IMPROVEMENTS IN COWLS OR GUARDS FOR CHIMNEYS AND OTHER LIKE SHAFTS."
Year: 1867

page_text: LETTERS PATENT to Walter Blundell, of Maddox Street, in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN COWLS OR GUARDS
FOR CHIMNEYS AND OTHER LIKE SHAFTS."
PROVISIONAL SPECIFICATION left by the said Walter Blundell at the
Office of the Commissioners of Patents, with his Petition, on the 21st
November 1867.
I, WALTER BLUNDELL, of Maddox Street, in the County of Middlesex,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
COWLS OR GUARDS FOR CHIMNEYS AND OTHER LIKE SHAFTS," to be as follows:-
The object of my Invention is so to construct cowls or guards as to prevent
all draught down the chimneys or shafts to which they are applied.
My Invention mainly consists in the employment of a conical cap, which,
no matter how frequently the wind changes, always protects the chimney or
shaft on the windward side, but allows free passage for the smoke on the
leeward side. My conical cap is fitted loosely on the top of a vertical rod
carried up from the centre of a cross bar or frame at the upper part of the
chimney or shaft, and the length of this rod and the size of the cap are so
proportioned that the lower part of the cap comes on the windward side below

page_text: the level of the top of the chimney when acted on by the wind. The cap
being fitted loosely on the top of the rod, the side of the cap acted upon by
the wind is forced against the side of the chimney, thereby preventing the
wind getting down the chimney, while the opposite side of the cap at the
same time rises, leaving an ample opening at the top of the chimney for the
egress of smoke. To secure the cap, but at the same time allow it to work
freely, as before described, I adopt the following arrangement :-I screw a
nut or form a projection on the rod at about its middle; below this nut and
bearing against it is a circular plate with a convex lower face, and below this
and bearing against it is a second circular plate with a convex upper face;
the central aperture of both plates is larger (that of the lower plate consider-
ably larger) than the diameter of the rod. The edge of the lower plate has
three or other convenient number of recesses, and the under side of the cap
has a corresponding number of undercut lugs or projections. The recesses
are passed over the lugs, and the cap or the plate is then moved partly round
to prevent the recesses repassing the lugs. The cap is thus prevented from
being lifted from the rod, while the central apertures and convex faces of the
plates allow the cap to accommodate itself to changes of wind, as before
explained. I do not, however, confine myself to this mode of securing the cap;
sometimes I I carry up a rod from the top of the cap and weight this rod.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Walter Blundell in the Great Seal Patent Office on the
21st May 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
BLUNDELL, of Maddox Street, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of November, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Walter Blundell, Her special licence that I, the said Walter Blundell,
my executors, administrators, and assigns, or such others as I, the said Walter
Blundell, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the

page_text: Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
COWLS OR GUARDS FOR CHIMNEYS AND OTHER LIKE SHAFTS," upon the condition
(amongst others) that I, the said Walter Blundell, my executors or adminis-
trators, 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 immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Walter Blundell, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the Drawings hereunto annexed,
that is to say:-
The primary object of my Invention is so to construct cowls or guards as to
prevent all draught down the chimneys or shafts to which they are applied.
My Invention mainly consists in the employment of a conical cap, which,
no matter how frequently the wind changes, always protects the chimney or
shaft on the windward side, but allows free passage for the smoke on the
leeward side. My conical cap is fitted or balanced on a spherical bearing or
point, ball and socket, or other suitable joint on the top of a vertical rod carried
up from the centre of a cross bar or frame at the upper part of the chimney
or shaft, and the length of this rod and the size of the cap are so proportioned
that the lower part of the cap comes on the windward side below the level of
the top of the chimney when acted on by the wind. The cap being balanced
on the top of the rod, the side of the cap acted upon by the wind is forced
against the side of the chimney, thereby preventing the wind getting down the
chimney, or by the pressure of its velocity hindering rapid discharge from the
orifice of the chimney, while the opposite side of the cap at the same time
rises, leaving an ample opening at the top of the chimney for the egress of
smoke. Or instead of carrying up a vertical rod from a cross bar or frame I
carry up a curved frame of suitable height, and I fit the cap to the top of this
frame.
My Invention and the mode in which I prefer to secure the cap will be
fully understood by the accompanying Drawings.
Figure 1 is a side elevation, Figure 2 a vertical section, and Figure 3 a
top view or plan of a cowl or ventilator constructed according to my
Invention.

page_text: a is a cylinder (preferably slightly tapered) forming the top of the chimney
or shaft; 6 is a curved frame carried up from the top of this cylinder to a
suitable height; c is the conical cap; d is a socket in the centre of the cap c,
and connected thereto by a central vertical rod f carried up from the socket
through the apex of the cap c; g is a weight or counterpoise on the rod f;
h is a ball working in the socket d, this ball is fixed to a short arm which is
passed through a hole in the top of the curved frame b, and secured by a
nut; the joint composed of the socket d and ball h allows the cap c to turn
on this joint in any direction; k, k, are vanes, feathers, fans, or wings on the
exterior of the cap c for the purpose of presenting a greater surface to the
action of the wind and concentrating its passage through the upper part of
the cone, by means of which a drawing off or updraught in the chimney is
effected. It is preferred to make the cap c of several overhanging parts, as
shewn, to allow of side ventilation through the spaces between them. When
the wind acts upon the cap c, the side or portion acted upon is blown against
or towards the side of the cylinder a, as shown in Figure 4, the opposite side
of the cap c being correspondingly raised; thus while no wind can get down
the chimney there is ample opening for the egress of smoke or vitiated air.
The size of the cap c in relation to the position of the joint d, h, must be such
that the lower edge of the cap c will overlap the top of the cylinder a, as seen
in Figure 4, on the windward side.
I do not limit myself to the mode herein-before described and shewn in the
Drawings of securing the cap c, as it may be secured in any other convenient
manner; and instead of the ball-and-socket joint any other equivalent joint
may be employed.
In cases where for the purpose of ventilation or otherwise an inward
current is required down the shaft instead of an outward current, as herein-
before described, I place the joint or pivot d, h, of the conical cap c so low
that the cap presents to the wind a greater surface above than below the level
of the joint. The wind will thus produce a contrary effect to that herein-
before described, that is to say, it will raise the cap on the windward and
lower it on the leeward side; in this case I employ a plain cone, that is to
say, a hollow cone without the overhanging parts herein-before referred to
and shown in the Drawings.
When my cowls are applied to railway carriages, ships, or other moving
bodies the conical cap will be acted upon by the resistance offered by the air
to the passage of the cowl.
And having now described the nature of my said Invention, and in what

page_text: manner the same is to be performed, I declare that I claim constructing cowls
or guards with a cap fitted or balanced, substantially as herein-before described
and represented in the accompanying Drawing, and so as to be acted on in
the manner herein-before explained.
In witness whereof, I, the said Walter Blundell, have hereunto set my
hand and seal, this Twenty-first day of May, in the year of our Lord
One thousand eight hundred and sixty-eight.
WALTER BLUNDELL. (L.s.)