e Iron Grates or Chimneys, that when
any accident befals the one, the other may be ready to be in its place, the
Coals being first well kindled in it: but when the fire is neer spent, the
Chimney or Grate being haled up to the dore, is to be supplied with fresh
fuel.

The Figure of the Fabrick, Chimney, and all the parts thereof being
hereunto annexed, the rest will be easily understood.

[Illustration]

_Figure_ 1.

A. The _Hole_ for taking out the Ashes.

B. The _Square-hole_, into which the Tube or Pipe for conveying the Air is
to be fixed.

C. The _Border_ or _Ledge_ of _Brick_ or _Iron_, upon which the
_Iron-grate_ or _Cradle_, that holds the burning Coals, is to rest, the one
being exactly fitted for the other.

D. The _Hole_ where the _Cradle_ is set.

E. The woodden _Tube_, through which the Air is conveyed towards the
_Cradle_.

F. The _Dore_, by which the _Grate_ and _Cradle_ is let in, which is {82}
to be set 8. or 10. foot higher than the Hole D. and the _Shutter_ made of
Iron, or Wood that will not shrink, that it may shut very close, this
_Dore_ being made large enough to receive the _Cradle_ with ease.

G. The _Grate_ or _Cradle_, which is narrower below than above, that the
Ashes may the more easily fall, and the Air excite the Fire; the bottom
being barred as the sides.

H. The _Border_ or _Ledge_ of the _Cradle_, that rests upon the _Ledge_ C.

I. Four _Chains_ of _Iron_ fastned to the four corners of the _Cradle_, for
taking of it up, and letting of it down.

K. The _Chain_ of _Iron_, to which the other are fastned.

L. The _Pulley_ of _Iron_ or _Brass_, through which the _Chain_ passeth.

M. A _Hook_, on which the end of the _Chain_ is fastned by a _Ring_, the
_Hook_ fixed being placed in the side of the Dore.

N. A _Barr_ of _Iron_ in the Walls, to which the _Pulley_ is fastned.

The higher the _Shaft_ of the Chimney is, the Fire draws the Air the
better. And this Invention may be made use of in the _Pits_ or _Shafts_,
that are _Perpendicular_, or any wise inclining towards it, when there is
want of fresh Air at the bottom thereof, or any molestation by unwholsom
Fumes or Vapors:

* * * * *

_A way to break _easily_ and _speedily_ the hardest _Rocks_, communicated
by the same Person, as he received it from Monsieur _Du Son_, the
Inventor._

[Illustration]

Though the invention of breaking with ease, and dispatch, hard Rocks, may
be useful on