METHODS OF VENTILATION. 



277 



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

 does not expand f T of its bulk at 40 for each degree, but T 

 of its bulk at 32. 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 400. Volume at 803. Cubic inch. Cubic inch. 



491 + 8 : 491-J-48 : : 100 : 108 



5. The annexed cuts represent 

 an improved method of ventilating 

 lean-to houses, and by which the 

 Fig. 52. 



Fig. 53. 



Fisr. 51. 



* Wyman on Vent. 



