and chimney foundation. If you fail to dig this
foundation the frost will work the ground under your chimney and the
chimney will work with the ground, causing it either to upset or to tilt
to one side or the other and spoil the looks of your house, even if it
does not put your fireplace out of commission.

Stone Chimney

In laying up the stones for your chimney, remember that it makes no
difference how rough and uneven it is upon the outside. The more uneven
the outside is the more picturesque it will appear, but the smoother and
more even the inside is the less will it collect soot and the less will be
the danger of chimney fires. Lay your stones in mortar or cement. See that
each stone fits firmly in the bed and does not rock and that it breaks
joints with the other stone below it. By breaking joints I mean that the
crack between the two stones on the upper tier should fit over the middle
of the stone on the lower tier; this, with the aid of the cement, locks
the stones and prevents any accidental cracks which may open from
extending any further than the two stones between which it started. If,
however, you do not break joints, a crack might run from the top to the
bottom of the chimney causing it to fall apart. Above the fireplace make
four walls to your chimney, as you did with your stick chimney (Fig. 271),
and let the top of the chimney extend above the roof at least three feet;
this will not only help the draught but it will also lessen the danger of
fire.

XLIII

HEARTHSTONES AND FIREPLACES

IN erecting the fireplace for your cabin the stone work should extend into
the cabin itself, thus protecting the ends of the logs from the fire. The
stone over the top of the fireplace (_A_, _B_, Fig. 274) rests upon two
iron bars; these iron bars are necessary for safety because, although the
stone _A_, _B_ may bridge the fireplace successfully, the settling of the
chimney or the heat of the fire is liable to crack the stone, in which
case, unless it is supported by two flat iron bars, it will fall down and
wreck your fireplace. The stone _A_, _B_ in Fig. 275, has been cracked for
fifteen years but, as it rests upon the flat iron bars beneath, the crack
does no harm.

Fig. 274. Fig. 275.

[Illustration: Fireplace in author's cabin, and suggestion for stone and
wood mantel.]

In Fig. 274 (the ends of the fireplace) the two wing walls of it are built
up inside the cabin to support a plank for a mantelpie