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By controlled inlets and outlets is meant that it should ba 

 possible to cut off the whole or any part of the inlet and outlet by 

 means of some kind of damper or key. 



The controls are necessary for the reason that very cold air 

 being a great deal heavier than warm air compels a very much more 

 rapid circulation or inflow and outflow of air in very cold weather 

 than in warm. This must be controlled or temperatures will fall too 

 low in cold weather and rise too high in warm weather. 



The dimensions of shafts or cutlets and inlets given above, 

 allow for friction of air currents in the shaft, for, while 8 to 10 

 square inches per head in outlet area might be sufficient in very 

 large stables, the same relative area in a small stable would certainly 

 be found faulty. Outlet shafts must be neither too small nor too 

 large. Where materially exceeding the area per head given above, 

 they are likely to work unsatisfactorily and to be constantly dripping 

 in warm weather and freezing in cold, due to the air currents being 

 too sluggish. Where less in area by any considerable amount, they 

 are sure to be wet and dripping practically all the time and to carry 

 imp/uire air off too slowly. 



Many systems of ventilation have been devised and advocated. 

 The perfect system has not yet been thought out. It is, besides, 

 practically certain that a system capable of operating satisfactorily 

 under any set of conditions that might be imposed never will be 

 constructed. During the last ten years, the writer has tested out 

 some thirty or forty different schemes, systems or devices for venti- 

 lating farm buildings such as cow barns, horse barns and piggeries, 

 and has, during that time, learned two things very thoroughly. These 

 two items of information well-learned are: 



(1.) Good ventilation is a necessary and very profitable feature 

 of any stable. 



(2.) No known' system of ventilation is absolutely automatic or 

 faultless. 



It has also been possible to come to some conclusion as to the 

 relative merits and adaptability of the various systems tried out. 

 Many systems have shown more or less effectiveness, but of the thirty 

 and odd systems experimented with, I may say that the system 

 commonly known as the Rutherford System of Ventilation has proven 

 much superior to any other tried. The superiority of this system 

 is due to various features, the chief being: 

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