Smithsonian Report, 1895. 



Plate V. 



7;,v.'.','"vv.';. ,, :'|" l "|'T^* 



sssssgssma " •'■'■' ■■■■ 



10.— Brown-SSquard experiment with expired air. 



11. —Ascent of warm air. 



A B 



12.— Principles of ventilation and heating. 



The Air of Towns. 



