GLASS STRUCTURES AND APPLIANCES, 



137 



front, the upper surface being let firmly into the 

 frame, level with its upper surface, while an inch or 

 so of the central portion stands up as high as the 

 lights, to keep them in position when sliding up 

 or down. In a two-light frame one rafter suffices, a 

 three-light needs two, and so on, an additional rafter 

 being needed for every added light. These rafters 

 are generally made of from two to four-inch stuif, 

 according to the width of the frame. 



The lights, whether one or many, are made of 

 two-inch stuff, the styles varying in width from two 

 inches to four, and the rails or ends from three 



stances, and hence the reason of using small squares 

 and a considerable number of sash-bars, which not 

 only add to the strength of the frames, but greatly 

 protect the glass against breakages. Notwithstand- 

 ing aU the improvements in glazing, and the rapid 

 develojjment of dry glazing, the old system of bed- 

 ding in putty — and filling each side of the rebated 

 rafter with the same so as to form an angle — is that 

 most generally used for garden frames. The glass 

 most commonly employed is about sixteen ounces to 

 the foot. Twenty-one ounce is sometimes used, but 

 on the whole the sixteen-ounce is better, being so 



Fig. 14.— Loose Frames usea to Protect Trees. 



to six inches. The sash-bars are formed of inch, 

 inch-and-quarter, inch-and-half, or two-inch deal, 

 and are rebated to receive the glass. These used to 

 be morticed in at each end, bat now mere rebated 

 splices of wood are frequently nailed on to the rails 

 at each end, and these serve most of the purposes of 

 the former mode of fitting sash-bars. The number 

 of sash-bars in frame-lights is now much less than 

 formerly, for broader as well as longer squares are 

 used. Eight rows of squares, five inches by eight, 

 used to be the orthodox number in three-feet lights. 

 Now half that number of squares, ten inches by six- 

 teen or eighteen inches, are generally used. For 

 common garden frames it is hardly advisable to 

 enlarge the squares beyond these sizes. The ex- 

 cessive portability — I had almost written mobility 

 — of the lights slipping up or down, maybe off and 

 on, several times a day, subjects the glass to exces- 

 sive risks of breakage. These risks are increased 

 by covering with mats and more dangerous sub- 



much lighter, and with careful glazing and handling 

 afterwards it is not much more liable to breakage. 



The risk of breakage is greatly reduced since the 

 number of laps has been lessened and their sizes 

 narrowed to an eighth of an inch or so. The wide 

 laps were not only the cause of the semi-obscurity 

 of the old frame-lights, but a fruitful source of the 

 breakage of the glass. 



The pitch or angle of garden frames is generally 

 secured by forming the back from a foot to eighteen 

 inches deeper than the front. Hence depths at back 

 of from eighteen inches to two feet, and in front of 

 from nine to fifteen inches. Much shallower frames 

 are also used for many purposes, such as the winter- 

 ing of Cauliflowers, Lettuces, Endive, &c. These 

 are frequently not more than from a foot to fifteen 

 inches at back, and from six to nine inches in front. 

 Such disparities of depth suffice to carry off the 

 water freely and to protect the frames against drip. 

 Serious inconveniences, however, very often arise in 



