in closed Fire-places. 499 



the heat applied to the bottom of the boiler ; and this 

 never fails to happen when a small fire is made in a 

 large fire-place, or when a part of the grate happens not 

 to be covered with burning fuel, especially when there 

 is no register to the ash-pit door. 



It should be remembered that whenever more air 

 enters a closed fire-place than is actually decomposed 

 by the burning fuel, all that superabundant air not only 

 is of no service whatever, but being itself heated at the 

 expense of the fire, and going off hot by the chimney, 

 occasions the loss of a quantity of heat that might have 

 been usefully employed. 



Ash-pit doors should always be furnished with reg- 

 isters of whatever size the fire-place may be, for they 

 are always indispensably necessary to the good man- 

 agement of a fire; and, where small fires are occa- 

 sionally made in large closed fire-places, the ascent of 

 air through that part of the grate that is not covered 

 with burning fuel should be prevented by sliding an 

 iron plate under the bars of the grate, or by some other 

 contrivance equally effectual. 



If the closed fire-places of boilers, great and small, 

 were properly constructed, and if due care were taken 

 to introduce in a proper manner and to regulate the 

 quantity of the air that is necessary to the perfect com- 

 bustion of the fuel, their grates might be made consid- 

 erably narrower than they now are, and the bottoms of 

 their boilers might be placed at a greater height above 

 them, from which arrangement several advantages would 

 be derived ; but as long as so little care is taken to keep 

 the door of the fire-place well closed, and to prevent too 

 much air from coming up through the grate by the 

 openings between its bars, the bottom of the boiler 



