VENTILATION OF ORCHID HOUSES. 51 



VENTILATION OF ORCHID HOUSES. 



rpilIS is of itself of great importance, but the manner in wliicli it is 

 J- carried out is equally if not more important ; for if cold chilly air 

 be allowed to pass among the plants they will not thrive, and all the care 

 which has otherwise been bestowed on them will be in vain. The means 

 of ventilation should be provided by ventilators fixed near the ground, 

 close to the hot-water pipes, in order that the air may be warmed as it 

 enters the house, and before it reaches the plants. Fresh air should 

 also be admitted by underground pipes, so that in cold weather a current 

 of pure air may be maintained. This can be accomplished by laying 

 drain-pipes from the outside under the foundation to the inside under 

 the hot-water pipes, so that the air is warmed immediately upon entering 

 the house by passing over the heated pipes. In the houses here, there 

 are three ventilators on each side to each house in the brickwork opposite 

 the pipes. The ventilating shutters are made of wood, about two feet 

 long, and one foot wide ; sliding slate ventilators answer perhaps better. 

 There should be one glass ventilator at the south end, near the roof, and 

 one at the north end. We have also four small ventilators near the 

 ridge of the roof, two on each side, on hinges, opening from the inside 

 with cords ; they are intended to let out the top-heat, the egress of 

 which we have found very essential to the well-being of the plants. 



There are several contrivances for working the ventilators, the most 

 popular being by means of iron rods and levers running fi-om end to end of 

 the house, so that all the ventilators may be opened at once. There are 

 also many other appliances, but great care is required in using them, so 

 that in cold windy weather too much air may not be given, as by all the 

 ventilators opening at once air is given simultaneously all over the 

 house, whereas it may only be expedient to give it at one end. No rule 

 can be laid down for ventilation, as so much depends upon the locality 

 where the plants are grown, and the period of growth at which the 

 plants have arrived, as well as on the temperature of the house, but at 

 all times there should be a free circulation of air, for these plants do not 

 naturally live half their lives in a vitiated atmosphere, but of course the 

 amount to be given will have to be regulated by the state of the 

 outside temperature. 



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