GRAPE VINES STRUCTURES. 275 



these on the inside, and placing perforated zinc over the outside of the openings. J5y 

 means of the ventilators and the 1 J-inch roof pipes, the house can be ventilated in any 

 weather, and moisture expelled or frost excluded. These root pipes prevent moisture 

 condensing on the glass, and are otherwise advantageous to the vines. The trellis should 

 be of galvanised wires, placed longitudinally of the house, 9 inches apart, supported by 

 iron bars (f by inch), pierced with holes at the proper distance apart, through which 

 the wires are passed, and the bars hold by iron hooks, as shown. The wires are threaded 

 and strained with thumbscrews at the ends. Long eyes are sometimes used to guide 

 and support the wires, but they are not so serviceable as iron bar guides, one to each 

 rafter, and angle iron at the ends for straining. Galvanised iron sometimes acts injuriously 



Fig. 84. THREE -QUARTERS SPAN-ROOF VINBEY. (Section through 02, Z>2, Ground Plan, Vol. I , page 71.) 



(Scale : inch= 1 foot.) 



References : a, ground level ; 6, outlet land drain ; c, longitudinal border drains ; d, rubble ; e, outside border ; 

 g, rain-water tank; h f path; i, 4-inch hot-water pipes; j, 1^-inch hot-water pipes; k, side lights; I, south top 

 lights ; m, north top lights. The angle of the roof is 35. 



on growths tied to it, but the defect is overcome by painting. The trellis should not be 

 less than 16 inches from the glass, and it need not exceed 2 feet. 



2. Three-quarters Span-roof Vinery. This shape is approved (as well as a lean-to) 

 for early forcing, Muscat, and late grapes. It has a comparatively low back wall, 

 provides plenty of light, and effective ventilation when the roof has both south and 

 north top lights for opening, as shown in Fig. 84. 



In frosty weather the back lights (m) often become icebound, unless hot -water pipes are 

 provided under the roof. They are desirable on both sides (/), so that the north lights 

 can be opened when the wind blows cold and strong from points between east round by 

 the south to the west, and the south top lights when the wind is fierce from the north. 



H N 2 



