AN IMPROVED CHIMNEY TOP AND VENTILATOR
Year: 1877

page_text: LETTERS PATENT to Edwin Dunn. of Finchley Road, in the County of
Surrey, Engineer, for the Invention of "AN IMPROVED CHIMNEY TOP AND
VENTILATOR."
Sealed the 4th June 1878, and dated the 8th December 1877.
PROVISIONAL SPECIFICATION left by the said Edwin Dunn at the Office
of the Commissioners of Patents on the 8th December 1877.
EDWIN DUNN, of Finchley Road, in the County of Surrey, Engineer.
IMPROVED CHIMNEY TOP AND VENTILATOR."
" AN
My Invention relates to an improved apparatus which will serve as a chimney
top or terminal, and also as a ventilator for rooms in dwelling houses and other
buildings.
The said Invention consists chiefly in the construction of the said apparatus with
double inner conical surfaces, in combination with outer conical surfaces extending
around the same, and provided with a series of radial partitions or divisions
between which are apertures leading from the exterior to the interior of the said
apparatus. The said outer conical surfaces are so arranged and inclined to each other,
that the said inlet spaces or apertures are smaller at the interior than at the exterior
of the said apparatus. The lower of these two outer cones or conical plates or
surfaces is attached to the body or neck of the apparatus by an inner conical plate
or surface, which forms an angle more or less obtuse with the said lower cone or
conical plate, and which extends entirely around the apparatus without any
opening or aperture, so that there can be no entrance of air at this part of the
apparatus. The upper outer cone or conical surface meets at its inner edge another
inner conical plate or surface, which extends entirely around the said apparatus
and whose upper edge forms the mouth or outlet of the chimney or ventilator.
Above these cones or conical surfaces I place a conical cap or cover, which extends
upward and inward from the outer edge of the upper outer cone or conical plate
above described. This cap or cover has no aperture or opening except at the top,
so that no draught or current of air can enter at the sides or bottom of the said
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page_text: cover, and any draught or current entering at the top of the same will be diverted
from the entrance of the chimney top by the said inner cone or conical surface. I
prefer to place above the said cap or cover a second cap, which is open at the top
and is so formed and arranged as to leave an annular space between it and the
surface of the first-named cap or cover. This upper conical cap is very advan- 3
tageous in many cases
When the said apparatus is used as a ventilator place above the said conical
cap or cover a plate or disc, so formed and arranged as to permit a free current
for ventilation, but to prevent the entrance of rain into the ventilator.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edwin Dunn in the Great Seal Patent Office on the 6th June
1878.
EDWIN DUNN, of Finchley Road, in the County of Surrey, Engineer.
IMPROVED CHIMNEY TOP AND VENTILATOR"
" AN
My Invention relates to an improved apparatus which will serve as a chimney
top or terminal, and also as a ventilator of the rooms of dwelling houses and other
buildings and for similar purposes
The said Invention consists chiefly in the construction of the said apparatus with
a peculiar combination of conical portions, inclined at different angles and extending
around the apparatus, and provided with a series of radial partitions or divisions
between which are apertures leading from the exterior to the interior of the said
apparatus.
The accompanying Drawing illustrates the construction of the said Invention
Figure 1 is a vertical cential section of one of my improved chimney tops or
ventilators; Figure 2 is a horizontal section of the same.
Figures 3 and 4 are similar views illustrating a modification of the said
apparatus.
Like letters indicate the same parts throughout the Drawing.
A. is the body or neck of the said apparatus, whereby it is secured to the chimney
or fixed on the roof or other portion of the house or building to be ventilated.
a is an outer conical portion of the said apparatus; b is another outer conical
portion; c, c', are inner conical portions; d, d, are the radial divisions; e, e, are the
inlet spaces or apertures.
I will first more particularly describe the apparatus shewn in Figures 1 and 2.
The said conical portions or surfaces are so arranged and inclined to each other that
the inlet spaces or apertures e are smaller at the interior than at the exterior of the
said apparatus, that is to say, the sides of these spaces are contracted or inclined
toward each other inwardly from the mouth e' to the throat e². The lower outer
cone or conical portion or surface a is attached to the body or neck A of the
apparatus by the inner inverted conical plate or surface f, which forms an angle
more or less obtuse with the said outer cone or conical plate a, and this plate f

page_text: extends entirely around the top of the neck A without any opening or aperture,
so that there can be no entrance of air at this part of the apparatus. The outer
cone or conical surface b meets at its outer edge the inner conical portion or
surface c, which at its inner edge meets the inner conical portion c¹. These two
conical portions c, c¹², form a double conical piece which extends entirely around
the said apparatus, and whose edge forms the mouth or outlet of the chimney or
ventilator. And the combination of this double conical piece with the other parts
of the said apparatus is the essential feature of this Invention. The conical portion b
has no aperture or opening except at its top, so that no draught or current of air
can enter at the sides or bottom thereof, and any draught or current entering at
the top of the same will be diverted from the entrance of the chimney top and
directed to the outside of the apparatus by the said conical surface c'. I prefer to
place above the said part ba second conical part or cap g, which is open at the top,
and is so formed and arranged as to leave an annular space at h between it and the
surface of the part b. This upper conical cap is very advantageous in many
cases.
When the said apparatus is used as a ventilator I place above the said conical
cap or cover a plate or disc, so formed and arranged as to permit a free current for
ventilation, but to prevent the entrance of rain into the ventilator.
In the modified form of the said apparatus, shewn in Figures 3 and 4, the conc
or conical portion a is carried up above the top of the part A, and there is an
annular space between these parts all around the same at i, through which space
the air may pass upward from the exterior to the interior of tho said apparatus.
The said conical portion a is supported upon the neck or body A by small rods, or
by division plates, as shewn at j. In this form of the said apparatus the upper
conical portion or cap g is not used, but the apparatus is finished at the top by a
reversed conical portion k, commonly termed a "vena-contracta," which greatly
assists the upward current or draught.
Having thus fully described my said Invention, and the manner of performing
the same, I wish it understood that I claim, in a chimney top or ventilator the
combination with the outer cones or conical portions a, b, of the inner conical
portions or surfaces c, c², either with or without the radial division d, as above
described, and as shewn in Figures 1 and 2, or in the modified construction of
the apparatus, shewn in Figures 3 and 4 of the Drawing, for the purposes
specified.
In witness whereof, I, the said Edwin Dunn, have hereunto set my hand
and seal, this Sixth day of June, in the year of our Lord One thousand
EDWIN DUNN. (L.S.)