A MACHINE, CONTRIVANCE, OR DEVICE FOR THE PREVENTION AND CURE OF SMOAKING CHIMNIES
Year: 1795

page_text: .CROOK AND GERMAN'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
CROOK, of Great Queen Street, Lincoln's Fields, in the County of Middle-
sex, Coachmaker, and THOMAS GERMAN, of Baldwin's Gardens, in the said
County of Middlesex, Gentleman, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by:
His Letters Patent under the Great Seal of Great Britaiu, bearing date
at Westminster, the Twelfth day of January, in the thirty-fifth year of His
reign, give and grant unto us, the said Thomas Crook and Thomas German,
His especial licence that we, the said Thomas Crook and Thomas German,
during the term of years therein mentioned, should and lawfully might
use, exercise, and vend, within England, Wales, and the Town of Berwick
upon Tweed, our Invention of "A MACHINE, CONTRIVANCE, OR DEVICE FOR THE
PREVENTION AND CURE OF SMOAKING CHIMNIES;" in which said Letters Patent
there is contained a proviso obliging us, the said Thomas Crook and Thomas
German, by an instrument in writing under our hands and seals, to cause a
particular description of the nature of our said Invention, and in what manner
the same is to be performed, to be inrolled in His Majesty's High Court
of Chancery within one calender month after the date of the said recited
Letters Patent, as in and by the same (relation being thereunto had) may
more fully and at large appear.

page_text: :
NOW KNOW YE, that in compliance with the said proviso, we, the said
Thomas Cook and Thomas German, do hereby declare that our said Invention
of a machine, contrivance, or device for the prevention and cure of smoaking
chimnics is described in manner following (that is to say):
The first principles of this discovery depend on keeping the air immediately
above the fire as it successively passes upward so much heated and rarified,
that is, ascends with great force and rapidity. And the better to explain the
nature and reason on which the Invention is founder it will not be improper
to mention a very common experiment dayly practised by almost every person
where a coal fire is used. When the fire is low, and in danger of going out,
it is usual to lay the fire shovel horizontally over the top of the fire, which,
unless it is too far gone, seldom fails to recover it. This is a simple experiment
in general use, but perhaps there are thousands who practice it for one that
has considered the reason on which it depends, and hence it is proper to eluci-
date it.
The reason then is that the fire shovel thus placed over the fire soon gets
considerably heated, as does also the air immediately under it, which air, thus
heated and rarified, rushes up by the sides of the shovel (or through the holes
of it if it be a sifting one, and which is must best for the experiment) with
great quickness, its place being continually supplied by other air coming from
under the grate, passing through the fire, and pressing it upwards, so that all
the air which successively passes through the fire under the shovel being
additionally heated by passing through the hot space under the shovel, it
successively ascends upwards with rapidity, and a quick circulation of air is
kept up through the fire, and thus the fire, which before was dying, is revived.
To ascertain what improvements might be made on the simple principles here
laid down, and to render them useful in the cure of smoaking chimneys, as
well as in quickly raising a dead fire, we have frequently covered the whole
top of the grate of a smoaking chimney horizontally just over the fire with a
plate of copper or iron, with holes in it like the holes of a sifting shovel for
the smoke to pass through, and always found the air under the plate to be so
rarified by this experiment as to rise through the holes with immense rapidity
and quickness. We have applied it to the most simoking chimnics, and
always found that if the other parts of the chimney place above the grate wero
closed in so as to prevent the smoke being driven back into the room through
the other parts of the chimney place, the chimney could not possibly smoke
(for all our experiments proved it to be impossible for any puff of wind, however
strong, to force the smoke back through the holes in the plate covering the
fire. We also found that, though the plate was placed some considerable

page_text: distance above the fire, so as to leave a considerable space above the fire
between that and the plate, yet if the checks and back of the grate were
continued up flush with the sides of the plate, and the other parts of the
chimney place closed, as before mentioned, the space above the firo between
that and the horizontal plate, though considerable, was not material, after the
horizontal plate, which is also called the rarifier, was once sufficiently heated, pro-
vided that space was not too large for the rarifier to have sufficient operation.
But because when a chimney is but little inclined to smoke, the rarifier or
horizontal plate, after it is sufficiently heated, will be more effectual at the dis-
tance of two feet or more above the fire than it will at the distance of half a
foot at the first lighting of the fire.when the chimney, from the wind or any
other cause, is violently disposed to smoke. In order that the Invention may
be universally useful, and a certain cure for chimnics of every description, and
in all circumstances, we have contrived several different methods for raising and
lowering the rarifier, so as to place it at any distance above the fire, from one
inch to two feet or more. In order to affect this, and prevent any smoke from
passing either upwards or downwards otherwise than through the holes of the
rarifier, and that the Invention may be applicable to all sorts of grates, we use
a three-sided oblong funnell of iron or other metal, which may be either cast
together in one piece, or composed of three plates fastened together at the
sides. The three sides of this funnell form two sides and a back, and must be
of the same depth and width as the upper part of the two checks or sides and
back of the fire grate and fire, and must extend in length from the top of the
grate up into the chimney behind the mantle piece somewhat higher than the
mantle piece, which length in a small chimney may be about a foot or a foot
and an half more or less, but in large chimnies it will sometimes require to be
much more, according to the distance from the top of the grate to the mantle
piece. Thus prepared, the two sides and back of the funnel are to rest at the
bottom upon and be fixed to the top of the two sides and back of the grate,
and thus standing, the front of the funnel is of course open from the top of the
grate up to the mantle piece, unless when closed by lowering the rarifier,
together with a moveable frontispiece, as will presently be explained. What-
ever space may be on each of the sides of this funnell, from thence to the sides
of the chimney must be compleatly closed either with brick, stone, or plates of
metal, or in any other manner as fancy may direct, provided it be so done as
to prevent any air passing either up or down the chimney otherwise than
through the funnel.
Now the rarifier, which consists of a plate of copper or any other metal full
of holes like the holes of a sifting shovel and of a size exactly sufficient co

page_text: cover the firo horizontally in any part of the funnel, which through its whole
length is uniformly of the same breadth and depth, the fire will bo compleatly
covered by the rarifier as well when it is higher up the funnel as when down
close to the fire. But it is necessary that the front part of the funnel above
described as open should, as well as its two sides and back, be at all times
closed above the rarifier, that no smoke may be forced when the rarifier is
down through the space above between that and the chimney piece, and because
whatever thus covers and closes the front of the funnel above the rarifier must
move up and down with the rarifier, as occasion may require. Another plato
of iron, copper, brass, or other metal (being the moveable front or fronticcpieco
above alluded to) must be prepared of dimensions sufficient to extend from
the top of the grate somewhat higher than the mantle piece, and of a width
exactly equal to the width of the funnel, so as to form a moveable front to the
funnel, which being suspended by a chain in such manner as to be drawn up
and let down behind the mantle piece, and close to the inside of it, will when
down compleatly close up the front of the funnel from the top bar of the grate
quite up to the mantle piece, so that when it is down no air can pass otherwise
than through the fire, but it may at pleasure be drawn up behind the chimney
piece so as to leave any space open from the top of the fire up to the mantle
piece, or so far as to go up entirely out of sight behind the mantle piece about
an inch above the bottom edge; and on the inside of this moveable front or
frontispiece the outside edge of the rarifier is fixed by binges, so as to be
turned up and stand perpendicularly against the inside of the moveable front
when the chimney is swept. At all other times it is to be down, and compleatly
cover the fire horizontally, or nearly so, resting upon two short bars or props,
fixed one of them on each side the moveable front immediately below the
rarifier. In this position the frontispiece being moved by means of its chain
upwards, or let downwards perpendicularly, carries the rarifier up and down
with it horizontally, so that the rarifier can be placed at pleasure either close.
over the top of the fire, or moved with the fronticepiece upwards, and placed so
high as to leave any open space at pleasure not exceeding the heighth of the
chimney piece above the grate. The better to keep the moveable front or
fronticepiece & rarifier in a steady possition, as it is thus drawn upwards or let
downwards, the two side edges of the moveablo front pass through grooves
formed for that purpose on each side the moveable frout in the plates of stone
or metal or other materials with which the two sides of the chimney piece are
before described to be closed. The chain by which the moveable front is.
raised up or let down is fixed at its lower end to the center of the moveable
front, and at its upper end to the end of a round metal plug of about an inch

page_text: or less in diameter, which passes through a round hole bored for that purpose
through the brickwork from the inside of the chimney into the room at the
distance of the length of the rarifier above the mantle piece; and that end of
the plag which comes into the room has a small wheel and catch, with a knob
or handle to turn it round, which together form a jack of the same nature as
the spring jack of a curricle, and which being turned either backward or
forward coils or uncoils the chain round the inner end of the plug, and raises
up or lets down the moveable front and rarifier as the spring jack of a curricle
raises up and lets down the body at pleasure; and the knob and wheel of the
jack being of a circular form, and placed just over the center of the mantle
piece, are, when made of polished and shining metal, besides their utility, an
ornament to the room. The apparatus being thus compleated at the first
lighting of the fire, and when the wind sets in such manner as violently to
incline the chimney to smoke, it will in a very desparate case be proper to let
down the front so low that the rarifier may cover the fire just above and almost
close to the top of the grate, in which position it is impossible that any chimney
can smoke the room; and when the fire has been lighted some little time, and the
rarifier becomes thoroughly heated, it may, together with the moveable front,
by means of the jack and chain, be moved and suspended further up from the
fire, so as to leave a considerable open space between the fire and bottom of
the moveable front; and when the wind is yet more favorable, and the chimney
less violently disposed to smoke, it may be moved still higher, and yet the
chimney will not smoke. Our rarifier, as already described, has nothing but
small holes in it for the smoke to pass through, but we have tried some expe-
riments with a small ventilator inserted in a circular hole cut or cast to receive
it in the centre of our rarifier, which ventilator is such as is often placed in a
window or door, with this difference, however, that our ventilator is composed
of copper, iron, or other metal sufficiently thick to bear the fire, and that,
instead of being in a perpendicular position, it moves horizontally in the middle
of the rarifier. In trying the force of the rarifier, both with and without a
ventilator, as our principle of reflecting down the heat upon the top of the fire
whilst the smoke ascends upwards is preserved, we have found the effect to be
the same whether a ventilators is placed in the center of the rarifier or not, and,
for this reason, that if there is a ventilator in the rarifier it admits the smoke
up through the ventilator, and all the small holes that surround it, and if there,
is not a ventilator, as its place is supplied by small holes, there are more small
holes which answer the same purpose, and hence we shall sometimes insert a
ventilator, and sometimes not. When near the fire our rarifier is either way

page_text: an infallible remedy in the most desparate cases; and when removed a foot or
even two feet above the fire it will seldom happen after the fire is thoroughly
lighted, and the rarifier heated, that any chimney in which it is placed will be
capable of smoking. If it does, the rarifier and moveable front must be let
further down, and the smoking in any case will instantly cease. In a parlor
or any room where cooking is not required it can never be any inconvenience
to have the rarilier down pretty near the fire, because where there is no
cooking a large space is never necessary above the grate, so that the frontice-
piece and rarifier may be always kept so near the fire in all parlors and sitting
rooms as to make it impossible for them ever to smoke; and though in kitchin
chimneys the rarifier must, when it is necessary to set large pots and kettles
on the fire, be moved up high enough conveniently to admit them, yet even
when so far elevated and removed up from the fire the rarifier will not be
deprived of all its effect, but will even then cause the smoke to ascend with
greater vivacity than it would without it; and as soon as the pots and kettles
are taken away, as well as before they are set, on being lowered it will produce
the same infallible effect as in other chimnies. As for roasting. that, so far
from requiring a great elevation of the rarifier, will be better performed when
it is lowered somewhat near the fire, because the draft will be the stronger, the
fire the more brisk and lively, and the heat the greater. But inasmuch as
the checks of a kitchen grate have screws, by which the fire is contracted or
widened as the purposes of cooking require, the two sides and back of the
funnell passing from the top of the grate up behind the chimney piece, as above
described, must be sufficiently wide, when applied to such grates, for the two
sides of the funnel to rest on the upper bar of the grate on the two outsides of
its checks when the checks and fire are the most widely extended; and then,
whether fire is contracted or expanded, it will not be material, because the
rarifier, which must be of dimensions sufficient to extend across the funnel, and
cover the whole fire when extended, will consequently cover it when contracted.
But we have another contrivance which we shall sometimes use to apply our
rarifier to kitchin chimnies; this is by means of a frame of barrs in tho form
of a gridiron, but sufficiently thick and strong for potts or kettles to
stand on, and being of somewhat larger size than the rarifier, the rarifier is
fastened close under it, and both together placed horizontally just over the fire,
and there supported by two strong legs which the frame has before at each end
of it, resting on the top bar of the grate, and supported on another bar, or two
props placed behind for that purpose, with hinges, on which it may be turned
up occasionally so as to stand up quite out of the way against the back of the

page_text: chimney. When it is down, resting by its legs on the top bar of the grate, it
compleatly covers the fire; and as the rarifier is undermost, any pots or kettles'
set upon the bars will, from the heat of the rarifier and hot air that passes
through it, be more quickly heated than it would otherwise be, and at the same*
time the chimney be less liable to smoke; and if a blower be at the same time
hung up before the chimney piece, it will, together with the rarifier, prevent
the chimney from smoking almost as well as the compleat apparatus first
described, but. for want of the three-sided funnel to the size of the fire some
of the effect will be lost. We have likewise contrived other means for the
sako of cheapness and conveniency to those who cannot so well afford the
expence of our compleat apparatus, such as fixing the rarifier at the bottom of
a blower, by which means it may be moved up and down with it, so as to be
placed at any distance above the fire; and if there is also a three-sided funnel
for it to move up and down in, it answers the purpose compleatly in point of
utility, though less agreeable to the eye. It is also to be observed that though
in our compleat apparatus we used a three-sided funnel, forming in its inside
an oblong square, it may be of any other form, and will have the same effect,
provided the rarifier is fitted to it so as to cover the fire horizontally in any part
of the funnel; and indeed the principle of the rarifier covering the fire hori-
zontally, or nearly so, and either close or occasionally close to the fire, being
rightly understood, and for which principle our Patent is obtained, many other
methods of applying it might be contrived besides those here described; but it
is unnecessary to specify them here, our Patent being for a new philosophical
principle never before applied to the purpose of curing smoking chimnies, and
which consists in covering the fire horizontally, or nearly so, with a plate of
any metal that will bear the fire, with either many or few small holes, or a
ventilator or open hole in it, or a passage by the side of it for the smoke.
And anything to cover the fire horizontally, or nearly so, and which can be
put close or nearly close over the fire, so as to rarify the smoke, and cause it to
ascend with greater rapidity, must be constructed upon our principle, and
consequently, if used by others, an infringement of our Patent, whether it
should have a number of holes in it or only one ventilator or hole for a
ventilator, or whether instead thereof it should only partially cover the fire.¨¨
It would likewise be equally an infringement of our principles to make or sell
anything of the same nature, whether it should be capable of moving upwards
and downwards in the manner first described, or whether a plate or other thing
covering the fire or partially covering it should be fixed and stationary hori--
zontally, either immediately above or a small distance above the grate; but a

page_text: register stove is not on our principle, because its register is always so high above
the fire that it can produce little or no effect; but to place its covering down
nearer to the fire would be pursuing our principle in part, and consequently
an infringement of our Patent. As a proof of the excellency of our principle
as an infallible remedy for smoking chimneys, we have tried it in various
instances, and particularly in a chimney so violently disposed to smoke that
nothing but our Invention had ever the least effect in proventing it. Register
stoves and every other project commonly supposed to be useful by thoso who
profess to cure smoking chimnics had been tried in this chimney in vain. It
was at length contracted, and a small close stove erected in it, with a blower,
which, when the blower was let down close to the top of the grate, so that no
air could pass otherwise than through the grate, had of course a very strong
draft; but even this, when the wind was in the smoking quarter, and blew
strong, was of no avail, and at every puff of wind a cloud of smoke was forced
through the grate, the only way by which it could pass, the blower being down,
into the room. This afforded an excellent opportunity of evincing the value
of our principle, for on raising the blower, and covering the fire with our rarifier,
properly fitted for the purpose, and then again letting down the blower to meet
the outside edge of the rarifier, the chimney, which the moment before (though
the blower was down) emitted clouds of smoke through the grate into the room,
entirely ceased to smoke. It not only ceased when the rarifier was down
pretty close to the fire, which was the possition it was first placed in, but even
on placing it considerably farther up the smoke did not return; and other
experiments in like cases we have since made with the same success with our
apparatus. Add to this, that our Invention, when prepared in the manner first
described, has other good qualities besides curing smoking chinnics, for it will
stop rain and wind from coming down on the grate, and keep the room clean;
and if, by the neglect of sweeping, the chimney should catch fire, water being
thrown on the fire in the grate. and a wet cloth placed over the top of it, and
the rarifier let down upon it, the holes in the rarifier will thereby be com-
pletely closed, and the circulation of air up the chimney ceasing, the fire up-in
the chimney will easily be extinguished. Our Invention likewise renders a
room much warnier with any fire, large or small, in the grate, than it would
otherwise be with the same fire, for at the same time that it rarifies the smoke,
and causes it to ascend with rapidity through the holes or crevices of the
rarifier, the solid parts of the rarifier reflecting back the heat down upon the
fire, it is thrown out into the room to a much greater degree than it would
otherwise be, as we have proved by unerring experriment. It likewise, by its

page_text: superior draft, quickly lights up a fire, and when lighted prevents the possi-
bility of its going out from any other cause than want of fuel.
In witness whereof, we, the said Thomas Crook and Thomas German, have
hereunto set our hands and seals, this Twenty-second day of January,
in the year of our Lord One thousand seven hundred and ninety-five.