Of Chimney Fireplaces. 539 



at the same time, it will be found to be very difficult to 

 get the fires to burn, and the rooms will both be filled 

 with smoke. 



One of the fires that which is made in the chimney 

 where the construction of the fireplace is best adapted 

 to facilitate the ascent of the smoke ; or, if both fireplaces 

 are on the same construction, that which has the wind 

 most favourable, or in which the fire happens to be 

 soonest kindled will overcome the other, and cause 

 its smoke to be beat back into the room by the cold air 

 which descends through the chimney. The most ob- 

 vious remedy in this case is to provide for the supply 

 of fresh air necessary for keeping up the fires by open- 

 ing a passage for the external air into the room by a 

 shorter road than down one of the chimneys ; and when 

 this is done, both chimneys will be found to be effectu- 

 ally cured. 



But chimneys so circumstanced may very frequently 

 be prevented from smoking, even without opening any 

 new passage for the external air, merely by diminishing 

 the draught (as it is called) up the chimneys ; which 

 can best be done by altering both fireplaces upon the 

 principles recommended and fully explained in the fore- 

 going chapters of this essay. 



Should the doors and windows of a room be closed 

 with so much nicety as to leave no crevices by which a 

 supply of air can enter sufficient for maintaining the fire, 

 after the current of air up the chimney has been diminished as 

 much as possible by diminishing the throat of the fireplace, 

 in that case there would be no other way of preventing 

 the chimney from smoking but by opening a passage for 

 the admission of fresh air from without; but this, I 

 believe, will very seldom be found to be the case. 



