16 



oiicniDs: now to grow them successfully. 



weather plenty of heat may be readily obtain(^d to ensure a 

 regular and perfect temperature without inducing strain or undue 

 pressure upon the boiler. Such a boiler as shown is one that 



can always be relied upon. In the event of making any 

 alteration in an existing house, or building new houses, it 

 is well to have more hot-water pipes fixed than are actually 

 sufficient, rather than not enough. For instance, a more genial 

 growing temperature is generated from, say, four pipes made 

 slightly warm, than from two pipes, v/hich would probably have 

 to be made very hot, and so give off diy, fiery heat. "When 

 there is more than one house heated from the same boiler, it is 

 best to have sufficient valves, so that the hot water can be turned 

 on to one house only, or to others also, as may be required. 



For the Cool Orchid house there must be sufficient heat at 

 command to maintain during severe weather a night temperature 

 averaging 45 degrees. For an Intermediate house there should be 



