IMPROVED APPARATUS FOR INCREASING THE DRAUGHT IN CHIMNEYS AND SHAFTS
Year: 1880

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LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVED
APPARATUS FOR INCREASING THE DRAUGHT IN CHIMNEYS AND SHAFTS."
A communication from abroad by Georges Eugène Wery, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 29th June 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. IMPROVED APPARATUS FOR INCREASING THE DRAUGHT
IN CHIMNEYS AND SHAFTS." [A communication from abroad by Georges Eugène
Wery, of Paris, France.]
This Invention relates to improved means for increasing the draft in chimneys
and shafts of all kinds, and it consists more particularly in enclosing the chimney
or smoke tube in a kind of jacket or casing communicating at the bottom with the
external air or an air reservoir, and at the top with the chimney, of which it forms a
prolongation that may be carried to any suitable height. The cold air entering at
the bottom of the jacket or casing becomes heated by contact with the internal
wall, which is the chimney itself, and which is heated by the smoke, and the heated
and rarefied air rising in the jacket escape through a narrow annular outlet at the
top into the chimney whereby a strong draught is created.
The Invention may be carried out in various ways, for example, the jacket may
be divided into a number of compartments one above the other, and each commu-
nicating with the air and with the chimney as above described, thus producing an
up-draught at different elevations in the chimney, which will effectually carry off
all smoke and gases therein. The jacket or casing may also be a thin tube passing
in a spiral direction around the iuterior of the chimney, and either open from end
to end or divided into compartments each communicating with the external air
and with the interior of the chimney as before described. Suitable dampers and
valves would be provided for regulating the admission of heated air to the chimney
or flue, and the passages communicating with the outer air may also be prevented
by a non-conducting material from heating the outer air. For chimneys of large
area it is proposed to provide them with several terminal tubes, parallel but

page_text: independent, and all surrounded by a jacket or jackets so that the heating surface
for the air is greater than with a single smoke tube.
The object of this arrangement is to prevent all down draught. The chief
advantages of this Invention are, that the height of factory chimneys may be
reduced, fuel is economised owing to more perfect combustion, and that
anthracite and other similar coal may be burnt in furnaces where, owing to deficient
draught, dearer coal has hitherto been used.
The accompanying Drawings illustrate different examples of the Invention.
Figures 1 and 2 show a vertical and cross section of a smoke stack or chimney.
F, smoke pipe; D,D, annular jacket surrounding F and divided by a partition G,G.
into two chambers, each communicating at its bottom end with a pipe E which
communicates with the outer air at such a distance as to ensure its being cool;
0, 0, are annular orifices through which the air heated and rarefied in the annular
casings D, D, escapes into the chimney at such a velocity as to carry with it the
smoke and gases therein.
Figures 3 and 4 show the Invention as applied to a brick shaft. The air casings
D, D, in this case line the brickwork M, and they receive cold air through
openings A, A, which, becoming heated, rises and escapes into tlie flue Fat o.
Figures 5 and 6 show the Invention as applied to a chimney of large area. The
chimney above the point A, A, at which air enters the jacket D, D, is divided into
four flues f, ff, f, surrounded with the air jacket, to which almost the whole of the
heat is given up.
Figures and 8 represent a chimney provided with an internal spiral, the upper
part of which gives passage by an aperture regulated by the heat of gases F to the
air heated in D.
This spiral tube which lines the interior of the smoke flue is divided by partitions
into a certain number of independent compartments each provided with a cold air
inlet at their external hase, and with a hot air inlet at their internal top end.
The heated air is thus brought in contact with the smoke at different points of the
height of the chimney, and imparts to it an ascensional rotary motion. This
arrangement is very effective. It will be understood that in all cases the cold air
may be supplied to the jacket by a pipe from a cellar or other cool place.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
29th December 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVED APPARATUS. FOR INCREASING THE DRAUGHT
IN CHIMNEYS AND SHAFTS." A communication from abroad by Georges Eugène
Wery, of Paris, France.
This Invention relates to improved means for increasing the draft in domestic
chimneys and factory shafts of all kinds, and it consists more particularly in
enclosing the chimney or smoke tube in a kind of jacket or casing communicating
at the bottom with the external air or with an air reservoir, and at the top with
The chimney, of which it forms a prolongation that may be carried to any suitable
height. The cold air entering at the bottom of the jacket or casing becomes heated
by contact with the internal wall, which is the chimney itself, and which is heated
by the smoke, and the heated and rarefied air rising in the jacket escapes through
a narrow annular outlet at the top of the jacket, or of a segment thereof into the
chimney, whereby a strong draught is created.
The Invention may be carried out in various ways; for example, the jacket may
be divided into a number of segments or compartments placed one above the other,
and each communicating with the air and with the chimney as above described,
thus producing au up-draught at different heights in the chimney, which will
effectually carry off all smoke and gases therein. The jacket or casing may also be
a thin tube passing in a spiral direction around the interior of the chimney, and
either open from end to end or divided into compartments each communicating
with the external air and with the interior of the chimney, as before described.
Suitable dampers and valves, would be provided for regulating the admission of
heated air to the chimney or flue, and the passages communicating with the
exterior may also be prevented by a nonconducting material from heating the
outer air, as it is essential for the proper action of the apparatus that the difference
of temperature between the external air and that in the casing should be as great
as possible in order to accelerate the upward eurgent and increase the draught.
Chimneys of large area are provided with several terminal tubes, parallel but
independent, and varying in number according to the diameter of the chimney, and
all surrounded by a jacket or jackets, so that the heating surface for the air is
greater and the draught stronger than with a single smoke fube. The object of
this arrangement is to prevent all down draught.
The chief advantages of this Invention are, that the height of factory chimneys
may be reduced, fuel is economised owing to the more perfect combustion ensured
ly the stronger draught, and anthracite and other similar coal may be burnt
in furnaces where owing to deficient draught, dearer coal has, hitherto, heen
required.
The accompanying Drawings illustrate different examples of the Invention.
Figures 1 and 2 show a vertical and cross section of a smoke stack or chimney;
F, smoke pipe D, D, annular jacket surrounding F and divided by a partition G.G.
into two chambers, each communicating at its bottom end with a pipe E. which is
open to the outer air at such a distance from the chimney as to ensure its being cool:
0, 0, are annular orifices through which the air heated and rarefied in the annular
casings D. D, escapes into the chimney at such a velocity-as-to-carry with it the
smoke, and gases therein..
Figures 3 and 4 show the Invention' as applied to a brick shaft. The annular
air casings D, D, are superposed and separate like the previous one, but in this
case they line the brickwork M, and they receive through openings A, A, therein
cold air which. becoming heated, rises and escapes into the flue T ut o. Valvos

page_text: operated in any convenient way are applied to regulate the hot air outlets o in
order that the jets of hot air shall enter the chimney at a sufficiently high velocity
to ensure the carrying off of the gases and smoke.
Figures 5 and 6 show the Invention as applied to a chimney of large area.
The chimney above the point A, A, at which air enters the jacket D, D, is
divided into four distinct flues f. f. f, f, which are all completely surrounded with
the air jacket to which almost the whole of the heat is given up.
Figures and 8 represent a chimney provided with an internal spiral, the upper
part of which gives passage by an aperture regulated by the heat of the gases in F
to the air heated in D. This spiral tube, which lines the interior of the smoke
flue, is divided by partitions into a certain number of independent compartments,
each provided with an external inlet for cold air at their base, and with an internal
outlet for hot air at their upper part. The heated air is thus brought in contact
with the smoke at different points of the height of the chimney, and imparts to it
an ascensional rotary motion. This arrangement is very effective.
It will be understood that in all cases the cold air may be supplied to the jacket
by a pipe from a cellar or other cool place instead of directly from the outer air.
Figures 9, 10, and 11 illustrate the application of the Invention to the small
portable chimneys employed for drawing the fires in certain kinds of cooking stoves
at the time of lighting. These generally consist of a cylindrical tube or chimney
having a flared or conical mouth at bottom large enough to enclose the top of the
stove over which it is placed when the fire is first lighted. This Invention is
applied by enclosing the pipe or chimney in a jacket communicating at bottom
with the outer air, and with the chimney by suitable openings at one or more
points of its height, through which the air heated in the annular jacket escapes,
and by reason of the ascensional force it thus acquires, carries with it the smoke
and gases of combustion. The apparatus is represented in vertical section, underside
plan, and elevation in Figures 9, 10, and 11. a, chimney with conical base;
b, c, are a number of openings at different heights in the chimney. It is surrounded
by a conical jacket or casing d having iulet holes for cold air in the lower part e.
The upper party of said jacket is cylindrical and forms a prolongation of chimney a.
The jacket is maintained at the proper distance from chimney a by distance
pieces i, and is provided with a handle h for lifting the entire apparatus.
Having described the nature of the said Invention, and the manner of performing
the same. I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.- .
1st. The improved means of increasing the draught in chimneys and shafts,
substantially as described and shown in the Drawings, and consisting in the
employment of jacket or jackets surrounding the flue or flues, so as to be heated
thereby, the said jacket being either continuous or in sections divided by partitions,
and communicating at bottom, or at bottom of each section, with the external air,
and at top or at different points of its height with the chimney by means of
annular or other openings, whereby the heated air produces a strong up-draught in
the chimney, as aud for the purpose specified.
2nd. The particular arrangements described for supplying cold air to the jacket
or casing, and for regulating the admission of heated air to the chimney.
In witness whereof. I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twenty ninth day of December. A.D. 1880.