CHAPTER XII 



CONSTRUCTION OF VENTILATORS AND FLOORS 



O""YNK of the Canadian houses has a unique venti- 

 I lator. Just before the gas is generated the 

 hinged trap is pulled up tightly against 

 the felt, and the rope fastened to a cleat on 

 the side of the house, as shown in Fig. 66. Before the 



FIG. 66 METHOD OF VENTILATING A FUMIGATING HOUSE 

 (AFTER LOCHHEAD) 



door is opened the rope is loosened, and the weight 

 brings down the trap and allows the gas to escape. A 

 ventilator of this kind having the trap opening into 

 the inside is protected from the weather, and is not 

 subject to the troublesome warping of exposed cap 

 ventilators. 



An Ohio arrangement. In his practical work in 



112 



