SMOKY CHIMNEYS. 61 



A. Because fresh air gets access to 

 the fire more easily ; and as the air is not 

 so intensely heated, its motion is not so 

 violent. 



Q. Wliy do some CHIMNEYS SMOKE ? 



A. If fresh air is not admitted into a 

 room, as fast as it is consumed by the fire t 

 a current of air will rush down the chimney 

 to supply the deficiency, and bring the 

 smoke along with it. 



Q. WJiat prevents air being supplied, as fast 

 as it is consumed by the fire ? 



A. Leather and curtains round the 

 doors ; sand-bags at the threshhold and 

 on the window-frames; and other con- 

 trivances to keep out the draught. 



Q. Why is it needful for cold fresh air to be 

 so constantly supplied ? 



A. If water be taken with a pail out 

 of a river, other water will rush towards 

 the hole, as soon as the pail is lifted out ; 

 and if air be taken from a room, (as it 

 is, when some of it goes up the chimney) 

 other air will rush towards the void to 

 fill it up. 



Q. Why will it come down the chimney ? 



G 



