DOUBLE GLAZING. 



15 



and the under layer added for double glazing. All the 

 difference in expense lies merely in the cost of the 

 glass, which is a trifle compared with the use of two 

 layers instead of one in early forcing. 



All good gardeners will doubtless see the advan- 

 tages attached to the plan of double glazing, and I have 



FIG. 9. SECTIONAL VIEW OF DOUBLE GLAZING, WITH SPRING BRASS CLIPS 

 AND SCREW. 



As in fig. No. 7, but with rebate, letter a, rising one and a half eighth of an inch. 

 or the thickness of double glas, so that the edges can butt up to it, thus render- 

 ing the glazing perfectly air-tight. The standards, a a a, need not be more than 

 one-quarter of an inch wide, the screws, B, going through it. The under layer of 

 glass is held in position by the thin metal clips, as in the illustration 2. 



no doubt that, if this is done without putty, or any 

 other material that will prevent the water from con- 

 densing into vapour, it will be seen at a glance that 

 this method while perfectly air-tight is not retentive of 

 water in the roof of the house, which when frosts occur 

 materially lowers the temperature of the place. This 

 is especially the case in single glazing, where extra fires 

 must be kept up to keep out the frost. It is not 

 necessary for me to say here that frost has a material 



