The Garden Under Glass

VENTILATING AND SHADING 263 ture, closing of the house during the afternoon is not neces-sary, and the ventilators are only shut to such an extent as to prevent too low a drop of the temperature during the night. In connection with a cold house it is also the custom to put air on at the bottom of the house, or, to be precise, on the sides. Sometimes the side is made to open, while at others a shutter is put in the wall, and when opened the air passing over the hot-water pipes becomes warmed Diagram 53.—Ventilating a Frame : 1. Frame tilted at side according to the wind. 2. The block set near edge of frame; will tend to warp the light. 3. Correct place to set tbe block or scotch. 4. A frame set on a brick at each corner, so that air may get beneath. 5. Shows how to draw back a light. If left as shown on dotted lines, the wind can easily blow it over. before it plays upon the plants. In the winter-time this is a great consideration. In ventilating a plant house it is usual to open the top ventilators first, and afterwards the lower ones, but in every case both upper and lower ventilators opened should be on the same side of the house. In a cool house some ventilation should be left on all night, and with skilful management it will scarcely be necessary to take it off entirely even during a frost up to io°. In