170 



If for any reason it is not considered advisable to pass under 

 the wall, then an opening through the wall at the level of the floor 

 will serve the purpose. In such case it will, however, be found 

 necessary to so surround the opening into the stable as to give the 



Plan C Rutherford System. 



entering air current an upward tendency. The air current would 

 then follow the directions indicated by the double-headed arrows. As 

 to outlet, the same plan serves as was described in writing of venti- 

 lation plan ' B.' 



SYSTEM OF VENTILATION ' D/ THE KING SY JTEM. 



Like the system just discussed, the King system is probably 

 known to many readers. It has many admirers, and many have 



