AIR AND VENTILATION 



101 



is sometimes raised to the method on account of the rain or snow 

 that sometimes finds its way in, but in the case of a double byre 

 or stable no harm can result as it would fall on the central passage, 

 and in the case of single buildings a gutter is suspended under 

 the ridge to catch and carry away any rain that may enter. 



When both sides of the ridge are open, the wind striking on 

 the weather side is directed upwards, passes across the opening 

 and, by producing an aspirating effect, assists the heated and foul 

 air to escape. The roof timbers that are exposed to the open are 

 protected from the weather by covering them with zinc or bitum- 

 astic sheeting. The sashes may be of wood or metal. 



The inlets for the fresh air are placed in the wall in front of 

 the cows, and are so constructed that the air on entering is deflected 

 in front of the animals. 



This system is without question the ideal method of ventilating 

 animal houses. It provides a perfectly free outlet for the foul air 

 and gives sufficient lighting without wall windows. 



Roof Lights or Skylights. Another form of combined lighting 

 and ventilating appliance is the roof light. It is most unsatis- 



FIG. 42. Three types of Fireclay Ridge Ventilators. 



factory in every respect. When made to open, as shown in figure 

 41, the wind blows inwards and downwards causing cold air-drops. 

 Skylights are usually situated about the middle of the roof slope, 

 and cause a dead hot air pocket in the upper part of the roof. The 

 hinges rust, quadrants or other opening appliances get out of order 

 with the result that they are often permanently open, shut or half 

 open. 



Fireclay Ridge Outlets. These are common on old-fashioned 

 and on many new but badly designed byres and stables. They take 

 a form similar to the ordinary fireclay T chimney can as shown in 

 figure 42. They are almost useless and usually of such a poor 

 outlet area as to be ineffective. 



Outlet Shafts. Outlet shafts and their uses have already been 

 referred to on page 94. They are often employed in lofted 

 buildings and may be circular or rectangular in section, the former 

 being the better, and more effective and economical. The material 



