en inches
for the depth of the fire-place. The next consideration will be the
width which it will be proper to give to the back. This, in fire-places
of the old construction, is the same with the width of the opening in
front; but this construction is faulty, on two accounts; first, because
the covings being parallel to each other, are ill contrived to throw out
into the room the heat they receive from the fire in the form of rays;
and, secondly, the large open corners occasion eddies of wind which
frequently disturb the fire and embarrass the smoke in its ascent, in
such a manner as to bring it into the room. Both these defects may be
entirely remedied, by diminishing the width of the back of the
fire-place. The width which in most cases it will be best to give it, is
one-third of the width of the opening of the fire-place in front. But it
is not absolutely necessary to conform rigorously to this decision, nor
will it always be possible. Where a chimney is designed for warming a
room of moderate size, the depth of the fire-place being determined by
the thickness of the breast to thirteen inches, the same dimensions
would be a good size for the width of the back, and three times thirteen
inches, or three feet three inches, for the width of the opening in
front, and the angles made by the back of the fire-place, and the sides
of it, or covings, would be just 135 degrees, which is the best position
they can have for throwing heat into the room. In determining the width
of this opening in front, the chimney is supposed to be perfectly good,
and well situated. If there is any reason to apprehend its ever smoking,
it will be necessary to reduce the opening in front, placing the covings
at a less angle than 135 degrees, and especially to diminish the height
of the opening by lowering the mantle. If from any consideration, such
as the wish to accommodate the fire-place to a grate or stove already on
hand, it should be wished to make the back wider than the dimension
recommended, as for instance, sixteen inches; it will be advisable not
to exceed the width of three feet three inches for the opening in front,
as in a very wide and shallow fire-place, any sudden motion of the air
in front would be apt to bring out puffs of smoke into the room. The
throat of the chimney being reduced to four inches, it will be necessary
to make a provision for the passage of a chimney sweeper. This is to be
done in the following manner. In building