GLASS HOUSES FOR VEGETABLE CROPS 



125 



Fig. 181. Ridge- and furrow-houses with iron gutters. 



When several houses are built with common gut- 

 ters between the adjacent houses, if they are used 

 for the same classes of crops, a row of posts to sup- 

 port the gutters will be all that is required. (Fig. 

 181.) Although less commonly used for vegetables 

 than for flowers, what is known as the ridge-and- 

 furrow style of construction has much merit, espe- 

 cially for tomatoes and cucumbers. As now con- 

 structed these establishments are made up of several 

 narrow houses, with a width of sixteen to twenty- 

 four feet, and at least six feet in height to the gut- 

 ters. As there is nothing but posts under all except 

 the outside walls, it practically makes one wide 

 house. There is less trouble from the shadows of 

 the gutters than in most narrow houses, as the 

 walks are located where the deepest shadows fall. 



The roof. 



For the construction of the roof of a green- 

 house there is no material equal to southern 

 cypress that is free from sap-wood. If soaked in 

 oil and the joints put together in white lead, a 

 cypress greenhouse will last for many years when 

 kept properly painted. Although iron rafters and 

 purlins make possible the use of lighter sash-bars 

 (Fig. 182), a great majority of vegetable-houses are 

 built without rafters, the framework of the roof 

 being formed of cypress sash-bars that run from 

 the plates to the ridge. These are two to two 

 and a half inches deep and about one and one- 

 eighth inches wide, according to the size of the 

 glass and the distance between the supports. The 

 plates may be either of wood, beveled so that the 

 water will run off, or formed into a gutter to 

 carry the water to a drain ; or various 

 forms of iron plates and gutters 

 may be used. The iron gutters 

 are of course more durable, 

 but the houses are harder to 

 heat and with some kinds 

 the ends of the sash-bars 

 decay sooner than with 

 wooden gutters and plates. 



Ventilating. 



Ample means should be 

 provided for the ventilation ' 

 of vegetable -houses. This 

 can be secured by means of 

 a row of ventilating sash at 



the ridge and another row beneath the plates, 

 which should have a width of two to three feet. 

 They should be supplied with some of the modern 

 ventilating machinery that will permit of opening 

 stretches of one hundred feet at a time. 



Glass. 



The glass most commonly used is sixteen by 

 twenty to twenty-four inches, double strength, and 

 of " B " quality, although " A " glass is better. For 

 small houses it answers fairly well if it has a width 

 of twelve to fourteen inches. The putty used for 

 bedding the glass should be mixed with about ten 

 per cent of white lead. In laying the glass, it 

 should be lapped about one-eighth of an inch. As 

 the lower edge of each pane will be raised from the 

 sash-bars the thickness of the glass, a sufficient 

 amount of putty should be placed on the rabbets 

 to fill this space before the glass is laid. Care 

 should be taken to select the panes so as to make 

 tight joints where they lap, and they should be held 

 in place by zinc shoe-nails, using four to six ac- 

 • cording to the size of the panes. The double-pointed 

 glazing tacks also answer well for holding- the 

 lower corners of the panes in place. No putty 

 should be used on top of the glass and all surplus 

 should be scraped off, care being taken to fill all of 

 the cracks. In addition to soaking the sash-bars in 

 oil, and giving them a coat of paint after they are 

 in place but before the glazing is done, the roof 

 should receive a final painting after the glass is in 

 place, care being taken to "draw" 

 the putty wherever it 

 shows. It is economy 

 to repaint every 

 five years. 



Fie. 182. Even-span greenhouse with iron rafters. 



