Of Chimney Fireplaces. 521 



may be used for preventing it. But of this subject I 

 shall treat more fully hereafter. 



It frequently happens that the iron backs of grates 

 are not vertical, or upright, but inclined backwards. 

 When these grates are so much too wide as to render it 

 necessary to fill them up behind with fire-stone, the in- 

 clination of the back will be of little consequence ; for 

 by making the piece of stone with which the width of 

 the grate is to be diminished in the form of a wedge, or 

 thicker above than below, the front of this stone, which 

 in effect will become the back of the grate, may be 

 made perfectly vertical, and, the iron back of the grate 

 being hid in the solid work of the back of the fireplace, 

 will produce no effect whatever; but, if the grate be 

 already so narrow as not to admit of any diminution of 

 its width, in that case it will be best to take away the 

 iron back of the grate entirely, and, fixing the grate 

 firmly in the brickwork, cause the back of the fireplace 

 to serve as a back to the grate. This I have very fre- 

 quently done, and have always found it to answer per- 

 fectly well. 



Where it is necessary that the fire in a grate should 

 be very small, it will be best, in reducing the grate with 

 fire-stone, to bring its cavity, destined for containing the 

 fuel, to the form of one half of a hollow hemisphere ; 

 the two semicircular openings being one above, to 

 receive the coals, and the other in front, or towards the 

 bars of the grate ; for when the coals are burned in such 

 a confined space, and surrounded on all sides, except in 

 the front and above, by fire-stone (a substance peculiarly 

 well adapted for confining heat), the heat of the fire will 

 be concentrated, and, the cold air of the atmosphere 

 being kept at a distance, a much smaller quantity of 



