BOOK I. GENERAL CULTURE IN FORCING STRUCTURES. 519 



and often also that against back walls. It is cheaper than wood, and, on account of its 

 lightness, fitter for the purpose, especially when placed on the roof, or against the end 

 lights. The distance at which the wires should be placed apart for grapes, is ten or 

 twelve inches ; for cherries or peaches, four or five. The distance of the wires from thd 

 glass, for grapes, a foot ; for peaches and nectarines, nine inches. But there should be 

 a lower trellis, with the wires placed at two feet apart, and a foot under the proper 

 trellis, on which to train the summer shoots of vines that are in a full-bearing state,, in 

 order that there may not be too great a confusion of fruit, shoots, and foliage. When 

 vines are trained up the rafters in a stove or green-house, they should not be nailed to 

 the beam ; but three rows of wire should be extended for them, at the distance of four 

 or five inches from each other, and three from the rafter ; being set out with studs of 

 wire, or of iron, made to screw into it, and with eyes to take in the wire. " 



2694. Ventilators. " The hot-house may require to be ventilated at times, when it 

 may be improper to open the sashes for that purpose. Ventilators are then useful. 

 They may be contrived in different forms, and may be placed in different situations. 

 If the hot-house have a shed behind it, they might be made to open, in the manner of a 

 common window, near to the top of the back wall ; and three in an ordinary-sized house 

 would be enough. I lately made four ventilators in a house that had no shed behind 

 it, in this manner : when the wall was raised to within a yard of its full height, aper- 

 tures were formed in the manner of a common chimney or fire-place, eighteen inches 

 wide, and two feet high, from which a small vent was carried through the coping. On 

 the top was fixed a horizontal tube, three inches square, and two feet long, with a 

 centre pipe fixed into the vent. The aperture or chimney was filled in front, with two 

 moveable panels or boards hung in the manner of common sashes, the one to move up 

 and the other down, for the admission of air through the tube at top, thus diverting or 

 breaking a strong current, which might be prejudicial to the grapes. Ventilators in 

 front, at the distance of six or eight feet from one another, may bo made thus : Pierce a 

 hole an inch diameter, through the bottom rail of the under sash if the house have no 

 upright glass, or through the upper rail of the upright sash, if it have. In this hole 

 insert a tin tube to fit, having a funnel mouth outwards, and a fine rose, like that of a 

 watering-pot, to fit to it inside. The tube should be made in lengths of two feet each, 

 that the air may be either diffused as it enters through the front, or be carried to the 

 centre of the house, or farther if thought necessary. When not in use, it should be 

 stopped with a cork or plug. When a full stream is wished, the rose need not be put 

 on ; but it should if the air be keen. In order the better to collect the air, the funnel 

 should be pretty large ; that is, about seven or eight inches diameter. With these and 

 with the ventilators at or near to the top of the back wall, as mentioned above, any hot- 

 house may safely be aired or ventilated, even in the severest weather; and also when it 

 may be improper to open the glasses, as during rain." 



2695. Annual repairs. The best gardeners clean the flues, white-wash the walls, and 

 paint the wood-work of hot-houses every year, or paint every other year. In general, 

 once in four or five years may suffice ; but every thing will depend on the purpose to 

 which the house is applied ; a system of early and severe forcing being evidently much 

 more trying for the roof than moderate sun-heat, aided by occasional fires. The breakage 

 of glass from frost amounts frequently, in the northern counties, to five per cent, on the 

 surface of the roof, especially in flat green-houses, and others, where there is not a sufficient 

 heat kept up to prevent the water from freezing in the unputtied interstices ; but we know 

 instances of pineries and other stoves where, for ten years, as many panes have not been 

 broken. A roof at an angle of not less than 45, diagonal or fragment glazing, or a 

 closed lap, seem preventives to breakage in cold-houses : Stewart's copper lap is still 

 more effectual, but produces a dark, heavy effect, not at all suitable to hot-houses of 

 any sort, and with difficulty admits of repairs. Our opinion is, that by using the best 

 crown glass, small panes, and a lap of not more than one eighth of an inch, no breakage 

 from frost will take place in any description of roof. If the work is performed in a 

 masterly manner, closing this lap by putty, lead, or copper, will be unnecessary even for 

 pineries or winter forcing. 



CHAP. VII. 



Of the general Culture in Forcing Structures and Culinary Hot-houses. 



2696. By general culture, we are here to understand the formation of the soil, the 

 arrangement of the trees or plants, and their general treatment when planted, in regard 

 to temperature, air, water, training, and other points of management. 



t 1 



