116 



HOTHOUSE-BUILDING. 



Fig. 117 the valley rafter, also one- 

 fourth the full size. 



The ridge rafters should always be in 

 one piece, as being the more readily 

 rendered waterproof, unless when their 

 framing and glazing are done before they 

 are put up. In this case each side of the 

 ridge must form a sash in one or more 

 pieces, as regards length ; the top and 

 bottom rails — that is, the ridge and gutter 

 rails — must then be so fashioned, that when 

 put up they may form one, and their 

 joining must be made good with white 

 lead, and covered with lead or copper. 

 Where the stretches are long, with- 

 out perpendicular tubular supports or 

 suspension-rods, it will be better to con- 

 struct the gutter rafter of cast-iron, and 

 to screw the bottom rail of the wooden 

 ridge to it. The iron gutter will act 

 better as a drain for the rain water than 

 a wooden one would do, and to a certainty 

 would be waterproof ; while, even though 

 the wooden gutter is covered with zinc, 

 lead, or copper, this seldom prevents the 

 water from finding its way into the house ; 

 and as the gutter itself must in such cases 

 be kept perpetually damp, its destruction 

 is certain to follow, and it will be the 

 first part of the structure to give way. 



The ridge and valley rafters are shown 

 above as if of timber. Wooden gutters 

 or valleys should, however, be used for 

 very temporary purposes only, such as 

 the Crystal Palace, in which this ma- 

 terial was used; and, notwithstanding 

 all the care taken of them, the leakage 

 through them in it was serious. In Plate 

 VIII. we have shown a form of gutter 

 which has been used in the new gardens 

 at Poltalloch and elsewhere. The idea of 

 this gutter arose when we were engaged 

 making out the drawings for the proposed 

 covered garden which has been just des- 

 cribed, so long ago as 1840 : and although 

 that design has not been executed, it has 

 been seen by many; and we have long 



ago been perfectly satisfied as to the prac- 

 ticability of covering in any space, how- 

 ever great, with glass upon the ridge- 

 and-furrow principle. This gutter is so 

 constructed that all necessity for wooden 

 ones is entirely removed. For description 

 and detailed drawings of it, vide Plate 

 VIII. and page 59. 



With ridge-and-furrow roofs there is 

 no necessity for having glass houses on 

 the lean-to principle — indeed, they ought 

 not to be so constructed : the valleys and 

 ridges should run level from side to side ; 

 and except in cold and exposed situa- 

 tions, where a back or northern wall may 

 be rendered necessary for shelter, it will 

 be better for the plants, as well as more 

 elegant, if all the sides are of glass to 

 within a foot of the ground. 



Sir Joseph Paxton recommends the 

 pediments to rise perpendicular to the 

 front upright sashes. We have placed 

 all ours at an angle of about 22°, the 

 angles of the roof being 25°. This is, 

 however, merely a matter of taste. A 

 rather massive wooden or cast-iron cornice 

 should cover the front wall-plate, which 

 will give the appearance of finish to that 

 part of the elevation, and may be made 

 to serve, at the same time, for taking 

 away the water that comes off the roof. 

 It is, however, better in most cases of 

 this kind to make the water pass down 

 through the cast-iron columns which 

 support the front of the house, and 

 which, with a view to this, as well as for 

 economy of metal, should be cast hol- 

 low. This plan is not so applicable to 

 houses of the lean-to form, as the front 

 sashes of these do not always reach to the 

 ground ; but for all houses whose points 

 of support are brought down to the 

 ground, this practice should be followed. 



In regard to the transparency of ridge- 

 and-furrow roofs, Mr Loudon remarks: 

 " If we take the area of the bases of the 

 ridges as the total area of the roof, and 

 then deduct from it the space occupied 

 by the bars forming the sides of the 

 ridges, and the ridge pieces and gutters," 

 these roofs " will not appear to admit the 

 same proportion of light as a roof in one 

 plane; but the practical result will be 

 different, in consequence of the sun's rays 

 being twice in the day perpendicular to 

 one-half of the roof, the advantage of 

 which to the plants will far more than 



