Of Chimney Fireplaces. 529 



very apt to commit, is to be avoided. In chimneys like 

 that represented in this figure, where the jambs A and B 

 project far into the room, and where the front edge of 

 the marble slab <?, which forms the coving, does not 

 come so far forward as the front of the jambs, the work- 

 men in constructing the new covings are very apt to 

 place them, not in the line c A, which they ought to do, 

 but in the line c o, which is a great fault. The covings 

 of a chimney should never range behind the front of the 

 jambs, however those jambs may project into the room; 

 but it is not absolutely necessary that the covings should 

 make a finish with the internal front corners of the 

 jambs, or that they should be continued from the back 

 c quite to the front of the jambs at A. They may 

 finish in front at a and , and small corners, A, o, a, may 

 be left for placing the shovels, tongs, etc. 



Were the new coving to range with the front edge of 

 the old coving <?, the obliquity of the new coving would 

 commonly be too great; or the angle d c o would exceed 

 135 degrees, which it never should do ', or at least never by 

 more than a very few degrees. 



No inconvenience of any importance will arise from 

 making the obliquity of the covings less than what is 

 here recommended; but many cannot fail to be pro- 

 duced by making it much greater ; and as I know from 

 experience that workmen are very apt to do this, I have 

 thought it necessary to warn them particularly against it. 



Fig. 1 1 shows how the width and obliquity of the 

 covings of a chimney are to be accommodated to the 

 width of the back, and to the opening in front and 

 depth of the fireplace, where the width of the opening 

 of the fireplace is less than three times the width of the 

 new back. 



VOL. ii. 34 



