524 Of Chimney Fireplaces. 



these 4 inches end (which must be marked with chalk, 

 or with a pencil), will show how far the new back is to 

 be brought forward. 



Through/draw the line h, parallel to the line A B, 

 and this line g h will show the direction of the new 

 back, or the ground line upon which it is to be built. 



The line f/will show the depth of the new fireplace ; 

 and if it should happen that c /is equal to about one 

 third of the line A B, and if the grate can be accom- 

 modated to the fireplace instead of its being necessary 

 to accommodate the fireplace to the grate, in that case 

 half the length of the line f/is to be set off from /on 

 the line g f h, on one side to k, and on the other to /', 

 and the line ; k will show the ground line of the fore- 

 part of the back of the chimney. 



In all cages where the width of the opening of the 

 fireplace in front (A B) happens to be not greater, or 

 not more than two or three inches greater, than three 

 times the width of the new back of the chimney (/' k\ 

 this opening may be left, and lines drawn from / to 

 A and from k to B will show the width and position 

 of the front of the new covings ; but when the open- 

 ing of the fireplace in front is still wider, it must be 

 reduced, which is to be done in the following manner. 



From c, the middle of the line A B, c a and c b 

 must be set off equal to the width of the back (/ k\ 

 added to half its width (//), and lines drawn from / to 

 a and from k to b will show the ground plan of 

 the fronts of the new covings. 



When this is done, nothing more will be necessary 

 than to build up the back and covings, and, if the fire- 

 place is designed for burning coals, to fix the grate in its 

 proper place, according to the directions already given. 



