VENTILATION OF EAELY FOllCING-HOUSES. 



113 



motion without admitting the external air; but it is obvious 

 that both might be combined, as in the following diagram (15), 

 which also represents an improvement upon the original plan. 



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A ^ 



„ .1 1 ! 1 1 1 U 



In this arrangement it will be seen that the cold external air 

 is supposed to pass through a heated chamber separate from the 

 tank, but admitting of communication for the purpose of supply- 

 ing moisture, if necessary. Thus the external air may be warmed 



VOL,. I. 1 



