CONSERVATORIES, GREENHOUSES, VINERIES AND FRUIT HOUSES. 



Whatever the form of the house, however, it is important that it should not be 

 made higher than is necessary, so as to limit the cubical area to be heated. It is 

 admitted by the most capable gardeners that glasshouses are usually built more loftily 

 than is necessary, in some instances so much so as to make successful plant growing 

 impossible. Probably the best growers in this country are those who supply Covent 

 Garden Market, whose plant and fruit houses are much lower than those usually met 

 with in private establishments. 



Another important point is the pitch of the roof. The use to which the house is 

 to be put will largely determine this, but, where there is much choice, four other factors 

 should be considered. The first of these is, that the natter the pitch is, the more evenly 

 the heat will be distributed, while, if it is steep, all the hot air will accumulate near the 



LEAN TO VINERY 



FIG. 282. 



LEAN TO PEACH-HOUSE 



FIG. 283. 



VittCRY WITH BACK LICHT 



FIG. 284. 



apex, and thus a flat pitch tends to sturdy growth. Again, a low pitch allows of all 

 the plants being brought very near to the glass, and this also is very desirable if they 

 are not to run away in long bare stalks. A third consideration is that by making the 

 roof steeper, drip, that is the dropping of condensed water vapour from the roof on to 

 the plants, is avoided ; while the fourth and most important consideration of all is to find 

 a pitch which will admit the most light. This means that the slope of the roof must 

 be about at right angles to the direction in which the rays of the sun will strike it 

 at the time of the year when sunlight is most precious, that is, in the Winter months. 

 At the worst period of all, the sun's altitude is only fifteen degrees, which would of 

 course involve an impossibly steep roof ; but extreme steepness is not of so much moment 

 as might be supposed, for if the sun's rays strike the glass as much as thirty degrees 



FIG. 285. 



FIG. 286. 



FIG. 287. 



out of the perpendicular, the loss in efficiency is only 2\ per cent. These various 

 factors, if considered independently, would result in very different slopes, and it is there- 

 fore a case for compromise and adjustment. This process coupled with experience has 

 resulted in most span houses, such as those shown in illustrations Nos. 285, 286 and 287, 

 being constructed with a pitch of twenty-six degrees from the horizontal, which gives a 

 rise of six inches in every foot of breadth, while the lean-to houses, such as those shown in 

 illustrations Nos. 282, 283 and 284, are made with from this span upwards according to 

 the use to which they are to be put, peach houses often having a very steep pitch indeed 

 Gables over doorways, the principal plant houses in a range having the gable end 

 towards the spectator as he views 1 the range as a whole (111. No. 280), and conservatories, 



223 



