SMOKY CHIMNEYS. 63 



A. Because the draught of a short 

 flue is too slack to carry the smoke up 

 the chimney. 



Q. Why is the DRAUGHT of a SHORT FLUE 

 more SLACK that that of a long one ? 



A. For many reasons. 1st The 

 fire is always dull and sluggish if the 

 chimney be too short. 



2ndly The smoke rolls out of the 

 chimney, before it has acquired its full 

 velocity. 



3rdly The wind, rain, and air, have 

 more influence over a short funnel, than 

 over a long one. 



Q. Why is the FIRE always DULL and sluggish 

 if the CHIMNEY-FLUE be very SHORT ? 



A. Because the draught is so bad : 

 and as the rarefied air passes up the 

 chimney very tardily, fresh air flows as 

 tardily towards the fire, to supply it with 

 oxygen. 



Q. On what does the INTENSITY of fire depend ? 



A. The intensity of fire is always in 

 proportion to the quantity of oxygen with 

 which it is supplied. 



G2 



