THE ORCHID HOUSE. 59 



A brick flue may be used for heating, with pans placed 

 on the top for the evaporation of water, but care must 

 be taken to prevent any escape of smoke or gas into the 

 house. 



VENTILATION AND TEMPERATURE. 



A careful system of ventilation is of great importance. 

 Let us bestow every care upon Orchids, all will be in 

 vain if we allow cold air to pass among them : the plants 

 will not thrive. Ventilators should therefore be provided 

 near the ground in the front wall close to the heating 

 pipes so that the air may be warmed as it enters the 

 house ; they may also be constructed in the brick- work at 

 the north and south ends. These ventilating spaces may 

 be closed by wooden shutters or by sliding slates ; they 

 should be two feet long and one foot wide, and should be 

 left every twenty feet ; if the house is span-roofed they 

 should be on each side, 



If the top lights are made to slide or rise, any ventila- 

 tion desired may be easily afforded ; but if not, ventilators 

 should be placed in the ends of the house near the roof, 

 which is a far better arrangement, but even with sliding 

 sashes the ventilators on the front must not be dispensed 

 with. As a general rule the air of the Orchid house 

 should be changed once a day ; this is best done by ven- 

 tilating into other houses ; therefore it is a good plan to 

 have the Orchid house a central house. The temperature 

 should be about 50 in the coldest weather ; if allowed to 

 fall much lower the plants will be chilled. During the 

 season of rest, which with most Orchids is from November 

 to February, the temperature should not be much higher. 

 This season of rest is essential to the production of a 



