Nuisances arising from Smoke and Foul Air.
Year: 1885

page_text: Nuisances arising from Smoke and Foul Air.
We WALTER JAMES GRIFFITHS of 22 Annandale Rd Greenwich in the County of
Kent Engineer, and AARON GIBBS of 433 Rotherhithe New Road Old Kent Road
in the County of Surrey Builder do hereby declare the nature of our invention
for IMPROVEMENTS IN THE CONSTRUCTION OF CHIMNEY COWLS AND VENTILATORS
AND IN APPLIANCES FOR THE PURPOSE OF ABATING NUISANCES ARISING FROM
SMOKE AND FOUL AIR, to be as follows:—
A chimney cowl constructed according to our improvements consists of a
cylindrical tube of about the diameter of an ordinary chimney-pot and around
this cylindrical centre tube and fixed to it two or three or any suitable number of
helical passages, they being arranged over the same part of the cylindrical tube in
the same way as the threads of a two or three thread screw, each helical passage
is preferably a complete turn so that its open ends may point in opposite direc-
tions. The sum of the areas of the cross-sections of these passages is approximately
equal to the area of the cross-section of the cylindrical tube of the cowl.
At about half way along each of the helical passages an opening or openings of
area about equal to the area of the cross-section of the passage is made in the side
of the cylindrical tube so as to allow the smoke to pass out of the centre tube into
the passages. The top of the cylindrical tube is closed a conical top being.
preferably used for the purpose and this top may extend as far out as the outside
of the helical passages so as to prevent snow or other substances lodging in their
entrances. The centre part of this cover, that is the part immediately over the
cylindrical tube may, instead of being rigidly attached to the remainder, be fixed
on a rod passing down the centre of the cowl and through guide holes in bars
fixed across the centre tube so that when the chimney is swept the brush may
push against the end of the rod and raise this part of the cover and so give
satisfactory proof of the brush having gone to the top of the chimney. Or instead
of being attached to a rod the cover may be hinged on one side so as to push up
and enable the brush to pass out at the top.
The effect of the cowl is that if the wind blows in at either end of the helical
passages in passing along the passages it keeps to the outside in consequence of

page_text: centrifugal action, and in whatever direction the wind may blow it cannot be
deflected so as to blow into the holes, which communicate with the inside of the
centre tube, and owing to the wind keeping to the outside of the passages
when passing the holes a suction is caused which draws the smoke out of the
chimney.
'
In accordance with another part of our improvements the helical passages may
be made to decrease in size as they advance from the end to the middle, where the
holes leading from the cylindrical tube are situated, and then increase gradually in
size again. This reduction in the size of the passages would cause the velocity of
the wind to be increased as it passed the holes through which the smoke comes and
in consequence increase the draft in the chimney.
For a ventilator we propose to use the same construction as just described for
chimney cowls. And for use as either a chimney cowl or ventilator they may con-
veniently be constructed in zinc, iron or earthenware or other convenient and
suitable materials.
A convenient way of forming the passages when constructed in sheet metal is to
attach to the outside of the cylindrical tube segments of sheet metal going around
the cylinder in a way similar to screw threads, the passages being completed by
attaching to the outside edges of the screw segments another cylindrical surface.
And when a cowl is to be formed in earthenware cores to form the inside of the
passages can conveniently be used as owing to the screw form of the passages the
cores can afterwards be drawn out.

page_text: Improvements in the Construction of Chimney Cowls and
Ventilators, and in Appliances for the Purpose of Abating
Nuisances arising from Smoke and Foul Air.
We WALTER JAMES GRIFFITHS of 22 Annandale Road Greenwich in the County
of Kent, Engineer, and AARON GIBBS of 433 Rotherhithe New Road, Old Kent Road
in the County of Surrey, Builder do hereby declare the nature of our invention
for IMPROVEMENTS IN THE CONSTRUCTION OF CHIMNEY COWLS AND VENTILATORS
AND IN APPLIANCES FOR THE PURPOSE OF ABATING NUISANCES ARISING FROM
SMOKE AND FOUL AIR, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
.
A chimney cowl constructed according to our improvements consists of a
cylindrical tube of about the diameter of an ordinary chimney pot and around
this cylindrical centre tube and fixed to it two or three or any suitable number of
helical passages, they being arranged over the same part of the cylindrical tube in
the same way as the threads of a two or three thread screw, these helical passages
are open at the ends and the sum of the areas of their cross-sections should not be
less than the area of the cross-section of the cylindrical tube of the cowl.
At about half way along each of the helical passages an opening or openings of
area about equal to the area of the cross-section of the passage is made in the side
of the cylindrical tube so as to allow the smoke to pass out of the centre tube into
the passages.
The top. of the cylindrical tube is closed, a conical top being
preferably used, and to facilitate sweeping this top may be attached to rods
passing through holes in lugs fixed inside the cylindrical tube so that the top may
be raised by the brush when the chimney is swept. Or instead of the rods the
cover may be hinged on one side so as to push up and enable the brush to pass out
at the top.
The effect of the cowl is that if the wind blows in at either end of the helical
passages in passing along the passages it keeps to the outside in consequence of
centrifugal action, and in whatever direction the wind may blow it cannot be
deflected so as to blow into the holes which communicate with the inside of the
centre tube and owing to the wind keeping to the outside of the passages
when passing the holes a suction is caused which draws the smoke out of the
chimney.
For a ventilator we propose to use the same construction as just described for
chimney cowls but as these ventilators will not in themselves cause much draft
they will be best suited to buildings and structures the air in which is usually at
n higher temperature than outside as while allowing the air to pass freely out they
will effectually prevent the wind blowing in or rain or water entering. The
chimney cowls and ventilators may conveniently be constructed in zinc, iron or
earthenware or other convenient and suitable materials, the form being well suited
to construction in earthenware as cores can be used to form the inside of the
helical passages and afterwards twisted out.

page_text: Now in order that our improvements may be clearly understood and readily
carried into practice we will proceed to illustrate the same by and describe the
drawings hereto annexed.
Fig. 1 is a vertical section Fig. 2 an elevation and Fig. 3 a plan with the top
removed of a three passage chimney cowl constructed in accordance with our
improvements. The cylindrical centre tube A has the helical passages B B B fixed
around it, the holes CCC allowing the smoke to pass out of the centre tube into the
passages. The helical passages are each a complete turn so that the two open ends
of each passage point in directly opposite directions and the wind cannot blow in"
at both ends at the same time. The top D of the cylindrical centre tube is
attached to the rods E E which pass through the holes in the lugs K K and allow
the lid to be lifted by the brush when the chimney is swept.
Figures 4, 5 and 6 are similar views of a four passage cowl, but the helical
passages are in this cowl shorter than in the other, each passage being one-third of
a turn in length. The ends of each passage are practically sheltered by the other
passages when the wind is in the direction that would cause it to blow into both ends
of the same passage at the same time, which of course if it could occur would when
the wind met at the middle of the passage opposite the hole leading to the chimney
cause the wind to turn in there. The conical lid D is in these figures shown
hinged at F so that it may lift up but a stop on the hinge prevents it going further
than the dotted position in fig. 4 which prevents the sweep's brush going so far out
that it might jam in returning.
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 construction of chimney cowls and ventilators with helical passages sur-
rounding a central tube closed at the top substantially as and for the purposes
described and illustrated by our drawings.