So much depends on the situation and surroundings that it is difficult to give particulars of a method of ventilating a photographer's dark room without seeing a sketch of the room. The following plan, however, may be tried. Cut an opening near the bottom of the door and screw over this opening on the inside a box with a partition, formed as shown in Fig. 1, and coated inside and out with a dead black, made by mixing lampblack with negative varnish A similar opening and box may be made for the top of the door. The air will enter by the bottom ventilator and pass out by the top one. When the light outside the dark room is strong, the opening may be fitted with two partitions, set at an angle as shown in Fig. 2. If it is not convenient to cut holes in the door, the ventilator may be formed in the jamb of the door, as in Fig. 3, covering the edge at X with soft baize to ensure a light-tight join when the door is closed. Fig. 4 shows a very usual method of ventilating just below the eaves by over-lapping boards.

Fig. I.

Fig. 2.

Ventilation of Photographer's Dark Room.