VENTILATION 67 



houses can be warmed, viz., by carefully constructed stoves, 

 or by hot-water pipes. There is no difficulty in carrying 

 these methods out, and low-pressure hot- water pipes are 

 absolutely free from danger. 



To raise the temperature of the air to 65° Fahr., it is 

 calculated that there should be twelve feet of low-pressure 

 piping for every 1,000 cubic feet of space. 



The whole question of heating hinges upon cost, which 

 fortunately renders it prohibitive for industrial stables, but 

 adds very little to the extravagance bestowed on some high- 

 class stables of the present day ; for cow-houses it is the 

 only solution of the problem of ventilation and warm air. 



Inlets and Outlets. 



From what has been said, it will readily be understood 

 that the inlets and outlets employed in natural ventilation 

 consist essentially of doors and windows. These only exist 

 in sufficient number and good position, when they have 

 been intentionally designed with this object in the construc- 

 tion of the building. Most stables and habitations for 

 animals are built without any reference to the requirements 

 of sanitary science, fresh air and sunlight being regarded 

 either as unnecessary or prejudicial. 



Ventilators are of two kinds, inlet and outlet ; the terms 

 need no definition. With artificial ventilation the function 

 as inlet or outlet is performed with fair regularity, but in 

 natural ventilation the term inlet and outlet is more of 

 theoretical than practical interest, for the reason that as 

 natural ventilation depends almost entirely on the wind, the 

 same opening may be an inlet one minute and an outlet the 

 next. 



What is aimed at is to have inlets in the wall and outlets 

 in the roof, but we shall have to show that openings in the 

 wall are always inlets on the windward side and outlets on 

 the lee side, while openings in the roof, as in ridge or 

 louvre ventilation, may be the same. It is not possible, 



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