^^5y^ J^OaeS ItJAV 75 



out, the fresh air should enter through the walls at the ceiling. This brings 

 the fresh air to the cows' noses before it has any chance of being contaminated 

 by passing over the gutters. 



6. The foul air outtakes should be so located as to insure a thorough 

 diffusion of the fresh air throughout the stable, leaving no "dead" spots of 

 foul air at the ends, sides or center of the barn. 



7. The outside opening of the outtake flue must be properly capped. We 

 have for many years been engaged in the designing of dairy barns which have 

 called for systems of ventilation; and during these years we have been called 

 on to examine hundreds of barns in which the ventilation was not working 

 properly. Very frequently the trouble has been traced to an improperly con- 

 structed cupola. 



The most frequent fault found is the tendency to make the cupola too 

 small. If the cupola is too small, the system will not work satisfactorily, 

 regardless of how carefully the balance of the system may be installed. 



Another frequent difficulty is found in making the cap too low, smothering 

 the draft. 



And sometimes trouble is caused by going to the other extreme, making 

 the cap too high, so that the wind blows down the outtake flues, forcing the 

 air out through the intake flues. 



One IS apt not to understand just how large a ventilator should be unless 

 the subject has been studied very carefully; and when a cupola is home-made, 

 or purchased in a local shop, one is likely to underestimate the size required. 



8. Ventilators of correct construction should be used in connection with 

 the system, to secure the added benefit of a forced draft or suction to pull foul 

 air out of the barn. These ventilators should be properly connected to the 

 outtake flues. See page 56. 



9. When the barn does not contain the number of animals for which it 

 is designed, the intakes may be partially closed, so as to restrict ventilation to 

 an amount proportioned to the number of cattle in the barn. This is some- 

 times necessary in a partially filled barn, to keep it from getting too cold. 

 There must, however, be enough cows in the stable to generate sufficient heat 

 to maintain the difference in temperature between the stable and out-of-doors 

 to secure the most efficient ventilation. 



Degree of Ventilation Necessary 



Authorities differ as to the amount of air to be provided in a stable, but at 

 the present time they seem well united in considering that when it does not 

 contain over 3'/). per cent of air once breathed, fairly good ventilation would 

 be provided. 



