84 VETEEINAEY HYGIENE 



METHODS OP EXAMINING THE SUFFICIENCY OF 

 VENTILATION. 



The sufficiency of ventilation is ascertained by calculating 

 the cubic and superficial space available per head, the 

 amount of fresh air supplied, and the composition from a 

 chemical and biological standpoint of the air of the build- 

 ing when fully occupied. 



Measurement of cubic contents is obtained by multiplying 

 the length, breadth, and height of the building into each 

 other.* Where roofs are angular, these are calculated 

 separately and added. As a rule no important deductions 

 have to be made for projections and fittings, but supporting 

 pillars, if large, should certainly be deducted from the 

 calculated air-space, and so should the space occupied by 

 the bodies of the animals ; for the large herbivora deduct 

 from 18 to 20 cubic feet per head. 



The cubic contents of a cylinder are obtained by multiply- 

 ing the area by the height. The area of a circle is obtained 

 by multiplying twice the diameter by '7854. These rules 

 enable the contents of stable pillars to be ascertained. 



The area of a rectangle is obtained by multiplying two 

 sides which are perpendicular to each other. This rule 

 gives the superficial area of a stall or stable. 



The area of a triangle is obtained by multiplying the 

 height by half the base, or the base by half the height. The 

 application of this rule enables the contents of an angular 

 roof to be calculated. 



Here is an example of the above measurements : — 



A stable for ten horses, with an angular roof, has the 

 following measurements — 



Feet. 

 Breadth ... ... ... ... ... 15 



Length ... ... ... ... ... 60 



Height to spring of roof ... ... ... 15 



Height of angular roof ... ... ... 5 



Supporting pillars, 8 ; diameter, 6 inches ; height, 15 feet. 



* In measuring buildings it considerably simphfies the calculations 

 if the measurements are made in feet and decimal parts of a foot, and 

 not in feet and inches. For the decimal parts of a foot, see Appendix. 



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