covered with metal. The door should be kept closed at all times during projection while an audience is present. Instrument Board T* 1#s a serious error to use the various ammeters, volt