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POULTRY CULTTJEE 



nish ideal conditions for the escape of the hght vitiated air 

 arising from the birds, while the cooler outside air comes in at 

 a lower level, causing an upward current, relieving the building 

 of polluted air by the process of diffusion and air currents. 



Air shafts or tubes may be used, and can be used as either 

 inlets from the sides or outlets from the top or roof. Air 

 passing along a tube suffers loss from friction; thus, air moving 

 through a tube at a velocity of 8 feet per second would be 

 reduced to 4 feet per second on striking a right angle. The 



Fig. 63. — Methods of hanging doors. 1, The upper half swings out; 

 2, the door swings botli ways on a two-way hinge; 3, each half swings out; 

 4, the door swings out; 5, the door slides to one side on a track. 



smaller the tube, the greater the friction and the greater inter- 

 ference with the velocity per volume of air. Tubes should be 

 made with rounded or U-shaped curves instead of abrupt 

 straight right angles. 



One foot square will admit 15,000 cubic feet of air per hour 

 with a calm air; that is, with the velocity of 3 miles per hour. 

 Light air, that is, 8 miles per hour velocity, 0.4 square foot 

 will admit 15,000 cubic feet of air per hour. A light breeze, 

 or 13 miles an hour, 0.2 square feet will admit 15,000 cubic 

 feet of air per hour. 



