METHODS OF VENTILATION. 



277 



of a gas at 40° would occupy at 80°, we must remember that it 

 does not expand ^^y of its bulk at 40° for each degree, but :f^y 

 of its bulk at 82°. Now, 491 parts of air at 32° become 492 

 at 33°, become 493 at 34°, and so on. Hence we can institute 

 a proportion between the volume at 40° and that at 80°. ^ 



Vol. at 4CP. Volume al 80^. Cubic inch. Cubic inch. 



491 + 8 



491 + 48 



...........^ 



: : 100 : 108 



5. The annexed cuts represent 

 an improved method of ventilating 

 lean-to houses, and by which the 

 Fig. 52. 



[ 



o c^ 



Fig. 53. 



Fig. 51. 



* Wyman on Vent. 



