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254 RICHARDSON'S BLUEBOOK OF PROJECTION
Other Ports
(35) Wall openings for effect and dissolving stereopticons should be stepped down until they are no larger than is necessary. It is best to start with ports of ample dimenions. After the projectors are permanently located and anchored down, project the light beam upon the openings, first shutting them off with a fireproof, sound absorbing material. The dimensions of the beams can then be marked, the piece removed and an opening cut in it the size of the light beam. The final openings may then be covered with optical glass if desired.
(36) The width and height of ports for spotlights will depend entirely upon how close the_ lens is to the wall and through how wide an angle it is necessary to swing the light beam. (37) Some theatres do not close spot ports with glass, opening the fire shutter only when the spot is in actual use, and at this time no conversation or other unnecessary noise should be permitted, tn some cases local authorities demand that spot ports be covered with glass.
Ports Fi;ared
(38) If the front wall is more than eight inches thick it is advisable to flare (slope) the bottomof all ports downward, at least to the angle of the axis of projection, provided it exceeds five degrees. If the wall is twelve or more inches thick, both bottom and sides of ports should be flared outward. This applies to all port openings.
Conduits
(39) Before installing sound equipment conduit the equipment manufacturer should be consulted and his advice followed. Unless this is done, very serious inconveniences may be encountered later on. (40) Exact location of all conduit runs and outlets should be indicated on the projection room plans, so that they may be embedded in the walls and floors during construction.