IMPROVEMENTS IN COWLS FOR CHIMNEYS AND SHAFTS
Year: 1869

page_text: LETTERS PATENT to Edward Hewett, of St. Leonards-on-Sea, in the
County of Sussex, Brewer, for the Invention of "IMPROVEMENTS IN
COWLS FOR CHIMNEYS AND SHAFTS."
Sealed the 11th May 1869, and dated the 19th February 1869.
PROVISIONAL SPECIFICATION left by the said Edward Hewett at the
Office of the Commissioners of Patents, with his Petition, on the
19th February 1869.
I, EDWARD HEWETT, of St. Leonards-on-Sea, in the County of Sussex,
Brewer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN COWLS FOR CHIMNEYS AND SHAFTS," to be as follows:-
My Invention relates to improvements in the construction of cowls to
be applied to chimneys and shafts whereby an efficient up draught is
obtained and all down draught at same time prevented.
According to one arrangement of my Invention I form the cowl of a
tube of considerable height and of about the same diameter as the
chimney itself, above which it is mounted so as to turn on a vertical

page_text: pivot. The top of this tube may either be closed and provided with an
aperture at one side for the exit of the smoke, or it may be of curved
form like an ordinary cowl, and is in each case provided with a suitable
vane. The top of the chimney is closed with the exception of a central
opening for a smoke tube of about half the diameter of the cowl mounted
on the top of the chimney and passing about halfway up the cowl. At
the bottom of the cowl and at the opposite side to the exit opening
above mentioned is a funnel-shaped opening for the admission of the
air which (as this opening is always kept facing the wind by the action
of the vane at the top) rushes in and passes up the annular space
surrounding the smoke tube and out at the top of the cowl. The air in
passing out of the cowl carries the smoke with it, thus creating a strong
upward draught in the chimney. A modification of this arrangement
consists in dispensing with the central smoke tube and providing the
revolving cowl with a longitudinal diaphragm extending about halfway
up the same. The lower part of the cowl is thus divided into two parts,
one of which is open to the chimney for the passage of the smoke, and
the other communicating as before with the outer air admits a strong
upward current of air through the cowl, which carries the smoke with it
and produces the draught desired.
According to another arrangement I mount the cowl at an angle to
the chimney instead of being perpendicular as before. In this case the
smoke tube forms part of the cowl and turns therewith instead of being
fixed to the chimney as before. The smoke tube projects upwards at the
same angle as the cowl (in which it occupies a central position) so as to
divert the smoke from its perpendicular course into a line with the
constant upward current of air passing through the cowl before coming
into contact therewith. The air, which enters at a funnel mouth at the
lower end of the cowl as before, passes through the annular space
between the smoke tube and cowl, and mixing with the smoke before
leaving the cowl creates a strong upward current in the chimney. In
a modified arrangement of this cowl which is open at either end as
before I provide an inclined diaphragm placed so as to deflect the smoke
on entering the cowl. A second diaphragm is placed parallel with and
in front of the first so, as to close up one-half of the chimney aperture
and cause the smoke on issuing, therefrom to pass between the two.
diaphragms in an inclined direction. The air passes through the cowl

page_text: above the diaphragms also in an upward direction by reason of its
slanting position, and catching the smoke before leaving the cowl creates
the draught required.
In each case I prefer that the volume of air admitted through the
cowl should be at least equal to the volume of smoke escaping at the
top of the chimney so as to insure a constant thorough up draught,
preventing also eddies of wind from entering the chimney. These cowls
are also applicable to malt kilns, hop oasts, and similar erections, and to
air shafts for ventilating purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Hewett in the Great Seal Patent Office
on the 18th August 1869..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
HEWETT, of St. Leonards-on-Sea, in the County of Sussex, Brewer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of February, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Edward Hewett, Her special licence that
I, the said Edward Hewett, my executors, administrators, and assigns,
or such others as I, the said Edward Hewett, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the terni therein expressed,
should and lawfully might make use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN COWLS FOR CHIMNEYS AND
SHAFTS," upon the condition (amongst others) that I, the said Edward
Hewett, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
inmediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said Edward Hewett, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the two Sheets of Drawings
hereunto annexed, and to the letters and figures marked thereon (that is
to say)-
My Invention relates to improvements in the construction of cowls to
be applied to chimneys and shafts whereby an efficient up draught is
obtained and all down draught prevented.
According to one arrangement of my Invention I form the cowl of
a tube of considerable height and of about the same diameter as the
chimney itself, above which it is mounted so as to turn on a vertical
pivot. The top of this tube may either be closed and provided with
an aperture at one side for the exit of the smoke, or it may be of
curved form like an ordinary cowl, and is in cach case provided with
a suitable vane. The top of the chimney is closed with the exception
of a central opening for a smoke tube of about half the diameter of
the cowl mounted on the top of the chimney and passing about half-
way up the cowl. At the bottom of the cowl and at the opposite
side of the exit opening above mentioned is a funnel-shaped opening
for the admission of the air which (as this opening is always kept
facing the wind by the action of the vane at the top) rushes in and
passes up the annular space surrounding the smoke tube and out at
the top of the cowl. The air in passing out of the cowl carries the
smoke with it, thus creating a strong upward draught in the chimney.
A modification of this arrangement consists in dispensing with the
central smoke tube and providing the revolving cowl with a longitudinal
diaphragm extending about halfway up the same. The cowl is thus
divided into two parts, one of which is open to the chimney for the
passage of the smoke, and the other communicating as before with the
outer air admits a strong upward current of air through the cowl, which
carries the smoke with it and produces the draught desired.
According to another arrangement I mount the cowl at an angle to
the chimney instead of being perpendicular as before. The smoke tube
projects upwards at the same angle as the cowl (in which it occupies a
central position) so as to divert the smoke from its perpendicular course
into a line with the constant upward current of air passing through the

page_text: cowl before coming into contact therewith. The air, which enters at a
funnel mouth at the lower end of the cowl as before, passes through the
annular space between the smoke tube and cowl, and mixing with the
smoke before leaving the cowl creates a strong upward current in the
chimney. In a modified arrangement of this cowl, which is open at
either end as before, I provide an inclined diaphragm placed so as to
deflect the smoke on entering the cowl. A second diaphragm is placed
parallel with the first so as to close up one-half of the chimney aperture
and cause the smoke on issuing therefrom to pass between the two
diaphragms in an inclined direction. The air passes through the cowl
above the diaphragms also in an upward direction by reason of its
slanting position, and catching the smoke before leaving the cowl creates
the draught required.
In each case I prefer that the volume of air admitted through the
cowl should be at least equal to the volume of smoke escaping at the
top of the chimney so as to ensure a constant thorough up draught,
preventing also eddies of wind from entering the chimney. These cowls
are also applicable to malt kilns, hop oasts, and similar crections, and
to air shafts for ventilating purposes, also for raising gases and vapors
which are either lighter or heavier than atmospheric air.

page_text: opposite side to the exit opening D above mentioned, is an opening G for
the admission of air, to facilitate which the opening G may further be
provided with a funnel-shaped mouth (as shown in dotted lines) if
desired. As this opening G is always kept facing the wind by the action
of the latter on the vane or vanes E, the air entering the cowl passes up
the annular space H contained between the smoke tube F and the outer
tube A of the cowl, and out at the exit opening D at the top of the cowl,
thus creating a strong upward draught in the chimney for withdrawing
the smoke contained therein. In order to prevent the cowl being carried
away by the wind, and also to allow perfect freedom in turning, I provide
the cowl with a central tube I, as seen, which encloses the pivot C
throughout the greater part of its length, at same time permitting of the
removal of the cowl for cleansing or other purpose: J, J', are flanges
formed around the base of the cowl and the top of chimney B to
prevent the admission of wind or rain, and which I prefer to keep as
nearly air-tight as possible. The black arrows show the direction of the
smoke and the red arrows that of the air currents.
Figure 4 illustrates a modification of the arrangement of cowl above
described in which the central smoke tube F is dispensed with, a longi-
tudinal diaphragm K being substituted therefor. This diaphragm may
only be carried about halfway up the cowl, but I prefer to carry it
entirely up in the manner shown. The lower part of the cowl is thus
divided into two parts L and M, the one M of which is
open to the
chimney B for the passage of the smoke, as seen, and the other L com-
municating as before with the outer air admits a strong upward current
of air through the cowl, which carries the smoke with it, and produces
the up draught desired.
According to another arrangement illustrated in side elevation and
section at Figures 5 and 6, I mount the cowl A at an angle to the
chimney B instead of it being in line therewith as before. The smoke
tube F passes first upwards perpendicularly, and is then carried at the
same angle as the cowl A, in which it occupies a central position, as
seen. By this arrangement the smoke is diverted from its perpendicular
course into a line with the constant upward current of air passing
through the annular space H before coming in contact therewith. In
Figures 5 and 6 a funnel mouth is shown at the lower end of the cowl to
facilitate the entrance of the air, which passes through the annular

page_text: space II, and mixing with the smoke before it leaves the cowl creates a
strong upward current in the chimney.
Figures 7, 8, and 9 show respectively a side elevation, section, and
face view of a cowl similar to that last described, the outer tube A and
smoke tube I being both considerably reduced in length, the funnel
mouth of the air tube being also dispensed with.
Figure 10 represents a modified arrangement of the cowl last
described. In this case an inclined diaphragm K is substituted for the
smoke tube F. This diaphragm is placed so as to deflect the smoke on
entering the cowl, a second diaphragm N serving to close up one-half of
the chimney aperture, and cause the smoke on issuing therefrom to pass
between the two diaphragms in an inclined upward direction. The air
passes through the cowl above diaphragm K also in an upward direction
by reason of its slanting position, and catching the smoke before leaving
the cowl creates the draught required.
In order to prevent an accumulation of soot in the several smoke
tubes F, which are inaccessible to the sweep's brush, I may place one or
more balls of cork or other suitable material in said tubes, the balls
being retained therein by wire netting placed at the top and bottom of
the tube, as indicated in red at x, x, Figure 8. These balls are maintained
continually in motion by the current of air created in the tube, thereby
preventing the soot from lodging therein.
The tubes composing the improved cowls of my Invention may either
be cylindrical, as shown, or in the form of truncated cones, or of other
shape desired.
Having described the nature of my Invention, and the manner of
performing the same, I declare that what I claim as my Invention to be
protected by the herein-before in part recited Letters Patent is,-
First. I claim the principle (in revolving cowls) of passing a current
of air upwards through the cowl in a vertical or inclined direction, and
in either case at least of an equal or greater volume than that of the
smoke or gases escaping from the chimney or shaft, for the purpose of
ensuring a thorough up draught therein.
Secondly. I claim the arrangements of cowls on this principle, together
with the modifications of the same, as herein-before described and
illustrated in the Drawings annexed.

page_text: Thirdly. I claim diverting the smoke from its perpendicular course
into a line with the upward current of air, as and for the purpose
specified and as illustrated in the Drawings.
In witness whereof, I, the said Edward Hewett, have hereunto set
my hand and seal, this Third day of August, in the year of our
Lord One thousand cight hundred and sixty-nine.
Witness,
A. M. CLARK,
Patent Agent,
53, Chancery Lane,
London.
EDWARD HEWETT. (L.S.)