259 



and admitting air at windows or openings near the eaves 

 (fig. 283), thus sweeping all the hot air out by tlie cur- 

 rent produced ; or the oppressive heat of half-story bed- 

 rooms may be similarly avoided, by creating a current of 

 air between the roof and the plastering (fig. 284). Two 

 modes may be adopted, as represented on each side of the 

 figure. 



Fig. 285 represents Griffith's patent ventilator, for chim- 

 neys, and for giving a current of air through apartments. 

 It is made of iron, working as a screw fan^ the slightest 

 wind causinof it to revolve and establish a current throusfh 

 the pipe which it surmounts. 



