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H E KB A CEO US CALCEOL A HI A S. 



THE GREENHOUSE AND ITS FLOWERS. 



BY a greenhouse is meant a glass structure for the cultivation of plants that are too 

 tender to stand the winter in the open ground, and at the same time do not 

 require very much heat. A minimum temperature of 4odeg., rising Sdeg. to iodeg. 

 during the day, should he maintained throughout the winter, and as spring advances 

 and the sun gains power, an additional iodeg. may he allowed in the daytime. In erecting 

 a greenhouse, its shape, size, and position w ill of course depend upon the space it is to 

 occupy, hut where possible it should be a span roofed structure, as the light is then 

 admitted on all sides, and consequently the plants grow symmetrical! v. Very often the 

 only position available is close to a wall or dwelling-house, in which case a lean-to green- 

 house is built — that is, one in which the rafters slope direct from the wall at the back" 

 to the front of the structure. A house of this description has one disadvantage, as the 

 plants contained in it grow one-sided, but on the other hand it does not occupy the 

 space needed for a span roofed building. Where a moderately high wall already exists, 

 another form of house, partaking of the characters of both, is often used. This is known 

 as the hip roof or half span, which has full length rafters in front, and at the hack- 

 short ones, extending from the top of the wall to the apex of the roof. All of these 

 lean-to houses should, it possible, face due south or nearly so, but a span routed structure 

 is best running due north and south, as it gets a maximum of light, and the summer's 

 sun at mid-dav does not shine full on the glass. 



Ventilation is very important, and in a span roofed erection provision should he 

 made for it along the highest part of the roof, while the lights at the sides must be 

 arranged to open or shut at will. Besides this, when the hot-water pipes extend around 

 the outside of the structure a few spaces in the brickwork which can be closed by a 

 small trap are of service, since in cold weather, when the pipes are hot, these traps may be 

 opened, and thus cause a circulation of air without lowering the temperature, as the 



