Improvements in Chimney and other Cowls.
Year: 1896

page_text: Date of Application, 5th Mar., 1896
Complete Specification Left, 5th Dec., 1896-Accepted, 23rd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in Chimney and other Cowls.
I, FREDERICK ROGERS, of No. 47, St. Paul's Road, Tottenham, in the
County of Middlesex, Builder's Foreman, do hereby declare the nature of this
invention to be as follows:-
My invention relates to cowls for chimney and ventilating shaft tops, and
comprises improved means for inducing a draught in the chimney or shaft.
This object is realized by arranging on the chimney or shaft top, the upper end
of which is contracted, a hood supported thereon by arms or ribs and extending
from a short distance below the aforesaid contracted end to a certain distance
above the same, the diameter of its bottom end being such as to afford a passage
for the air. The top part of this hood is also contracted, but its upper orifice
is of a larger diameter than the orifice of the chimney or ventilating
shaft top.
By means of arms or ribs the said hood supports in turn a helmet so that its
top orifice will be in the same horizontal plane as the bottom end of the helmet,
and will leave a passage for the air. The lower portion of this helmet is made
taper and joins a cylindrical portion of approximately the same diameter as the
upper orifice of the hood. The upper portion of this helmet is likewise contracted
and usually furnished with a perforated ring at its orifice. For the purpose of
preventing a downward draught I may arrange a perforated disc or plate either
at the orifice of the said helmet or ring or at a certain distance above the same.
In the case of a cowl for ventilating shaft tops I prefer to make use of a plain
instead of a perforated disc or plate, and support the same either by the before
mentioned perforated ring or by special arms.
This cowl, which may consist of any suitable material, is simple and occupies
little space so that a number of such cowls may stand side by side on a chimney
stack.
Dated this 5th day of March 1896.
PHILLIPS & LEIGH,
Agents for the Applicant.
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I, FREDERICK ROGERS of No. 47 St. Paul's Road, Tottenham, in the County
of Middlesex, Builder's Foreman, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to improvements in cowls for the tops of chimneys and
ventilating shafts.
It consists in a novel combination of contracted shaft top, hood with a contracted

page_text: top held in a certain position about the said contracted top and a second hood
with expanded bottom and contracted top held in a certain position over the one
last mentioned.
Referring to the accompanying figures which are to be taken as part of this
specification and read therewith,
Figure 1 is a sectional elevation of two cowls made according to the present
invention.
Figure 2 is a side elevation of one.
Figures 3 and 4 are plans of, respectively, a perforated and a plain top
disc.
a is the shaft of a chimney cowl or of the upper portion of a ventilating shaft,
as the case may be. b is the contracted top of it. The side of this top 6 stands at
an angle of 143° with the side of the shaft a.
C is the first mentioned hood. It is held to and about the contracted top 6 by
webs c, c. The lower portion e' of this hood is concentric with the shaft a while
the upper portion of it, c, is parallel with the contracted top b, so giving the hood
itself a top contracted to the same angle as is the contracted top b. The position
of this hood C with respect to the shaft a and the contracted top b, is of
importance. About half of the lower portion el stands opposite the upper portion
of the said shaft a and the remainder, opposite to and overtops, by a little, the
contracted portion b. Consequently, the upper portion 2 starts at a level entirely
above the contracted top b; and its minor diameter, that across the top of it, is
greater than the minor diameter of the said top b, being, in fact, intermediate of
the two diameters, major and minor, of this latter.
D is the second hood above mentioned. It is held axially over the hood C and
the shaft a by means of webs d, d, in the same way as the hood C is held to the
said shaft. It consists of three principal parts, the bottom one d' the middle one d
and the top one d³.
The important features of this second hood are as follows. The bottom part d¹
is parallel with the upper portion c2 of the hood C, and stands above it at a distance
about half that which separates the portion c from the contracted top b. The
minor diameter of this bottom part d' is larger than that of the said portion c
being in fact, the same as that of the shaft a, while its major diameter is less than
the major diameter of the said portion c². The middle part d' is axially concentric
with the shaft a and the portion e'. The height of it is, preferably, the relative
one illustrated. The angle made by the top part d³ with the middle part d' is
more obtuse than those made by the portion c and the bottom part d' with the
portion and the part d, respectively.
The contracted portion b, the upper portion c2 and the bottom part above
mentioned resemble in some respects, the well known louvres, but the novel
feature in respect of them in the present invention, is their relative position and
dimensions. The importance of the relative positions and diameters of the louvres,
at well as of the other above described parts and portions of the invention will be
apparent from a consideration of the fate of a down draught that enters through
the top part d³ of the hood D. It is very likely to expand a little in the middle
part d. In any case, its presence in, and passage down, the said hood, will
generate a congestion or higher pressure in and immediately over the contracted
top b. The said draught will consequently flow out where 'there is the least
resistance, viz., between the bottom part d' and the upper portion c².
The perforated ring E about the top of the hood D may be used or dispensed
with as may be preferred. The disc is supported at a suitable distance above
the hood D by suitable arms. It may either be plain or perforated, the former
for preference, for then it serves as a preventer of down draught in the cowl.
Neither the ring E nor the disc F are essential to the invention.
My improved cowl may be made in any suitable material. It is distinguished
in respect of its external shape, by its compactness; the advantage of such
'compactness being that they can stand close together side by side, as illustrated in

page_text: Figure 1, instead of it being necessary to make the shaft of one long enough to
carry its cowl above that of the adjacent one.
Having now particularly described and ascertained the nature of my said inven--
tion and in what manner the same is to be performed, I declare that what I
claim is :-
The combination with a shaft of two hoods, each consisting of the several.
portions and parts, as set forth and illustrated.
Dated this 5th day of December 1896.
PHILLIPS & LEIGH,
No. 22 Southampton Buildings, Chancery Lane, London, W.C.,.
Agents for the Applicant.