VENTILATION 85 



Ascertain the available cubic contents after making the 

 usual deductions. 



The first thing is to estimate the body of the building • 

 this is ' 



15 X 60 X 15 = 13,500 cubic feet. 



The contents of the angular roof are next ascertained. 

 _ In the figure which represents the roof under considera- 

 tion, A B is the base, which we know from the breadth of 

 the building to be 15 q 



feet, and C is the 

 vertical angle ; the /^ 



distance from C to ^-^ 



the base, shown by ^^ 



the dotted line, is the 

 height of the angle, given as 5 feet. The rule to obtain 

 the area of this angle is to multiply the base by half the 

 height, or the height by half the base ; taking the former, 

 the sums stands, 15x2^ = 37^ square feet of area, multi- 

 plied by 60 (the length of the building) = 2,250 cubic feet 

 for the roof alone. 



Adding this to the amount already found for the body of 

 the building, gives 15,750 cubic feet for the gross con- 

 tents of the stable. 



From this make the deductions, viz., ten horses occupy- 

 ing 18 cubic feet each = 180 cubic feet ; eight pillars, 

 6 inches diameter, 15 feet high — each pillar therefore 

 occupies 11'78 cubic feet of space x 8 = 94^ cubic feet. 



Deducting 180-I-94J cubic feet from the gross amount 

 found, leaves within a fraction 15,476 cubic feet of space 

 for the ten horses ; or 1547*6 cubic feet per head. 



The next step in examining the sufficiency of ventilation 

 is to obtain the size of all the doors and windows, and any 

 other means of ventilation which may exist, such as 

 Sheringham valves, tubes, ridge opening, etc. 



Observe whether there are opposite doors and windows, 

 the place on which they open, whether the air is likely to 

 be well mixed in its passage across the stable. Eegard all 

 the openings on one side of the building as inlets, and calcu- 



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