FARM SANITATION 



533 



fresh air fast enough to prevent the air from becoming foul 

 beyond the permissible standard. The process of dilution 

 may be accomplished in at least four different ways, as follows: 



1. By a process of diffusion through cloth curtains. 



2. By the action of winds. 



3. By the difference in weight of masses of air of un- 

 equal temperature. 



4. By mechanical methods. 



Cloth Curtain Ventilators. Poultry houses quite gener- 

 ally and dairy barns in several instances have been ventilated 

 by providing thin muslin or cheesecloth curtains in place of 

 the usual window glass. The theory of ventilation in this 

 case holds that there is a diffusion of the foul air outward and 

 the pure air inward through these 

 curtains. Experiments which have 

 been conducted to date, to deter- 

 mine definitely the efficiency of this 

 system, would indicate that it is 

 unsatisfactory and unreliable. It 

 is quite impossible with any rea- 

 sonable amount of curtain surface 

 to provide the necessary pure air. 



Action of Winds. The action 

 of the winds is one of the sim- 

 plest methods of producing venti- 

 lation. For instance, the wind pro- 

 vides ventilation when two windows Fig. 321. A window ar- 



, .. . , „ ranged so as to allow air to 



are Opened On Opposite Sides Of a enter with the least draft. It 



i mj. o i i ma y be hinged at the bottom 



DUllamg. feUCh an arrangement and made to close between the 



would not be satisfactory on ac- 

 count of the direct drafts produced, subjecting the animals 

 to chills. The dangers from drafts are overcome to a large 

 extent by providing suitable inlets and outlets. 



