34 Of the Management of Fire 



rises up perpendicularly from below the fire-place into 

 the fire. By surrounding the fire on all sides by a 

 wall, the cold atmosphere is prevented from rushing in 

 laterally from all quarters to supply the place of the 

 heated air or vapour, which, in consequence of its in- 

 creased elasticity from the heat, continually rises from 

 the fire, and this causes the current of air below (the 

 only quarter from which it can with advantage flow 

 into the fire) to be very strong. 



But in order that a fire-place may be perfect, it 

 should be so contrived that the combustion of the fuel 

 and the generation of the heat may occasionally be 

 accelerated or retarded, without adding to or diminish- 

 ing the quantity of fuel ; and, when the fire-place is 

 closed, this may easily be done by means of a register 

 in the door which closes the passage leading to the ash- 

 pit; for, as the rapidity of the combustion depends 

 upon the quantity of air by which the fire is fed, by 

 opening the register more or less, more or less air will 

 be admitted into the fire-place, and consequently more 

 or less fuel will be consumed, and more or less heat 

 generated in any given time, though the quantity of 

 fuel in the fire-place be actually much greater than what 

 otherwise would be sufificient. Fig. 9 shows the form 

 of the register I commonly use for this purpose. 



In order that this register may produce its proper 

 effect, a valve, or a damper, as it is commonly called, 

 should be placed in the chimney or canal by which the 

 smoke is carried off ; which damper should be opened 

 more or less, as the quantity of air is greater or less 

 which is admitted into the fire-place. This register 

 and this damper will be found very useful in another 

 respect, and that is, in putting out the fire when there 



