HYGIENE AND SANITATION 



171 



2. The action of the winds. 



In the process of diffusion the various gases present in the 

 building mix. This process is slow. It rnay mix by diffusion 

 through more or less porous walls or by cracks. The latter is 

 extremely dangerous should the draft be directed over the 

 roosts and strike the roosting birds. 



Winds are a great natural power of ventilation. The wind 

 sets the masses of air in motion, and is a means of flushing and 

 renewing the air in the buildings. Wind blowing 3 miles an 



Fig. 62. — Methods of hanging windows. 1, Swings from the side; 2, 

 the sash may be raised or lowered; 3, slides to one side; 4, swings in from the 

 top; 5, swings out from the bottom; 6, swings out at the top; 7, swings from 

 pivots in the center; 8, swings from pivots from the ends; 9, upper half 

 sash swings out from hinges above. 



hour (which is a little more than is perceptible) through a 

 ventilator 1 foot square in size will force the passage of 15,840 

 cubic feet of air in one hour time. Thus, through such a 

 ventilation in a space of 1000 cubic feet +he carbon dioxid 

 content of the air may be reduced from 0.6 per thousand to 0.1 

 per thousand. The objection to using wind as a ventilating 

 agent is that the velocity may mean a draft. 



In supplying heat to brooders and in their ventilating prob- 

 lems the fact that heated air becomes light and rises must be 

 kept in mind, thus the monitor and half monitor houses fur- 



