184 SOME FEATURES OF THE DAIRY FARM 



commodious to permit 600 cubic feet of air space per cow. This, 

 as a necessity, however, must depend upon the rate of exchange 

 of the air. There should be some inflow and outflow of air even 

 in the largest stables. Too much circulation in winter is 

 obviously detrimental. In this aggravating matter the southern 

 dairyman, with his lattice-sided bams, has a decided advantage. 



The forces that produce ventilation in stables are (a) a 

 wind pressure against the side of the building tending to force 

 air in ; and a suction on the opposite side which tends to draw it 

 out; (&) the air friction over the top of the ventilator flue caus- 

 ing a draft as in tall chimneys and (c) the difference in the 

 temperature between the air of the stable and that of the outside. 

 The relative values of these three forces vtdll naturally vary 

 continually with conditions (Fig. 64). 



A Choice of Systems. — ^Poorly constructed stables will need 

 no system of ventilation. Many northern bams need battening 

 rather than more airing. 



During much of the year, even of winter in the northern 

 states, windows may safely be opened to hasten air circulation, 

 especially if the windows be hinged at the bottom and set to slant 

 inward when open (Fig. 65). 



On many occasions, when the wind is blowing strongly, a 

 curtain of common cotton cheesecloth or muslin, or burlap sack- 

 ing, may be tacked over the window. This is best done by 

 first tacking the muslin onto a frame and slipping the frame 

 into place when needed in cold weather. There are times and 

 conditions, however, when a more systematic ventilation is 

 desirable. For such there is probably none better than the 

 well known King system, developed by Prof. F. H. King, of 

 Wisconsin University. 



The essential features of the King system are: (l) An out- 

 going air duct and (2) an opportunity for air to enter to take 

 the place of that drawn out. The out-going ventilator shaft 

 should be comparatively large and smooth to reduce friction 

 within, as straight as consistent with the plan of the barn and ex- 

 tending up through the roof, not terminating in the hay loft but 

 open into the cupola. The air duct should be of wood or if of 



