AN IMPROVEMENT IN COWLS FOR CHIMNIES AND SHAFTS
Year: 1864

page_text: LETTERS PATENT to George Bohn, of Victoria Street, in the City of
Westminster, Civil Engineer, for the Invention of "AN IMPROVEMENT IN
COWLS FOR CHIMNIES AND SHAFTS."
Sealed the 8th August 1864, and dated the 15th February 1864.
PROVISIONAL SPECIFICATION left by the said George Bohn at the Office.
of the Commissioners of Patents, with his Petition, on the 15th.
February 1864.
I, GEORGE BOHN, of Victoria Street, in the City of Westminster, Civil
Engineer, do hereby declare the nature of the said Invention for "AN IMPROVE-
MENT IN COWLS FOR CHIMNIES AND SHAFTS," to be as follows:-
My Invention consists in constructing cowls for creating an upward draught
in chimnies and ventilating shafts in manner hereafter stated. Upon a
vertical tube open at top and bottom I fix a horizontal tube open at both ends,
and insert in one end thereof a conical pipe extending about midway, more or
less, into the horizontal tube; I fit this cowl upon a spindle, the lower end of
which is carried by a support inside the chimney or shaft, or inside a tube
fixed thereon, and upon and round which the cowl is free to turn. A vane on
the cowl causes it to expose that end in which the conical pipe is fixed to the
wind, which rushing through the conical pipe creates a partial vacuum and
causes a draught or suction up the chimney or shaft to which the cowl is
applied.

page_text: Instead of the upper tube being at a right angle to the vertical tube it may
be fixed at a slight angle thereto.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Bohn in the Great Seal Patent Office on the 15th
August 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
Boux, of Victoria Street, in the City of Westminster, Civil Engineer, send
grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of February, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said George Bohn, Her special licence that I, the said George Bohn,
my executors, administrators, and assigns, or such others as I, the said George
Bohn, 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 Channel
Islands, and Isle of Man, an Invention for "AN IMPROVEMENT IN COWLS FOR
CHIMNIES AND SHAFTS," upon the condition (amongst others) that I, the said
George Bohn, 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 immediately after.
the date of the said Letters Patent.
NOW KNOW YE, that I, the said George Bohn, do bereby 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, reference being had to the Drawings hereunto annexed, that is
to say:-
My Invention consists in constructing cowls for creating an upward
draught in chimnies and ventilating shafts in manner hereafter stated.:
Upon a vertical tube a, Figures 1 and 2, open at top and bottom, I fix a
horizontal tube b, open at both ends, and insert, in one end thereof a conical
pipe c extending about midway into the horizontal tube. I fit this cowl

page_text: upon a spindle d, the lower end of which is carried by a support inside the
chimney or shaft, or inside a tube fixed thereon, and upon and round which
the cowl is free to turn. A vane e on the cowl causes it to expose that end
in which the conical pipe is fixed to the wind, which rushing through the
conical pipe creates a partial vacuum and causes a draught or suction up the
chimney or shaft to which the cowl is applied. Instead of the upper tube
being at a right angle to the vertical tube it may be fixed at a slight angle
thereto.
At Figure 3 I have shewn the cowl applied to a ventilating shaft a, fixed
in the roof of a railway carriage. It is not necessary in all cases that the
cowl should be free to rotate, as for instance, for railway carriages it may be
a fixture upon the shaft, and then two ventilators instead of one, facing in
opposite directions may be used. When two fixed cowls are used, I employ
a valve to shut off that ventilator, not required for use according to the direc-
tion in which the carriage is travelling. I do not limit myself to placing my
ventilating cowls in the roof of railway carriages as they may be fitted on
shafts at the sides. Instead of fitting a complete conical pipe inside the
horizontal tube I insert a flap or valve centered in a line with the axis of the
vertical shaft which forms a partially conical surface, and acts in a manner
similar to the complete conical pipe. A ventilator so constructed is double
acting, as in whatever direction the wind or draught the valve would be turned
so as to produce an upward draught in the shaft, chimney, or flue to which
the ventilator is fitted.
Figure 4 is a sectional elevation of the ventilator last described. A is
the shaft or pipe to be fixed on a shaft or compartment to be ventilated; B is
the horizontal tube; and C, a valve centered on an axis D, on which it is free
to play.
And having now described the nature of the said Invention, and in what
manner the same is to be performed I, declare that I claim constructing cowls
for creating an upward draught in chimneys and shafts in manner herein-
before described.
In witness whereof, I, the said George Bohn, have hereunto set my
hand and seal, this Fifteenth day of August, One thousand eight
hundred and sixty-four.
GEORGE BOHN. (L.S.)