VENTILATION. 



115 



essary that an outlet tube should chanp^e its course, it should be 

 done in a curve rather than by a right angle bend. All parts of 

 such shafts and tubes siiould be accessible for cleaning purposes, 

 as it is no uncommon thing for them to become obstructed by cob- 

 webs and dust so as to be practically useless. In a general way 

 the outlet tube if near an outside wall, should be placed on the 

 south side of the building, so as to economize the heat of the 

 sun in rendering it more effective. Central outlet tubes are gen- 

 erally more efficient. 



FIG. 44. VENTILATION. (PAIOE.) 

 Sheringham window in section. sheringham' window, opening in- 



ward. Seen from outside. 



Several small inlets are always better than one or two large 

 ones, as they admit the same volume of air, and give it better dis- 

 tribution, without direct currents. 



Sheringham valve. — The Sheringham valve is simple and 

 efficient for a stable of suitable construction. This system con- 

 sists essentially of windows hinged at the bottom and guarded 

 at the sides as to make troughs as the windows open inward. 

 This gives the air an upward current, passing over the backs of 

 the animals and settling down without direct current. There 

 should be two sets of windows on each side, the lower windows 

 being generally used for inlets on the windward side, and the 

 higher windows for the outlets on the leeward side. This af- 

 fords a very simple, inexpensive and easily manipulated method 

 of ventilation, and may be combined with ventilating shafts. 

 Ventilating shafts should have openings near the ceiling, and also 



