THIRTY USEFUL DEVICES 



101 



that can be closed tightly by means of cords or chains 

 answers the purpose admirably and may be constructed 

 with little expense. The ease and convenience of 

 operation are important points, and should not be 



Way 



FIG 96 I INTERIOR CONVENIENCES 



neglected when the building is being constructed. It 

 is a simple matter for the attendant to open or close 

 a ventilator as he passes through the house if the 

 appliances for operating it are within easy reach. 



