CHAPTER VIII 



VENTILATION AND VENTILATING 

 MACHINERY 



Greenhouse ventilation has not yet been 

 worked out with the same care and precision 

 as has the ventilation of dwellings, public 

 buildings, or even barns for the use of live 

 stock. On the other hand, greenhouses are 

 seldom or never built without some special 

 attention being given to the question of 

 ventilation, whereas, dwellings and even 

 public buildings are often erected without 

 any reference whatever to this important 

 subject. 



This anomaly may be partly explained by 

 the following facts: (i) The transpiration of 

 plants is not so well understood nor is it so 

 easily measured as is the transpiration of ani- 

 mals. (2) Windows are necessary in dwell- 

 ings and public buildings to admit light and 

 they may be utilized, when necessary, to pro- 

 vide ventilation. (3) In greenhouses, ventila- 

 tion is not only provided for the purpose of 



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