LIVE STOCK breeders' ASSOCIATION. 201 



which contains more than 3.3 per cent of air once breathed, and that 

 with stables, having reasonably warm ceilings and walls, the moisture, 

 given off by the animals from skin and lungs, will be removed rapidly 

 enough so as not to condense upon the walls. If our domestic animals 

 were obliged to stand continuously in the water from which they must 

 drink, as they do in the air they are compelled to breathe, we would 

 have no difficulty in realizing that a rapid flow of water across the 

 floor of a stable of 40 cows, even if it were deep, would have to be 

 maintained in order that it should be sufficiently pure to be wholesome 

 drinking water. 



Suppose a cow were placed in an air-tight compartment 40 feet 

 wide and 10 feet to the ceiling, how long would it have to be to hold 

 enough so that at the end of 24 hours only 3.3 per cent of the air would 

 have been once breathed? 231 feet. The volume of air required for 

 a horse during 24 hours would necessitate a similar room 262 feet long; 

 for a pig, one 82 feet; and for a single sheep, one 55 feet in length. 

 From these statements it will be clear that the provision for needed air 

 supply must be one of rapid change of air in the stable, rather than one 

 of capacity. The necessity is for cubic feet of air moving continually 

 in and out of the stable, rather than cubic air in the stable at any one 

 moment. 



To supply 20 cows with air of the degree of purity stated requires 

 a ventilating flue 2 feet by 2 feet, through which the air moves at the 

 rate of 3 miles per hour or 264 feet per minute. A flue of this size, 

 too, will be required to supply 17 horses, 51 pigs, or yj sheep. Double 

 the number of animals named will require ventilation flues having nearly 

 double the area of cross-section ; while for smaller numbers the size 

 should be larger than in proportion to the number of animals to be 

 served, for the reason that in flues of small cross-section there is rela- 

 tively more friction and the velocity of the air current is less. The most 

 common mistake made is in erecting flues too small. Several small 

 flues arc never equal in capacity to a single one of the same total cross- 

 section. 



ESSENTIAL FEATURES OF A VENTILATING FLUE. 



A good ventilating flue should possess all of the essential features 

 and surroundings which are necessary for a perfect chimney. To pro- 

 duce the strongest draft it must be straight, either round or as nearly 

 square in cross-section as possible, because then the friction is least; 

 the walls must be permanently air-tight, so that no air may enter except 

 from the stable ; its top should rise well above th<e ridge of the roof ; 

 and it is best, though not necessary, to place it af^ m-j^x '(S^ center ojt the 



