IMPROVEMENTS IN CHIMNEY OR VENTILATING COWLS
Year: 1885

page_text: We THOMAS SILK WILSON and HENRY THOMAS JOHNSON of Albert Square
Manchester in the County of Lancaster, Sanitary Engineers do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN CHIMNEY OR VENTILATING
COWLS" to be as follows:-
=
Our Invention relates to the cowls which are applied to chimney tops and to the
outlet openings of ventilating pipes or air discharge shafts in order to prevent
down draughts and to promote effluent currents. The upper end of the discharge
pipe or shaft is surrounded by an outer shell which extends upward above the top
of the pipe and downward below the said top. This shell is so much larger in
inside diameter than the outer diameter of the said discharge pipe as that a space
or spaces is or are left for the downward flow of air or gases all around the said
pipe. In some cases we may contract or conc the upper part of this outer shell or
make the walls of the same incline inward. Above this outer shell we mount a
covering shield which is larger in diameter than the upper end of the said outer
shell and extends downward below the said upper end the sides of the shield by
preference inclining inward. The top of the shield is made of a conical form or of
any other suitable shape. Strong winds blowing against this cowl do not under
ordinary circumstances enter the cowl so as to produce down draughts but on the
contrary have an exhaustive action which increases the efficiency of the cowl for
ventilating purposes. A cowl constructed as herein before described does not permit
the entrance of rain or snow to the interior of the ventilating shaft.

page_text: Improvements in Chimney or Ventilating Cowls.
We THOMAS SILK WILSON and HENRY THOMAS JOHNSON of Albert Square,
Manchester in the County of Lancaster Sanitary Engineers do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN CHIMNEY OR VENTILATING
COWLS and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement and accompanying
drawings:-
,,
Our Invention relates to cowls adapted particularly for application to the outlet
openings of ventilating pipes or air discharge shafts in order to prevent down
draughts and to promote effluent currents and suitable also for application to
chimney tops for a like purpose. The upper end of the discharge pipe or shaft is
surrounded by an outer shell which extends upward above the top of the pipe
and downward below the said top. This shell is so much larger in inside diameter
than the outer diameter of the said discharge pipe as that a space or spaces is or
are left for the downward flow of air or gases all around the said pipe. Above this
outer shell we mount a covering shield of a conical form or of any other suitable
shape.
The nature of our Invention will be best understood when the same is described
with reference to the accompanying drawing wherein one of our improved cowls is
represented in vertical section. In the said drawing a represents the upper end of
the upcast shaft or discharge pipe forming the base or support of the cowl. This
part may be made cylindrical, square or rectangular in cross sectional form or be
made of any suitable shape and may form part of the complete apparatus adapted
for application to the upper end of a ventilating or upcast shaft or of a chimney as
the case may be. Upon this part a is secured an outer shell b. which in the cases
wherein the part a. is cylindrical is larger in diameter than the said part a. so that
an annular space c. for the outflow of air, smoke or gases is provided. In the
cases wherein the part a. is rectangular or polygonal the shell b. is made of such
form and proportions as that there shall be a space c. entirely around or on each
side of the part a. or on two or more sides of the same. The lower edge of the
shell b. extends downward below the top edge of the part a. The upper edge of
the shell b. is beveled or inclined inward at b¹ so that the area of the opening at
the top of the said shell is about the same as or a little less than the area of the
passage through the part a. Above the shell b. is secured a covering shield d.
which covers the said opening in the top of the said shell and extends beyond the
edge or edges of the said opening so as to check the entrance thereinto of rain or of
downward currents. Between the lower edge of this shield d. and the inclined
edge b¹ is a second opening e. for the escape of air or of smoke or gases as the case
may be. In the cases wherein the part a is cylindrical the shield d would by
preference be made partly cylindrical and partly conical as shown in the drawing.
In the cases of rectangular shafts the drawing would indicate the cross sectional
form of the shield. Below the mouth c. we prefer to fix a shield f. to check the
inlet of upwardly moving currents of air. The arrows g. and h. indicate the move-
ments of outflowing air, smoke or gases. The arrows and dotted lines i. indicate

page_text: the inductive action of downward blowing air currents in promoting the discharge
from the cowl the arrows and dotted lines k. indicating the corresponding effect of
upwardly moving air currents. In some cases we may apply an internal baffler to
still further check down draughts. Such a baffler is indicated in dotted lines by l.
Strong winds blowing against this cowl do not under ordinary circumstances enter
the cowl so as to produce down draughts but on the contrary have an exhaustive
action which increases the efficiency of the cowl for ventilating purposes. A cowl
constructed as hereinbefore described does not permit the entrance of rain or snow
to the interior of the ventilating shaft.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is
The ventilating or chimney cowl of the formation substantially as set forth and
indicated herein before and by the accompanying drawing.
Dated this 16th day of December 1885.
DUTTON & FULTON,
Agents,
1, St. James' Square, Manchester.